Antioxidant principles from Bauhinia tarapotensis

A new cyclohexenone (1) and a new caffeoyl ester derivative (2), together w ith the known compounds (-)-isolariciresinol 3-alpha -O-beta -D-glucopyrano side (3), (+)-1-hydroxypinoresinol 1-O-beta -D-glucopyranoside (4), isoacte oside (5), luteolin 4'-O-beta -D-glucopyranoside (6), and indole-3-carboxyl ic acid (7), were isolated from the leaves of Bauhinia tarapotensis. The st ructures of these new compounds were determined by spectroscopic data analy sis. The antioxidant activities of 1-7 were determined by measuring their f ree radical scavenging effects, using the 1,1-diphenyl-2-dipicrylhydrazyl f ree radical (DPPH) and Trolox equivalent antioxidant activity (TEAC) method s, and the coupled oxidation of beta -carotene and linoleic acid. Compounds 3-5 showed good activities in the DPPH and TEAC tests, while compounds 1 a nd 2 were active in the coupled oxidation of beta -carotene and linoleic ac id bioassay.