Phytochemical and GC–MS Characterisation of Polyscias fruticosa Leaf Essential Oil and Its Antimicrobial Activity Against Selected Pathogens

Abstract

The growing threat of antimicrobial resistance has reinvigorated the search for bioactive compounds of natural origin, particularly from medicinal plants. Polyscias fruticosa (L.) Harms (Araliaceae), a shrub long valued in ethnomedicine, was selected for investigation to establish a preliminary phytochemical, gas chromatography–mass spectrometry (GC–MS), and antimicrobial profile of its leaf essential oil. Authenticated leaves (voucher deposited) underwent qualitative phytochemical screening of the aqueous extract, while the volatile fraction was obtained by hydrodistillation and characterised by GC–MS, with tentative identifications based on mass spectral library matching. Antimicrobial activity was assessed in triplicate by agar well diffusion and minimum inhibitory concentration (MIC) assays against eight bacterial and three fungal pathogens, using ciprofloxacin and fluconazole as positive controls. The aqueous extract contained alkaloids, flavonoids, saponins, tannins, phenolics, glycosides, phytosterols, terpenoids, reducing sugars, and proteins, but no anthraquinones. GC–MS resolved twenty-three constituents, tentatively dominated by capsaicin (28.91%), zingerone (22.35%), and γ-sitosterol (13.10%), alongside oleic, linoleic, and palmitic acids and the sesquiterpene alcohol farnesol; these assignments warrant confirmation by retention index matching and authentic standards. The oil exhibited concentration-dependent inhibition zones of 10–20 mm across 5–40 mg mL⁻¹, with the strongest activity against Escherichia coli, Salmonella typhi, and Trichophyton rubrum (20 mm at 40 mg mL⁻¹), and MIC values of ≥40 mg mL⁻¹ in nine of eleven isolates. These findings support aspects of the plant’s ethnomedicinal use and identify it as a candidate matrix warranting further pharmaceutical and nutraceutical investigation.