Essential Oil of Polyalthia obliqua Leaves: GC-MS Composition, Antioxidant, Anti-Inflammatory, Antimicrobial Effects,...

Polyalthia obliqua Hook.f. & Thomson is a noteworthy species of the genus Polyalthia with promising medicinal value. The leaf essential oil was analyzed for its chemical composition and biological activities. Gas chromatography-mass spectrometry identified 59 constituents (85.98% of total oil), predominantly oxygenated sesquiterpenoids (73.20%) with spathulenol (28.72%) as the major compound. The oil exhibited antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl assay (IC₅₀ = 157.74 ± 3.93 µg/mL); the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assay (IC₅₀ = 170.00 ± 0.88 µg/mL), and notable inhibition of nitric oxide production (IC₅₀ = 54.85 µg/mL). Selective antibacterial effects were observed against Staphylococcus aureus (MIC = 64 µg/mL). Molecular docking suggested that khusinol contributes to anti-inflammatory activity via inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), while both khusinol and 14-oxy-α-muurolene may contribute to antibacterial activity via dihydrofolate reductase (DHFR) and UDP-N-acetylglucosamine enolpyruvyl transferase (MurB). These findings underscore the chemotaxonomic and bioactive potential of P. obliqua essential oil.