ANTIMICROBIAL ACTIVITY OF SELECTED TANZANIAN MEDICINAL PLANTS

Traditional medicines have been used in the treatment of infections for decades, but unlike most clinical antibiotics, they remain effective against microbial infections. Antimicrobial activity of selected medicinal plants was evaluated against selected Gram negative bacteria. The plants selected were Rhus natalensis, Lannea schweinfurthii, Tarchonanthus camphoratus, Toddalia asiatica, Solanecio cydoniifolius, Ziziphus mucronata and Cyanthnla orthocantha. The extracts were obtained by sequential extraction. The extracts were then assayed for antimicrobial activity using broth microdilution method. The results revealed that R. natalensis leaf ethyl acetate extract had antimicrobial activity with MIC values> 3.125mg mL -1 against all tested microorganisms. The leaf ethyl acetate extract of L. schweinfurthii showed significant antimicrobial activity against tested Gram negative bacteria, with MIC values that ranged from 1.563mg mL -1 to 6.25 mg mL -1 . Interestingly, T. asiatica leaf methanolic extract had the highest antimicrobial activity with MIC values of 0.195 mg mL -1 against P. vulgaris. The leaf methanolic extract of T. camphoratus had MIC value of 0.391mg mL -1 against P. aureginosa. Despite weaker antibacterial activity, C. orthocantha leaf ethyl acetate extract exhibited a better antifungal activity against C. albicans at MIC value of 3.125 mg mL -1 . These antimicrobial activity results agree well with the medicinal applications of the selected medicinal plants.