Antimicrobial Effects of Leaves of Eucalyptus camaldulensis on Some Microbial Pathogens

Background: Plants are important sources of medicinal materials and have been in use since ancient times. Although numerous plants have been explored for their medicinal properties, there still remains much to be studied.

Aim: To evaluate the phytochemical constituents of Eucalyptus camaldulensis extracted using ethanol, methanol and petroleum ether and the antimicrobial activity of the leaf extracts.

Place and Duration of Study: The study was conducted in Jos, Plateau State, Nigeria over a period of 18 months.

Methodology: Methanol, ethanol and petroleum ether extracts of E. camaldulensis leaves were obtained and phytochemical constituents were determined following standard procedures. The antimicrobial effect of the extracts obtained was tested against three bacterial species including Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and two fungi namely Penicillium expansum and Candida albicans using the agar well diffusion method, at concentrations of 400, 200, 100 and 50 mg/ml. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) were also determined.

Results: The phytochemical analysis of the leaf extracts revealed that they contained alkaloids, tannins, flavonoids, saponins, carbohydrates, steroids and cardiac glycosides. All the test organisms (both bacteria and fungi) were inhibited by each of the extracts at concentrations of 400, 200, 100 and 50 mg/ml with variations. The highest concentration (400 mg/ml) of ethanol extract showed the highest inhibition for C. albicans (27 mm) and B. subtilis (27 mm), while those of methanol and petroleum ether were most effective against C. albicans (27.7 mm) and B. subtilis (27 mm). The MIC ranged between 50 mg/ml and 200 mg/ml, while MBC and MFC ranged between 100 mg/ml and 400 mg/ml for all extracts. The inhibitory effects of the plant extracts were comparable to that of commercially available antibiotics used as controls.

Conclusion: The leaf extract of E. camaldulensis could be a better option in the treatment of infections caused by test organisms studied if properly processed and harnessed.