Experimental and theoretical exploration of biological activities of different extracts of Equisetum arvense: Enzyme inhibition, DFT, molecular docking and molecular dynamics analyses

In this study, the antioxidant and enzyme inhibition capacities of acetone, ethanol, and water extracts of E. arvense were comprehensively investigated using both experimental and theoretical approaches. The phytochemical constituents of the extracts were characterized by a validated LC-MS/MS method, which identified 53 bioactive molecules commonly found in medicinal plants, including prominent compounds such as Isoquercitrin, Quinic acid, Acacetin, Aconitic acid, Caffeic acid, and Protocatechuic acid. Among the tested extracts, acetone exhibited the highest levels of phenolic and flavonoid contents, and accordingly demonstrated the strongest antioxidant activity as evaluated by DPPH, ABTS, CUPRAC, FRAP, and other assays. Enzyme inhibition studies showed the strongest effect for the ethanol extract in cholinesterase inhibition tests. Similarly, the greatest inhibition of tyrosinase was observed with the ethanol extract. To elucidate the molecular basis of these bioactivities, dominant compounds were subjected to density functional theory (DFT) calculations and molecular docking simulations against key enzymes. Theoretical results confirmed that Isoquercitrin and Acacetin possess favorable electronic and binding properties, suggesting their role in the observed bioactivities. These findings highlight E. arvense as a promising natural source of multifunctional phytochemicals with potential applications in managing oxidative stress and metabolic disorders.