Evaluation of Antimicrobial Activity, Synergistic Efficacy, Qualitative and Quantitative Phytochemical Determination of Alstonia Boonei Leaf and Stem Bark on Selected Clinical Isolates

Abstract

This study evaluated the antimicrobial activity, of Alstonia boonei leaf, stem bark and the synergistic efficacy of A. boonei leaf plus stem bark on seven bacteria (Gram positive and Gram negative bacteria) which are strains of Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Proteus viridans, Salmonella typhi and Klebsiella pneumoniae, and three fungal isolates which are Candida albicans, Aspergillus flavus and Trichophyton rubrum. This study also evaluates the quantitative and qualitative phytochemical properties of A. boonei leaf and stem bark, as well as the minimum inhibitory concentration of A. boonei leaf and stem bark crude extracts on the selected clinical isolates.  A. boonei was collected from ore in Odigbo local government of Ondo state. Crude extraction of air dried leaf and stem bark was carried out by soaking the plant in dichloromethane, standard agar good diffusion method was used for sensitivity testing and the minimum inhibitory concentration values are obtained by agar dilution method. The crude extract from both plant parts shows high antimicrobial property, while the synergistic effect of the leaf and stem bark shows comparatively higher antimicrobial property to the individual tissue. Sensitivity test revealed that the highest zone of inhibition was observed from the synergy of A. boonei leaf and stem bark against E. coli with 25mm at 100mg/ml, while the least zone of inhibition is observed from the stem bark extract against K. pneumoniae with 2mm at 6.25mg/ml. the highest antifungal activity is from the synergistic effect against C. albicans with 20mm zone of inhibition at 100mg/ml, and the least antifungal activity is observed against T. rubrum with 11mm zone of inhibition at 100mg/ml to the leaf extract of A. boonei. The qualitative and quantitative phytochemical analysis reveals the presence of phytochemicals such as Alkaloid, cardiac glycoside, steroids, tannin, saponin, flavonoid, anthraquinone, phenol and reducing sugars in the different tissues and it supports their antimicrobial activities.