Novel HIV-1 non-nucleoside reverse transcriptase inhibitors: a patent ...

Review

Novel HIV-1 non-nucleoside reverse transcriptase inhibitors: a patent review (2011 -- 2014) 1.

Background

2.

Medicinal chemistry approaches in NNRTI hits discovery

3.

Expert Opin. Ther. Patents Downloaded from informahealthcare.com by 114.176.57.61 on 10/14/14 For personal use only.

of NNRTIs Traditional core-refining and substituents-decorating approach 5.

NNRTIs as HIV microbicides

6.

NNRTIs with novel mechanism of action

7.

†

Shandong University, School of Pharmaceutical Sciences, Department of Medicinal Chemistry, and Department of Pharmacology, Key Laboratory of Chemical Biology (Ministry of Education) Shandong, PR China

New medicinal chemistry insights into the optimization

4.

Xiao Li, Lingzi Zhang, Ye Tian, Yu’ning Song, Peng Zhan†, & Xinyong Liu

Expert opinion

Introduction: There is a continuous need for next-generation non-nucleoside RT inhibitors (NNRTIs) with different resistance profiles, improved safety, excellent tolerability, and favorable physicochemical properties. Areas covered: In this review we intend to narrate a general and cutting-edge overview of current state of NNRTI patents during the 2011 -- 2014 (June) period and future perspectives. Particular focus is placed on the highlighting of some emerging medicinal chemistry principles and insights in the discovery and development of NNRTIs. Expert opinion: The development of effective NNRTIs is moving on from trialand-error approaches to sophisticated subconscious strategies. Several newly emerging structure-based virtual screening methodologies (such as Monte Carlo free energy perturbation calculations) or new drug design insights, such as taking full use of the specific noncovalent reverse transcriptase/NNRTIs interactions, stereochemical diversity-oriented conformational restriction, novel strategies to enhance solubility and early absorption, distribution, metabolism, excretion, and toxicity (ADMET) assessment, will continue to evolve to complement the classical NNRTIs discovery approaches (structurebased core-refining and substituents-decorating). Keywords: AIDS, drug design, HIV-1, inhibitor, medicinal chemistry, non-nucleoside RT inhibitors , patent, reverse transcriptase Expert Opin. Ther. Patents [Early Online]

1.

Background

HIV-1 reverse transcriptase (RT) is a primary target for antiviral chemotherapy. Among RT inhibitors, non-nucleoside RT inhibitors (NNRTIs) are proving to be a standard component of highly active antiretroviral therapy for the treatment of HIV-1 infection. In particular, the usage of NNRTIs in combination with nucleoside RT inhibitors, integrase inhibitors or protease inhibitors, is an extensively employed first-line therapy for HIV/AIDS patients [1-5]. NNRTIs elicit RT inhibition (DNA polymerization) in a noncompetitive manner, by binding with an allosteric and hydrophobic pocket (termed NNRTIs binding pocket, NNIBP), located 10 A˚ away from the DNA polymerase active site. The NNRTIs’ family has very intriguing antiretroviral agents known for their high potency, selectivity, and relatively lower cytotoxicity (in contrast to nucleoside RT inhibitors) [1-5]. Another superiority is that they do not require intracellular metabolism for their potency [6-8]. Up to now, >50 structurally diverse classes of compounds have been reported as NNRTIs [5]. Among them, five NNRTIs were approved by US FDA for HIV-1 treatment, namely, nevirapine (NVP) (1), delavirdine (DLV) (2), efavirenz (EFV) (3), etravirine (ETR, TMC125) (4), and rilpivirine (RPV, TMC278) (5) 10.1517/13543776.2014.964685 © 2014 Informa UK, Ltd. ISSN 1354-3776, e-ISSN 1744-7674 All rights reserved: reproduction in whole or in part not permitted

1

X. Li et al.

of one prior patent review by us [15]. For further information, interested readers can refer to a series of related reviews [12-16].

Article highlights. .

.


.

.

.

.

There is emerging evidence that phenotypic high-throughput screen is experiencing a renaissance in non-nucleoside RT inhibitors (NNRTIs) lead identification. We emphatically analyzed the patent WO2013056003, in which virtual screening based on NNRTIs binding site yielded a weakly potent but tractable chemotype that was rapidly progressed into a series of catechol diethers as highly potent NNRTIs. The strength and benefit of structure-based virtual screening and modifications of NNRTIs have been even more evident recently when this traditional approach is coupled with novel computer-aided technologies such as Monte Carlo free energy perturbation calculations. Particular attention was given to some novel insights, such as the specific noncovalent RT/NNRTIs interactions, stereochemical diversity-oriented conformational restriction, medicinal chemistry strategies to enhance solubility and early ADMET assessment in NNRTIs’ modifications. The crystal packing analysis approach has afforded a strategy and a paradigm for the discovery of novel NNRTI molecules with improved aqueous solubility. The replacement of the central core (Core-refining) in bioactive NNRTI hits or leads combined with optimization of substituted groups (substituents-decorating) is still a common practice in medicinal chemistry to find proprietary and novel NNRTI candidates.

This box summarizes key points contained in the article.

(Figure 1) [5,9,10]. The three first-generation NNRTIs were prone to decreased efficacy with long-term therapy due to the emergence of clinically relevant RT mutations [5]. The second-generation NNRTIs (ETR and RPV) possessed a high genetic barrier to oppose various NNRTI-resistant mutations. Nonetheless, clinical cases with Stevens-Johnson syndrome, hypersensitivity reactions, or other adverse effects were observed [9]. Besides, more drug resistance occurred in patients with failed treatment using RPV as compared to EFV [10]. Therefore, it is imperative to develop novel NNRTIs with potent and broad spectrum anti-mutant activities, and excellent pharmacokinetic profiles [11-16]. As shown in Figure 2, in this review, we will discuss the recent progress in the emerging medicinal chemistry principles and insights in the identification of newly emerging NNRTI scaffolds and further development of existing families from recent prominent advances of NNRTI patents in the period encompassing 2011 and mid-2014 (Table 1) [17-55]. This review is mainly divided into three sections: i) general approaches for NNRTI hits or leads discovery; ii) new medicinal chemistry insights into the optimization strategies from hits or leads to candidates; and iii) traditional core-refining and substituents-decorating approach. Lastly, the NNRTIs with potential as potent candidates for pre-exposure prophylaxis in the prevention of sexual HIV transmission and the newly emerging nucleotide-competing RT inhibitors were also described. This mini-review aims to provide an update 2

Medicinal chemistry approaches in NNRTI hits discovery

2.

Undoubtedly, hit generation is a critical first step in the drug discovery process. Despite the availability of > 100 NNRTIbound RT PDB structures, structure-based de novo design of original scaffolds generally remains challenging due to their broad structural diversity and the fact that the NNRTIs bind to RT via an induced fit mechanism, giving rise to large variations in binding modes. Given this, over the past few years, serendipitous or high-throughput screen (HTS) campaign of compound collections continues to remain a major paradigm for NNRTI hits or leads discovery. On the other hand, the successful cases in virtual screening were still rare, as there are some thorny problems and challenges in current computational chemistry approaches. Serendipitous or high-throughput screen campaign

2.1

In recent years, HTS aimed at finding new anti-HIV agents combined with subsequent medicinal chemistry optimization campaign led to the identification of several novel series of NNRTIs. For example, 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) 6d,e were first identified from an HTS campaign based on in vitro inhibition of HIV-1 replication. Refinement of these two initial hits by synthesizing a focused compound library for structure--activity relationships (SARs) investigation gave compound 6f with improved metabolic stability, which could serve as an attractive lead to further develop novel potent NNRTIs (Figure 3) [17,18,56,57]. In 2012, the aryl-substituted triazine 7a was discovered as an active NNRTI in a cellular assay-based HTS campaign [18]. Further hits to leads chemistry provided pyridine derivative 7b, retaining a marked activity against wild-type (WT) HIV-1 (EC50 = 0.2 nM) and a broad range of HIV-1 strains, including NNRTI-resistant mutants with key mutations, such as Y181C and K103N mutant strains. Introduction of a chlorine atom in the pyrazole heterocycle significantly decreased the inhibition effects for human ether-a-gogo-related gene (officially abbreviated as hERG) and the cytochrome P450 superfamily (CYP), resulting in highly advanced leads for further modifications [58]. Besides, SARs obtained in this study were beneficial for further lead optimization. Besides, diarylpyrazole-[imidazolidinone]-carboxamide AIC292 (8) [19,20,59], sulfonamide IPK1(43) [60], and AH0109 (44) [61] were also identified as additional NNRTIs with robust anti-HIV activities against WT and/or clinically relevant multidrug-resistant HIV strains via the implementation of HTS assay. Especially, AIC292 demonstrated robust antiviral potencies in vitro against WT and NNRTI-resistant HIV-1 isolates (including the most prevalent variants,

Expert Opin. Ther. Patents (2014) 24(11)

Novel HIV-1 non-nucleoside reverse transcriptase inhibitors: a patent review (2011 -- 2014)

CN

CN

CN

O N

N N

HN

O

N

Cl

N NH

NH

N

N H O

O

F3C

N H

CH3SO3H

O

O O

Br

N

NH N

NH2

Nevirapine (1) BI-RG-587 1996

Delavirdine (2) BHAP U-90152 1999

Efavirenz (3) DMP-266(L-743,726) 1998

Etravirine (4) TMC-125 2008

HN

N

NH N

Rilpivirine (5) TMC-278 2011

Figure 1. Chemical structures of the licensed non-nucleoside RT inhibitors by US FDA for clinical use (with nicknames and the years of their approval).

Optimization of NNRTIs

Burgeoning

Classical New insights

Serendipitous

• Specific noncovalent RT/NNRTIs interactions • Monte carlo free-energy perturbation • Stereochemical diversity-oriented conformational restriction • Medicinal chemistry strategies to enhance solubility • Early ADMET assessment

Dockingbased virtual screening

HTS campaign Traditional approach

Drug candidates


CN

S

• Core-refining • Substituents-decorating

NNRTIs hits discovery

Figure 2. Diagram depicting the medicinal chemistry approaches in non-nucleoside RT inhibitor hits discovery and optimization.

K103N, Y181C, and G190A) and in vivo inhibition in an engineered mouse xenograft model when applied once daily [59]. Taken together, these studies demonstrated that diverse compound collections screening could yield original NNRTIs and provided starting points for the development of potent NNRTIs towards drug candidates for the treatment of HIV-1 infection. Docking-based virtual screening and further modifications

2.2

In the last two decades, the virtual screening approach has been used in NNRTI hits discovery. However, no significant breakthroughs in potency or drug resistance profiles have been made. In recent years, the researchers from the Yale University reported several elegant papers, which demonstrated the power of virtual screening and free energy perturbation

(FEP) calculations-guided optimization in the discovery of catechol diethers as potent anti-HIV agents with picomolar inhibition. More specifically, among the mutations involved in resistance, the Y181C mutation is of special interest because it is arising early in patients. Consequently, with aim to seek NNRTIs that are effective against both WT and Y181C-mutant HIV-1, docking-based virtual screening using multiple scoring functions was performed using >2 million commercially available compounds and three RTs (PDB codes: 1RT4, 2BE2, 1JLA. The proteins 1RT4 and 2BE2 are both WT RTs bearing different conformations of Y181, whereas the 1JLA contains the Y181C mutant). Though only nine compounds were purchased, three of them showed 5 -- 12 µM (EC50) inhibition against one or both viral strains in infected T-cell assays. Among them, 46 exhibited moderate inhibition against both the WT and Y181C mutations in the low micromolar range, whereas 47


3

X. Li et al.

Table 1. NNRTIs disclosed in the patent literatures during the 2011 -- 2014 (June) period. NNRTI families

General formula/graphical representation B

Dihydropyrimidone R3

Ref.

NC

[17] Cl

R5

X N

W


R4

Y

Representative compounds

R1 R8

N R2

N

R6 N

R7 S

B = (un)substituted (hetero)aryl; W = O, S and NR; Y = a bond, O, S, NR, C1-8 alkyl, C2-8 alkenyl, C2-8 alkynyl, C1-8 alkoxy, C1-8 thioalkyl and C1-8 alkyl NR; R, R1, R2 and R3 are independently H, C1-8 alkyl, C1-8 haloalkyl, C1-8 alkylaryl, (un)substituted (hetero)aryl, and so on; X is azolyl; R4, R5, R6, R7 and R8 are independently H, OH and derivs., halo, CN, NO2, SH and derivs., SO1-2H and derivs., NH2 and derivs., C1-8 haloalkyl, and so on. Substituted biaryl and arylheteroaryl

NH O

N H

6a EC50: > 1.0 to 5.0 μM, CC50: > or ＝100.0 μM.

OH

m(R2) E

HN X

C

A

B

(X)o

NH

O

Z

N H

(R2)n 1

R1

N H

[18]

O Y

A

*

D

m(R )

O

6b N

N

N

N H

N NH

7a

Pyrazolylcarbonyl imidazolidinone

O

HN

HN

N O

O Cl

O

N N

[19,20]

N N

R2

N

R1

F Cl

R1 = Substituted Phs; R2 = Substituted Ph.

8

R1 = Substituted Phs; R2 = Substituted Ph. R3

Catechol diethers

F

Cl

[21]

W R5 O

R1 A

R2

A

X Y

A A

N O

R6

Cl

R1 is H, OH, halo, (un)substituted C1-6 alkyl, and so on; R2 is H, OH, halo, CN, NO2, (un)substituted C1-6 alkyl, and so on; R3 is H, OH and (un)substituted C1-3 alkyl; R4 and R5 are independently H, OH, halo, CN, NO2, (un)substituted C2-6 alkene, and so on; R6 is (un)substituted C1-6 alkyl and (un)substituted 5to 6-membered heterocycle; W is C and N; W, R4 and R5 taken together can form (un)substituted pyrrole, dihydrofuran and dihydropyrrole ring; each A is independently absent and (CH2)1-3.

N H

O

9b WT EC50 = 55 pM Y181C EC50 = 49 nM K103N/Y181C = 0.22 μM

NNRTIs: Non-nucleoside RT inhibitors.

4

CN O

R4



Table 1. NNRTIs disclosed in the patent literatures during the 2011 -- 2014 (June) period (continued). NNRTI families

General formula/graphical representation


O

2(1H)-pyridinone

O

O R1

HN

[22]

HN

HN

OR2

R3

Ref.

O

O

1

R = CO2Et, i-Pr, CH2OH, H, Br, I, and so on; R2 = cyclopentyl, cycloheptyl, cyclohexylmethyl, cyclohexylethyl, or substituted cyclohexyl; R3 = benzyl, 4-fluorobenzyl, 4-chlorobenzyl, PhCH2CH2, cyclohexyl, cyclohexylmethyl, cyclohexylethyl, thienylmethyl, and so on O


Pyridinone R1

O

R5 N

N

R2

[23]

O O O

R3 1

2

N

N

F

3

R = alkyl, (un)substituted cycloalkyl, aryl; R -R = H, alkyl, haloalkyl, and so on; R4 = H, alkyl, halo, and so on; R5 = H, alkyl. 5-Oxo-4,5-dihydro1H-1,2,4-triazol-3-yl

F

F

MK-1439 (11) F

O

N R5

R2

O

CN

N

Cl H

F

O

12

F

Cl

CN

[25]

O

O N

O

N N N RP

Q

R

N

N N N

F3C

RP = base salt of alkyl phosphate, acid salt of C(O)N (RA)-C1-6-alkylene-N(RA)RB, acid salt of C(O)-C1-6alkylene-N(RA)RB, C(O)ORC; RA, RB = independently, H, C1-4-alkyl; RC = C1-3-alkyl; RQ = CF3, halogen.

O K O P O HO

13a

R

H

3,4-Dihydroquinazolin-2 (1H)-one

N NH

R1 = halogen, C1-6 alkyl or C1-6 alkoxy; R2 = hydrogen, halogen or C1-6 alkyl; R3 = a phenyl substituted with one to three substituents independently selected from the group consisting of C1-6 alkyl, C3-8 cycloalkyl, C1-6 haloalkyl, C1-6 haloalkoxy, halogen, and cyano; R4 = CH2OH, CH2C(=O)(CH2)2C(=O)OH or CH2C (=O)C1-6 alkyl; R5 = hydrogen or C1-6 alkyl;

O

[24]

O

NC

N R4

N

R1

Alkyl phosphate prodrugs Cl of pyridinones

O

N NH

F R3

10b IC50 = 0.1338 μM

N

Cl

N NH

R4

F

10a IC50 = 22.2 nM

[26]

H H F3C

H F3C

NH

Cl

R1 N H

NH

O

R is C1-6 alkyl, cyclopropyl, cyclopentyl, cyclohexyl, Ph, 1-naphthyl, 2-furanyl, 2-pyridinyl; R1 is F, Cl, Br, NO2, amino, C1-3 alkyl, C1-3 alkoxy; and their racemates, (R) or (S)- enantiomers.

N H

O

14 EC50 = 6.48 nM



5

X. Li et al.


General formula/graphical representation O

4,4-Disubstituted-dihydro2(1H)-quinazolinone or thione-like compounds Z1

Representative compounds NO2

R1

2

Z

[27]

CF3 NH

F3C

Cl

N H

NH

X

N H

Z1 and Z2 independently = H, halo, alkoxy, and so on; X = O or S; R1 = alkyl, cycloalkyl, alkenyl, and so on

F

O

F

F3C

O

F

S

15a IC50 = 1.66 nM

F3C OH COOR2

Indoles

Ref.

NH O N H

S

15b IC50 = 3.39 nM

F3C OH COOEt

[28]


O2N R1 N R3

N H

R1 is H, 2-Me, 4-OH, 4-NO2, 4-COOMe, 5-CHO, 5-CN, 5-F, 5-Br, 5-Cl, 5-NO2, 5-COOMe or 6-F; R2 is Me or Et; R3 is H, Boc, Me and so on F3C

Y R3 R2

OH

16 EC50 = 45 nM CC50 = 63.2 μM SI = 1405 F3C

Br

O

O

N H

X R1

NHCO2C2H5 R N H

17 IC50 = 5.8 µM

HO R1 CF3

CF3

R

N H

O

Y = C, O, H, halogen; X = N, O, S; R1, R2 = C1-C10 alkyl, R4 substituted benzyl, phenyl or -(CH2)nZ(CH2)m-, Z is C, O, N, NCH3, n,m are 1, 2, 3, 4, R4 is H, halogen, -NH2, -Me, -Et, -isopropyl and so on; R3 = H, C1-C10 alkyl. O

NHCO2C2H5

[30] HO

N H

[31] I

HN N

O O R3

R3

R1 is Cl, Br, I, NO2, NH2, NHCH3, N(CH3)2, and so on; R2 is CH3, Ph or substituted aryl; R3 is H or F; and R is H or CH2.

19a IC50 = 0.010 μM

R3

O R1

N

O

[32] I

HN

N

O

18b

O

R R2

N H

18a

N

O

N O

R R2

R1 = halo, NHCH3, N(CH3)2, and so on; R2 = H, Me, Ph and substituted arene; R3 = OH, NH2, N(CH3)2, and so on; R is O and CH2.

19b IC50 = 0.0034 μM


6

NHCO2C2H5

NHCO2C2H5 N H

R1

CF3

Br

O HN

HO

CF3

Br

R = H, 5-F, 5-Cl, 5-Br, 5-OMe, 5-OEt, 5-OCH(CH3)2, 6-Cl, 6-F, 7-NO2, 5,7-diCl; R1 = acetonyl, C1-C4 alkyl, C1-C4 unsaturated alkyl. Pyrimiinediones (HEPT)

[29]

OH





Representative compounds O

O

Pyrimidones (DABO)

R1

HN R2

N

N

N

O

R1 = C1-3 alkyl; R2 = H or Me; R3 = benzoyl or 2-furanylcaroxyl.

20 EC50 = 0.0135nM; SI = 8548000 O


O R1

HN

S N

N

O

N

R1 = H, Me or Et; R2 = 2-acetophenone, p-methyl2-oacetophenone, p-chloro-2-acetophenone, pnitro-2-acetophenone, p-cyano-2-acetophenone, pmethoxy-2-acetophenone, p-fluoro2-acetophenone, benzyl, p-methylbenzyl, pchlorobenzyl, p-nitrobenzyl, p-cyanobenzyl, pmethoxybenzyl or p-fluorobenzyl.

21 EC50 = 0.24 μM SI = 1218

O

O R2

HN

22a IC50 = 1.54 μM

O

O S

N

S

N

N

[35] I

HN

R1 = SH, C6H5CH2S, C6H5CH2CH2S, or C6H5CH2CH2CH2S, and so on; R2 = H or I. Thiadiazines

[34]

HN

N

R2

R1

[33]

HN HN

R3

S

Ref.

O N

NH

O S NH

[36]

HN

X R

X = substituted NH, OH, or SH; R = (un)substituted Ph, aryl, or heteroaryl, and so on CN

23 IC50 = 1.54 μM

O

Pyrimidones (R1) 0-5

O R2

N N

Z

O

NC

R3

M = CH2, CH2CH2, CH2CH2CH2, CH(CH3), C(CH3)2 or C(O)N(RA); Z = pyridazine, pyridazinone, pyrimidine, and so on, each optionally substituted; each R1 is independently halogen, CN, NO2, C1-4 alkyl, and so on; R2 = H, C1-6 alkyl, C1-6 haloalkyl, and so on; R3 = H, C1-6 alkyl, halogen, CN, C1-6 fluoroalkyl, and so on

F3C

[37]

N

O M

N N

N

Cl

N H

O

24 IC50 = 191 nM



7

X. Li et al.



2-Pyridinones

N

O

O

HN

Representative compounds O

N

N

O

HN

HN

Ref. [38]

N

HN CN

CN

R

R

O

25a

O

25b

R = aldehyde, ester, cyan group

R = aldehyde, ester, cyan group. N


Diaryl-pyrimidine (DAPY) analogues

N

[39]

R2

R3

R1

N3

N

HN

NH

N

HN

N

NH N

R1, R2, and R3 are independently N3 or lower alkyl, with the proviso that at least one of R1, R2, and R3 is N3. R1 R3

[40]

NC

R2

N

26

N

Ar

Y

N H

N X

N Cl

27a

R1 and R2 are independently H, halo, CN, NO2, and EC = 0.17 μM; CC = 32.9 μM; SI = 193 50 50 so on; R3 is H, halo, C1-6 alkyl, OH, and so on; Ar is (un)substituted aryl; Y is O, S, NH, CO, and so on; X is F, Cl and Br. [41]

Ar2

G

CN

N N Ar1 Y

X Z

M

NH N

HN

W

N

Ar1, Ar2 are substituted aryl or heteroaryl; X is O, NH, S, and so on; G is O or H; Y, Z, M and W are independent N, NH, CH, and so on

NH N

NH

28a EC50 = 7.0 nM

Ar

R1

S O O

N CN N O

NH O

R2 1

R = CN or Me; R = nitro, amino, or acetylamino; Ar = Ph, 4-pyridyl, 4-nitrophenyl, 4-aminosulfonylphenyl, 4-methylsulfonylphenyl, 4-aminocarbonylphenyl, 4-acetylphenyl, 4-hydroxymethylphenyl, 4-carboxyphenyl, or 4-methoxycarbonylphenyl. NNRTIs: Non-nucleoside RT inhibitors.

8

NH

2


NO2

29 EC50 = 22 nM

[42]



General formula/graphical representation A

R6 X

CN

R7

R4

R5 Y

NH

R3


R1

O

NH

F3C

NH2


X = NH or O; Y = CH or N; A = (CH2)n, n is 0 to 4; R1 = NH2, OH, or halo, and so on; R2 = H; R3 = H, OH, halo, or CN, and so on; R4 = CN, NO2, CO2H, or CF3, and so on; R5 and R6 independently = halo, (un)substituted alkyl, or alkoxy, and so on.; R7 = NH2, OH, NO2, or SO3H, and so on R1

R4

X

Z Y

CN

NH

R2 O

R3 NH N

R2 O

N

N

HN

F

6

R -R are independently H, CN, halo, and so on; X and Y are independently N and C; Z is O and NH; and wherein either R1, R5, and R6 are not H, or R2, R3, and R4 are not H.

Cl

[44]

R6

R2

1

CN

R5

[43]

30 EC50 = 1.13 nM; CC50 >7.1 μM.

R2

R3

CN

Ref.

O

R3 N N R1

NH F

31 EC50 = 1.6 nM Cl

[45]

R4

N

Br

Br O

R1 = H, CH3, C2H5; R2 = subtituted aryl; R3 = subtituted aryl; R4 = H, CH3, C2H5

NH

Cl

N

N

32 EC50 = 34 nM R5

R3

R6

CN

NH

O

CN

[46]

R4 N

X N

N N

R1 R2

NH NH2

33a

R1 and R2 are independently H halo, NO2, NH2 and EC50IIIB = 2.5 nM, SI = 13740; derivs., CN, OH, C1-6 alkyl, C1-6 alkoxy, CF3, COOH, EC50RES056 = 0.33 μM, SI =107 SO3H, and so on; R1R2 may be taken together to form -O-CH2-O-; R3 and R4 are independently halo, Cl CN C1-6 alkyl, C1-6 alkoxy, CF3, NH2, OH, COOH, SO3H, 5 and so on; R is CN, -CH=CH-CN, halo, C1-6 alkyl, C1-6 alkoxy, NH2, OH, NO2, CF3, -CH=CH-, -CC-, Cl Cl and so on; R6 is CN, -CH=CH2, -CCH, C1-6 alkyl, N O NH Ο C1-6 alkoxy, CF3, halo, NH2, and so on; X is NH, O, S, CH2, -CH(OH)-, -CH(OR)-, -NR-, -NCO-R-; N N CF3 R is C1-4 alkyl. H 33b EC50ROD = 5.57 μM, SI > 11 NNRTIs: Non-nucleoside RT inhibitors.


9

X. Li et al.


General formula/graphical representation R1

Triazolopyrimidines

Ar X

NH N

N

NH N

N

HN

Ref. [47]

NH

N

N

N

N

N

N

N


CN

R1

Ar X


N

X is NH or O; Ar is (un)substituted Ph, which is 34 selected from 2,4,6-tri-Me-Ph, 2,4,6-trichlorophenyl, 2,4,6-tribromophenyl, 2,4,6-trifluorophenyl, EC50 (IIIB) = 0.02 μM, SI = 8986; 2,6-dibromo-4-methylphenyl, 2,6-dimethylEC50 (RES056) = 7.6 μM, SI = 25 4-bromophenyl, 2,6-dimethyl-4-cyanophenyl, 2,6-dimethyl-4-chlorophenyl, 2,6-dimethylphenyl, 2,6-dichlorophenyl or 2,6-dimethoxy-Ph. Pyrazolo[1,5-a]pyrimidine

[48]

Y

X N

CN

R2

R1

N

HN

N

NH N

N

N X and Y are independently NH, O or S, and R1 and R2 are one to three substitute groups independently 35 selected from alkyl, alkenyl, and so on on benzene EC50 (IIIB) = 0.07 μM, ring.

SI = 3999 H N

N

S

N S

N S

H N

S

Ar2

O

[49]

N Br

O

Ar1

36a

Ar1 = (un)substituted aryl; Ar2 = 2-fluorophenyl, 2-chlorophenyl, 2-chloro-3-pyridyl, 2-bromophenyl, 2-bromo-4-methylphenyl, 2-nitro-Ph, 2-nitro4-methylphenyl, 2-methylphenyl, Ph, 4-methylphenyl, 4-chlorophenyl, 2,3-dimethylphenyl, 2,6-dimethylphenyl, 2-pyridyl, 2-thiazolyl, 5-methyl-2-benzo[d]thiazolyl, or 3-methoxy carbonyl-2-thienyl]

EC50 (IIIB) = 0.044 μM, SI = 3917 N S

N H N

S O Cl

36b

N

EC50 (IIIB) = 0.019 μM, SI = 6436 X3 X2

X4 Ar X1

N

X5

H N

S O

N Ar2

N

H N

S O

1

Ar

X1-X5 = (un)substituted N or CH; Ar1= (un) substituted Ph, Bn, 5- or 6-membered heteroaryl, and so on; Ar2 = (un)substituted Ph or pyridinyl. NNRTIs: Non-nucleoside RT inhibitors.

10


[50]

Br

37a EC50 = 18 nM

SO2NH2



General formula/graphical representation X1

X2


Ref.

N

[51]

H N

N

N

X3

H N

X4 N

S

N

SO2NH2

O Br

S O

Ar2

38 EC50 =210 nM, SI = 46 (WT)

Ar1

X1-X4 = (un)substituted N or CH; Ar1= (un) substituted Ph, Bn, 5- or 6-membered heteroaryl, and so on; Ar2 = (un)substituted Ph or pyridinyl. O O S N


O O S

N

N

R

N

O

N

[52]

N

O F

R′

R is benzyl, m-fluoro benzyl, m-chloro benzyl, or mbromo benzyl; R’ is cyanomethyl, (un)substituted benzyl. Thiazole derivatives

R1

NC

39 EC50 = 5.1 μM SI > 63 [53]

S R3 N

R2 1

O

S

R = (un)substituted CH3, OH, SH, NH2, or C(O)H; R2 = (un)substituted alkyl, cycloalkyl, or aryl, and so on; R3 = (un)substituted NH2.

NH N Cl

40

WT IC50 = 0.046 μM; Six HIV-1 mutants RT: IC50: 0.24-5.11 μM

O S

O NH

N F

Daiayltriazines (DATAs) as R1 HIV microbicides

N R2 R3 1

R4

N R6

2

H N

N

X

R5

NC

F

40 WT IC50 = 0.447 μM K103N IC50 = 0.29 μM Y181C IC50 = 0.13 μM H2N N NH N N NH

[54]

3

R , R and R are independently C1-6 alkyl, halo and 41 CH=CHCN; R4 and R5 are independently H, CN and CN 6 CH=CHCN; R is H and NH2. WT EC50 = 1.3nM; Y181C EC50 = 2.6nM; V106A EC50 = 1.9nM; L100I+K103N EC50 = 6.8nM; K101E+K103N+V108VI +V179M+Y181C+E138Q EC50 = 23nM; L100I+E138K+T369I EC50 = 89nM; NcRTIs

[55]

N N O O S

N

42 NNRTIs: Non-nucleoside RT inhibitors. Expert Opin. Ther. Patents (2014) 24(11)

11

X. Li et al.

OH

OH HO

Cl

Cl O

HN

O

HN

N H

O

Hit to lead chemistry

O

O

S

HN

O

O

N H

(S)-6d EC50 = 38 nM

N

6e EC5019 nM HLM t1/2 36 min RLM t1/2 7 min

N H

6f EC50 78 nM HLM t1/2 682 min RLM t1/2 30 min


Human (HLM) and rat (RLM) liver microsomes

N

N

N Hit to lead chemistry

N H

N

N NH

Cl N H

N NH

NC

7a Hit from HIV-1 cell-based assay

N

7b

O HN N O Cl

N

Cl O

N

S

O

O NH

O

S

O F

O

Cl Cl

Cl

NH

O N

NH

F

AIC292 (8)

IPK1 (43)

AH0109 (44)

Figure 3. Discovery of novel non-nucleoside RT inhibitor hits via high-throughput screen (or combined with subsequent medicinal chemistry optimization campaign).

had 7.5 mM potency against the Y181C mutant, and 9a was a 4.8 mM NNRTI toward the WT strain. This research illustrated a viable protocol to disclose HIV inhibitors with improved resistance profiles [21,62]. Then, refinement of this initial 4.8-µM docking hit 9a by synthesizing a focused library for SAR studies guided by FEP calculations provided an extraordinarily potent NNRTI 9b (EC50 = 55 pM) [63]. The crystallographic study of 9b complexed with RT (PDB code: 4H4M) has been determined and provided insights on the crucial binding interactions with HIV-1 RT. For instance, the essential interactions with conserved residues Pro95 and Trp229, multiple hydrogen bonds between pyrimidinone moiety and Lys103 were observed, which likely help elucidate the structural origins of the extreme antiviral activityof 9b (Figure 4) [64]. 9b was regarded as a suitable lead compound to develop novel NNRTIs endowed with promising anti-HIV potential. 12

Besides, through an ensemble-based virtual screening strategy and hierarchical assay (luciferase-based reporter assay and RT-based polymerase assay), two compounds (48, 49) were recently discovered as potent NNRTIs from 2864 National Cancer Institute compounds (with potency similar to the positive control, the FDA-approved drug nevirapine), thus offering an excellent starting point for optimization into advanced inhibitors (Figure 5) [65]. Though structure-based de novo NNRTI design was generally considered to be a tough challenge owing to several difficulties, in silico screening of chemical libraries, which dramatically saved the load of organic synthesis, provided an alternative to experimental HTS for the discovery of newer NNRTIs retain marked activities [66]. In reality, HTS and virtual screening approaches are allies that could greatly complement each other, and further efforts should be made to better align both approaches.



O N O

CN

H N 4

NH

O

N

N

N

N O

N HO

45, NIC 14129 IC50 = 18.9 μM Note: Nevirapine IC50 = 4.20 μM

S

NH

46

47 HN O

Cl

Cl S

N

Cl

48 O


O

N O

9a

CN O

N H

N O

O Cl

9b

N H

O

Cl

O HO

EC50 = 55 pM, IC50 = 3 nM

N H

O O

49

Figure 4. Discovery of novel non-nucleoside RT inhibitor hits through virtual screening and further hit-to-lead optimization.

TRP-229

LEU-234 PHE-227

TYR-318 PRO-236

PRO-95

TYR-188

TYR-181 GLY-190

LYS-103

VAL-179

Figure 5. Cocrystal structure of HIV-1 RT with compound 9b (orange colored). [This image was prepared from PDB entry: 4H4M, using PyMol (www.pymol.org)]. Key H-bond interactions were shown as yellow dashed lines

New medicinal chemistry insights into the optimization of NNRTIs

3.

A perusal of the literature revealed that several novel and creative strategies or concepts offered powerful means to optimize potent NNRTIs in the past few years, which will be described in the following sections. Specific noncovalent RT/NNRTIs interactions: implications for rational drug design

3.1

It is well known that NNRTIs as reversible inhibitors bind to RT through noncovalent interactions including hydrogen

bonds, halogen bonds, and hydrophobic interactions. In fact, within a determined type of NNRTIs, tiny modifications in their structures can improve and even restore the potency of the new resulting derivatives against the WT or resistant strains. For instance, as disclosed in WO2012143415, using a computation-guided approach, a class of catechol diethers (exemplified by 9b) were identified as potent NNRTIs with picomolar inhibition (Figure 6). It was demonstrated by comparative structural analysis that the conformations of the ethoxy uracil motif dependent on the strength of a van der Waals interaction with the C5 substitution and the Cg of Pro95. The 5-F and 5-Cl analogues position the ethoxy uracil to gain more hydrogen bonding interactions, whereas the smaller 5-H and larger 5-Br position the ethoxy uracil to form fewer hydrogen bonding interactions. As illustrated in Figure 7, compound 9e (5-Br) and 9f (5-H) exhibited greatly different binding orientations of the ethoxy uracil. Antiviral activities (EC50 values) correlated with the trends observed in the binding modes. The effects of C5 substitutions on the ethoxy uracil conformation were prominent, and back-up analogues to investigate the SAR at C5 substitutions can possibly be modulated to make additional hydrogen bonds with resistant variants of RT, allowing significant improvements in potency [21,67]. X-ray crystal structures were disclosed for HIV-1 RT with two complexes of catechol diethers (PDB ID: 4LSN, 4LSL). The possibility of halogen bond interactions between the Pro95 and inhibitors was addressed. The current complexes provide a structural basis for the rational design of NNRTIs with high activities and favorable resistance profiles, by taking advantage of the key interactions with conserved residues Trp229 and Pro95 [21,67]. Herein, what needs to be stressed is that halogen bonding has emerged as a crucial element in molecular recognition.


13

X. Li et al.

Cl

F

CN

O O

O

N H

9b

F

EC50 = 55 pM, IC50 = 3 nM

9c

CN O

N O

O

Br

O

CN O

N O

Cl

F

N H

O

EC50 = 0.32 nM

9d

O

N O

Cl

O Cl

EC50 = 3.2 nM, IC50 = 10 nM

9e

CN O

N

O

N H

O

CN

O

N H

N O

O Cl

9f

N H

O

EC50 = 5.2 nM, IC50 = 30 nM


Figure 6. Structures of novel catechol diethers via halogen bonding-based scaffold decoration.

TRP-229 PRO-95

TRP-229 PHE-227

PHE-227 TYR-318

PRO-236

PRO-236

PRO-95

TYR-188 TYR-188

TYR-181 GLY-190

LYS-103

TYR181

LYS-103 LYS-101

Figure 7. Cocrystal structures of HIV-1 RT with compounds 9e (pink colored) and 9f (yellow colored), and superimposed ligands. [These images were prepared from PDB entry: 4LSN and 4LSL, respectively, using PyMol (www.pymol.org)]. Key Hbond interactions were shown as yellow dashed lines.

14



O

O HN

I

O

HN

O

HN

HN

O

O

O H

10c

10a

10a-trans

O CH3 H

H

H CH3

10a-cis


Figure 8. Novel pyridinone derivatives bearing chiral cycloalkyloxy unit as potent non-nucleoside RT inhibitors.

The effect of the addition of halogen bonding to medicinal compounds was striking, resulting in binding enhancements in the 1 -- 2 kcal/mol range [68]. Thus, halogen bonding-based scaffold decoration has recently experienced a renaissance, gaining increased recognition as a useful tool in the NNRTIs discovery [69-71]. Moreover, the methyl and nitrile groups also play important roles in the NNRTIs’ drug design [72-75]. For example, methyl substitutions ortho to an aryl ring could be particularly effective at improving potency by inducing a propitious conformational change [72,73]. The introduction of nitrile group to bioactive molecules can also have significant effects on pharmaceutical profiles such as activity, selectivity, and metabolism as well as physicochemical properties including lipophilicity and solubility [74,75]. Therefore, the medicinal chemists have become more and more conscious that incorporation of halogen atom(s), methyl, and nitrile groups to optimize the noncovalent interactions between the RT and NNRTI, such as hydrogen bonds, halogen bonds, dipole--dipole interaction, and p-p stacking interaction, is a common tactic in medicinal chemistry to improve potency of NNRTIs and to address ADME issues. We envisioned that additional manners of noncovalent interactions will be investigated to address the drug resistance issue. Monte Carlo free-energy perturbation In patent WO2013056003, the Jorgensen group published the inspiring studies involving the optimization of a micromolar docking hit (4.8-µM) into extremely potent WT or mutant HIV RT inhibitors (55 pM) by medicinal chemistry and FEP [21]. This example highlighted the feasibility and importance of the FEP calculations to predict relative free energies of binding and to identify optimal substitution patterns in NNRTIs’ optimization. This approach has been optimized and continuously employed to further identify pyrimidinylphenylamines and benzyloxazoles NNRTIs with improved efficacy [76-78]. 3.2

Stereochemical diversity-oriented conformational restriction

3.3

Stereochemical diversity-oriented conformational restriction, namely, introducing of suitable stereocenters into vital pharmacophoric sites of promising drug scaffold, could allow the emergence of a set of enantiopure molecules with improved efficacy and potential applications in managing drug-induced mutations [79,80]. Owing to its inherent conformational

diversity and structural novelty, chiral cyclopropyl unit has been widely utilized in NNRTIs discovery. Recently, based on the diversity-oriented conformational restriction strategy using key chiral cycloalkyloxy group, two 6-substituted-4-cycloalkyloxy-pyridin-2(1H)-ones, 10c (3-iodine) and 10a (3-isopropyl), were identified as highly active NNRTIs against WT and mutated HIV-1 strains (Figure 8). In theory, the stereocenters provided the opportunity to provide structures with stereochemical complexity and bioactive conformation in a straightforward manner. The 10a-trans isomer possessed an inhibition about 400-fold more effective than that of 10a-cis. The pair of 10a-trans enantiomer (WT: EC50 = 4 nM, SI = 75,000) also displayed high potency against a wide variety of variants including K103N and/or Y181C, the two most prevalent NNRTI-resistant RT mutants [22,81]. Medicinal chemistry strategies to enhance aqueous solubility

3.4

The intrinsic solubility is an essential physicochemical property of an organic small molecule drug and an important factor in determining its bioavailability. It was collectively realized that the initial solubility could increase drug exposure and improve bioavailability. Because of hydrophobic nature of the NNRTIs’ binding site, poor aqueous solubility, which has been a common challenge for many NNRTIs, often leads to inconclusive biological assay results, low bioavailability, high dosages, and difficulties in formulation. Currently, the clinical advancement of many promising NNRTIs was hindered initially by poor aqueous solubility and bioavailability. For instance, despite the achieved potency and drug resistance profiles, the approved NNRTIs TMC125 and TMC278 suffered from poor aqueous solubility. Taking into account these shortcomings, in the last few years, increased attention was focused on the modifications to enhance solubility and mitigate solubility-limited bioavailability. This section summarized valid structure optimization strategies for improving aqueous solubility including solubilizing group introduction, crystal packing analysis, and prodrug approach. Introducing solubilizing groups into solvent exposed areas

3.4.1

In general, the knowledge of X-ray crystallography complex could be rationally employed to guide the improvement of the physicochemical properties and solubility of drug


15

X. Li et al.

O N

O N O

O CN

N N

O N

N H

O

N

51b

CN O

O

N

51a N

O

CN

N N H

N

O


N H

N

N H

50

CN

N

O N

O

51c

CN HN N

HN CN

N N

N H

52a

N N

O

HN CN

N N

O

N

N H

N

O

CN

N

N

O

52b

N H

52c

Figure 9. Disovery of novel non-nucleoside RT inhibitors by introducing solubilizing substituents.

candidates by allowing placement of solubilizing moieties into solvent exposed areas. Consequently, the drawbacks of NNRTIs can be addressed through the application of computer-aided and structure-based drug design to increase aqueous solubility. Recently, structure-based rational designs have guided the introduction of solubilizing substituents to the ‘Het-NH-Ph’ and diaryltriazine (DATA) scaffold (Figure 9). ‘Het-NH-Ph’ NNRTIs 51b, 51c were reported that have markedly improved solubility compared with lead compound 51a and the structurally related drugs ETR and RPV, while retaining low nanomolar anti-HIV potency [82]. DATA derivatives 52a and 52b also demonstrated low-nanomolar potency similar to ETR toward WT HIV-1 and key resistant strains (Table 2) [83,84]. The co-crystal structures of inhibitors 51b and 52c bound to RT were subsequently determined (Figure 10), revealing several salient features informing the remarkable improvement of solubility [82,84]. Concretely, the solubility enhancements resulted from strategic placement of the novel morpholinylalkoxy substituent in the RT/solvent interface (the entrance channel near Glu138) of the NNRTIs’ binding site [82,84]. Moreover, other investigations have demonstrated the utility of this approach and could be used to other agents in general [85]. For instance, because of the low solubility of bromodomain inhibitor 53a, the polar groups including morpholine side chain were incorporated to improve the charge and polarity of lead compounds. Especially, 53b and 53c, which reduced the inhibition about 3 -- 5 fold, had 200 -- 500 fold improvement of solubility (Figure 11) [85]. 16

To sum up, we envisioned that further modifications of NNRTI scaffolds with additional solubilizing substituents (such as oxetanyl sulfoxide [86]), which extend into the RT/ solvent interface, will generate more potent compounds and may well be an effective approach for developing novel derivatives with improved pharmacological profiles. Crystal packing analysis for improved aqueous solubility

3.4.2

The patent WO2011120133 disclosed the identification of a highly potent pyridone NNRTI candidate MK-1439 (11) with IC50 of 12, 9.7, and 9.7 nM against WT, K103N, and Y181C RT, respectively. In cell cultures, MK-1439 displayed excellent potency in suppressing the replication of a range of WT and clinically relevant, resistant HIV mutants, which was superior overall to that of EFV and comparable to that of ETR and RPV [23,87,88]. Overall, the favorable preclinical pharmacokinetic profiles of MK-1439 were conducive to a once daily low dose regimen in clinical usage. MK-1439 fulfills all expectations for an effective drug candidate, which has progressed to clinical trial for the treatment of HIV infection. N

Cl O O F F

N

N

O

N NH F

MK-1439 (11)

The structural investigations in the crystal packing revealed that the higher solubility of MK-1439 was attributed to the



Table 2. Anti-HIV-1 activity, cytotoxicity (human MT-2 cells) and aqueous solubility (pH 6.5). Compounds

EC50(mM)


51a 51b 51c 52b NVP EFV dapivirine (TMC120) ETR RPV

WT

Y181C

0.011 0.092 0.095 0.0012 0.11 0.002 0.0007 0.001 0.00067

0.012 NA 0.010 0.039 0.008 0.00065

S, mg/ml

CC50(mM) K103N/Y181C 0.0013 NA 0.030 0.039 0.005 0.002

42 2.5 3.6 4.5 > 100 15 2.0 11 8

0.1 42.2 52.3 68.1 0.15 0.24 (pH 7.4); 0.02 (pH 7.0)

ETR: Etravirine; EVP: Efavirenz; NVP: Nevirapine;

PHE-227

TRP-229 TYR-188

PRO-236

TRP-229

PHE-227 PRO-236

TYR-318 TYR-181

TYR-188

TYR-318

GLU-138 LYS-101

TYR-181

LYS-103

ILE-135 GLU-138

LYS-101

GLU-28

Figure 10. Illustration of the crystal structures of 51b (gray) and 52c (pink) with HIV-1 RT; the morpholinoethoxy side chain in 51b projects towards Glu28B. Coordinates have been deposited in the PDB as structures 4KKO and 4O44, respectively [82,84].

presence of 4-methyl-5-oxo-1,2,4-triazole motif with reduced van der Waals interactions of CH/p and p-p and weaker intermolecular hydrogen bonding interactions [87]. By coincidence, the 4-methyl-5-oxo-1,2,4-triazol-3-yl motif was also observed in other potent NNRTIs (compound 12) [24]. Also coincidentally and more recently, the successful application of this strategy resulted in the discovery of diaryl amine-based kinesin spindle protein inhibitors with improved aqueous solubility [89]. Besides, the relationship of the physicochemical properties and packing energy calculations of the crystals was investigated, providing the rationale behind this concept.

Taken together, we anticipate that the crystal packing analysis approach will provide a unique tool for developing potent agents with improved solubility. Phosphate ester-base prodrug approach In further improving drug efficacy and mitigating solubilitylimited bioavailability (dissolution-rate limited absorption) of NNRTIs, a newer prodrug approach based on a phosphate ester was reported [25]. The patent WO 2011126969 described the synthesis of phosphate ester prodrugs of 13c with improved aqueous solubility profiles [25]. As shown in Figure 12, prodrug 13a displayed better water 3.4.3


17

X. Li et al.

O HN

N N O O O S N H

O O S N H

N O

N O

53a

N O

53b

BRD4: 1.0 μM; Solubility: < 1 μg/mL at pH 7 Expert Opin. Ther. Patents Downloaded from informahealthcare.com by 114.176.57.61 on 10/14/14 For personal use only.

O O O S N H

53c

BRD4: 5.2 μM; Solubility: 540 μg/mL at pH 7

BRD4: 2.6 μM; Solubility: 210 μg/mL at pH 7

Figure 11. Discovery of bromodomain inhibitors with improved aqueous solubility. O

O O

NC

O

NC

N

N N N

F3C

N

Alkaline phosphatase F3C Cl

Cl

13a K

O O P O OH K

HO O P O OH

N N N

13b

Spontaneous

HO

HCHO (Formaldehyde)

12 mg/mL O NC

O F3C Cl

N

N N NH

13c 0.0002 mg/mL

Figure 12. Hydrolysis of 13a via an unstable intermediate 13b to liberate 13c.

solubility (12 mg/ml) than the parent molecule 13c (0.0002 mg/ml). As listed in Figure 13, this approach has also been further validated by the successful applications in the phosphonooxymethyl prodrug-based HIV-1 attachment inhibitors BMS-663749 and BMS-663068 [90-92], Aurora kinase inhibitor SNS-314 [93], and antifungal ravuconazole [94]. In particular, their phosphonooxymethyl-derived prodrugs (BMS-663749, BMS-663068, 56b, BMS-379224, and BMS-315801) had significantly enhanced solubility and were converted to the biologically active parents in vivo [90-92]. As illustrated in Figure 12, it was believed that these prodrugs can be cleaved by alkaline phosphatase, primarily located in the brush border membranes of the small intestinal epithelium, which removes the phosphate moiety to afford the hydroxymethyl compounds. These intermediates were inherently unstable and readily eliminates formaldehyde to give the extremely permeable parent compounds proximal to the absorbing membrane thus enabling favorable absorption [25,90]. The present findings provided an important new direction for further efforts to obtain effective NNRTIs with high solubility. 18

The concept of early ‘ADMET’ considerations (beyond solubility)

3.5

In new drug design, development and clinical usage, drug disposition (absorption, distribution, metabolism, excretion, ADME) and toxicity (T) properties are vital criteria for assessing drug-likeness of candidates. absorption, distribution, metabolism, excretion, and toxicity (ADMET) evaluation of new chemical entities (NCEs) plays a significant role in the translation research throughout innovative drug discovery and development process. Thus, ADMET evaluation at the early stage of drug research will be beneficial for improving the success rate and reducing costs, and further access to safe, promising drugs [95]. As described above, several members of the catechol diether class were highly active NNRTIs. The most potent compounds gave EC50 values of < 0.5 nM in HIV-1 infected human T-cells assay. However, the cyanovinylphenyl (CVP) moiety that has been featured in prior NNRTIs including RPV was considered to be an uncommon substructure (toxophore) in drugs that gave reactivity concerns and



O

O

O

O

O

O N

N H

O

N

O

N

N N

N

N

O O O P HO OH

O

BMS-448043 (54a) Aq. sol.: 0.04 mg/mL (pH 4-8)

N

N

N H

N

O


N

N

N

N S

HN

NH O

S

N

NH

N

O

F

Cl

N

N

CH OH 3

N

56b Aqueous solubility: 4.70 mg/mL

N

CN

CN

S

F

Cl

SNS-314 (56a)

CH3 S

F

BMS-379224 (57b)

N

Aqueous solubility: 0.014 mg/mL

O

N

N

N

S

HN

O O O P OH

HO O P HO O

P ONa O ONa

S

HO

BMS-663068 (55b) Aq. sol.: >250 mg/mL (pH 5.7) (as trimethamine salt)

O

NH

N

N

BMS-626529 (55a) Aq. sol.: 0.022 mg/mL (pH 4-8)

N

N N

N

N

BMS-663749 (54b) Aq. sol.: >12 mg/mL (pH 5.4) (as lysine salt)

N

O

O

O

N

N N

O

O

O

F N

Ravuconazole (57a) N O O P O HO

N

CH OH 3

N

CN

S

F

F

BMS-315801 (57c)

Figure 13. Other applications of phosphonooxymethyl prodrug approach.

NC

NC Cl

N

N O

O N H

O

O

9b EC50 = 55 pM, IC50 = 3 nM

9f

O

N

N O

Cl

F

O

O

CN O

N H

O

O

EC50 = 0.38 nM (WT); EC50 = 11 nM (K103N/Y181C); CC50 > 100 mM

N

F

9g

N H

O

EC50 = 0.4 nM (WT); EC50 = 10 nM (K103N/Y181C); CC50 = 50 mM

Figure 14. Scaffold-switching to remove CVP toxophore.

unexpected toxicity, ultimately, precluding from further investigation [96]. To counteract these problems, further strategy focused on the structure-based and computer simulations-guided (MC/ FEP calculations) replacements of the CVP moiety to avoid the reactivity concerns. Then, subsequent multidisciplinary medicinal chemistry research led to the discovery of a series of 5,6-fused bicyclic derivatives, which is akin to CVP in structure, avoiding metabolically labile functional groups (Figure 14) [21,96]. It should be noted that 5,6-fused bicyclic derivatives were frequently occurring motifs in drug-like compounds, and were frequently adopted with the intention of being bioisosteric replacements for p-system functionalities.

Among the 5,6-fused bicyclic derivatives, the most potent compounds were the indolizines 9f and 9g, which were strikingly active with EC50 values of 0.4 nM toward the WT virus and 10 nM toward the double mutant strain K103N/Y181C. In comparison to EFV, 9f and 9g displayed improved potency toward the WT and K103N/Y181C mutant strain, diminished potency toward the Y181C mutant, reduced cytotoxicity, and solubility at the same level. Excitedly, in comparison to ETR and RPV, these novel NNRTIs displayed similar efficacy toward the WT virus and the K103N/Y181C mutant, poorer inhibition toward the Y181C mutant, reduced cytotoxicity, and greatly improved solubility (at least 100-fold). Collectively, these results strongly encouraged further medicinal chemistry-


19

X. Li et al.

TRP-229 PHE-227 PRO-236 TYR-318


TYR-188

TYR-181 LYS-103

Figure 15. (A) X-ray crystal structure for 9f (gray) in complex with HIV-RT at 2.88 e´ resolution (PDB: 4MFB). (B) Overlay of the RT co-crystal structure of 9a (orange) (PDB code: 4H4M) and 9f (gray) (PDB code: 4MFB). Key H-bond interactions were shown as yellow dashed lines.

oriented optimization of indolizines as novel lead compounds for development of more potent NNRTIs. Furthermore, the structural characterization and binding modes were investigated by X-ray crystallography of 9f in complex with HIV RT (Figure 15). An overlay of the X-ray structures of the indolizine scaffold and the lead compound 9a within their complexes with RT displayed a high degree of overlap. To sum up, there is no doubt that this is an intriguing and smart practice for optimizing druglike properties of NNRTIs in early stage. Coincidentally, the inhibition effects for human ether-ago-go-related gene (officially abbreviated as hERG) and the cytochrome P450 superfamily (CYP) of phenylaminopyridine-based NNRTIs were investigated [58]. Besides, drug-like physicochemical properties assessments and ligand efficiency-guided optimization were taken into account in current endeavors towards the discovery and development of NNRTIs, such as DAPYs and S-1153 analogues [74,97-100]. These newly established approaches efficiently incorporated the concept of early ‘ADMET’ considerations and provided the basic platform for medicinal chemistry-driven efforts.

Traditional core-refining and substituentsdecorating approach 4.

Scaffold refining via the replacement of the central core in the existing bioactive lead compounds combined with introducing privileged substituents, namely ‘follow-on’-based drug discovery, was considered to be a common practice in contemporary medicinal chemistry to obtain intellectual property (IP) and novel hits, as well as to improve drug-like properties and synthetic accessibility. For many years our group has 20

always been involved in the discovery of novel NNRTIs based on the ‘follow-on’-based approach. In recent years, based on the existing NNRTIs lead compounds, novel back-up derivatives were synthesized by us and counterparts to obtain additional SAR information and to further explore the salient features controlling the activity. Their structure types included EFV analogues [26,27], indoles [28-30,101], 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) derivatives [31,32,102], 3,4-dihydro-2-alkoxy-6-benzyl4-oxopyrimidines (DABOs) [33-36,103-106], pyrimidinone and pyridone [37,38], diarylpyrimidines (DAPYs) [39-42,107-116], arylazolyl(azinyl)thioacetanilides [80-82,117-123], pyrrolo[1,2-b] [1,2,4,6]thiatriazines [52,124-126], capravirine analogues [53,127], and so on. Figure 16 and part of Table 1 summarized recent progress in ‘follow-on’-based NNRTIs discovery, especially, recent significant contributions from our group [26-53]. In 2014, a novel series of trifluoromethyl indole derivatives were identified as anti-HIV-1 agents in MT-2 cells. Compounds 18a and 18b displayed highly potent activities against WT HIV-1 with IC50 values in the low nanomolar range, similar to EFV, better than NVP, and also had higher activity towards the NNRTI-resistant mutant strain Y181C than NVP [30,101]. Several 1-[(2-benzyloxyl/alkoxyl)methyl]-5-halo-6-aryluracils, the HEPT analogues, were reported to exhibit high anti-HIV-1 potency against both WT and drug-resistant HIV-1 mutants. Notably, compound 19b, which possessed the highest selectivity index (SI = 38,215), was more active than NVP and TNK-651 [31,32,102]. DB-02 (20), a C-6-cyclohexylmethyl substituted pyrimidinone NNRTI with nanomolar activity, displayed great sensitivity against K103N or Y181C mutants [33,103]. Novel S-



O I

HN F3C

F3C

OH

H N

NH

Br

OH

O O

H N

HN O

O

O

S

N

O

NH

Br

O N

O

19b 18a

18b

O


S

I

HN N

S

O

O

O

O

HN

DB-02 (20)

IC50 = 0.003 μM; EC50 = 0.002 μM; SI = 38215

I

HN S

N

N

O S

NH

HN

N

N

21 EC50 = 0.24 μM SI = 1218

Br

O

22a IC50 = 0.35 μM

22b

23

IC50 = 0.41 μM

EC50 = 22.7 μM; SI = 6

CONH2 CN

CN

Cl

CN

CN

R

N N

NH N

Cl

N

N

HN

NH

N

N

N

27c: R = Br EC50 = 9.0 nM (WT);

27d

N

NH

N O

NH

N

N

NO2

HN

28a

EC50 = 67 nM (WT);

N

O

NH

HN 27b: R = Cl EC50 = 5.0 nM (WT);

SO2CH3

28b

EC50 = 7.0 nM (WT); SI = 3240

EC50 = 4.61 nM (WT); SI = 5945

29 EC50 = 22 nM (WT); SI > 10770

Figure 16. Identification of back-up series of non-nucleoside RT inhibitors by core-refining and substituents-decorating approach (continued).

DABO analogue 21 (EC50 = 0.24 µM) demonstrated improved or comparable HIV-1 potency compared with NVP (EC50 = 0.21 µM) and DLV (EC50 = 0.32 µM) [34,104]. S-DABOs 22a and 22b demonstrated high potency against HIV-1 RT with IC50 values of 0.35 µM and 0.41 µM, respectively, which was much better than that of NVP [35,105]. Based on the structural features, binding mode, and SARs conclusions of two pyrimidine-typed NNRTIs, DABOs, and DAPYs, in our lab, a new series of 1,2,6-thiadiazine1,1-diones were rationally designed via bioisosterism and molecular hybridization principles, synthesized, and evaluated as potent HIV inhibitors. Especially, compound 23 was found to have moderate inhibition against HIV-1 replication with EC50 value of 23 µM [36,106]. In 2014, a series of novel DAPYs characterized by a halogen atom on the methylene linker between the left wing

and the pyrimidine core was reported as potent NNRTIs (27a-d). Two most potent compounds 27b and 27c displayed excellent potency against WT HIV-1 with EC50 values of 5 and 9 nM, respectively. Especially, 27c also demonstrated favorable potency against the double (K103N/Y181C) mutation in RT with an EC50 value of 8.2 µM [40,107]. To further probe the chemical structural space of the right wing, in our group, a novel series of piperidine-substituted triazine/aniline derivatives were identified as active HIV inhibitors in MT-4 cells. Some of them showed excellent potency against WT HIV-1 with low nanomolar EC50 values in low nanomolar concentration level (especially compounds 28a, b, 29, with EC50 = 7.0 nM, 4.61 nM, and 22 nM, respectively) and moderate inhibition against the double mutant (K103N/Y181C) strain with EC50 values in a low micromolar range [41,42,109-111].


21

X. Li et al.

CN

CN

CN

NH

O

CN

CN

CN

Br

Br O

O

NH

Cl

N

N

N

O2N

EC50 (IIIB) = 34 nM, SI = 565;

Scaffold refining

NH

N

54

32

N

HN

NH2

N

N N

33a

EC50 (IIIB) = 56 nM, SI = 1251;

EC50 (IIIB) = 2.5 nM, SI = 13740; EC50 (RES056) = 0.33 μM, SI =107

HN

NH N

N

NH N

34

N 35

EC50 (IIIB) = 0.07 μM, SI = 3999

EC50 (IIIB) = 0.02 μM, SI = 8986; EC50 (RES056) = 7.6 μM, SI = 25

Newly designed fused heterocyclic compounds bearing bridgehead nitrogen Potent DAPY analogues discoveryed in our lab N

N

N

S

N

Br

H N

N

H N S


O N Br

N

H N

S

N

O

SO2NH2

Cl Structure-based bioisosterism

O

37a EC50 = 18 nM

COOK

N

RDEA-806 (55) N

37b EC50 = 46.3 nM

N

NO2

H N

S Cl

H N

N S

N

O

O

O

O

SO2NH2 Br

37c

38

EC50 = 1.7 μM

EC50 =210 nM, SI = 46 (WT)

O O

NO2

O S

O

N

N

S

S

N

N

Ligand-based bioisosterism

S

S N

N

O

O

N

F

O

X CN QM 96521 (56a) X = H QM 96639 (56b) X = F QM 96539 (56c) X = CI

NC Cl

39 EC50 = 5.1 μM SI > 63

QM 96652 (56d)

1,1,3-trioxo-2H,4H-thieno[3,4-e][1,2,4]thiadiazine (TTDs)

pyrrolo[1,2-b][1,2,4,6]thiotriazine-1,1,3-trione

Figure 16. Identification of back-up series of non-nucleoside RT inhibitors by core-refining and substituents-decorating approach.

To discover highly potent DAPYs with favorable drug-like properties that are easier to synthesize or to avoid existing patent art, diverse modifications were focused on the replacement of the pyrimidine core with an array of aromatic scaffolds. In most cases, the pyrimidine core of DAPYs was replaced with other six-membered bioisosteric moieties with the aim of exploring novel structural motifs and establishing SARs [43-46]. In this regard, previous research in our laboratory using structure-based drug design and isosteric principle resulted in the discovery of novel series of DAPYs back-up analogues, such as pyridazines (32), nitropyridines (54), and 22

pyrimidines (33), which was found to be highly active in inhibiting HIV-1 replication at low or double-digit nanomolar concentrations [45,46,112-114]. Furthermore, our group has successfully exploited other bicyclic scaffolds like 1,2,4triazolo[1,5-a]pyrimidine and pyrazolo[1,5-a]pyrimidine in the design of DAPYs analogues. Particularly, 1,2,4triazolo[1,5-a]pyrimidine 34 demonstrated striking potency against WT and K103N/Y181C double mutant strain of HIV-1, possessing EC50 values of 0.02 µM and 7.6 µM, respectively, which were much better than or similar to NVP (EC50 = 0.15 µM, 2.9 µM) and DLV



O H2N

HN NH

N N NC

N

NH N

F NC

NH

TMC120 (57)

N

N

N F

MC1220 (58)

NH

UAMC01398 (41)

CN


Figure 17. Representative non-nucleoside RT inhibitors as HIV microbicides.

(EC50 = 0.07 µM, > 36 µM). Compound 35 proved to be the most promising analogue in pyrazolo[1,5-a]pyrimidine series with an EC50 of 0.07 µM against WT HIV-1 and high selectivity index (SI = 3999). It was more potent than the reference drugs NVP (by twofold) and DLV (by twofold). These encouraging results prompted us to evaluate other bicyclic scaffolds during the course of our lead generation effort for the NNRTIs’ project [47,48,115,116]. Over the past few years, our considerable efforts have also been devoted to the structural modifications of arylazolyl (azinyl)thioacetanilides, starting from the previously identified drug candidate RDEA806 in Ardea Biosciences Company [49-51,117-122]. We carried out comprehensive and systematic SARs investigation of the center core, aided by structure-based design. Optimization of the triazole portion of RDEA806 (through use of a ring-expansion core modification) led to identification of six-membered and fused heterocycles, which showed remarkable potency against HIV-1. Among the six-membered core series, the most promising compound was 1,2,4-triazin-6-yl thioacetamide 37a with double-digit nanomolar activity against WT HIV-1 (EC50 = 18 nM) and moderate activity against the K103N/ Y181C double mutant strain (EC50 = 3.3 µM). Our continued effort toward the development of benzo/ heterothiadiazine dioxide-derived antiviral agents led to the discovery of pyrrolo[1,2-b] [1,2,4,6]thiotriazine-1,1,3-trione scaffold as potent NNRTIs [52,124,125]. The most effective compound 39 based on this scaffold has the EC50 of 5.1 µM. Very recently, novel 2,4,5-trisubstituted thiazole derivative 40 was reported to exhibit inhibitory effects against WT RT at low micromolar concentrations (0.046 µM), and against six NNRTI-resistant RTs with IC50 values ranging from 0.24 to 5.11 µM, which were better than those of NVP [53,128]. In recent years, activity cliffs were generally defined as pairs of active molecules with a large difference in potency and represent an extreme form of SARs discontinuity [129-131]. Obviously, in the structure modifications of NNRTIs, activity cliffs were observed by structurally similar compounds with significant differences in activity. Thus, in the effects to further get insights into activity cliffs of the existing NNRTIs, the traditional medicinal chemistry strategies should keep close cooperation with the crystallography and molecular modeling to provide untapped

opportunities for the design of structurally diverse structures, which will populate previously inaccessible regions of chemical space. 5.

NNRTIs as HIV microbicides

Pre-exposure prophylaxis and topical microbicides were regarded as essential strategies in the prevention of transmission of HIV-1 infections. Up to now, TMC120 (dapivirine, 57) and MC1220 (58) have been identified as microbicides with great potential for the prevention of sexual HIV transmission (Figure 17). In particular, TMC120 has entered the Phase III clinical trials [132]. Very recently, UAMC01398 (41) in diaryltriazines (DATAs) series was chosen as a lead microbicide candidate that warrants further investigation for its potency against dapivirine-resistant viruses, favorable in vitro potency, superior safety and biopharmaceutical profiles [54,133,134]. 6.

NNRTIs with novel mechanism of action

The quick drug-resistant mutations of HIV-1 strains underscore the demand for additional inhibitors with novel mechanism, which will offer expanded therapeutic options in the clinic [96]. Several labs have recently reported on the identification of nucleotide-competing RT inhibitors (NcRTIs), a new type of RT inhibitors, which reversibly inhibit binding of the incoming nucleotide to the RT polymerase active site but do not work as chain terminators, unlike the nucleos(t)ide RT inhibitor (NRTI) family [135-137]. The X-ray co-crystal comprising an HIV-1 RT and 2-methylsulfonyl-4-dimethylamino-6-vinylpyrimidine (DAVP-1, 42) was disclosed in patent WO2011073959, which revealed a relatively untapped binding site close to the RT active site (Figure 18) [55]. 7.

Expert opinion

In this review, based on the overview of the patent applications on NNRTIs published from 2011 to 2014, this review mainly described the following contents successively: general approaches for NNRTI hits or leads discovery, new medicinal chemistry insights into the optimization strategies from hits or leads to candidates, and traditional core-refining and substituents-decorating approach.


23

X. Li et al.

N O O S

N N

42


Figure 18. Crystal structure of DAVP-1 (carbon: colored in pink) bound to the unligated RT (PDB code: 3ISN). The sulfone forms multiple H-bonds with the amino acid residues around it. Key H-bond interactions were shown as yellow dashed lines.

Obviously, in the past few years, great progress has been made in the application and development of traditional and newly emerging methodologies to facilitate both NNRTIs lead generation and optimization. Still, drug resistance (pharmacodynamics) and poor aqueous solubility (pharmacokinetics) were considered to be the two major basic questions that need to be addressed in NNRTIs research field. Therefore, there will be a continuous need for next-generation NNRTIs with different resistance profiles, improved safety, excellent tolerability, and favorable physicochemical properties. Regarding NNRTIs lead generation, the HTS campaign revealed a lot of hits that were nominated for further optimization investigations. We envisioned that combining new technologies (such as microarray) with orthogonal HTS methods will emerge as a powerful approach for rapid screening of large chemical libraries. Besides HTS and random approaches, structure-based virtual screening and computational hit expansion methodologies were undoubtedly beneficial to seek novel effective chemical entities, utilizing already existing information of RT/NNRTIs complexes. In the NNRTIs lead optimization process, extension of the initial hit class into alternative structural classes via the classical medicinal chemistry principles and strategies (structurebased core-refining and substituents-decorating) (core-refining and substituents-decorating) will demonstrate huge opportunities, such as improved synthetic accessibility, the capacity to explore additional inaccessible regions, the potential amelioration to drug resistance profiles, physicochemical profiles, and a more favorable IP position. It is well-known that the generation of synthetic molecules bearing exclusive specificity and high affinity with target is a huge challenge of molecular recognition and requires novel design strategies, in particular for mutated protein RT. Computational technologies, typically Monte Carlo FEP calculations, have contributed significantly through advances in de novo design, virtual screening, prediction of

24

pharmacologically important properties, and the estimation of RT-NNRTI binding affinities. Several newly emerging drug design methodologies or new insights, such as the specific noncovalent RT/NNRTIs interactions, stereochemical diversity-oriented conformational restriction, and early ADMET assessment, will continue to evolve to complement the classical NNRTIs discovery approaches. Equally important, in the last few years, increased attention was focused on the structure modification strategies for improving aqueous solubility of NNRTIs including introduction of solubilizing group, crystal packing analysis, and novel prodrug approach. All in all, the development of effective NNRTIs is moving on from trial-and-error approaches to sophisticated subconscious strategies. Undoubtedly, no single strategy or technology is likely to be a universal panacea. It can be predicted that traditional medicinal chemistry in combination with novel principles and computer-aided drug design technologies (such as FEP calculations) would further revolutionize the lead-seeking and lead-optimization phases in NNRTIs’ drug discovery.

Declaration of interest The authors were supported by the financial support from the National Natural Science Foundation of China (NSFC No.81102320, No.81273354), Key Project of NSFC for International Cooperation (No. 81420108027), Research Fund for the Doctoral Program of Higher Education of China (No. 20110131130005, 20110131120037), and China Postdoctoral Science Foundation funded project (No. 2012T50584) is gratefully acknowledged. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.



Bibliography Papers of special note have been highlighted as either of interest () or of considerable interest () to readers. 1.


2.

.

Asahchop EL, Wainberg MA, Sloan RD, et al. Antiviral drug resistance and the need for development of new HIV-1 reverse transcriptase inhibitors. Antimicrob Agents Chemother 2012;56:5000-8 Reynolds C, de Koning CB, Pelly SC, et al. In search of a treatment for HIVcurrent therapies and the role of nonnucleoside reverse transcriptase inhibitors (NNRTIs). Chem Soc Rev 2012;41:4657-70 This article provided an overview of the status quo of HIV infection and addresses currently used drugs, with specific emphasis on new developments of non-nucleoside RT inhibitors (NNRTIs).

paradigms was translated into a set of drug discovery strategies. 12.

Zhan P, Liu X, Li Z. Recent advances in the discovery and development of novel HIV-1 NNRTI platforms: 2006-2008 update. Curr Med Chem 2009;16:2876-89

13.

Song Y, Fang Z, Zhan P, et al. Recent Advances in the Discovery and Development of Novel HIV-1 NNRTI Platforms (Part II): 2009-2013 Update. Curr Med Chem 2013;21:329-55

14.

Zhan P, Chen X, Li D, et al. HIV-1 NNRTIs: structural diversity, pharmacophore similarity, and implications for drug design. Med Res Rev 2013;33:E1-E72 A comprehensive overview of the general approaches in NNRTI lead discovery and optimization was provided. The successful applications of medicinal chemistry strategies, crystallography, and computational tools for designing alternative NNRTIs were highlighted. Future directions for NNRTIs discovery were also outlined.

..

3.

Jayaweera D, Dilanchian P. New therapeutic landscape of NNRTIs for treatment of HIV: a look at recent data. Expert Opin Pharmacother 2012;13:2601-12

4.

Rawal RK, Murugesan V, Katti SB. Structure-activity relationship studies on clinically relevant HIV-1 NNRTIs. Curr Med Chem 2012;19:5364-80

15.

Zhan P, Liu X. Novel HIV-1 nonnucleoside reverse transcriptase inhibitors: a patent review (2005 - 2010). Expert Opin Ther Pat 2011;21:717-96

5.

Available from: http://aidsinfo.nih.gov/ guidelines

16.

6.

Available from: www.who.int/hiv/pub/ guidelines/en/

Zhan P, Liu X, Li Z, et al. Design strategies of novel NNRTIs to overcome drug resistance. Curr Med Chem 2009;16:3903-17

7.

Available from: www.eacsociety.org/ Guidelines.aspx

8.

Available from: www.iasusa.org/ guidelines-archive

9.

Croxtall JD. Etravirine: a review of its use in the management of treatmentexperienced patients with HIV-1 infection. Drugs 2012;72:847-69

10.

11.

..

Schafer JJ, Short WR. Rilpivirine, a novel non-nucleoside reverse transcriptase inhibitor for the management of HIV-1 infection: a systematic review. Antivir Ther 2012;17:1495-502 Li D, Zhan P, De Clercq E, et al. Strategies for the design of HIV-1 nonnucleoside reverse transcriptase inhibitors: lessons from the development of seven representative paradigms. J Med Chem 2012;55:3595-613 In this review, the general knowledge gained from seven representative

17.

Heil ML, Cosford Nicholas DP, Pagano N, et al. Preparation of 5(thiazol-2-yl)-3,4-dihydropyrimidones as HIV replication inhibitors useful in the treatment of HIV infections. WO2013033003A1; 2013

18.

Kim J, Cechetto J, No Z, et al. Preparation of substituted biaryl and arylheteroaryl derivatives as antiviral agents. WO2010046780A2; 2010

19.

Thede K, Greschat S, Wildum S, et al. Preparation of pyrazolylcarbonylimidazolidinones as antiviral agents. WO2009115213A1; 2009

20.

Verhoeven E, Voorspoels J, Gonnissen Y, et al. Solid dispersion comprising a chlorofluorophenyl pyrazolylcarbonyl imidazolidinone anti-HIV agent. WO2011029909A1; 2011


21.

Jorgensen WL, Anderson KG. Preparation of catechol diethers as antiHIV agents. WO2013056003; 2013

22.

Li A, Wang X, Ma L, et al. Preparation of 2(1H)-pyridinone derivatives as HIV-1 reverse transcriptase inhibitors. CN102001994A; 2011

23.

Burch J, Cote B, Nguyen N, et al. Preparation of 1-[(5-oxo-4,5-dihydro1H-1,2,4-triazol-3-yl)methyl]-pyridin-2 (1H)-one compounds as non-nucleoside reverse transcriptase inhibitors. WO2011120133A1; 2011

24.

Dunn JP, Elworthy TR, Zachary KS. Heterocyclic antiviral compounds. US2011207688; 2011

25.

Jolly SM, Anthony N, Gomez R, et al. Prodrugs of an HIV reverse transcriptase inhibitor. WO2011126969A1; 2011

26.

Ma J, Guo Y, Zhang F, et al. 4-(trans-3Buten-1-ynyl)-4-(trifluoromethyl)-3,4dihydroquinazolin-2(1H)-one compounds as HIV replication inhibitors and their preparation, pharmaceutical compositions and use in the treatment of HIV infections. CN103524430A; 2014

27.

Jiang B, Zhang C, Li J, et al. Preparation of 4,4-disubstituted-dihydro-2(1H)quinazolinone or thione-like compounds as HIV reverse transcriptase inhibitors for the treatment of HIV. CN102718721A; 2012

28.

Wu S, Zhou H, Tian B, et al. Preparation of indole derivatives as HIV1 reverse transcriptase inhibitors. CN103113285A; 2013

29.

Jiang B, Zhang C, Li J, et al. Preparation of indole derivatives as HIV reverse transcriptase inhibitors. CN102675280A; 2012

30.

Jiang B, Zhang C, Jiang H, et al. Preparation of indole derivatives as HIV reverse transcriptase inhibitors. CN102766083A; 2012

31.

Zhang L, Wang R, Wang X, et al. 1,5,6Substituted pyrimidine derivatives with anti-HIV virus activity and their preparation, pharmaceutical compositions and use in the treatment of AIDs. CN102838549A; 2012

32.

Wang X, Zhang J, Liu J. Uracil derivatives as HIV-1 reverse transcriptase inhibitors and their preparation, pharmaceutical compositions and use in the treatment of AIDs. CN102295608A; 2011

25

X. Li et al.

33.


34.

46.

Liu X, Zhang J, Zhan P. 2-Aryl methylthio-6-(tetrahydroquinolin-1ylmethyl)-4-pyrimidone derivatives useful in the treatment of HIV-1 and their preparation. CN102285967A; 2011

47.

35.

Liu C, Liu J. Preparation of 6-(1naphthalenylmethyl)-4(3H)-pyrimidinone derivatives as HIV-1 reverse transcriptase inhibitors. CN102134223A; 2011

36.

Liu X, Tian Y, Zhan P. Preparation of thiadiazine derivatives as anti-HIV agents. CN102775371A; 2012

37.

38.

the treatment of AIDs. CN102731410A; 2012

Zhang S, Wang X, Fang X, et al. 6Cyclohexylmethyl-2-aromatic ring carbonyl-substituted N-DABO-like compounds, their synthetic method and application as anti-HIV agents. CN103288747A; 2013

Arrington KL, Burgey C, Gilfillan R, et al. Preparation of pyrimidinyl nonnucleoside reverse transcriptase inhibitors for treatment of HIV infection and AIDS. US20140100231A1; 2014 Huang X, Zhang B. Method for synthesizing pyridone lead compounds as non-nucleoside HIV inhibitors. CN103288719A; 2013

48.

49.

Liu X, Li X, Zhan P. m-Diarene-pyrimidine derivatives as HIV-1 reverse transcriptase inhibitors and their preparation, pharmaceutical compositions and use in the treatment of HIV infection. CN103483272A; 2014 Liu X, Wang L, Zhan P. Triazolopyrimidines as HIV-1 reverse transcriptase inhibitors and their preparation, pharmaceutical compositions and use in the treatment of AIDs. CN103360398A; 2013 Liu X, Tian Y, Zhan P. Substituted pyrazolo[1,5-a]pyrimidine derivative, its preparation method and application in preparation of drug for treatment and prevention of human immunodeficiency virus (HIV) infection. CN103570728A; 2014 Liu X, Jiang X, Zhan P. Preparation of 1,2,3-thiadiazole derivatives for treatment of HIV infection. CN102659714A; 2012

50.

Liu X, Zhan P, Li X, et al. Preparation of heterocyclic compounds as anti-HIV agents. CN102276535A; 2011

Rios A. Inactivation of reverse transcriptases by azidodiarylpyrimidines. WO2011109697A1; 2011.US2011217331; 2011

51.

Liu X, Zhan P, Li X. Preparation of sixmembered heteroaryl fused imidazole thioacetamide derivatives as anti-HIV agents. CN102516244A; 2012

40.

Chen F, Yan Z, He Q. Preparation of diaryl pyrimidine derivatives useful in the treatment of HIV infection. CN103787985A; 2014

52.

41.

Liu X, Chen X, Zhan P. N-1-substituted piperidine-4-arylamine derivative useful in the treatment of HIV infection and its preparation. CN102285969A; 2011

39.

42.

43.

44.

45.

26

Liu X, Zhang L. Preparation of 2-(Narylmethylpiperidine-4-ylamino)-4(substituted-phenoxy)benzene derivatives as HIV-1 inhibitors. CN103497146A; 2014 Xie L, Chen CH, Sun L, et al. Preparation of diarylaniline or diarylpyridinamine derivatives as antiHIV agents. WO2014012467A1; 2014

53.

Guo C, Guo Y, Li Z, et al. Preparation of thiazole derivatives as anti-HIV agents. CN103159695A; 2013

54.

Heeres J, Van Der Veken P, Joossens J, et al. Triazines with suitable spacers for treatment and/or prevention of HIV infections and their preparation. WO2013139727A1; 2013

55.

Radi M, Botta M, Angeli L, et al. Crystal structure of HIV-1 reverse transcriptase bound to a nucleotidecompetitive reverse transcriptase inhibitor and its use for the design and identification of inhibitors. WO2011073959A2; 2011

Franck P, Heeres J, Maes B, et al. Preparation of fluoroaromatic derivatives useful as anti-HIV compounds. WO2014072419A1; 2014 Liu X, Li D, Zhan P. Pyridazine derivatives as HIV-1 reverse transcriptase inhibitors and their preparation, pharmaceutical compositions and use in

Liu X, Chen W, Zhan P. N2,N4-Bissubstituted-2H,4H-pyrrolo[1,2-b] [1,2,4,6]thiotriazine-1,1,3-trione derivatives useful in the treatment of AIDS and their preparation. CN102321102A; 2012

56.

Kim J, Park C, Ok T, et al. Discovery of 3,4-dihydropyrimidin-2(1H)-ones with inhibitory activity against HIV-1 replication. Bioorg Med Chem Lett 2012;22:2119-24


57.

Kim J, Ok T, Park C, et al. A novel 3,4dihydropyrimidin-2(1H)-one: HIV-1 replication inhibitors with improved metabolic stability. Bioorg Med Chem Lett 2012;22:2522-6

58.

Kim J, Lee D, Park C, et al. Discovery of phenylaminopyridine derivatives as novel HIV-1 non-nucleoside reverse transcriptase inhibitors. ACS Medicinal Chemistry Letters 2012;3:678-82

59.

Wildum S, Paulsen D, Thede K, et al. In vitro and in vivo activities of AIC292, a novel HIV-1 nonnucleoside reverse transcriptase inhibitor. Antimicrob Agents Chemother 2013;57:5320-9

60.

Kim TH, Ko Y, Christophe T, et al. Identification of a novel sulfonamide non-nucleoside reverse transcriptase inhibitor by a phenotypic HIV-1 full replication assay. PLoS One 2013;8:e68767

61.

Chen L, Ao Z, Jayappa KD, et al. Characterization of antiviral activity of benzamide derivative AH0109 against HIV-1 infection. Antimicrob Agents Chemother 2013;57:3547-54

62.

Nichols SE, Domaoal RA, Thakur VV, et al. Discovery of wild-type and Y181C mutant non-nucleoside HIV-1 reverse transcriptase inhibitors using virtual screening with multiple protein structures. J Chem Inf Model 2009;49:1272-9

63.

Bollini M, Domaoal RA, Thakur VV, et al. Computationally-guided optimization of a docking hit to yield catechol diethers as potent anti-HIV agents. J Med Chem 2011;54:8582-91

64.

Frey KM, Bollini M, Mislak AC, et al. Crystal structures of HIV-1 reverse transcriptase with picomolar inhibitors reveal key interactions for drug design. J Am Chem Soc 2012;134:19501-3

65.

Ivetac A, Swift SE, Boyer PL, et al. Discovery of novel inhibitors of HIV-1 reverse transcriptase through virtual screening of experimental and theoretical ensembles. Chem Biol Drug Des 2014;83:521-31

66.

Garcı´a-Sosa AT, Sild S, Takkis K, et al. Combined approach using ligand efficiency, cross-docking, and antitarget hits for wild-type and drug-resistant Y181C HIV-1 reverse transcriptase. J Chem Inf Model 2011;51:2595-611


67.

68.


69.

70.

Frey KM, Gray WT, Spasov KA, et al. Structure-based evaluation of C5 derivatives in the catechol diether series targeting HIV-1 reverse transcriptase. Chem Biol Drug Des 2014;83:541-9 Jorgensen WL, Schyman P. Treatment of halogen bonding in the OPLS-AA force field; application to potent anti-HIV agents. J Chem Theory Comput 2012;8:3895-01

82.

Bollini M, Frey KM, Cisneros JA, et al. Extension into the entrance channel of HIV-1 reverse transcriptase--crystallography and enhanced solubility. Bioorg Med Chem Lett 2013;23:5209-12

83.

Bollini M, Cisneros JA, Spasov KA, et al. Optimization of diarylazines as anti-HIV agents with dramatically enhanced solubility. Bioorg Med Chem Lett 2013;23:5213-16

Lian J, Wang J, Sun HF, et al. Application of methyl in drug design. Yao Xue Xue Bao 2013;48:1195-208

73.

Leung CS, Leung SS, Tirado-Rives J, et al. Methyl effects on protein-ligand binding. J Med Chem 2012;55:4489-500

76.

77.

78.

Rotili D, Tarantino D, Nawrozkij MB, et al. Exploring the role of 2-chloro-6fluoro substitution in 2-alkylthio-6benzyl-5-alkylpyrimidin-4(3H)-ones: effects in HIV-1-infected cells and in HIV-1 reverse transcriptase enzymes. J Med Chem 2014;57:5212-25

Wilcken R, Zimmermann MO, Lange A, et al. Principles and applications of halogen bonding in medicinal chemistry and chemical biology. J Med Chem 2013;56:1363-88

72.

75.

80.

Fang Z, Song Y, Zhan P, et al. Conformational restriction: an effective tactic in ’follow-on’-based drug discovery. Future Med Chem 2014;6:885-901

81.

Lu Y, Liu Y, Xu Z, et al. Halogen bonding for rational drug design and new drug discovery. Expert Opin Drug Discov 2012;7:375-83

74.

79.

Zimmermann MO, Lange A, Wilcken R, et al. Halogen-enriched fragment libraries as chemical probes for harnessing halogen bonding in fragment-based lead discovery. Future Med Chem 2014;6:617-39

71.

84.

Fleming FF, Yao L, Ravikumar PC, et al. Nitrile-containing pharmaceuticals: efficacious roles of the nitrile pharmacophore. J Med Chem 2010;53:7902-17 Lyn HJ, Nicholas WS, Nigel AS, et al. Aromatic chloride to nitrile transformation: medicinal and synthetic chemistry. Med Chem Commun 2010;1:309-18 Jorgensen WL, Bollini M, Thakur VV, et al. Efficient discovery of potent antiHIV agents targeting the Tyr181Cys variant of HIV reverse transcriptase. J Am Chem Soc 2011;133:15686-96 Bollini M, Gallardo-Macias R, Spasov KA, et al. Optimization of benzyloxazoles as non-nucleoside inhibitors of HIV-1 reverse transcriptase to enhance Y181C potency. Bioorg Med Chem Lett 2013;23:1110-13 Cole DJ, Tirado-Rives J, Jorgensen WL. Enhanced Monte Carlo sampling through replica exchange with solute

transcriptase inhibitor potent against a wide range of resistant mutant HIV viruses. Bioorg Med Chem Lett 2014;24:917-22

tempering. J Chem Theory Comput 2014;10:565-71

85.

Li A, Ouyang Y, Wang Z, et al. Novel pyridinone derivatives as non-nucleoside reverse transcriptase inhibitors (NNRTIs) with high potency against NNRTIresistant HIV-1 strains. J Med Chem 2013;56:3593-608

Mislak AC, Frey KM, Bollini M, et al. A mechanistic and structural investigation of modified derivatives of the diaryltriazine class of NNRTIs targeting HIV-1 reverse transcriptase. Biochim Biophys Acta 2014;1840:2203-11 Paul B, Hawa D, Jonathan DG, et al. Fragment-based discovery of bromodomain inhibitors part 2: optimization of phenylisoxazole sulfonamides. J Med Chem 2012;55:587-96

89.

Takeuchi T, Oishi S, Kaneda M, et al. Kinesin spindle protein inhibitors with diaryl amine scaffolds: crystal packing analysis for improved aqueous solubility. ACS Med Chem Lett 2014;5:566-71

90.

Timmins P, Brown J, Meanwell NA, et al. Enabled clinical use of an HIV-1 attachment inhibitor through drug delivery. Drug Discov Today 2014; Epub ahead of print

91.

David KL, Shawn KP. Preparation of phosphonooxymethyl prodrugs of HIV-1 attachment inhibitors. Org Process Res Dev 2013;17:1440-4

92.

Kadow JF, Ueda Y, Meanwell NA, et al. Inhibitors of human immunodeficiency virus type 1 (HIV-1) attachment 6. Preclinical and human pharmacokinetic profiling of BMS-663749, a phosphonooxymethyl prodrug of the HIV-1 attachment inhibitor 2-(4benzoyl-1-piperazinyl)-1-(4,7-dimethoxy1H-pyrrolo[2,3-c]pyridin-3-yl)-2oxoethanone (BMS-488043). J Med Chem 2012;55:2048-56

93.

Oslob JD, Heumann SA, Yu CH, et al. Water-soluble prodrugs of an Aurora kinase inhibitor. Bioorg Med Chem Lett 2009;19:1409-12

94.

Ueda Y, Matiskella JD, Golik J, et al. Phosphonooxymethyl prodrugs of the broad spectrum antifungal azole, ravuconazole: synthesis and biological properties. Bioorg Med Chem Lett 2003;13:3669-72

95.

Liu Y, Hong L, Yu LS, et al. The role of ADME evaluation in translation research of innovative drug. Yao Xue Xue Bao 2011;46:19-29

86.

Skoda EM, Sacher JR, Kazancioglu MZ, et al. An uncharged oxetanyl sulfoxide as a covalent modifier for improving aqueous solubility. ACS Med Chem Lett 2014;5:900-4

96.

Lee WG, Gallardo-Macias R, Frey KM, et al. Picomolar inhibitors of HIV reverse transcriptase featuring bicyclic replacement of a cyanovinylphenyl group. J Am Chem Soc 2013;135:16705-13

87.

Lai MT, Feng M, Falgueyret JP, et al. In vitro characterization of MK-1439: A novel HIV-1 non-nucleoside reverse transcriptase inhibitor. Antimicrob Agents Chemother 2014;58:1652-63

97.

Liu N, Qin B, Sun LQ, et al. Physicochemical property-driven optimization of diarylaniline compounds as potent HIV-1 non-nucleoside reverse transcriptase inhibitors. Bioorg Med Chem Lett 2014;24:3719-23

88.

Coˆte B, Burch JD, Asante-Appiah E, et al. Discovery of MK-1439, an orally bioavailable non-nucleoside reverse

98.

Wu ZY, Liu N, Qin B, et al. Optimization of the antiviral potency and lipophilicity of halogenated 2,6-


27

X. Li et al.

diarylpyridinamines as a novel class of HIV-1 NNRTIS. ChemMedChem 2014;9:1546-55


99.

Sun LQ, Zhu L, Qian K, et al. Design, synthesis, and preclinical evaluations of novel 4-substituted 1,5-diarylanilines as potent HIV-1 non-nucleoside reverse transcriptase inhibitor (NNRTI) drug candidates. J Med Chem 2012;55:7219-29

100. Kang D, Song Y, Chen W, et al. "Old Dogs with New Tricks": exploiting alternative mechanisms of action and new drug design strategies for clinically validated HIV targets. Mol Biosyst 2014;10:1998-2022 101. Jiang HX, Zhuang DM, Huang Y, et al. Design, synthesis, and biological evaluation of novel trifluoromethyl indoles as potent HIV-1 NNRTIs with an improved drug resistance profile. Org Biomol Chem 2014;12:3446-58 102. Wang X, Zhang J, Huang Y, et al. Design, synthesis, and biological evaluation of 1-[(2-benzyloxyl/alkoxyl) methyl]-5-halo-6-aryluracils as potent HIV-1 non-nucleoside reverse transcriptase inhibitors with an improved drug resistance profile. J Med Chem 2012;55:2242-50 103. Zhang XJ, Lu LH, Wang RR, et al. DB02, a C-6-cyclohexylmethyl substituted pyrimidinone HIV-1 reverse transcriptase inhibitor with nanomolar activity, displays an improved sensitivity against K103N or Y181C than S-DABOs. PLoS One 2013;8:e81489 104. Zhang J, Zhan P, Wu J, et al. Synthesis and biological evaluation of novel 5alkyl-2-arylthio-6-((3,4-dihydroquinolin-1 (2H)-yl)methyl)pyrimidin-4(3H)-ones as potent non-nucleoside HIV-1 reverse transcriptase inhibitors. Bioorg Med Chem 2011;19:4366-76 105. Zhang L, Tang X, Cao Y, et al. Synthesis and biological evaluation of novel 2arylalkylthio-5-iodine-6-substitutedbenzyl-pyrimidine-4(3H)-ones as potent HIV-1 non-nucleoside reverse transcriptase inhibitors. Molecules 2014;19:7104-21 106. Tian Y, Rai D, Zhan P, et al. Design, synthesis, and biological evaluation of novel 3,5-disubstituted-1,2,6-thiadiazine1,1-dione derivatives as HIV-1 NNRTIs. Chem Biol Drug Des 2013;82:384-93

CHX-DAPYs as HIV-1 non-nucleoside reverse transcriptase inhibitors. Bioorg Med Chem 2014;22:3220-6 108. Yan ZH, Huang XY, Wu HQ, et al. Structural modifications of CH(OH)DAPYs as new HIV-1 non-nucleoside reverse transcriptase inhibitors. Bioorg Med Chem 2014;22:2535-41 109. Chen X, Zhan P, Liu X, et al. Design, synthesis, anti-HIV evaluation and molecular modeling of piperidine-linked amino-triazine derivatives as potent nonnucleoside reverse transcriptase inhibitors. Bioorg Med Chem 2012;20:3856-64 110. Chen X, Zhan P, Pannecouque C, et al. Synthesis and biological evaluation of piperidine-substituted triazine derivatives as HIV-1 non-nucleoside reverse transcriptase inhibitors. Eur J Med Chem 2012;51:60-6 111. Zhang L, Zhan P, Chen X, et al. Design, synthesis and preliminary SAR studies of novel N-arylmethyl substituted piperidine-linked aniline derivatives as potent HIV-1 NNRTIs. Bioorg Med Chem 2014;22:633-42 112. Li D, Zhan P, Liu H, et al. Synthesis and biological evaluation of pyridazine derivatives as novel HIV-1 NNRTIs. Bioorg Med Chem 2013;21:2128-34 113. Wang J, Zhan P, Li Z, et al. Discovery of nitropyridine derivatives as potent HIV-1 non-nucleoside reverse transcriptase inhibitors via a structurebased core refining approach. Eur J Med Chem 2014;76:531-8 114. Li X, Chen W, Tian Y, et al. Discovery of novel diarylpyrimidines as potent HIV NNRTIs via a structure-guided corerefining approach. Eur J Med Chem 2014;80:112-21 115. Tian Y, Du D, Rai D, et al. Fused heterocyclic compounds bearing bridgehead nitrogen as potent HIV-1 NNRTIs. Part 1: design, synthesis and biological evaluation of novel 5,7disubstituted pyrazolo[1,5-a]pyrimidine derivatives. Bioorg Med Chem 2014;22:2052-9 116. Wang L, Tian Y, Chen W, et al. Fused heterocyclic compounds bearing bridgehead nitrogen as potent HIV-1 NNRTIs. Part 2: discovery of novel [1,2,4]triazolo[1,5-a]pyrimidines using a structure-guided core-refining approach. Eur J Med Chem 2014;85C:293-303

107. Yan ZH, Wu HQ, Chen WX, et al. Synthesis and biological evaluation of

28


117. Zhan P, Li Z, Liu X, et al. Sulfanyltriazole/tetrazoles: a promising class of HIV-1 NNRTIs. Mini Rev Med Chem 2009;9:1014-23 118. Song Y, Zhan P, Liu X. Heterocycle-thioacetic acid motif: a privileged molecular scaffold with potent, broad-ranging pharmacological activities. Curr Pharm Des 2013;19:7141-54 119. Zhan P, Chen W, Li Z, et al. Discovery of novel 2-(3-(2-chlorophenyl)pyrazin-2ylthio)-N-arylacetamides as potent HIV-1 inhibitors using a structure-based bioisosterism approach. Bioorg Med Chem 2012;20:6795-802 120. Zhan P, Li X, Li Z, et al. Structure-based bioisosterism design, synthesis and biological evaluation of novel 1,2,4-triazin-6-ylthioacetamides as potent HIV-1 NNRTIs. Bioorg Med Chem Lett 2012;22:7155-62 121. Song Y, Zhan P, Kang D, et al. Discovery of novel pyridazinylthioacetamides as potent HIV1 NNRTIs using a structure-based bioisosterism approach. Med Chem Commun 2013;4:810-16 122. Li X, Zhan P, Liu H, et al. Arylazolyl (azinyl)thioacetanilides. Part 10: design, synthesis and biological evaluation of novel substituted imidazopyridinylthioacetanilides as potent HIV-1 inhibitors. Bioorg Med Chem 2012;20:5527-36 123. Li X, Lu X, Chen W, et al. Arylazolyl (azinyl)thioacetanilides. Part 16: structure-based bioisosterism design, synthesis and biological evaluation of novel pyrimidinylthioacetanilides as potent HIV-1 inhibitors. Bioorg Med Chem 2014;19:5209-7 124. Zhan P, Liu X, De Clercq E. Recent advances in antiviral activity of benzo/ heterothiadiazine dioxide derivatives. Curr Med Chem 2008;15:1529-40 125. Chen W, Zhan P, De Clercq E, et al. Design, synthesis and biological evaluation of N2,N4-disubstituted-1,1,3trioxo-2H,4H-pyrrolo[1,2-b] [1,2,4,6] thiatriazine derivatives as HIV-1 NNRTIs. Bioorg Med Chem 2013;21:7091-100 126. Chen W, Zhan P, Rai D, et al. Facile synthesis of derivatives of 1,1,3-trioxo2H,4H-pyrrolo[1,2-b][1,2,4,6] thiatriazine: a new heterocyclic system. Heteroatom Chem 2013;24:495-501


127.


128.

Li X, Zhan P, De Clercq E, et al. The HIV-1 non-nucleoside reverse transcriptase inhibitors (Part V*): capravirine and its analogues. Curr Med Chem 2012;19:6138-49 Xu Z, Ba M, Zhou H, et al. 2,4,5Trisubstituted thiazole derivatives: a novel and potent class of nonnucleoside inhibitors of wild type and mutant HIV-1 reverse transcriptase. Eur J Med Chem 2014;85C:27-42

129.

Stumpfe D, Hu Y, Dimova D, et al. Recent progress in understanding activity cliffs and their utility in medicinal chemistry. J Med Chem 2014;57:18-28

130.

Stumpfe D, Bajorath J. Exploring activity cliffs in medicinal chemistry. J Med Chem 2012;55:2932-42

131.

Dimova D, Stumpfe D, Bajorath J. A method for the evaluation of structureactivity relationship information associated with coordinated activity cliffs. J Med Chem 2014;57(15):6553-63

132.

Fetherston SM, Geer L, Veazey RS, et al. Partial protection against multiple RTSHIV162P3 vaginal challenge of rhesus macaques by a silicone elastomer vaginal ring releasing the NNRTI MC1220.

J Antimicrob Chemother 2013;68:394-403 133.

Arie¨n KK, Venkatraj M, Michiels J, et al. Diaryltriazine non-nucleoside reverse transcriptase inhibitors are potent candidates for pre-exposure prophylaxis in the prevention of sexual HIV transmission. J Antimicrob Chemother 2013;68:2038-47

134.

Grammen C, Arie¨n KK, Venkatraj M, et al. Development and in vitro evaluation of a vaginal microbicide gel formulation for UAMC01398, a novel diaryltriazine NNRTI against HIV-1. Antiviral Res 2014;101:113-21

135.

Rajotte D, Tremblay S, Pelletier A, et al. Identification and characterization of a novel HIV-1 nucleotide-competing reverse transcriptase inhibitor series. Antimicrob Agents Chemother 2013;57:2712-18

136.

James CA, DeRoy P, Duplessis M, et al. Nucleotide competing reverse transcriptase inhibitors: discovery of a series of non-basic benzofurano[3,2-d] pyrimidin-2-one derived inhibitors. Bioorg Med Chem Lett 2013;23:2781-6


137. Tremblay M, Bethell RC, Cordingley MG, et al. Identification of benzofurano[3,2-d]pyrimidin-2-ones, a new series of HIV-1 nucleotidecompeting reverse transcriptase inhibitors. Bioorg Med Chem Lett 2013;23:2775-80

Affiliation Xiao Li1, Lingzi Zhang1, Ye Tian1, Yu’ning Song*,2, Peng Zhan†,1 & Xinyong Liu*,1 †, *Authors for correspondence 1 Shandong University, School of Pharmaceutical Sciences, Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), 44, West Culture Road, 250012, Jinan, Shandong, PR China Tel: +86 531 88382005; Fax: +86 531 88382731; E-mail: [email protected], [email protected] 2 Shandong University, School of Pharmaceutical Sciences, Department of Pharmacology, Key Laboratory of Chemical Biology (Ministry of Education), 44, West Culture Road, 250012, Jinan, Shandong, PR China Email: [email protected]

29