Phenolic constituents from stem bark of Erythrina poeppigiana and their inhibitory activity on human glyoxalase I

A novel isoflavone, erythgianin A ( 1 ), along with nine known compounds 2 – 10 , was isolated from the stem bark of Erythrina poeppigiana (Leguminosae). The unusual isoflavone structure of 1 , possessing a highly oxidized 3″,4″-dihydroxy-2″-hydroxymethyl-2″-methyl-2″,3″-dihydropyrano substituent, was determined on the basis of spectroscopic analyses. All of the isolated compounds were evaluated for their in vitro inhibitory activity toward human glyoxalase I. Among the isolates, isolupalbigenin ( 10 ) with two prenyl groups showed the highest inhibitory activity.