Integrated Enzyme and Computational Screening of Plant-Derived Phytoconstituents as Alpha-Amylase Inhibitors

Alpha-amylase plays a key role in carbohydrate metabolism and is a validated target for managing type 2 diabetes. This study aimed to identify natural α-amylase inhibitors from 16 ethnobotanically important plants. Methanolic extracts were screened for antioxidant and enzyme inhibition activity. Seven extracts showed notable α-amylase inhibition, with inhibitory concentration (IC₅₀) values ranging from 44.7±2 to 313.1±4 μg/mL and antioxidant activity between 17.0% and 40.81%. A total of 122 phytochemicals from the active extracts were subjected to molecular docking against α-amylase (PDB ID: 4GQR), revealing strong binding affinities (-9.4 to -8.0 kcal/mol) for key compounds such as lawnermis acid and apigenin-7-O-rutinoside. The top candidates were further evaluated through 200 ns molecular dynamics simulations. Stability was confirmed by root-mean-square deviation, solvent accessible surface area, radius of gyration, and hydrogen bond analysis, while MMPBSA-based binding free energy calculations supported spontaneous and thermodynamically stable interactions. These findings suggest that the selected phytoconstituents hold promise as natural inhibitors of α-amylase and warrant further in vitro, in vivo, and pharmacokinetic studies for potential development into anti-diabetic therapeutics.