A new aurone and two rare metabolites from the leaves of Diospyros melanoxylon

A new aurone, 4,6-dihydroxy-2-[α,α-(4-hydroxyphenyl)hydroxy]methylene-3(2H)-benzofuranone (2) and two rare metabolites viz. selin-4(15)-en-1β,11-diol (5) and 5,7-dihydroxy-3-O-β-D-glucopyranosyl-1′′′ → 6′′glucopyranoside-2-{4-hydroxyphenyl}-4H-benzopyran-4-one (6) in addition to the known protocatechuic acid methyl ester (1), quercitin (3) and gallic acid (4) were isolated from the methanol extract of Diospyros melanoxylon leaves. The structures were elucidated by a combination of chemical and spectroscopic analysis. Interestingly, compound 2 was found to exist in both E- and Z-isomeric forms in a 15 : 85 ratio. The present isolation of compounds 2 and 5 assumes taxonomic significance as aurones and sesquiterpenes have not yet been reported from the Diospyros genus, consisting of more than 350 identified species.

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