Flavonol pentaglycosides of Cordyla (Leguminosae : Papilionoideae : Swartzieae): Distribution and taxonomic implications

A survey of foliar flavonoids in the swartzioid legume genus Cordyla s.l. revealed that three species, C. haraka, C pinnata and C. richardii, were rich in flavonol pentaglycosides. Their structures were elucidated by spectroscopic and chemical methods as the 3-O-alpha-L-rhamnopyranosyl(1 -> 3)-alpha-L-rhamnopyranosyl (1 -> 2)[alpha-L- rhamnopyranosyl(1 -> 6)]-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranosides of quercetin and kaempferol (cordylasins A and B, respectively). These compounds were not found in the remaining species, C africana, C densiflora, C madagascariensis (two subspecies) and C. somalensis, which exhibited different profiles of flavonoid glycosides. The distribution of flavonol pentaglycosides in Cordyla s.l. does not support a recent proposal to place both C haraka and C madagascariensis in the genus Dupuya [Kirkbride, J.H., 2005. Dupuya, a new genus of Malagasy legumes (Fabaceae). Novon 15, 305-314]. The generic relationship between Cordyla s.l. and Mildbraediodendron is also reassessed on the basis of chemical characters, as the O-linked tetrasaccharide that characterises cordylasins A and B is the same as that found in mildbraedin (kaempferol 3-O-alpha-L-rhamnopyranosyl(1 -> 3)-alpha-L-rhamnopyranosyl(1 -> 2)[alpha-L-rhamnopyranosyl(1 -> 6)]-beta-D-galactopyranoside), the main foliar flavonoid of Mildbraediodendron excelsum. Mildbraedin itself was found to be a minor constituent of leaflet extracts of C. haraka, C pinnata and C. richardii, and a major constituent of C. somalensis. (C) 2008 Elsevier Ltd. All rights reserved.