Isolation and Structure modification of Oxyresveratrol from Artocarpus Lakoocha for Tyrosinase inhibitory activity

Abstract

Oxyresveratrol (2, 4, 3’, 5’-tetrahydroxystillbene), a major compound found in the heartwood of artjocarpus lakoocha roxb. (moraceae), has been known for its potent tyrosinase inhibitory activity. this study focused primarily on the isolation and strcture modification of oxyresveratrol for tyrosinase inhibitory activity. for the isolation experiments. it was found that the eyoh-soxhlet extraction method gave the highest yield of crude oxyresveratrol, and al2 o3 was a good adsorbent for separation of the obtained extract. an analytical method using reverse-phase high performance liquid chromatography was developed. the method was validated on the parameters for accuracy, precision, linearity, limit of detection and limit of quantitation. the method was used for quantitative determination of oxyresveratrol in plant extracts and puag-haad. the results were satisfactory and reliable. thirteen derivatives of oxyresveratrol have been prepared, and their anti-tyrosinase activity was determined. almost all of the analogues prepared in this study were devoid of activity, but dihydrooxyresveratrol showed potent activity than did the parent compound and kojic acid, a strong tyrosinase inhibitor widely used in cosmetic products. kinetic studies on the enzyme indicated that dihydrooxyresveratrol had higher affinity to tyrosinase than two compounds. dihyrooxyresverattrol, similar to oxyresveratrol, showed non-competitive inhibition while kojic acid was a mixed-type inhibitor. additionally cytotoxicity studies were performed on the o-methylated compounds using kb, bc and nci-h187 cancer cells. cis-tetra-o-methylated oxyresveratrol showed strong cytotoxicity, with potency comparable to those of ellipticine and doxyrubicin. the findings in this study suggest that oxyresveratrol could be a good source of starting material for the development of whitening agents and anticancer drugs.