Inhibitory Potential of Chemical Constituents from Paeonia suffruticosa Against [alpha]-Glucosidase and [alpha]-Amylase

Phytochemical study of the root bark of Paeonia suffruticosa plant led to the isolation and characterization of paeoniflorigenone (1), benzoylpaeoniflorin (2), betulinic acid (3), oleanolic acid (4), [beta]-sitosterol (5), and caffeic acid octadecyl ester (6). The enzymatic activities of compounds 1-6 were evaluated by in vitro inhibition assay of [alpha]-glucosidase and [alpha]-amylase. Compounds 1-6 with IC.sub.50 values ranging from 30 to 180 [mu]M inhibited [alpha]-glucosidase more efficiently than the standard compound acarbose (IC.sub.50 = 1463.0 ± 29.5 [mu]M). Conversely, these compounds (with IC.sub.50 values ranging from 40 to 200 [mu]M) were less potent against [alpha]-amylase compared to acarbose (IC.sub.50 = 16.6 ± 0.9 [mu]M). Kinetic analysis showed that compound 1 was a mixed-type inhibitor, compounds 3 and 4 were noncompetitive inhibitors, while compound 6 was an uncompetitive inhibitor of glucosidase.