Antioxidant phenylpropanoid-substituted epicatechins from Trichilia catigua

Two new phenylpropanoid-substituted epicatechins, namely, catiguanin A (1) and catiguanin B (2), were isolated from the bark of Trichilia catigua along with four known compounds, cinchonain Ia (3), cinchonain Ib (4), cinchonain Ic (5), and cinchonain Id (6). The structures of 1 and 2 were elucidated by analysis of spectroscopic data and by comparison of their NMR data with those of previously reported cinchonains. The isolated compounds exhibited potent antioxidant activity in the alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical scavenging test, with IC50 values in the 2.3-9.4 mu M range.