Phytochemical screening and antibacterial activity of leaf and stem bark extracts of Adansonia digitata on E. coli, S. aureus and S. typhi

Abstract

Background:  Adansonia digitata L (Baobab) contains different classes of bioactive compounds which were identified from various parts of the plant such as seed, leaves, and roots and also stem bark. The study was designed to determine the antibacterial activityof Adansonia digitata leaf and stem bark extracts. Methods: The plant material was extracted using aqueous, ethanol and methanol; and their activity against the three clinical isolates Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Salmonella typhi (S. typhi) was ascertained using agar well diffusion method. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the different extracts were also determined. One way analysis of variance was conducted using Stata/SE11.1 and t-test to determine the significant difference between the effects at p ≤ 0.05. Results: The extracts were found to be effective against the tested organisms. The methanolic extracts showed significantly higher activity against the test organisms compared to aqueous and ethanolic extracts (p = 0.000). The result also demonstrated that the leaf extract is more active than the stem bark extract with significant difference (p=0.000). The methanolic and ethanolic leaf extracts exhibited highest inhibitions zone of 19mm and 16mm against E. coli at concentration of 1000mg/mL respectively. The MIC result of the study showed that the methanolic and ethanolic extracts inhibited the growth of the organisms at 25 mg/ml. The methanolic and ethanolic extracts have MBC at 25 mg/mL. Conclusion: The methanolic and ethanolic leaf extracts have significant effect against the test organisms at all concentration tested.