Two New Pyranoflavanones from the Stems Derris reticulata

Abstract

Two new flavonoids, 4′,5-dihydroxy-8-hydroxymethyl-6′′,6′′dimethylpyrano[2′′,3′′:7,6]flavanone (1), and 2′′,3′′-dihydroxylupinifolin (2) were isolated from the stems of Derris reticulata.Both compounds showed cytotoxic activity in the P-388 cell line.The structures were established by spectroscopic analysis and chemical transformations.The biosynthetic origin and the mechanism of formation of the hydroxymethyl group in compound (1) are proposed.The Leguminosae is known to be a rich source of flavonoids and most of the prenyl derivatives have been found in this family. 1,2The flavonoids exhibit diverse biological activities and recent interest has been focussed on their medicinal and nutritional values. 3Recently, some biologically active prenylated flavonoids have been reported 4-6 and, significantly, it was found that the prenyl groups on the flavonoid skeleton play an important role in anti-HIV activity. 7Derris reticulata (Leguminosae) is a well known Thai herbal medicine used for the relief of thirst and as an expectorant.Previously, we have reported the isolation and structural characterization of four prenylated flavanones, lupinifolin, 2′′′,3′′′epoxylupinifolin, dereticulatin, 8 and 1′′′-hydroxy-2′′′,3′′′-epoxylupinifolin from the stems of Derris reticulata. 9Further investigation of this herb has led to the isolation of two new cytotoxic flavonoids, 4′,5-dihydroxy-8-hydroxymethyl-6′′,6′′-dimethylpyrano[2′′,3′′:7,6]flavanone (1), and 2′′,3′′-dihydroxylupinifolin (2).In this report we present the isolation, structure determination, and biological evaluation of these two new compounds.Compound (1) was obtained as a yellow solid, mp 141-142 °C, [α] D -18.2°(c 0.12, CHCl 3 ).The UV