Bioactive phenolics from artocarpus gomezianus and millettia erythrocalyx

Abstract

Phytochemical study of the roots of Artocarpus gomezianus Wall. Ex Tree. led to the isolation of a new dimeric stilbene, namely, artogomezianol, together with the known stilbene dimer andalasin A. From the stem bark of Millettia erythrocalyx Gagnep., 3 new compounds, namely, millettocalyxins A-C, and two new natural products pongol methyl ether and 2'-hydroxy-3,4-methylenedioxy-4'-gamma,gamma-dimethylallyloxychalcone were isolated, along with 14 other known compounds. The known compounds are derricidin, 7-( gamma,gamma -dimethylallyloxy)flavanone, ponganone I, karanjin, milletenone, ovalifolin, milletenin C, 3',4'-methylenedioxy-7-methoxyflavone, pongaglabrone, prunetin, vicenin II, isovitexin, lupeol, and dihydrophaseic acid-4'-O-beta-D-glucopyranoside. The roots of M. erythrocalyx Gagnep. yielded 2 new compounds, 6-methoxy-[2'',3'':7,8]-furanoflavanone and 2,5-dimethoxy-4-hydroxy-[2'',3'':7,8]-furanoflavan, and the new natural product 3,4-methylenedioxy-2',4'-dimethoxychalcone, together with 10 other known flavonoids, i.e. 1-(4-hydroxy-5-benzofuranyl)-3-phenyl-2-propen-1-one, derricidin, purpurenone, pongaglabol, ponganone I, pongamol, ovalitenone, milletenone, ponganone V and lanceolatin B. The structures of all of these isolates were determined by extensive spectroscopic studies, including comparison of their UV, IR, MS and NMR properties with previously reported data. Each of these compounds was evaluated for its tyrosinase inhibitory activity, free radical scavenging activity and anti-herpes simplex virus (HSV-1 and HSV-2) effect. It was found that the stilbene dimers artogomezianol and andalasin A from A. gomezianus were moderate tyrosinase inhibitors and moderate free radical scavengers. In addition, andalasin A showed strong activity against HSV-2 but moderate activity against HSV-1. All of the compounds from M. erythrocalyx were devoid of tyrosinase inhibitory activity. Most of them showed weak free radical scavenging activity and weak activityagainst herpes simplex viruses except for 4 flavonoids, including ovalifolin, pongol methyl ether, millettocalyxin A and prunetin, which showed moderate activity against both types of herpes simplex virus.