Antihyperglycemic effects of N-containing sugars from Xanthocercis zambesiaca, Morus bombycis, Aglaonema treubii, and Castanospermum australe in streptozotocin-diabetic mice

The aqueous MeOH extract of the leaves and root of Xanthocercis zambesiaca (Leguminosae) and eight structurally related nitrogen-containing sugars, fagomine (1), 4-O-β-D-glucopyranosylfagomine (2), 3-O-β-D- glucopyranosylfagomine (3), 3-epifagomine (4), 2,5-dideoxy-2,5-imino-D- mannitol (5), castanospermine (6), α-homonojirimycin (7), and 1- deoxynojirimycin (8) were evaluated for antihyperglycemic effects in streptozotocin (STZ)-diabetic mice. The insulin-releasing effects of 1 were also investigated. The blood glucose level fell after ip injection of the extract (50 mg/kg). Compounds 1, 2, 5, and 6 reduced the blood glucose level after ip injection of 150 μmol/kg. Compound 1 increased plasma insulin level in STZ-diabetic mice and potentiated the 8.3-mM glucose-induced insulin release from the rat isolated-perfused pancreas. The 1-induced potentiation of insulin release may partly contribute to antihyperglycemic action.