Smilax aristolochiifolia Root Extract and Its Compounds Chlorogenic Acid and Astilbin Inhibit the Activity of α-Amylase and α-Glucosidase Enzymes

Regulating activities of alpha-amylase and alpha-glucosidase through the use of specific inhibitors is a main strategy for controlling type 2 diabetes. Smilax aristolochiifolia root decoctions are traditionally used in Mexico as hypoglycemic and for weight loss, but the active principles and mechanisms underlying such putative metabolic effects are yet unknown. Here, we isolated the major bioactive compounds from a hydroethanolic extract of S. aristolochiifolia root by fast centrifugal partition chromatography and evaluated their effects against pancreatic alpha-amylase and yeast alpha-glucosidase. Achlorogenic acid-rich fraction (CAF) inhibited alpha-amylase activity with an IC50 value of 59.28 mu g/mL in an uncompetitive manner and alpha-glucosidase activity with an IC50 value of 9.27 mu g/mL in a noncompetitive mode. Also, an astilbin-rich fraction (ABF) inhibited alpha-glucosidase activity with an IC50 value of 12.30 mu g/mL, in a noncompetitive manner. CAF inhibition alpha-amylase was as active as acarbose while both CAF and ABF were 50-fold more potent inhibitors of alpha-glucosidase than acarbose. The molecular docking results of chlorogenic acid and astilbin with alpha-amylase and alpha-glucosidase enzymes correlated with the inhibition mechanisms suggested by enzymatic assays. Our results prove that S. aristolochiifolia roots contain chlorogenic acid and astilbin, which inhibit carbohydrates-hydrolyzing enzymes, suggesting a new mechanism for the hypoglycemic effect reported for this plant.