Studies on the constituents of Cyclanthera pedata fruits: Isolation and structure elucidation of new flavonoid glycosides and their antioxidant activity

The isolation of six flavon glycosides (1-6), among them four new natural c ompounds (1-4), from the CHCl3/MeOH extract of the fruits of Cyclanthera pe data is reported. All of the structures were elucidated by spectroscopic me thods, including the concerted application of one-dimensional (H-1, H-1 TOC SY, C-13, and C-13 DEPT-NMR) and two-dimensional NMR techniques (DQF-COSY, HSQC, and HMBC). For all of the isolated compounds the antioxidant activity was determined by measuring the free radical scavenging activity, using th e Trolox equivalent antioxidant capacity (TEAC) method, and the coupled oxi dation of beta -carotene and linoleic acid.