Phenolics from Bidens bipinnata and their amylase inhibitory properties

A new chlorinated flavonoid, 3, 6, 8-trichloro-5, 7, 3', 4'-tetrahydroxyflavone (1), a new biscoumaric acid derivative, 4-O-(2 '', 3 ''-O-diacetyl-6 ''-O-p-coumaroyl-beta-D-glucopyranosyl)-p-coumaric acid (2), and 8, 3', 4'-trihydroxyflavone-7-O-beta-D-glucopyranoside (3) together with twenty-four known compounds (4-27) were isolated from the whole plant of Bidens bipinnata. All chemical structures were established on the basis of UV-, MS- and NMR (H-1, C-13, H-1-H-1 COSY, HMQC and HMBC) spectroscopic data. Some of the isolated compounds were tested for the inhibition of alpha-amylase. The result showed that isookanin (6) was a potent inhibitor of alpha-amylase (IC50 = 0.447 mg/ml). (C) 2012 Elsevier B.V. All rights reserved.