molecules Article
Study on Chemical Profile and Neuroprotective Activity of Myrica rubra Leaf Extract Pinghong Chen 1,2,† , Xianzong Lin 1,† , Ching-Hsu Yang 3,† , Xu Tang 2 , Yu-Wei Chang 4 , Weibing Zheng 5 , Lianzhong Luo 1,6 , Changan Xu 2, * and Yung-Husan Chen 1,6,7, * ID 1 2 3 4 5 6 7
* †
Department of Pharmacy, Xiamen Medical College, Xiamen 361023, China;
[email protected] (P.C.);
[email protected] (X.L.);
[email protected] (L.L.) Engineering Research Center of Marine Biological Resource Comprehensive Utilization, Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China;
[email protected] Fineboon Dairy Nutrition Institute, Shanxi Dairy Co., Ltd., Xianyang 712000, China;
[email protected] Department of Food Science, National Taiwan Ocean University, Keelung 202, Taiwan;
[email protected] Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China;
[email protected] Xiamen Key Laboratory of Marine Medicinal Natural Products and Cell Engineering, Xiamen Medical College, Xiamen 361008, China Key Laboratory for Dao-Di Herbs Biotechnology of Fujian Province, Xiamen Medical College, Xiamen 361023, China Correspondence:
[email protected] (C.X.);
[email protected] (Y.-H.C.); Tel.: +86-139-5013-8631 (C.X.); +86-133-1385-7670 (Y.-H.C.) These authors contributed equally to this work.
Received: 7 June 2017; Accepted: 18 July 2017; Published: 24 July 2017
Abstract: The chemical profile of Myrica rubra (a native species in China) leaf extract was investigated by UPLC-PDA-HRMS, and the neuroprotective activity of two characteristic constituents, myricanol and myricetrin, was evaluated with N2a cells using H2 O2 -inducedoxidative challenge through a series of methods, e.g., MTT assay, ROS assay and [Ca2+ ]i assay. Among the 188 constituents detected in the extract of Myrica rubra leaf, 116 were identified definitely or tentatively by the comprehensive utilization of precise molecular weight and abundant multistage fragmentation information obtained by quadrupole orbitrap mass spectrometry. In addition, 14 potential new compounds were reported for the first time. This work established an example for the research of microconstituents in a complex analyte and revealed that suppression of H2 O2 -induced cytotoxicity in N2a cells was achieved by the pretreatment with myricanol. The evidence suggested myricanol may potentially serve as a remedy for prevention and therapy of neurodegenerative diseases induced by oxidative stress. Keywords: UPLC-PDA-HRMS; Myrica rubra; neuroprotective activity
1. Introduction Myrica rubra is a subtropical perennial plant belonging to the Myricaceae genus [1], and widely distributed in the east of Asia, e.g., China, Japan and Korea. For a long period of time, it had been used as traditional medicine for the treatment of skin diseases and diarrhea [2]. Moreover, it could be taken orally for traumatic injury, bone fracture, diarrhea, stomach and duodenal ulcer in ethno-medicine [3]. Various phytochemicals isolated from the leaves of Myrica rubra have been extensively investigated and generally reported to show numerous bioactivities, such as melanin synthesis-inhibitory [4], antitumor [5], and anti-influenzavirus activity [6]. However, there had been little information concerning the possible neuroprotective activity of Myrica rubra. Molecules 2017, 22, 1226; doi:10.3390/molecules22071226
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Molecules 2017, 22, 1226
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A comprehensive chemical profile of Myrica rubra has not been reported. Instead, there are some reports focused on its low polarity constituents—sesquiterpenes—and their pharmacological activities [7,8]. Considerable research has been directed towards the identification and characterization of anthocyanins and flavonols [9,10], aiming at the discovery of constituents with radical scavenging activity, especially for the major ones which are easy to isolate and purify. Nevertheless, its microconstituents which may play an important role in the biological system still need to be discovered. Consequently, a sensitive tool should be applied to achieve this goal which calls for little amounts of analytes. UPLC-PDA-HRMS is an emerging technology widely used to analyze complex samples, owing to its high resolution and sensitivity. It not only provides exact mass values (
