Identification of natural curcumins as potential dual inhibitors of PTP1B and α-glucosidase through experimental and computational study

Abstract

Curcuma longa is a rich source of curcumin (1) and its major analogs, demethoxycurcumin (2), and bisdemethoxycurcumin (3), among the Curcuma species. In this study, curcumins (1–3) were purified from C. longa, and their inhibitory effects against protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase enzymes were assayed. These compounds potential inhibited PTP1B and α-glucosidase activities with IC₅₀ values ranging from 37.8 to 72.6 μM, and 78.2–90.6 μM, respectively. In addition, density functional theory (DFT) accompanied by molecular docking (MD) were employed to analyze the ligand stability and the interaction of curcumins 1–3 with PTP1B and glucoside hydrolase proteins. The assay-based results and MD data obtained showed a high correlation, suggesting that the deterioration of enzyme activity caused by the distortion of the structural conformation of PTP1B and glucoside hydrolase may be related to the arrangement of amino acids in the protein structure. Our findings reveal the significant role of methoxylation in the variation of inhibitory effects of these curcumins against PTP1B and α-glucosidase. These in vitro and in silico activities of curcumins (1–3) against PTP1B and glucoside hydrolase have been examined and reported for the first time.