ANTIBACTERIAL EFFECTS OF KHAYA SENEGALENSIS (AFRICAN MAHOGANY) METHANOLIC LEAF EXTRACT ON SALMONELLA SPECIES

Abstract

Khaya senegalensis is a deciduous evergreen tree belonging to the Meliaceae family that is native to the sub-Saharan savannah. It is one of the most popular traditional medicines in Africa. This study aimed to evaluate the antibacterial effects of Khaya senegalensis methanolic leaf extract on Salmonella species. The presence of phytochemicals in the methanolic extract of Khaya senegalensis leaf was tested using both qualitative and quantitative screening methods. The cultural and biochemical characteristics of clinical isolates of Salmonella spp. were determined. Susceptibility of bacteria to the extract was assessed by gauging the diameter of the inhibition zones. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the plant extract were determined against the isolate. The results of quantitative and qualitative phytochemical analysis of the leaf extract of Khaya senegalensis showed the presence of alkaloids (0.234±0.10), flavonoids (0.019±0.30), saponins (0.563±0.20), phenols (0.044±0.30), tannins (0.023±0.12) and glycosides (0.067±0.20). At the same time, terpenoids were absent in the extract. The results of cultural and biochemical characteristics of clinical isolates of the bacteria Salmonella spp. showed colourless, smooth and transparent properties on MacConkey Agar. The biochemical test confirmed that the bacterium was methyl red, motility and catalase positive but Voges-Proskauer, citrate, coagulase, indole and oxidase negative. The results of the MIC and MBC revealed a significant zone of inhibition against Salmonella species by the plant extract at different concentrations. The highest zone of inhibition activity was recorded by the extract at 500mg/mL (38.00mm), at 400mg/mL (25.00mm), at 300mg/mL (21.00mm), at 200mg/mL (16.00mm), at 100mg/mL (11.00mm) and the standard (22.00mm). In conclusion, the results obtained indicated that methanolic leaf extract of Khaya senegalensis has an effect on preventing Salmonella infection and opens new perspectives in the strategies of controlling the prevalence of Salmonella by plant secondary metabolites.