Thesis (M.A. in Pharm)--Chulalongkorn University, 1999

Phytochemical studies of Fissistigma polyanthoides (DC.) Merr. and Ochna integerrima (Lour.) Merr. have resulted in the isolation of four flavonoids. A known flavonoid named 5,8-dihydroxy-6,7-dimethoxyflavone was isolated from the stem bark of F.polyanthoides, while three new flavonoids, namely 6-gamma,gamma-dimethylallyl taxifolin 7-O-beta-D-glucoside, 2",3"-dihydroochnaflavone and 2",3"-dihydroochnaflavone 7"-O-methyl ether were isolated from the leaves of O.integerrima. In addition, the structure of a previously alkaloid isolated from F.polyanthoides (ALK1) was revised. The structures of these compounds were determined by analysis of their spectroscopic data and chemical evidence, as well as comparison with the data of other related compounds. All of the isolated flavonoids were tested for their tyrosinase inhibitory activity, but none of them showed activity.