Effect of flavonoids from Exellodendron coriaceum (Chrysobalanaceae) on glucose-6-phosphatase.

From the n-butanol extract of the aerial parts of Exellodendron coriaceum (Benth.) Prance the flavonoids quercetin-3-O-beta-D-galactopyranoside (1), quercetin-3-O-alpha-L-arabinopyranoside (2), quercetin-3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-rhamnopyranoside (3), and quercetin-3-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-galactopyranoside (4) were isolated. Additionally from this extract three flavonoids were isolated and partially characterized as quercetin glycosides. All these compounds were tested for their hypoglycemic activity using the glucose-6-phosphatase microsomal hepatic system. The flavonoids inhibited the activity of the enzyme when intact microsomes were used, the highest percentage of inhibition being 65%. To the best of our knowledge, this is the first report of chemical and biological activity of E. coriaceum.