Phytochemical analysis and antioxidant potential of the leaves of Garcinia travancorica Bedd.

Phytochemical analysis of the leaves of Garcinia travancorica, a hitherto uninvestigated endemic species to the Western Ghats of south India, resulted in isolation and characterisation of the polyisoprenylated benzophenones 7-epi-nemorosone (1) and garcinol (2) along with biflavonoids GB-1a (3), GB-1 (4), GB-2 (5), morelloflavone (6) and morelloflavone-7-O--d-glycoside or fukugiside (7). The compounds were identified using various spectroscopic techniques, mainly through NMR and MS. The methanol extract and the biflavonoids 3, 4, 5 and 7 showed potential in vitro antioxidant activities. The IC50 value of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of compound 7 was 8.34 +/- 2.12g/mL, comparable to that of standard ascorbic acid (3.2 +/- 0.50g/mL). In the superoxide radical scavenging assay, compound 7 gave IC50 value of 6.95 +/- 1.33g/mL close to standard ascorbic acid with IC50 value of 5.8 +/- 0.25g/mL. Validated HPTLC estimation revealed G. travancorica as a rich source of morelloflavone-7-O--d-glycoside (7.12% dry wt. leaves).