Flavonol tetraglycosides and other constituents from leaves of Styphnolobium japonicum (Leguminosae) and related taxa

Two flavonol tetraglycosides comprising a trisaccharide at C-3 and a monosaccharide at C-7 were isolated from the leaves of Styphnolobium japonicum (L.) Schott and characterised as the 3-O-alpha-rhamnopyranosyl(1 -> 2)[(alpha-rhamnopyranosyl(1 -> 6)]-beta-glucopyranoside7-O-alpha-rhamnopyranosides of quercetin and kaempferol. The 3-O-alpha-rhamnopyranosyl(1 -> 2)[alpha-rhamnopyranosyl(1 -> 6)]-beta-galactopyran oside-7-O-alpha-rhamnopyranoside of kaempferol, the 3-O-alpha-rhamnopyranosyl(1 -> 2)[alpha-rhamnopyranosyl(1 -> 6)]-beta-glucopyranosides of kaempferol and quercetin and the 3-O-alpha-rhamnopyranosyl(1 -> 2)[alpha-rhamnopyranosyl(1 -> 6)]-p-galactopyranoside of kaempferol were also obtained from this species for the first time. Some or all of these flavonol tetra- and triglycosides were detected in 17 of 18 specimens of S. japonicum examined from living and herbarium material, although the most abundant flavonoid in the leaves was generally quercetin 3-O-alpha-rhamnopyranosyl(1 -> 6)-p-glucopyranoside (rutin). The triglycosides, but not the tetraglycosides, were detected in herbarium specimens of Styphnolobium burseroides M. Sousa, Rudd & Medrano and Styphnolobium monteviridis M. Sousa & Rudd, but specimens of Styphnolobium affine (Torrey & A. Gray) Walp. contained a different profile of flavonol glycosides. The flavonol tetra-and triglycosides of S. japonicum were also present in leaves of Cladrastis kentukea (Dum. Cours.) Rudd, a representative of a genus placed close to Styphnolobium in current molecular phylogenies. An additional constituent obtained from leaves of Styphnolobium japonicum was identified as the maltol derivative, 3-hydroxy-2-methyl-4H-pyran-4-one 3-O-(4'-O-p-coumaroyl-6'-O-(3-hydroxy-3-methylglutaroyl))-beta-glucopyranoside. (C) 2007 Elsevier Ltd. All rights reserved.