Phytochemical and Antimicrobial Activity of Ocimum suave Against Selected Human Pathogenic Bacteria

Abstract

Worldwide, the use of antibiotics is losing effectiveness due to the substantial resistance to the antimicrobial developed by many pathogenic bacteria. African populations including Rwanda, use frequently traditional medicine for primary care. This study aimed to determine the phytochemicals and the antimicrobial activity of Ocimum. suave (O. suave) against selected human pathogenic bacteria (two strains of S. aureus, P. aeruginosa, two strains of E. coli, S. pneumonia, S. pyogene, K. oxytoca, H. influenza, S. sonei). The leaf and stem extracts were prepared using maceration technique. The antimicrobial activities of extracts were evaluated using the impregnated disc and agar well diffusion methods. The tests revealed the presence of phytochemical substances such as tannins, flavonoids, saponins, steroids alkaloids and phenolics in leaves and only saponins in stem. S. aureus ATCC 43300 was the most sensitive while H. influenza was the most resistant among the microorganisms tested. Aqueous and methanolic crude extract of O. suave displayed maximum diameter of inhibition zone against bacteria (9-26.5 mm and 9-23.5 respectively) and Two-way ANOVA showed statistical significance difference between their means. T-test was used in comparison with standards antibiotics and showed that the distilled water extracts exhibited much higher activity against all tested organisms than activity of streptomycin. Combination of distilled water and methanol extracts with streptomycin revealed synergistic activity against E. coli ATCC 25922 and S. pneumonia ATCC 49618. The leaves of O. suave have a great potential antibacterial activity and should be fully explored for future treatment. Keywords: phytochemical; antimicrobial activity; Ocimum suave, Rwanda