Isoflavonoids from the Root Bark of Piscidia erythrina and a Note on the Structure of Piscidone

Abstract
A methanolic extract of Piscidia erythrina root bark has been found to contain various isofla-vonoids including rotenone (rotenoid), lisetin (coum aronochrom one) and six known isoflavones (ichthynone, piscidone, piscerythrone, 2′-deoxypiscerythrone, 6′-prenylpiscerythrone and 3′,5′-diprenylgenistein). The extract additionally yielded three new 5-hydroxyisoflavones (piscery-thrinetin, 2′-hydroxypiscerythrinetin and isow ighteone) and a previously unreported coum arono­ chrom one (8-prenyl-lisetin). All four com pounds were identified using a com bination of spectro­ scopic (UV , MS, 1H NMR) and chemical methods. Although several other 5-hydroxyisoflavones were also isolated from the root bark extract, the quantities of each were sufficient only to permit their partial characterization. Structure 2 for piscidone has been confirmed by 1H NMR spectros­ copy.