Inhibitory Potential of Chemical Constituents from Paeonia suffruticosa Against α-Glucosidase and α-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 ), β-sitosterol ( 5 ), and caffeic acid octadecyl ester ( 6 ). The enzymatic activities of compounds 1-6 were evaluated by in vitro inhibition assay of α-glucosidase and α-amylase. Compounds 1-6 with IC 50 values ranging from 30 to 180 μM inhibited α-glucosidase more efficiently than the standard compound acarbose (IC 50 = 1463.0 ± 29.5 μM). Conversely, these compounds (with IC 50 values ranging from 40 to 200 μM) were less potent against α-amylase compared to acarbose (IC 50 = 16.6 ± 0.9 μM). 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.