Homoisoflavanones from Ledebouria floribunda

Abstract

The bulbs of Ledebouria floribunda (Baker) Jessop have yielded two novel compounds, 7-O-[alpha-rhamnopyranosyl-(1-->6)-beta-glucopiranosyl]-5-hydroxy-3-(4-methoxybenzyl)-chroman-4-one (1) and 7-O-[alpha-rhamnopyranosyl-(1-->6)-beta-glucopiranosyl]-5-hydroxy-3-(4'-hydroxybenzyl)-chroman-4-one (2) along with five other known compounds, 5,7-dihydroxy-3-(4'-methoxybenzyl)-chroman-4-one or 3,9-dihidroeucomin (3), 5,7-dihidroxy-6-methoxy-3-(4'-methoxybenzyl)-chroman-4-one (4), 5,7-dihidroxy 3-(4'-hydroxybenzyl)-chroman-4-one or 4,4'-demethyl-3,9-dihydropuctatin (5), 5,7-dihidroxy-3-(4'-hydroxybenzyl)-6-methoxy-chroman-4-one or 3,9-dihydroeucomnalin (6) and 7-hydroxy-3-(4'-hydroxybenzyl)-5-methoxy-chroman-4-one (7). Their structures were elucidated by spectra analysis. The seven homoisoflavanones were found to be antioxidant against DPPH radical and beta-carotene/linoleic acid system.