Accepted Manuscript Curcumin derived Schiff base ligand and their transition metal complexes: Synthesis, spectral characterization, catalytic potential and biological activity Abdul Kareem, Mohd Shoeb Khan, Shahab A.A. Nami, Shahnawaz A. Bhat, Azar Ullah Mirza, Nahid Nishat PII:
S0022-2860(18)30557-X
DOI:
10.1016/j.molstruc.2018.05.001
Reference:
MOLSTR 25173
To appear in:
Journal of Molecular Structure
Received Date: 8 January 2018 Revised Date:
8 April 2018
Accepted Date: 2 May 2018
Please cite this article as: A. Kareem, M.S. Khan, S.A.A. Nami, S.A. Bhat, A.U. Mirza, N. Nishat, Curcumin derived Schiff base ligand and their transition metal complexes: Synthesis, spectral characterization, catalytic potential and biological activity, Journal of Molecular Structure (2018), doi: 10.1016/j.molstruc.2018.05.001. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
Graphical Abstract:
ACCEPTED MANUSCRIPT
Curcumin derived Schiff base ligand and their transition metal complexes: Synthesis, spectral characterization, catalytic potential and biological activity a
Abdul Kareema, Mohd Shoeb Khanb, Shahab A.A. Namic, Shahnawaz A. Bhat , Azar Ullah
a
RI PT
Mirzaa, Nahid Nishata,* Material Research Lab, Department of Chemistry, Jamia Millia Islamia, New Delhi-110025,
India. b
c
SC
Department of Chemistry, Aligarh Muslim University, Aligarh-202002, India
Department of Kulliyat, Faculty of Unani Medicine, Aligarh Muslim University, Aligarh-
TE D
M AN U
202002, India.
EP
*Corresponding author: Nahid Nishat, E-mail id.
[email protected],
AC C
Contact No. +91-9540884412
ACCEPTED MANUSCRIPT
Abstract: Curcumin derived Schiff base ligand, (CL), was prepared by condensation of 1,7-bis-(4-hydroxy3-methoxyphenyl)-1,6-heptadiene-3,5-dione (curcumin) with amino ethylene piperazine (AEP).
RI PT
The transition metal complexes of CL were also successfully synthesized and characterized by various spectroscopic techniques. Non-electrolytic nature of complexes was ascertained by molar conductance values. Thermo gravimetric analysis confirms that all the metal complexes are
SC
stable up to 600oC. The metal to ligand stoichiometry of synthesized metal complexes was confirmed by micro analytical data as 1:1 (metal: ligand). Co(II), Ni(II) and Zn(II) ion forms the
M AN U
complexes with an octahedral geometry while the geometry of Cu(II) complex can ascribed as square planar by UV-vis and EPR spectroscopic studies. Catalytic power and antioxidant activity of these complexes have been evaluated and results shows that Co(II) complex is catalytically more active while the Cu(II) and Zn(II) complex were found with more potent antioxidant
TE D
activity, comparatively. The synthesized compounds have also been tested for their in-vitro cytotoxic potential, the obtained results shows moderate to good cytotoxicity on tested human cancer cell lines. The most effective compounds on cell lines MDA-MB-231 and KCL22 was
EP
[(CL)Cu] while on HeLa cell line the [(CL)Zn(H2O)2] was found with prominent cytotoxicity. Anthelmintic activities of these compounds have been performed using Pheretima posthuma.
AC C
The recorded order of anthelmintic activity of ligand (CL) and their metal complexes was found to have the trend as: [(CL)Cu]>[(CL)Zn(H2O)2]>[(CL)Co(H2O)2]>[(CL)Ni(H2O)2]>CL. Keywords: Schiff base; curcumin; catalytic potential; anticancer; anthelminthic.
ACCEPTED MANUSCRIPT
1. Introduction 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (curcumin), one of the most effective constituent of the everyday using turmeric commonly known as Indian spice
RI PT
scientifically termed as curcuma longa. A typical substituted β-diketone that mainly resemble with acetylacetone is the main constituent of the naturally occurring curcumin [1]. The derivatives along with synthetic analogs of curcumin and its various type of in-house synthesized
SC
metal complexes are mainly the substances which have attracted scientists and are still receiving paramount attention in that era due to their dramatic and very special properties [2-5]. Curcumin
M AN U
has been found nontoxic for human being up to an everyday dose of 12-14 gm. for an adult person [6]. It is well known for its medicinal properties since ancient times and was most frequently used in traditional Chinese and Ayurvedic medicines from more than 4000 years [7]. In Ayurveda curcumin is known as a blood purifier and recently, its chelating ability with
TE D
different metal ions have been explored which is responsible for reduction of the deposition of metal ions in the human body [8].
Curcumin exhibits keto–enol tautomerism (Scheme 1) depending on nature of the solvent and it
EP
can also exist in different types of conformations [9]. It is evident that the enolic form of isomer is comparatively more stable than the keto form due to strong intramolecular hydrogen bonding
AC C
[10]. The solubility of naturally occurring curcumin moiety is very poor in water at physiological PH and it confirms its hydrophobic nature [11]. Due to the poor bioavailability, rapid metabolism, limited absorption in body and excretion, there is a need to enhance the bioavailability and its solubility in water and other nontoxic solvents in order to increase its medicinal benefits and biological activity [12, 13]. There are several methods which have been proposed to short out the problem of bioavailability along with solubility of that includes its
ACCEPTED MANUSCRIPT
conjugation to water soluble polymers [14] or their encapsulation in a colloidal carriers comprises of silver nanoparticles [15], gold nanoparticles [16] along with polymeric nanomaterials [17]. The introduction or attachment of dimethylaminoethyl group as a substituent
RI PT
on aromatic rings in the curcumin which enhances its aqueous solubility by converting the final or target compounds into the salt forms [18]. The formation of transistion metal complexes of curcumin, such as Mn(II), Fe(II), Cu(II) and Zn(II) ions, is another effective strategy for
SC
improvement of the bioavailability of curcumin and has become an attractive field of research for inorganic researchers [1, 19]. There are a number of reported complexes which represents
M AN U
comparatively much higher stability than the free curcumin molecule [20, 21]. The complexation of curcumin with Zn(II) at a buffer of PH 7 is responsible for an tremendous enhancement in stability of curcumin (≈20 times) [22]. The stable curcumin derived metal complexes are mainly useful in two manners: firstly the enhanced solubility of compounds after successful
TE D
complexation with metal ions, secondly it behaves as a metal based curcumin containing antioxidant that generally reduces the toxic power of that particular metal ion [23]. The curcumin complexation with Pd(II) ion including their conjugation to the additional functionalized
EP
biologically active ligating moiety, has found to enhance the cytotoxicity on a prostate cancer cell lines with the process of apoptosis signal transduction pathway that overcomes due to
AC C
increased aqueous solubility of that particular compounds which attract our attention towards the future possibility of the potent anticancer agents based on curcumin [24]. There are a large number of reported metal complexes of curcumin but the metal complexes of Cu(II) and Zn(II) ions have received more attention because of their immense and diverse biological or biomedical applications [25]. The past studies have been reported that the Cu(II) interaction with curcumin, results in the formation of a Cu-curcumin complex and was found with anti-amyloid [26], and
ACCEPTED MANUSCRIPT
anticancer properties [27]. In 2015, metallo-curcumin complexes of Cu(II) and Zn(II) have been successfully synthesized and also tested for their antioxidant properties, the results indicates that the Cu-curcumin complexes is more potent with recyclable activity than Zn-curcumin complex
antimicrobial/antifungal
activity,
antiarthritic,
antiviral,
RI PT
[28]. It can be concluded that the curcumin derived metal complexes possess anticancer, anti-HIV,
biological
imaging/
radioimaging and DNA intercalating properties [29]. In view of these we herein, report the
SC
design and development of a new curcumin derived Schiff base ligand and their transition metal complexes. The synthesized compounds were also examined for their catalytic and biological
M AN U
properties. 2. Experimental 2.1. Materials & methods
The chemical and solvent used in the preparation of Schiff base ligand and their metal complexes
TE D
were of analytical grade and purchased from Merck, excluding curcumin, was procured from Himedia and was used without further purification. The elemental analyses of newly prepared compounds were obtained by Perkin Elmer CHN
EP
2400, (USA) analyzer. Molar conductance of metal complexes were measured by a Systronics type 302 conductivity bridge, equilibrated at 25±0.01oC using one millimolar solutions in
AC C
DMSO. To record the electronic absorption spectra at room temperature in DMSO, UV-vis. Spectrophotometer (Shimadzu-UV-260, with 1 cm quartz cuvettes) was used. Infrared spectra of all the compounds were recorded on Perkin Elmer-2400 FT-IR spectrophotometer using KBr discs in the range of 4000-400 cm-1. 1H NMR of CL and its Zn(II) complex along with 13C NMR of CL were performed on a JEOL GSX-300 MHz FX-1000 spectrometer in DMSO-d6 and TMS (tetramethylsilane, Me4Si) as internal standard. Metal and chloride ions contents were
ACCEPTED MANUSCRIPT
determined by volumetric [30] and gravimetric analysis [31], respectively. Shimadzu thermal analyzer was used for thermal analyses (TGA/DTA) under N2 atmosphere and alumina powder was used as reference. X-ray diffraction (XRD) pattern of ligand and its metal complexes along
RI PT
with different parameters have been collected from Rigaku, Mini Flex II powder diffractometer. Electron paramagnetic resonance (EPR) spectrum of copper complex was recorded on ESDTV4spectrometer at 9.167 GHz at room temperature using DPPH (g =2.0036) as standard. The
SC
WATER Q-TOF premier mass spectrometer with turbo spray was used to determine the mass spectra of CL and their Co(II), Ni(II), Cu(II) and Zn(II) metal complexes. The scanning electron
2.2. Chemistry 2.2.1. Synthesis of ligand (CL)
M AN U
micrographs (SEM) were captured with ‘JEOL JSM-6510LV’ instrument.
Curcumin (0.92 gram, 2.5 mmol) in methanol (30 mL) was stirred under hot conditions for 1 h.
TE D
Amino ethylene piperazine, (AEP) (0.33 mL, 2.5 mmol) was added drops wise to the well stirred curcuminic solution and refluxed for 6 h. After 30 minutes of addition of AEP the colour of the resultant reaction mixture changes from pale yellow to dark brownish in the form of thick
EP
precipitate. Finally, the resultant reaction mixture was evaporated with the help of hot plate up to half of its volume and then leaves it for overnight, filtered with Whatman filter paper wash
AC C
several times with methanol and ether and kept in desiccator overnight. The experimental setup to synthesize the Schiff base ligand, [C27H33O5N3], using curcumin with amino ethylene piperazine is given in Scheme 2. 2.2.2. Synthesis of transition metal complexes In order to obtained the transition metal complexes of CL, a general method have been devised to achieve the appreciable yields using selected metal salts.
ACCEPTED MANUSCRIPT
The metal salt (Co2+, Ni+2, Cu2+ or Zn2+ chlorides) was dissolved in minimum amount of methanol and added drop wise to the hot stirred methanolic solution of CL in 1:1 molar ratio. After successful addition the reaction mixture was left for 4-5 h continuous stirring with reflux.
RI PT
Now the solid compound with changed colour was separated by filtration and washed several time with methanol and ether. The resulting precipitate was left to dry at room temperature, the structural representation of designed complexes are given in Fig. 1. The experimental setup used
SC
to synthesize these metal complexes is given in scheme 2. Obtained yield, composition, color, molar conductance values and empirical formula are tabulated in Table 1.
M AN U
2.2.3. Catalysis
Ligand (CL) and their Co(II), Ni(II), Cu(II) and Zn(II) complexes were tested for their catalytic potential by recording the rate of decomposition of H2O2 with known molarity solution. The test compounds (8.2×10-3-8.4×10-3 mmol) were mixed with 50 mL of hydrogen peroxide (0.15 N) in
TE D
a conical flask with constant (250 rpm) stirring at room temperature. Extent of H2O2 decomposition in the presence of applied compounds was observed by titrating 5 ml aliquots of the reaction mixture solution containing 0.01 M KMnO4 and 0.01 H2SO4 at different time
EP
intervals (each 30 min.; from 0 to 4.5 h). The consumed volume of known molarity solution of KMnO4 for each 30 min. was recorded manually. In addition, the characteristic changes in color
AC C
of the reaction mixture were observed during the reactions with production of small oxygen bubbles. The blank experiment (experiment without a catalyst) was also conducted and it was observed that there is no hydrogen peroxide decomposition under the applied reaction conditions.
ACCEPTED MANUSCRIPT
2.2.4. Antioxidant power study Free radical scavenging ability was performed according to modified Brand-Williams’s protocols as described elsewhere [32]. Freshly prepared stock solutions (1 mg/mL) of CL and their
RI PT
complexes were diluted to a final concentration of 5, 10, 15 and 20 µM in DMSO. The methanolic solution of DPPH (2, 2-diphenyl-1-picrylhydrazyl) (1 mL, 0.3 mmol) was mixed in a beaker with 3.0 mL of CL and metal complex solutions of above mentioned concentrations.
SC
Meanwhile, methanol (1 mL) was added with test samples (3.0 mL) for the preparation of blank solutions. Negative control was made up of DPPH solution (1 mL) and 3 mL DMSO. The
M AN U
solution was kept in an ambient temperature for at least 30 min. and then absorption was recorded at 517 nm. % scavenging ability of test compounds was calculated with the help of below equation:
% Scavenging = [(AB‒AA/AB)] × 100
TE D
where, AB is the absorption of blank sample and AA is the absorption of test samples. The DPPH solution in methanol (1 ml, 0.3 mmol) was used as control. The ascorbic acid was used as positive control.
2.3.1. MTT assay
EP
2.3. Biology/Pharmacology
AC C
MTT assay is a colorimetric assay for determining the cellular growth which reduces the tetrazolium yellow dye (MTT) to an insoluble formazan of purple colour, by the process of mitochondrial dehydrogenases of living cells. Generally, MTT assay is used for determination of cytotoxicity of drugs and newly prepared or other compounds [33, 34]. Three different human cancer cell lines viz. MDA-MB-231, KCL22 and HeLa along with normal cells (PBMCs) were maintained in RPMI-1640 culture media that was supplemented with 10% inactivated fetal
ACCEPTED MANUSCRIPT
serum (FCS) and antibiotic antimycotic solution. These cells were plated with density of 5×103 cells per well in a 96 well plate and cultured for 24 hours at 37oC. Stock solutions of test compounds were prepared in an equimolar mixture of DMSO and THF. All the cells were
RI PT
successively exposed to these compounds. The cell proliferation was measured by addition of 20 µL of MTT dye (5 mg/L in phosphate buffered-saline) per well after 48 hours incubation of the plates. These plates were further incubated for additional 4 hours at 37oC in a humidified
SC
chamber with 5% carbon dioxide. On the reduction of dye by effect of viable cell in each well that was dissolved in 150 µL DMSO the purple formazan crystals were produces and the
M AN U
absorption was noted at 570 nm. The values of absorption were articulated in the form of % cell viability with accordance to the control group taken as 100%. The concentration of test compounds required for 50% inhibition of cell viability is commonly termed as IC50 calculated by graph pad “Prism 3.0” software [35].
TE D
Isolation of blood peripheral mononuclear cell:
Approximately 20 mL of the human blood sample was diluted in 1:1 ratio with phosphate buffer saline (PBS). After successful mixing diluted blood sample coated on Ficoll-Histopaque. The
EP
resulting mixture was centrifuged on 400 rpm for 30 min at 22-24 oC, the uninterrupted lymphocyte layer was successfully transferred out, washed carefully and pelleted with PSB in
AC C
1:3 ratio twice and resuspended RPMI-1640 medium with antibiotic and antimycotic solution 10% v/v fetal calf serum (FCS). The cell counting was done to determine the peripheral blood mononuclear cell (PBMC) numbers with same volume of the trypan blue [36]. 2.3.2. Anthelmintic activity:
Anthelmintic activity of newly prepared compounds of two different concentrations was tested against the earthworms with reported standard protocol [37]. The Indian earthworm worm
ACCEPTED MANUSCRIPT
(Pheretima posthuma) was selected for study because of its resembles anatomically and physiologically with most dangerous parasites commonly known as helminthes and that is why Pheretima posthuma has been frequently used as model animal for anthelminthic property of any
RI PT
compounds [38]. Earthworms of 4-6 cm in length and 2-3 mm in diameter were collected from land with moist soil. The test compound and the standard drug Albendazole were completely dissolved in minimum volume of solvent and make the working solution to 10 ml in volume with
SC
normal saline to make the final concentration of 0.5% w/v and 0.20% w/v, respectively. The group of three earthworms of almost equal length and diameter were taken independently for
M AN U
every concentration and put it in the different petri plates with test compounds, standard drug solution and normal saline as control at room temperature. Time were noted for every individual earthworms to become paralyzed or mortalityzed and the mean paralysis time and mortality time of earthworms for Schiff base ligand (CL), their metal complexes as well as standard drug as
3. Result and discussion
TE D
mean ± S.E.M of three different worms in each group.
Curcumin derived Schiff base ligand (CL) and their Co(II), Ni(II), Cu(II) and Zn(II) complexes
EP
were found stable at room temperature and fairly soluble in DMSO and DMF. Several attempts have been made to crystalize CL and its complexes but we were failed to obtain a single crystal.
AC C
The thermal decomposition patterns of newly synthesized compounds have been inferred by thermo gravimetric and differential thermal analysis (TGA/DTA). The characteristics bands and position in NMR spectra provides confirmatory information about the formation of CL and its complexes. Geometry around Co(II), Ni(II), and Cu(II) after complexation with CL have been confirmed from the position of electronic absorption band in UV-visible spectra, molar conductance and magnetic moment values. Zn(II) complex was found to be diamagnetic and has
ACCEPTED MANUSCRIPT
no any absorption that can ascribed as charge transfer. On the basis of metal to ligand stoichiometry, molar conductance and other data confirm the Zn(II) complex having octahedral geometry. The magnetic moment value, EPR and electronic spectrum of Cu(II) complex confirm
RI PT
a square planar geometry. Crystallinity, unit cell parameter and surface morphology were estimated by XRD and SEM analysis, respectively. Catalytic, antioxidant, anticancer and anthelmintic activity were performed with standard protocols and methodologies as described in
SC
preceding section. 3.1. Molar conductance
M AN U
Molar conductance of prepared curcumin containing Schiff base transition metal complexes were measured in DMSO with 10-3 M solution at room temperature. The recorded values are given in Table 1. The molar conductance values of Co(II), Ni(II), Cu(II) and Zn(II)-CL complexes indicates that these are non-electrolytic nature [39].
TE D
3.2. Infrared spectra
The structural features of the 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (curcumin) derived Schiff base ligand (CL) and their Co(II), Ni(II), Cu(II) and Zn(II) complexes
information, S1.
EP
have been studied by infrared spectroscopy. The detailed discussions are given in supplementary
AC C
3.3. Electronic absorption spectra and magnetic moment: The electronic absorption spectroscopy is a helpful characterization technique to ascertain spatial arrangement of metal ions and it can be used as a supportive technique for metal complex structural investigation. The curcumin derived Schiff base transition metal complexes were found insoluble in common organic solvents viz. methanol, acetonitrile and ethanol and were found partially soluble in chloroform and completely soluble in DMSO and DMF. The UV-
ACCEPTED MANUSCRIPT
visible spectra of CL display main absorption band in the region at 268, 136 (shoulder) and 430 nm. The band at 336 and 265 nm may corresponds to π→π* transition, while the band at 430 nm may corresponds to n→π* transition or a combination of both π→π* and n→π transitions. In all
RI PT
the metal complexes the appearance of these band have been observed with slight shift, indicate the chelation of CL with respective metal ions [40, 41] as illustrated in Fig. 2(a-c). The UVvisible spectral data of newly synthesized compounds and their magnetic moment values are
SC
given in Table 2. The spectra of all these compounds were recorded in one millimolar solution in DMSO.
M AN U
The diffuse electronic spectrum of Co(II) complex was found with three absorption band at 14,925, 16,350 and 29,230 cm-1 that can assigned to the electronic transition: 4T1g→4T2g(F), 4
T1g→4A2g(F) and charge transfer, respectively. The UV-visible absorption bands along with
magnetic moment value (4.52 B.M) suggest a low-spin Co(II) complex with octahedral geometry
TE D
[41, 42]. The value of magnetic moment in case of Ni(II) complexes at room temperature was calculated and found to be 3.12 B.M that is in the range of a high spin electronic configuration. Moreover, the geometry of Ni(II) complex of CL can ascertained by the appearance of three
transitions as:
3
EP
bands in the spectrum at 12,250, 15160 and 20,780 cm-1 assigned to three spin allowed A2g(F)→3T2g(F),
3
A2g(F)→3T1g(F) and
3
A2g(F)→3T1g(P), respectively [42].
AC C
Slightly lower magnetic moment values of the complexes can attribute to antiferromagnetic coupling. In the present study the obtained subnormal (Table 2) value of magnetic moment in case of these complexes ascribed to the presence of a magnetically coupled metal centers, conjugated systems and may due to distortion in geometrical structures [43]. Electronic absorption spectrum of Cu(II) complex display three transitions at 16,550, 30,857 and 40,240 cm-1, the first one can assigned to the transition 2B1g→2A1g while the last two can attribute to
ACCEPTED MANUSCRIPT
charge transfer (intra-ligand). The observed electronic transition and magnetic moment value of 1.49 B.M. suggests a square planar geometry around Cu(II) ion in the complex [44, 45]. 3.4. Mass spectrometry
RI PT
Mass spectrometry is one of the most powerful techniques for the confirmation of any naturally occurring or manually prepared compounds using its isotopic mass. The formation of newly prepared Schiff base ligand (CL) derived from naturally occurring curcumin molecule was
SC
further confirmed by its mass spectrum analysis [Attached as supplementary information, S2]. 3.5. NMR spectroscopy
H NMR (proton nuclear magnetic resonance) spectra of ligand based on curcumin (CL) and its
M AN U
1
Zn(II) complex were recorded in d6-DMSO. The obtained spectra are presented in Fig. 3(a) and (b). The assignment based on chemical shift of CL and [(CL)Zn(H2O)2] in the form of structural formulation are numbered on the basis of downfield chemical shift or increasing chemical shift
TE D
in ppm are also shown in Fig.3(a) and (b), respectively. The interpretation of obtained NMR peaks along with the structure of ligand and its Zinc complex are given in supplementary material, S3.
EP
3.6. Electronic paramagnetic resonance spectra EPR spectrum of Cu(II) complex was recorded in X-band spectrometer (microwave frequency of
AC C
9.1 GHz and field set was 3000 G at modulation frequency of 100 kHz) in DMSO under liquid nitrogen and at room temperature. The EPR spectrum of Cu(II) complex is represented in Fig. 4. The spectrum was recorded in order to confirm the stereochemistry and bonding site of complex along with the determination of magnetic interaction in the metal complex. The spectrum of Cu(II) complex was recorded in the solid state. The obtained EPR spectrum of the Cu(II) complex display well defined single isotropic feature at g// (parallel) value of 2.14 and g﬩
ACCEPTED MANUSCRIPT
(perpendicular) value of 2.07 which is generally associated with square planar geometry of metal ions. It is well known that in case of square planar Cu(II) complexes, the unpaired electron may available in the dx2-y2 orbital producing g// > g┴ > 2, whereas if the unpaired electron available
RI PT
in the dz2 orbital of the pattern of g values follow the trend: g┴> g// >2. perusal of literature data on Cu(II) complex confirm that the unpaired electron is localized in the dx2-y2 orbital with 2B1g ground state [46].
SC
3.7. X-ray diffraction analysis
Since several attempts to obtain single crystal of complexes was unsuccessful, so the crystallinity
M AN U
of these complexes was established X-ray powder diffraction analysis. X-ray diffraction pattern of all the newly prepared compounds were scanned in the range 10–70o at wavelength 1.540 Å. CL and its Co(II), Ni(II) and Zn(II) complexes were found amorphous in nature (noncrystalline). The X-ray diffraction pattern of Cu(II) complex was found with well resolved
TE D
crystalline peaks as given in Fig. 5, which crystallized in a triclinic crystal pattern with P1 space group. The diffractogram of this complex registered 20 reflection peaks in the range of (2ߠ) 0 to 70° with maxima at 17.167° with corresponding ݀ spacing value of 3.4450 Å. The cell
EP
dimensions: a (6.1253 Å), b (9.6362 Å), c (20.4288 Å), ߙ (61.1285°), ߚ (110.2553°), and ߛ (62.7821°) are in good agreement with the refined triclinic crystal system. The particle size was
AC C
calculated by Debye-Scherrer’s formula: D=0.9 λ/ β.cosθ
where, λ is the wavelength of radiation, β is the full width with half maximum (FWHM) of characteristics peak and θ is the diffraction angle of the hkl plane [47, 48]. The average particle size 30.4 nm suggests its nanocrystalline nature.
ACCEPTED MANUSCRIPT
3.8. Scanning electron microscopy (SEM) analysis Powder samples of all the newly prepared compounds were taken onto a carbon tapping copper stubs and coated by gold in the auto fine coater for 30 seconds at 20 mA. The coated samples
RI PT
were mounted into a sample holder for SEM analysis with an accelerating voltage between 15-20 KV. The scanning electron microscopy was used to investigate significant changes in the surface morphology of the complexes after metal ion insertion in the curcumin bearing ligating moiety,
SC
CL. SEM micrographs of CL and their Co(II), Ni(II) and Zn(II) complexes are given in Fig. 6(a-d) and we observed a significant changes in the surface morphology of metal complexes
M AN U
comparing with CL due to insertion of transition metal ion and also differing over changing in metal centers. SEM micrograph of CL (a) demonstrates non-uniform cloudy structure with variable lateral dimensions [49, 50]. Moreover, inhomogeneous matrix with spongy fog like structure has been observed in the SEM micrograph of [(CL)Co(H2O)2] (b) The SEM
TE D
micrograph of [(CL)Ni(H2O)2] (c) displays flattered morphology with small sized grains scattered on solid matrix and gives the appearance of river base like structure. In the SEM micrograph of [(CL)Zn(H2O)2] (d), small sized particles smashed together to give rock-like
EP
structure with a bit cotton-like appearance [49]. 3.9. Thermal (TGA/DTA) studies
AC C
Thermo gravimetric and differential thermal analysis (TGA and DTA) in N2 atmosphere using α–Al2O3 as the reference with heating rate of 20 oC min-1 from ambient to 700 oC have been successfully done. The thermogram of CL exhibits two random weight loss steps while the metal complexes of CL undergo with three or more weight loss steps, the pictorial representation are given in Fig. 7(a-e). In the metal complexes the peak around 200 oC may ascribed to the elimination of coordinated water molecules in Co(II), Ni(II) and Zn(II) complexes, whereas in
ACCEPTED MANUSCRIPT
case of Cu(II) complex this peak arise at ̴ 100 oC, can attributed to the removal of lattice water molecules, confirms the absence of coordinated water molecules in Cu(II) complex of CL. The second weight loss is due to melting of the metal complex, the third step may correspond to the
RI PT
complete decomposition of the complex. Last thermal decomposition step in all the metal complexes is noticed at ̴ 400 °C, which is indicated by the establishment of the horizontal TG curve. This step interprets the formation of stable corresponding metal oxide residue [42]. The
SC
obtained TGA data clearly confirms that the metal complexes are comparatively more stable than the Schiff base ligand (CL).
M AN U
3.10. Catalytic activity
In order to obtain the catalytic activity of newly prepared compounds the decomposition of hydrogen peroxide (H2O2) was used as model reaction to study the catalytic power. Decomposition of H2O2 catalyzed by Schiff base transition metal complexes have been
TE D
monitored by titrating the un-decomposed H2O2 with standard 0.01 M KMnO4 solution. The effect of time on decomposition of H2O2 at a constant concentration (0.15 N) and at constant concentration of metal complexes (8.2 × 10-3 ‒ 8.4 × 10-3 mmol) at 25oC was calculated and the
EP
data is given in Table 3. The obtained results clearly indicate that the metal; complexes decomposes hydrogen peroxide which is in accordance with the previous findings [50] and in
AC C
graphical format is given in Fig. 8. It can conclude that 4.5 hours is optimum reaction time for the decomposition of H2O2 (from 36.5 to 51.5%). The % decomposition of H2O2 in the absence of test metal complexes was only 20% after 24 hours. According to previously reported literature [51] the catalytic decomposition reaction of hydrogen peroxide by metal complexes may propagate by following three step mechanisms (1-3): H2O2
HO2‒ +
H+ ……………. (1)
ACCEPTED MANUSCRIPT
Metal complexes [M = Co(II), Ni(II), Cu(II) or Zn(II)] may interact with anionic species [HO2-] by forming an intermediate complex: M-CL + HO2‒
[M-CL(HO2)]‒ ……………. (2)
RI PT
Finally [M-CL(HO2)‒] may interact with another molecule of H2O2 and produces the following products: [M-CL(HO2)]‒ + H2O2
M-CL + H2O +OH‒+O2……………. (3)
SC
The catalytic decomposition of H2O2 by interaction of metal complex overcomes due to the formation of an intermediate species that bind with the surface of the complex and
M AN U
decomposition of H2O2 initiate, the formation of peroxo species (HO2-) may responsible for enhancement in catalytic power of complexes [50, 51]. 3.11. Antioxidant Activity
Transition metal ions catalyze the oxidation and reduction that can correlate with antioxidant of
TE D
the concerned organism system that makes it biologically important. The different behavior of transition metals usually depends on ionization potential, chemical environment and nature of attached or coordinated ligand. The remarkable antioxidant potential of CL and its transition
EP
metal complexes can explained in the basis of electron donation capability of oxygen atoms and the transition metal ions in their complex from that may responsible for free radical species or
AC C
scavenging of hydroxyl ions. The metal complexes depict enhanced activity due to their ability to act as a free radical acceptor and it is well known observation that the activity increase with increasing the metal complex concentration. For comparison with these test metal complexes the ascorbic acid was used as a standard antioxidant. The results of radical scavenging propensity of CL and its metal complexes at different concentrations (5-15 µM), are given in Table 4, as well as in the form of concentration dependent curve is given in Fig. 9. The results reveal that the CL
ACCEPTED MANUSCRIPT
shows comparatively less scavenging activity as compared to its metal complexes may concluded due to chelation of curcumin bearing organic ligand with the selected transition metal ions [52]. The [(CL)Cu] and [(CL)Zn(H2O)2] were found to possess effective scavenging activity
RI PT
compared to other complexes. The difference in the antioxidant activity of metal complexes may conclude due to coordination environment and their redox properties [53]. The comparative study of CL and their metal complexes confirms the better antioxidant activity of complexes,
SC
which warrant them for their further in-vivo pharmacological evaluation. 3.12. In-vitro cytotoxicity
M AN U
The cytotoxicity of newly prepared compounds against different human cancer cell lines (i.e. MDA-MB-231, KCL22 and HeLa) were assessed by determining the number of viable cells surviving after exposure with aforesaid compounds for stipulated time applying the well-known MTT assay using standard protocols as described briefly in section 2.3.1. In-vitro cytotoxicity
TE D
assay or MTT assay shows a varying cytotoxic potential of CL and their complexes for MDAMB-231, KCL22 and HeLa cell lines which can attribute to the intrinsic anticancer property of the metal complexes. The difference in each complex arise due to change in transition metal i.e.
EP
Co(II), Ni(II), Cu(II) and Zn(II). The dose dependent curves based on the effect of test compounds on cell viability of different human cancer cell lines (MDA-MB-231, KCL22 and
AC C
HeLa) including effect on normal cells (PBMC) are given in Fig. 10(a-e). The experiment reveals that all the test compounds illustrate substantial increase in cytotoxicity on the cell lines with increasing their exposure. The absorption values were expressed as % cell viability, in accordance with control gap taken as 100%. All the experiments were performed in triplicate, independently. The concentration of test compounds required for 50% inhibition of cell viability is termed as IC50 value and was calculated using “Prism 3.0” software. The IC50 of test
ACCEPTED MANUSCRIPT
compounds on each cancer cell lines with normal cell were calculated and the results are summarized in Table 5. The obtained values of IC50 reveal that among all the test compounds CL shows least cytotoxicity as compare to its metal complexes. The metal complexes showed
RI PT
remarkable inhibitory property against tested human cell lines. The IC50 value of metal complexes ranges from moderate to good cytotoxic performances on cancer cell lines. The results confirmed that the [(CL)Co(H2O)2] is more effective against human cervical carcinoma
SC
(HeLa) with IC50 value 13.11±1.80 µM comparing with two other cell lines. The Ni(II) complex is more effective on breast cancer (MDA-MB-231) cell lines with IC50 value 12.11±2.50 in
M AN U
respect to two other cell lines. Among all these compounds the [CuL], exhibits good cytotoxicity against MDA-MB-231 and KCL22, with IC50 values of 09.13±1.18 µM and 09.87±1.95 µM, respectively. These results also confirm that the Zn(II) complex is more effective against human cervical carcinoma (HeLa) cells with IC50 value 12.19±1.52 µM as compare to other test
TE D
compounds. The present study confirms that all these three human cancer cell lines is sensitive to most of the metal complexes. 3.13. Anthelmintic activity
EP
Anthelminthic efficiency of CL and their transition metal complexes against Indian earthworms at two different concentrations are given in Fig. 11 and Table 6. The results indicate that the
AC C
Cu(II) complex has more anthelminthic potential as compare to other complexes against standard drug albendazole [54]. It was observed that the transition metal complexes having higher activity as compare to free ligand (CL) under same experimental conditions which overcome due to chelation [55]. The enhance activity of metal complexes can attribute to the presence of azomethine bond in the chelate ring. Moreover the lipophilic nature of the metal ions favors its penetration through the lipid layer of cell membrane, enhancing its activity. The recorded order
ACCEPTED MANUSCRIPT
of
anthelminthic
activity
of
newly
prepared
compounds
follow
the
trend
as:
[(CL)Cu]>[(CL)Zn(H2O)2]>[(CL)Co(H2O)2]>[(CL)Ni(H2O)2]>L. 4. Conclusion
RI PT
Schiff base ligand, (CL), and their Co(II), Ni(II), Cu(II) and Zn(II) complexes were successfully synthesized and characterize by various spectroscopic techniques. The Co(II), Ni(II) and Zn(II) complexes were found to possess the octahedral geometry while the Cu(II) complex was
SC
confirmed as square planar. The catalytic potential and antioxidant activity of these compounds have been evaluated, the obtained results shows that Co(II) complex is more potent for catalytic
M AN U
power and Cu(II) and Zn(II) complexes have comparatively more antioxidant activity. The complexes during their in-vitro anticancer evaluation, displayed moderate to good cytotoxicity on different cancer cell lines. The most effective compound on cell lines MDA-231 and KCL22 was [(CL)Cu] and on HeLa the most effective compound was [(CL)Zn(H2O)2], comparatively.
TE D
The anthelminthic activity was performed using Pheretima posthuma. The order of anthelminthic activity of CL and its complexes confirms that the copper and zinc complex was comparatively more effective. Ultimately it is comprehensible that the further development of curcumin derived
EP
Schiff base ligand and its transition metal complexes can serve as new template with novel properties in the field of bioinorganic chemistry.
AC C
Acknowledgements:
We wish to thank the Head, Department of Chemistry, Jamia Millia Islamia, New Delhi, for providing necessary research facilities. The Cell Repository-National Centre for Cell Science, Pune (India) for providing cancer cell lines. Author Abdul Kareem wish to acknowledge University Grand Commission (UGC), New Delhi, India, for providing financial support.
ACCEPTED MANUSCRIPT
Reference: [1] S. Wanninger, V. Lorenz, A. Subhan, F.T. Edelmann, Chem. Soc. Rev. 44 (2015) 4986– 5002.
[3] Y. Mawani, C. Orvig, J. Inorg. Biochem.132 (2014) 52–58. [4] P. Gupta, P. Garg, N. Roy, Mol Divers 15 (2011) 733–750.
RI PT
[2] M.I. Khalil, A.M. AL-Zahem, M.M. Qunaibit, Med Chem Res 23 (2014) 1683–1689.
SC
[5] F. Caruso, M. Rossi, A. Benson, C. Opazo, D. Freedman, E. Monti, M.B. Gariboldi, J. Shaulky, F. Marchetti, R. Pettinari, C. Pettinari, J. Med. Chem. 55 (2012) 1072−1081.
M AN U
[6] B.B. Aggarwal, A. Kumar, A.C. Bharti, Anticancer Res. 23 (2003) 363–398. [7] A. Kareem, Laxmi, M. Arshad, S.A.A. Nami, N. Nishat, J. Photochem. Photobiol. B: Biology 160 (2016) 163–171.
[8] R.S. Priya, S. Balachandran, J. Daisy, P.V. Mohanan, Univ J Phys Appl. 3 (2015) 6–16.
TE D
[9] K.I. Priyadarsini, Curr. Pharm. Des. 19 (2013) 2093–2100.
[10] L. Nardo, R. Paderno, A. Andreoni, M. Masson, T. Haukvik, H.H. Tonnesen, Spectroscopy 2 (2008) 187–198.
EP
[11] K. Bairwa, J. Grover, M. Kania, S.M. Jachak, RSC Adv. 4 (2014) 13946–13978. [12] P. Basnet, N. Skalko-Basnet, Molecules 16 (2011) 4567–4598.
1652.
AC C
[13] H. Hatcher, R. Planalp, J. Cho, F.M. Torti, S.V. Torti, Cell. Mol. Life Sci. 65 (2008) 1631–
[14] C. Banerjee, S. Maiti, M. Musta, J. Kuchlyan, D. Banik, N. Kundu, D. Dhara, N. Sarkar, Langmuir 30 (2014) 10834–10844. [15] S. Kundu, U. Nithiyanantham, RSC Adv. 3 (2013) 25278–25290.
ACCEPTED MANUSCRIPT
[16] D.K. Singh, R. Jagannathan, P. Khandelwal, P.M. Abraham, P. Poddar, Nanoscale 5 (2013) 1882–1893. [17] S. Bisht, G. Feldmann, S. Soni, R. Ravi, C. Karikar, A. Maitraand A. Maitra, J.
RI PT
Nanobiotechnol. 5 (2007) 1–18.
[18] X. Fang, L. Fang, S. Gou, L. Cheng, Bioorg. Med. Chem. Lett. 23 (2013) 1297–1301.
[19] (a) X.-Z. Zhao, T. Jiang, L. Wang, H. Yang, S. Zhang, P. Zhou, J. Mol. Struct. 984 (2010)
SC
316–325; (b) T.M. Kolev, E.A. Velcheva, B.A. Stamboliyska, M. Spiteller, Int. J. Quantum Chem. 102 (2005) 1069–1079; (c) S. Sardar, S. Sarkar, M.T. Myint, S. Al-Harthi, J. Dutta, S.K.
M AN U
Pal, Phys. Chem. Chem. Phys. 15 (2013) 18562–18570; (d) P. Kar, S. Sardar, E. Alarousu, J. Sun, Z.S. Seddigi, S.A. Ahmed, E.Y. Danish, O.F. Mohammed, S.K. Pal, Chem.–Eur. J. 20 (2014) 10475–10483.
[20] D. Pucci, A. Crispini, B.S. Mendiguchia, S. Pirillo, M. Ghedini, S. Morelli, L. De Bartolo,
TE D
Dalton Trans. 42 (2013) 9679–9687.
[21] E. Ferrari, R. Benassi, S. Sacchi, F. Pignedoli, M. Asti, M. Saladini, J. Inorg. Biochem. 139 (2014) 38–48.
EP
[22] B. Zebib, Z. Mouloungui, V. Noirot, Bioinorg. Chem. Appl., 2010 (2010) id:292760. [23] S. Daniel, J.L. Limson, A. Dairam, G.M. Watkins, S. Daya, J. Inorg. Biochem. 98 (2004)
AC C
266–275.
[24] A. Valentini, F. Conforti, A. Crispini, A. De Martino, R. Condello, C. Stellitano, G. Rotilio, M. Ghedini, G. Federici, S. Bernardini, D. Pucci, J. Med. Chem. 52 (2009) 484–491. [25] M. H. Leung, D. T. Pham, S. F. Lincoln, T. W. Kee, Phys. Chem. Chem. Phys.14 (2012) 13580–13587.
ACCEPTED MANUSCRIPT
[26] L. Rossi, S. Mazzitelli, M. Arciello, C.R. Capo, G. Rotilio, Neurochem. Res. 33 (2008) 2390–2400. [27] V.D. John, G. Kuttan, K. Krishnankutty, J. Exp. Clin. Cancer Res. 175(21) (2002) 219–224.
RI PT
[28] D. Bagchi, S. Chaudhuri, S. Sardar, S. Choudhury, N. Polley, P. Lemmens, S.K. Pal, RSC Adv., 5 (2015) 102516–102524.
[29] (a) K. Krishnankutty, V.D. John, Synth. React. Inorg. Met.-Org. Chem. 33 (2003) 343–358;
SC
(b) T. Chandrasekar, N. Pravin, N. Raman,Inorg. Chem. Commun. 43 (2014) 45–50; (c) S. Kanhathaisong, S. Rattanaphani, V. Rattanaphani, T. Manyum, Suranaree J. Sci. Technol. 18
M AN U
(2011) 159–165; (d) S.E.H. Etaiw, D.M. Abd El-Aziz, E.H. Abd El-Zaher, E.A. Ali, Acta A 79 (2011) 1331–1337; (e) N. Shahabadi, M. Falsafi, N.H. Moghadam, J. Photochem. Photobiol. B: Biology 122 (2013) 45–51.
[30] A.I. Vogel, A Text Book of Quantitative Inorganic Analysis, 3rd ed., Longmans, 1961.
TE D
[31] C.N. Reilly, R.W. Schmidt, F.A. Sadek, J. Chem. Educ. 36 (1959) 619–626. [32] S.A.A. Nami, M. Alam, A. Husain, M. Parveen, Spectrochim. Acta Part A 96 (2012) 729– 735.
EP
[33] S. Khan, S.A.A. Nami, K.S. Siddiqi, J. Organomet. Chem. 693 (2008) 1049–1057. [34] T. Mosmann, J. Immunol. Methods 65(1-2) (1983) 55–63.
AC C
[35] M. Alam, M.J. Alam, S.A.A. Nami, D.-U. Lee, M. Azam, S. Ahmad J. Mol. Struct., 1108 (2016) 411-426.
[36] S.K. Yeap, N.B. Alitheen, A.M. Ali, A.R. Omar, A.R. Raha, A.A. Suraini, A.H. Muhajir, J. Ethnopharmacol. 114 (2007) 406–411. [37] E.O. Ajaiyeoba, P.A. Onocha, O.T. Olarenwaju, Pharma. Biol. 39 (2001) 217–220. [38] L.C. Garg, C.K. Atal, Indian J. Pharm. Sci. 59 (1963) 240–245.
ACCEPTED MANUSCRIPT
[39] W.J. Geary, Coord. Chem. Rev. 7 (1971) 81–122. [40] Y.M. Song, J.P. Xu, L. Ding, Q. Hou, J.W. Liu, Z.L. Zhu, J. Inorg. Biochem. 103 (2009) 396–400.
RI PT
[41] F.A. Cotton, G. Wilkinson, C.A. Murillo, M. Bochmann, Advanced Inorganic Chemistry, sixth ed., Wiley, New York, 1999.
[42] S.A.A. Nami, A. Husain, I. Ullah, Spectrochim. Acta Part A 118 (2014) 380–388.
Chemistry, vol. 3, Pergamon Press, 1975.
SC
[43] J.C. Bailar, H. Emeleus, J.R. Nyholm, A.F. Dickenson, Comprehensive Inorganic
M AN U
[44] R. Natrajan, K. Antonysamy, C. Thangaraja, Trans. Met. Chem. 28 (2003) 29–36. [45] N. Raman, Y. Pitchaikaniraja, A. Kulandaisamy, Proc. Ind. Acad. Sci. (Chem. Sci.) 113 (2001) 183–189.
[46] E.H. Ismail, D.Y. Sabry, H. Mahdy, M.M.H. Khalil, J. Sci. Res. 6(3) (2014) 509–519.
Lett. 2(4) (2012) 1–7.
TE D
[47] A.A. Al-Amiery, Y.K. Al-Majedy, H.H. Ibrahim, A.A. Al-Tamimi, Organ. Med. Chem.
[48] M.I. Khan, A. Khan, I. Hussain, M.A. Khan, S. Gul, M. Iqbal, I. U. Rahman, F. Khuda,
EP
Inorg. Chem. Commun. 35 (2013) 104–109.
[49] C.J. Dhanaraj, I.U. Hassan, J. Johnson, J. Joseph, R.S. Joseyphus, J. Photochem. Photobiol.
AC C
B: Biology 162 (2016) 115–124.
[50] C.M. Lousada, M. Jonsson, J. Phys. Chem. 114 (2010) 11202–11208. [51] (a) O.A.M. Ali, S.M. El-Medani, D.A. Ahmed, D.A. Nassar, Spectrochim. Acta Part A 144 (2015) 99–106; (b) O.A.M. Ali, Z.H.A. El-Wahab, B.A. Ismail, J. Mol. Struct. 1139 (2017) 175– 195.
ACCEPTED MANUSCRIPT
[52] Y. Zhang, Y. Fang, H. Liang, H. Wang, K. Hu, X. Liu, X. Yi, Yan Peng, Bioorg. Med. Chem. Lett. 23 (2013) 107–111. [53] P. Molyneux, Songklanakarin J. Sci. Technol. 26 (2004) 211–219.
Photochem. Photobiol. B: Biology 142 (2015) 8–19.
RI PT
[54] H. Zafar, A. Kareem, A. Sherwani, O. Mohammad, M.A. Ansari, H.M. Khan, T.A. Khan, J.
[55] C.T. Prabhakara, S.A. Patil, A.D. Kulkarni, V.H. Naik, M. Manjunatha, S.M. Kinnal, P.S.
AC C
EP
TE D
M AN U
SC
Badami, J. Photochem. Photobiol. B: Biology 148 (2015) 322–332.
ACCEPTED MANUSCRIPT
Empirical formula of ligand and complexes (Mol. Wt. g/mol, cal./obtained)
Color / yield %
[C27H33O5N3]
Brown / 74%
—
15
(572.52/569.60)
Dark red / 68%
3
[(C27H35O7N3)Ni] (572.28/570.10)
Light green / 65%
28
4
[(C27H31O5N3)Cu] (541.10/539.70)
Dark green / 66%
5
[(C27H35O7N3)Zn] (578.96/573.90)
Fire brick / 70%
1
C 67.62 (67.62)
N 8.76 (8.76)
56.64 (56.64)
6.16 (6.16)
7.34 (7.34)
10.29 (10.29)
[(CL)Co(H2O)2]
56.67 (56.64)
6.16 (6.16)
7.34 (7.34)
10.26 (10.26)
[(CL)Ni(H2O)2]
32
59.93 (59.93)
5.77 (5.77)
7.77 (7.77)
11.74 (11.74)
[(CL)Cu]
30
56.01 (56.01)
6.09 (6.09)
7.26 (7.26)
11.29 (11.29)
[(CL)Zn(H2O)2]
M AN U
TE D
EP
AC C
[(C27H35O7N3)Co]
M —
Short notation of Ligand & complexes
H 6.94 (6.94)
(479.57/478.11) 2
Elemental analysis (%) found (calcd.)
SC
S. No.
Molar conductance (ohm1cm2mol-1)
RI PT
Table 1. Elemental analysis and physical data of ligand and their metal complexes.
CL
ACCEPTED MANUSCRIPT
Table 2. UV-vis spectral bands assignments and magnetic moments of the complexes Spectral data (cm-1)
CL
37735-23809
T1g→4T2g(F) T1g→4A2g(F) Charge transfer
4
20,780
3
A2g(F)→3T1g(F) 3
A2g(F)→ T1g(P)
M AN U
3
A2g(F)→3T2g(F)
B1g→2A1g Charge transfer Charge transfer
Octahedral/ 3.12 B.M
2
16,550 30,857 40,240
AC C
EP
TE D
[(CL)Cu]
15,160
Octahedral/ 4.52 B.M
SC
3
12,250
Stereochemistry/mag. Mom. ----
π→π* n→π* 4
14925 [(CL)Co(H2O)2] 16503 19250
[(CL)Ni(H2O)2]
Electronic transition
RI PT
Compounds
Square planar/1.49 B.M
ACCEPTED MANUSCRIPT
Concentration of complex (mmol) 8.2 x 10-3
[(CL)Ni(H2O)2]
8.4 x 10-3
[(CL)Cu]
8.3 x 10-3
[(CL)Zn(H2O)2]
8.2 x 10-3
51.50
36.50
AC C
EP
TE D
M AN U
[(CL)Co(H2O)2]
Decomposition of H2O2 (%)
SC
Complexes
RI PT
Table 3. The concentration of metal complexes and % decomposition of H2O2 (0.15 N) at 4.5 h.
49.10
47.70
ACCEPTED MANUSCRIPT Table 4. Antioxidant activity data of ligand (CL) and its metal complexes. The values represent the mean ± standard error mean (SEM), % scavenging activity of the complex taking ascorbic acid as standard. Concentrations in µM
CL
14.3±1.50
17.9 ±1.42
[(CL)Co(H2O)2]
17.9±1.32
20.4±1.25
[(CL)Ni(H2O)2]
18.8±1.61
21.0±2.00
[(CL)Cu]
25.5±1.40
38.9±1.20
[(CL)Zn(H2O)2]
25.2±1.48
L-ascorbic acid (Standard)
41.5 ±1.20
18.9±1.60
28.3±1.48
29.2±1.74 41.2±1.75
38.1±1.18
40.5±1.39
53.6±1.15
53.4 ± 1.29
TE D EP AC C
15 µM
RI PT
10 µM
M AN U
5 µM
SC
Compounds
ACCEPTED MANUSCRIPT Table 5. IC50 values in µM of ligand and its transition metal complexes.
Compounds
MDA-MB-231
KCL22
HeLa
PBMC
29.38±2.60
25.16 ±2.30
22.18±1.74
[(CL)Co(H2O)2]
21.76±0. 62
18.75±1.16
13.11±1.80
51.08±1.54
[(CL)Ni(H2O)2]
12.11±2.50
17.95±1.80
20.10±1.55
55.01±1.80
[(CL)Cu]
09.13±1.18
09.87±1.95
19.39±1.20
54.12±1.30
[(CL)Zn(H2O)2]
13.05±1.14
15.02±1.80
12.19±1.52
52.22±1.38
Doxo
4.18 ± 1.70
6.20 ± 2.50
6.74 ± 2.68
-
FU
2.11 ± 1.94
4.86 ± 2.15
3.68 ± 1.21
-
SC
M AN U
TE D
EP
Doxo = Doxorubicin and FU = 5-Fluorouracil used as reference drugs
AC C
56.35±1.80
RI PT
CL
ACCEPTED MANUSCRIPT
Table 6. Anthelmintic studies of Schiff base ligand (CL) and its metal complexes (1- 4).
0.50
-
CL
6.6
5.8
1
[(CL)Co(H2O)2]
4.2
3.9
2
[(CL)Ni(H2O)2]
5.3
4.2
3
[(CL)Cu]
2.9
2.4
4
[(CL)Zn(H2O)2]
3.2
2.9
5
Albendazole
1.6
6
DMSO
AC C
EP
TE D
--
0.20
0.50
RI PT
0.20
M AN U
S.No. Compounds
Mean death time (minutes) Conc. in % w/v
8.3
7.4
6.3
5.6
6.5
5.9
SC
Mean paralysis time (minutes) Conc. in % w/v
5.1
3.9
6.2
4.6
1.1
3.5
2.9
--
--
--
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
TE D
Fig. 1. (a) Octahedral complexes of cobalt, nickel or zinc and (b) square planar copper complex.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
Fig. 2. UV-vis spectra of (a) curcumin, (b) ligand, (CL), and Co(II) complex.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
Fig. 3. (a) 1H NMR spectrum of curcumin derived ligand (CL) in d6-DMSO.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
Fig. 3. (b) 1H NMR spectrum of Zn(II) complex [(CL)Zn(H2O)2] in d6-DMSO.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
Fig. 3. (c) 13C NMR spectrum of curcumin derived ligand (CL) in d6-DMSO.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
TE D
Fig. 4. EPR spectrum of Cu(II) complex [(CL)Cu].
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
Fig. 5. X-Ray diffraction pattern of Schiff base ligand (CL), and its Cu(II) complex.
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
Fig. 6. SEM photograph of (a): ligand, (b): Co(II), (c): Ni(II) and (d): Zn(II) complexes.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 7. TGA and DTA curves of (a) ligand, (b) Co(II), (c) Ni(II), Cu(II) and Zn(II) complexes.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
TE D
Fig. 8. Effect of time on decomposition of H2O2 with newly prepared complexes at 250C.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
TE D
Fig. 9. Antioxidant activity (%) of newly prepared compounds by using DPPH assay.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 10. Dose dependent curves of CL and its metal complexes on cell viability of MDA-MB231, KCL22 and HeLa cell lines along with normal cells (PBMCs).
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
TE D
Fig. 11. The efficacy of the tested compounds as anthelmintic agent against earthworms at
AC C
EP
0.20% w/v and 0.50% w/v concentrations.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT
Highlights Preparation of Schiff base ligand from curcumin and its transition metal complexes.
•
Characterization by various spectroscopic techniques.
•
TGA/DTA, XRD and SEM images.
•
Comparative study of catalytic potential of synthesized compounds.
•
Antioxidant, cytotoxicity and anthelminthic study.
AC C
EP
TE D
M AN U
SC
RI PT
•
