Polyphenols isolated from antiradical extracts of Mallotus metcalfianus

Six flavonoids including two new flavones, luteolin 7-O-(4 ''-O-(E)-coumaroyl)-beta-glucopyranoside), chrysoeriol-7-O-(4 ''-O-(E)-coumaroyl)-beta-glucopyranoside) and a mixture of two pairs of diastereoisomeric flavonolignans, (+/-)-hydnocarpin 7-O-(4 ''-O-(E)-coumaroyl)-beta-glucopyranoside)/(+/-)-hydnocarpin-D 7-O-(4 ''-O-(E)-coumaroyl)-beta-glucopyranoside) with a 2:1 ratio were isolated from the whole plant of Mallotus metcalfianus Croizat, in addition to 10 known compounds. Their structures were evaluated on the basis of different spectroscopic methods, including extensive 1D and 2D NMR spectroscopy. Some extracts have moderate antimicrobial properties and interesting antiradical (DPPH) activity, as well as some compounds isolated from this species. Tannins were also identified in some active extracts. (C) 2008 Elsevier Ltd. All rights reserved.