Antimicrobial and antioxidant activities of Tetracera macrophylla Hook.f. & Thomson leaf extracts: insights from Q-ToF-LCMS, pharmacokinetics and molecular docking approach

This study investigated the antimicrobial and antioxidant properties of Tetracera macrophylla leaf extracts to support its traditional use in treating infections. Five extracts were prepared (Hexane HEX, ethyl acetate EA1, EA2, and methanol ME1, ME2), among which ME2 exhibited the strongest bioactivity. ME2 showed high total phenolic content (TPC: 254.96 ± 0.43 mg GAE/g), total flavonoid content (TFC: 162.53 ± 0.89 mg QE/g), ferric reducing antioxidant power (FRAP: 1605.94 ± 0.32 mg AAE/g), and potent radical scavenging activity (DPPH• IC50: 3.46 ± 0.09 µg/mL; ABTS•+ IC50: 0.62 ± 0.01 µg/mL). Antimicrobial assays revealed that ME2 exerted the strongest inhibitory effect against S. aureus (ZOI: 8.51 ± 0.05 to 10.53 ± 0.03 mm; MIC and MBC: 0.625 mg/mL), with additional activity against S. mutans and C. albicans. To identify bioactive constituents, Q-ToF LCMS profiling of ME2 was performed, followed by molecular docking against S. aureus DNA gyrase B protein (PDB ID: 3U2D). Several compounds demonstrated strong binding affinities and favourable drug-likeness properties including (-)-epicatechin-3-O-gallate (-9.4 kcal/mol), epigallocatechin-3-O-caffeate (-9.1 kcal/mol), luteolin-4'-sulfate (-8.5 kcal/mol), 5,7,4'-trihydroxyflavanone 7-sulfate (-8.0 kcal/mol), 4,2',3',4'-tetrahydroxychalcone (-7.9 kcal/mol), isovitexin (-7.9 kcal/mol), 7,8,4'-trihydroxyflavanone (-7.7 kcal/mol), betulinic acid (-7.0 kcal/mol), and gallic acid (-6.0 kcal/mol). These findings provide scientific support for the traditional use of T. macrophylla in managing infections and highlight its potential as a promising source of lead compounds for novel antibacterial drug development.