Chemical constituents, antioxidant and antibacterial activities of essential oils of Ochna afzelii (R. Br. ex Oliv.)

ABSTRACT      Essential oils (EOs) from Ochna afzelii leaves, stems and roots were extracted and characterised by hydrodistillation and Gas Chromatogragphy-Mass Spectrometry (GC/MS) techniques, respectively. Antioxidant activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH*) method while antibacterial activity was determined using agar well diffusion and broth microdilution methods. Leaf, stem, and root oils afforded thirteen, ten and seven compounds, respectively, which were characterized by a high percentage of oxygenated sesquiterpenes and sesquiterpene hydrocarbons. The major compound in O. afzelii leaf and root EOs was β-Atlantol, while the O. afzelii stem EO had (E)-β-ionone as its major compound. The leaf oil displayed highest antioxidant activity (IC50 = 238.14 µL/mL). All the EOs showed antibacterial activities against Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Streptococcus pneumoniae, with the zones of inhibition and MIC values ranging from 12.0–18.0 mm and 2.5–10 µL/mL, respectively. O. afzelii has a mild antioxidant effect, but can be a potential source of natural antibacterial agents.