Antimicrobial activity and phytochemical screening of Adansonia digitata stem bark extract on some clinical isolates

Abstract

Adansonia digitata is a massive and deciduous tree with a height of about 24 m and of significant economic importance. The antimicrobial and  phytochemical screening of the aqueous and ethyl-acetate extract of stem bark of the plant were determined on some clinical isolates. The stem bark of the plant was collected and washed o properly before drying at 28 C. The pulverised stem bark was extracted with water and ethyl-acetate and screened for phytochemicals (qualitative and quantitative) using standard methods. The clinical isolates used were identified as Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli and Candida albicans. The antimicrobial activities of the crude extracts were carried out using the agar well diffusion methods. The minimum inhibitory concentration (MIC), minimum bactericidal and fungicidal concentrations were carried out using standard methods. The aqueous extract exhibited a higher zone of inhibition against S. aureus (14.00 ± 0.57 mm) at a concentration of 200 mg/ml while a zone of inhibition of 11.66±0.33 mm was observed for E. coli using ethylacetate extract. Candida albicans had a zone of inhibition of 11.66±0.88 mm and 11.00±0.57 mm using aqueous and ethyl-acetate extracts respectively at 200 mg/ml. The MIC was 200 mg/ml for the crude extracts against the clinical isolates. The qualitative ethyl-acetate phytochemical screening revealed the presence of phenol, flavonoids, tannins, alkaloids, saponin and terpenoids. Phenol had the highest concentration of 2.02±0.25 mg/ml while terpenoids had a value of 1.38±0.02 mg/ml. Aqueous and ethyl-acetate extract of A. digitata possess significant antimicrobial activity against E. coli, S. aureus and C. albicans. However, K. pneumoniae showed resistance to ethyl acetate extract. Key words: Adansonia digitata, Antimicrobial activity, Clinical isolates, Phytochemical  screening