Dual Enzymatic Inhibition and Toxicity Profiling of Polymethoxylated Flavones Isolated from Knema Malayana

The present study reports the isolation and characterization of secondary metabolites from the methanolic extract of Knema malayana leaves, including five polymethoxylated flavones 3′,4′,5,7-tetramethoxyflavone (1), 3′,4′,5′,5,7-pentamethoxyflavone (2), 4′-hydroxy-3′,5′,5,7-tetramethoxyflavone (3), 3-hydroxy-3′,4′,5′,5,7-pentamethoxyflavone (4), and 3,3′,5′,5,7-pentamethoxyflavone (5). Structural elucidation was performed using 1D and 2D nuclear magnetic resonance (NMR), IR, MS, and, in the case of compound (2), single-crystal X-ray diffraction. The isolated compounds were evaluated for their inhibitory activity against acetylcholinesterase (AChE) and 5-lipoxygenase (5-LOX). Among them, compound (2) exhibited the most notable dual inhibitory activity, with IC50 values of 10.2 μM (AChE) and 12.6 μM (5-LOX). Molecular docking supported these findings, with binding affinities of –10.5 kcal/mol (AChE) and –7.2 kcal/mol (5-LOX), revealing key hydrogen bonds and π–cation interactions within active site residues. Other flavonoids, particularly compounds (1) and (5), also displayed notable binding profiles. In silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) evaluation using the Toxometris.ai platform indicated favorable drug-likeness and safety profiles, including non-mutagenic and non-cardiotoxic predictions, along with acceptable pharmacokinetic properties such as aqueous solubility, Caco-2 permeability, plasma protein binding, and microsomal stability. These findings were further supported by promising physicochemical and medicinal chemistry properties, including quantitative estimate of drug-likeness (QED) scores ranging from 0.65 to 0.75 and the absence of pan-assay interference compounds (PAINS) alerts, among other parameters. This study highlights the therapeutic relevance of K. malayana polymethoxylated flavones as promising dual-target AChE and LOX inhibitor with favorable safety and pharmacokinetic properties, supporting their potential development for neuroinflammatory disorders.