New biflavonoid and other constituents from Luxemburgia nobilis (EICHL)

Chromatographic fractionation of the organic extracts from the leaves and branches of Luxemburgia nobilis (Ochnaceae) afforded sitosterol, sitosterol-3-O-betaD-glucopyranoside, friedelin, friedelinol, a mixture of triterpenes lupeol, alpha-amyrin and beta-amyrin, rutin, epicatechin, a mixture of two chalcones, 2,4,3', 4'-tetrahydroxychalcone and 2,4,4'-trihydroxychalcone, two known biflavones, amentoflavone and robustaflavone along with a new biflavonoid, 5,7,4'-trihydroxyflavone-(3'-O4''')-5",7"-dihydroxyflavanone. The structures were established from spectral data, including 2D-NMR experiments of the natural substances and of the acetyl and methyl ether derivatives of the new biflavone.