New flavonoids and other constituents from Ouratea hexasperma (Ochnaceae)

Chromatographical fractionation of the methanol extract from the branches of Ouratea hexasperma (Ochnaceae) afforded two new flavonoids, 7-O-beta-D-glucopyranosyl-6-(3-methylbut-2- enyl)-5,4'-dihydroxyflavanonol (6-beta,beta-dimethylallylaromadendrin-7-O-beta-D-glucoside)and 7-O-beta-D-glucopyranosyl-6-(3-methylbut-2-enyl)-3,5,4'-trihydroxyflavone (6-beta,beta-dimethylallylkaempferol-7-O-beta-D-glucoside) besides a mixture of sitosterol and stigmasterol, lupeol, sitosterol-3-O-beta-D-glycopyranoside and 2,4-dihydroxyphenylacetic acid. The structures were established by analysis of IR, ESI-MS, and NMR spectra of the natural substances, and those of the dimethyl ether and peracetyl-derivatives of the new flavone, as well as comparison with literature values.