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Aims: The aim of this study is to investigate the phytochemical constituents and antimicrobial activity of the leaves extracts of Eucalyptus camaldulensis and Eucalyptus microtheca.
Study Design: Extraction of E. camaldulensis and E. microtheca leaves using five solvents of different polarities, and screening their phytochemical constituents and antimicrobial activity against five microorganisms.
Place and Duration of Study: Industrial chemistry and microbiology Departments, International University of Africa, Khartoum – Sudan, January 2017.
Methodology: The leaves of E. camaldulensis and E. microtheca were extracted using water, ethanol, chloroform, ethyl acetate and petroleum ether; the extracts were used for phytochemical screening. Five concentrations (100, 50, 25, 12.5 and 6.25 mg/mL) of each extracts prepared and tested against five organisms; Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. Muller Hilton agar was used for growth of microorganism strains. The inhibition activity was evaluated using cup plate method with slight modification.
Results: The results of the phytochemical screening revealed the presence of tannins, steroids, saponins, flavonoids and phenolic compounds in all tested extracts of both plants. In addition, the leaf extracts from E. camaldulensis and E. microtheca were found to be effective against S. aureus, P. aeruginosa, E. coli, K. pneumonia and C. albicans. The aqueous and ethanolic extracts of both plants displayed the highest antimicrobial activity compared to other extracts. These two extracts were significantly inhibited the growth of the five pathogenic microorganisms particularly at high concentrations (100 and 50 mg/mL); while there was no inhibition effect detected at low concentrations (25 and 12.5 mg/mL). The diameter of inhibition zones at concentrations of 100 and 50 mg/mL were found to be between 11 and 35 mm.
Conclusion: These results indicated that E. species might be exploited as natural antibiotic for the treatment of several infectious diseases caused by these five microorganisms.