A New Class of Biflavonoids: 2′-Hydroxygenistein Dimers from the Roots of White Lupin

Abstract

Two novel isoflavonoid dimers presumably originating from 2′-hydroxygenistein, 5,7,4′- trihydroxycoumaranochroman-4-one-(3→5″)-5′,7′,2″,4″-tetrahydroxyisoflav- one (1, lupinal- bisone A) and 5,7,4′-trihydroxycoumaranochro-man-4-one-(3→6′)-5′,7′,2'′,4″-tetrahydroxy- isoflavone (2, lupinalbisone B) were isolated from the roots of Lupinus albus L., and their structures involving relative stereochemistry were elucidated by spectroscopic methods. Using horse radish peroxidase and 2′-hydroxygenistein (3) as the substrate revealed the formation of these dimers together with 5,7,4′-trihydroxycoumaronochromone (4, lupinalbin A). Dimerization of 3 caused a remarkable increase of antifungal activity. © 2000, Verlag der Zeitschrift für Naturforschung. All rights reserved.