Antibacterial Screening of Extracts of Stem Bark of Prunus africana and Its Heavy Metal Determination

In Ethiopia, the traditional healers use fusions of leaves and decoctions of stem barks of the Prunus africana to treat diarrhea, wound dressing and other bacterial diseases. This provided us an impetus to investigate the antibacterial activities of crude extracts of the plant. In line with, the bioactive molecules from the plant were extracted using Soxhlet and maceration extraction techniques with solvents of different polarities. The Soxhlet technique showed relatively better extraction efficiency in extracting the secondary metabolites of the plant than maceration technique. Among the different solvents examined for their better extraction yield potential, methanol was found to be the best extractant with extraction yield of 22.5%. The antimicrobial activities of crude extracts of petroleum ether, diethyl ether, chloroform, acetone, ethanol and methanol were investigated using agar well disc diffusion and agar dilution antimicrobial susceptibility testing methods. The methanolic extract showed antibacterial activity against both Staphylococcus aereus and Bacillus subtilis with 18.00±1.53 mm and 19.33±2.08 mm diameter of zones of inhibition, respectively. Similarly, diethyl ether extract showed antibacterial activity against Bacillus subtilis with 17.00±1.15 mm of zones of inhibition. The levels of seven heavy metals (Zn, Cu, Mn, Cr, Ni, Pb and Cd) were determined using Flame Atomic Absorption Spectroscopy (FAAS) and microwave digester at optimized conditions. Concentrations of Cr, Ni, Pb and Cd were below the method detection limit while Zn, Mn and Cu metal ions were detected and found to be in the Permissible Levels (World Health Organization standards). The concentration of Mn was the highest as compared to that of metals in both stem and leaves the plant