Extraction and Characterisation of Essential Oil from Eucalyptus Leaves for Industrial Antimicrobial Applications in Enugu State

The growing demand for plant-derived antimicrobial agents in Nigerian pharmaceutical and household product industries has stimulated interest in essential oil extraction from locally cultivated aromatic plants. This study extracts and characterises essential oil from Eucalyptus camaldulensis leaves harvested from plantations in Enugu State, South East Nigeria, and assesses its antimicrobial activity against selected clinical and food spoilage microorganisms. Leaves were collected during peak oil season, hydro-distilled using a Clevenger apparatus, and the extracted oil was characterised for yield, specific gravity, refractive index, and chemical composition via gas chromatography-mass spectrometry. Antimicrobial activity was evaluated using agar disc diffusion and minimum inhibitory concentration assays against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Aspergillus flavus. Oil yield from Enugu-sourced leaves averaged 1.87% (v/w), and GC-MS analysis identified 1,8-cineole (eucalyptol) as the dominant constituent at 68.4%. Zone of inhibition diameters for Staphylococcus aureus and Candida albicans were 22.4 mm and 19.7 mm, respectively, indicating strong antimicrobial activity. Minimum inhibitory concentration values against all tested organisms ranged from 0.5 to 4.0 mg/mL. The oil demonstrated stability under accelerated storage conditions for 90 days. The findings support the commercial viability of Enugu eucalyptus essential oil for incorporation into antiseptic formulations and food preservatives. Keywords: eucalyptus essential oil, antimicrobial, GC-MS, 1,8-cineole, Enugu State