Fagomine Isomers and Glycosides from Xanthocercis zambesiaca

Abstract

50% aqueous MeOH extracts from the leaves and roots of Xanthocercis zambesiaca (Leguminosae) were subjected to various ion-exchange column chromatographic steps to give fagomine (1), 3-epi-fagomine (2), 3,4-di-epi-fagomine (3), 3-O-β-d-glucopyranosylfagomine (4), and 4-O-β-d-glucopyranosylfagomine (5). Their structures were determined by spectroscopic analyses, particularly by extensive 1D and 2D NMR studies. Compounds 3 and 4 are new natural products. Compound 1 is a good inhibitor of isomaltase and certain α- and β-galactosidases. Whereas 2 is a more potent inhibitor of isomaltase and β-galactosidases than 1, it does not inhibit α-galactosidase. Compounds 3−5 exhibited no significant inhibition against the glycosidases used.