Polyphenolic metabolites of Rhamnus disperma

A new quercetin dirhamnoside has been isolated and identified as quercetin 3,4'-di-O-alpha-L-rhamnopyranoside together with 24 structurally known phenolic metabolites from the fruits and aerial parts of Rhamnus disperma for the first time. The known compounds have been characterized as kaempferol 3-O-robinoside, 3-O-rhamninoside, 4'-O-rhamninoside, rhamnocitrin 3-O-rhamninoside, 4'-O-rhamninoside, quercetin 3-O-rhamnoside, 3-O-galactoside, 7-O-galactoside, 3-O-methyl 7-O-galactoside, 3-O-robinoside, 3-O-rhamninoside, rhamnetin 3-O-rhamninoside, rhamnazin 3-O-robinoside, 3-O-rhamninoside, two phenolic acids 2,5-dihydroxybenzoic and protocatechuic acids, a coumarin isofraxetin: three aglycones identified as quercetin 3-methyl ether, eriodictyol and taxifolin, together with five flavonols kaempferol, quercetin, rhamnocitrin, rhamnetin and rhamnazin. The structures of the isolated compounds have been established on the basis of chemical and NMR spectroscopic evidence as well as negative ESI-MS in some cases. (C) 1999 Elsevier Science Ltd. All rights reserved.