Phytochemical Screening, Antibacterial Activity and Bioautography of Sorindeia madagascariensis , Mucuna stans , and Albizia harveyi

This study investigated the antibacterial activities of crude extracts of three Tanzanian plants; Sorindeia madagascariensis, Mucuna stans and Albizia harveyi, following reports on their ethnomedicinal applications and those of their related species. The reported ethnomedicinal applications of the selected plants include treatment of; tuberculosis, urinary tract infections and bacterial infections of the skin among other applications. Plant material were collected from Njombe, Iringa and Pwani regions of Tanzania. Phytochemical screening and bioautography were conducted as per adopted methods. Screening for antibacterial activity was done by broth microdilution assay against the standard and clinical isolates of bacteria. Phytochemical screening revealed the presence of phenolics, tannins, flavonoids, terpenoids and glycosides among the plant extracts. Antibacterial activity-study displayed weak to moderate antibacterial activities of the plant extracts, whereby S. madagascariensis leaf extract displayed the highest activity against; Staphylococcus aureus (ATCC 25923), clinical isolate of S. aureus and a methicillin-resistant S. aureus (MRSA) isolate, at a minimum inhibitory concentration (MIC) of 192±0.00 µg/mL. Bioautography of S. madagascariensis indicated this antibacterial activity to be associated with polar compounds. MICs observed due to M. stans ranged from 770 to 3080 µg/mL against all tested bacterial species whereas the observed MICs due to A. harveyi ranged from 1283 to > 3080 µg/mL. These findings reveal the antibacterial activities of the selected plants, corroborating their ethnomedicinal applications. Bioautography-guided isolation of compounds from these plants particularly S. madagascariensis, may give leads for newer antibacterial agents.