Received: 31 January 2012                                                         Revised accepted: 11 August 2012

Purpose: To investigate the essential oil content of Clausena suffruticosa leaf for its in-vitro antibacterial, antifungal and cytotoxic activities. 

Methods: The essential oil of Clausena suffruticosa leaf was extracted by hydrodistillation using a modified Clevenger-type apparatus and was analyzed by GC-MS using electron impact ionization method. Antibacterial, antifungal and cytotoxic screenings were made by disc diffusion technique, poisoned food technique and brine shrimp lethality bioassay, respectively.   Minimum inhibitory concentration (MIC) of the oil was determined by measuring the zone of inhibition, with tetracycline as reference standard. Fluconazole served as standard in the antifungal assessment.

Results: A total of twenty two compounds, of which Estragole, Anethole and β-Ocimene were the major ones, were found in the essential oil of C. suffruticosa. The oil showed higher antibacterial activity against Shigella flexneri than the reference, tetracycline (p < 0.05). Significant activity (p < 0.001) against other Gram-positive microbes - Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Bacillus polymyxa and Bacillus megaterium – was also observed. However, Gram-negative bacteria - Salmonella typhi, Shigella flexneri, Proteus mirabilis and Escherichia coli. Klebsiella pneumoniae and Shigella sonnei - showed no sensitivity to the oil. In the antifungal assay, the oil exhibited greater activity (p < 0.001) against Aspergillus ochraceus than the reference, fluconazole, Inhibition of other fungal strains tested was also statistically significant (p < 0.001). The lethal concentration (LC₅₀) of the oil against brine shrimp was 41.2 µg/ml in the cytotoxic assay.

Conclusion: It is evident that the essential oil of C. suffruticosa is a potent antimicrobial and cytotoxic agent that should be further evaluated.