Analysis of Kigelia africana (Lam.) Benth for anti-microbial activities

Abstract

Fungal infections and bacterial infections, including tuberculosis, are among the illnesses that have plagued humanity for a very long time. Numerous medications have been utilized to treat these infections thus far. However, there has been a challenge of microbial resistance which puts much of the population to be vulnerable to diseases and infections. There is, therefore, a need for research to overcome the existing health challenge. Throughout Africa, traditional medicine practitioners have utilized Kigelia africana as a plant remedy for persistent cough and other infectious disorders. In this research, the stem bark of Kigelia africana was analyzed for anti-tuberculosis, antibacterial and antifungal activities. 1000 g was extracted from the ground powder of stembark using dichloromethane: methanol, 1:1 for 24 h at room temperature. The extract was subjected to column chromatographic separations to obtain different fractions which were further purified and four compounds were isolated; Stigmasterol (1), a long aliphatic chain ester; 4-Hydroxyphenethyl butyrate (2), a coumarin derivative; 6- demethylkigelin (3) and Stearic acid (4). The structures were established using nuclear magnetic resonance (NMR) Spectroscopic techniques. Compounds 2 is hereby isolated for the first time from the plant whereas compound 3 is hereby reported for the first time from the stem bark of K. Africana, but previously isolated from the roots of the tree. Anti-tuberculosis activities for the plant extract and four isolated compounds were expressed as MIC values (μg/mL). Antibacterial and antifungal activities were expressed as mean zones of inhibition (mm). The crude extract was moderately active against M. tuberculosis with MIC of 44.2 ±0.5 (μg/mL). Compounds 1-3 exhibited strong activity against M. tuberculosis (33.5±0.4, 31.2±0.4 and 34.5±0.7, respectively) whereas compound 4 was moderately active (43.3±0.1) against M. tuberculosis. All the four compounds were weakly active in the antibacterial tests (7.0±0.4, 7.0±0.3, 9.5±0.7 and 7.5±0.4, respectively) and antifungal tests (8.0±0.5, 7.0±0.4, 7.5±0.4 and 7.5±0.7, respectively). There was a noticeable moderate antibacterial activity (10.0±0.3) against Staphylococcus aureus and antifungal activity (11.3±0.5) against Candida albicans exhibited by the crude extract. The findings show that K. africana stem bark has potential for treating bacterial and fungal-related diseases in addition to aiding in the fight against tuberculosis.