Hypoglycemic effects and constituents of the barks of Cyclocarya paliurus and their inhibiting activities to glucosidase and glycogen phosphorylase.

The various fractions of the barks of Cyclocarya paliurus were systematically tested for hypoglycemic effects in alloxan-induced diabetic rats. The results showed that the chloroform fraction of the 75% EtOH extract of the barks of this plant exhibited significant blood sugar reducing activity, most of which were significantly higher than that of positive-drug metformin hydrochloride. A new compound, together with nine known compounds, was isolated from the most active fraction. The structure elucidation was based on spectroscopic methods, including two-dimensional NMR experiments (¹H-¹H COSY, HMQC, and HMBC). All of the isolates were evaluated for their α-glycosidase and glycogen phosphorylase inhibitory activities.