Phytochemical Screening and Antibacterial Activity of Leaf and Steam Bark Extracts of Baobab (Adansonia Digitata) Against Methicillin-Resistant Staphylococcus Aureus Isolate
TL;DR
The study concluded that A. digitata is a potential antibacterial agent against MRSA infection due to the presence of phytochemical constituents in the ethanolic leaf extract.
Abstract
The Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogenic bacterium that causes infection and is resistant to several classes of commonly available antibiotics. The rise of resistance of microorganisms to commonly used antibiotics calls for the need to investigate the use of medicinal plants for developing new alternative antibacterial. The present study was carried out to assess the phytochemical content, antibacterial activity, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and preliminary toxicity of extracts of leaves and stem barks of Adansonia digitata against MRSA. Extraction was carried out using water, methanol, and ethanol as solvents for the plant parts. The phytochemical analysis was done to establish the type of secondary metabolites present, while the antibacterial activity of the extracts was assessed using the agar well diffusion technique. MIC and MBC were estimated. The brine shrimp lethality test was used for assessing the preliminary toxicity of the extracts. The results revealed the presence of alkaloids and saponins in all extracts, while other phytochemicals such as flavonoids, tannins, and terpenoids were found at different levels. The highest antibacterial activity was exhibited by the ethanolic leaf extract with an inhibition zone of 23.0 mm at a concentration of 400 mg/mL, whereas the lowest antibacterial activity was shown by the aqueous stem bark extract with an inhibition zone of 11.0 mm. The lowest MIC (25 mg/mL) and MBC (50 mg/mL) values were exhibited by the ethanolic leaf extract, showing higher antibacterial activity compared to other extracts. The preliminary test for brine shrimp lethality indicated relatively low toxicity, having LC₅₀ value more than 500 µg/mL for all the extracts. The bioactive constituents in the most potent ethanolic leaf extract, as determined by GC–MS analysis, included hexadecanoic acid methyl ester, phytol, 9,12-octadecadienoic acid methyl ester, oleic acid methyl ester, squalene, vitamin E, β-sitosterol, and stigmasterol. The study concluded that A. digitata is a potential antibacterial agent against MRSA infection due to the presence of phytochemical constituents in the ethanolic leaf extract.