Insight into the alpha-glucosidase inhibitory potentials of Curcuma longa methanolic extracts and phytochemicals: An in vitro and in silico study

Diabetes is a metabolic disease of global concern, causing death due to triggered oxidative and inflammatory complications. Alpha-glucosidase has become a popular drug target for managing diabetes. This study, therefore, investigated the potential of Curcuma longa (Tumeric) rhizome methanolic extract (MECL) to inhibit Alpha-glucosidase and screened its phytochemical library through molecular biology docking for potential new drug candidates. Quantitative phytochemical analysis of MECL showed that the plant extract was abundant with phenols (790.32 ± 129.20 mg/100g), alkaloids (494.99 ± 1.27 mg/100g), flavonoids (171.08 ± 0.04 mg/100g) and terpenoids (131.99 ± 6.59 mg/100g). Moreover, in vitro inhibitory studies showed a dose-dependent increase in the inhibition of alpha-glucosidase by MECL, and the maximum inhibition (37.01%) was observed at 30 µg/ml, possibly a better inhibition with increased concentration. Further scrutiny was performed using molecular docking to screen for Turmeric phytochemicals (retrieved from PubChem) with alpha-glucosidase (PDB ID: 3W37) inhibitory potentials. Based on their binding affinity, the Top three compounds [Guaiacol (-7.422), Eriodictyol (-5.266,) and p-Tolyl-MethylCarbinol (-3.939)] were analyzed for their intermolecular interactions in the binding pocket of alpha-glucosidase and ADMET properties; and compared to the standard drug, Acarbose (-9.522). Interestingly strong and weak interactions, such as hydrogen bonding, pi-pi stacking, and charged and hydrophobic interactions, were observed with Guaiacol in the binding pocket of alpha-glucosidase. Although Acarbose had a better docking score, Guaiacol showed better ADMET (including Physiochemical, drug-likeness, and pharmacokinetic) properties. Future studies could evaluate those potential anti-diabetes drug candidates against other targets and analyze them through in vivo experiments.