Antimicrobial activity and phytochemical screening of the fruit pulp of Dialium guineense (Velvet Tamarind) on some microbial isolates

Abstract

The antimicrobial activities of the aqueous, ethanol and n-hexane fruit pulp extracts of Dialium guineense were evaluated against clinical isolates of Klebsiella pneumonia, Staphylococus aureus, Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis and Candida albicans using the agar well diffusion technique. The results reveal that the crude aqueous and ethanol extracts possess antimicrobial activities on the tested organisms with the exception of n-hexane extract which showed no zone of inhibition. The highest zone of inhibition diameter at 24.67 mm of the ethanol extract and 19.33 mm of the aqueous extract was recorded against C. albicans while S. aureus showed the lowest inhibition zone to the aqueous extract with 7.33 mm in diameter. However, statistical analysis indicates no significance as P>0.05. The minimum inhibitory concentration (MIC) of the aqueous and ethanol extracts to the isolates was between 100 - 200 mg/ml with only C. albicans at 50 mg/ml of the ethanol extract. Also, the minimum lethal concentration (MLC) of the aqueous and ethanol extracts on majority of the organisms was above 200 mg/ml but P. aeruginosa and P. mirabilis showed MLC at 200 mg/ml and, C. albicans at 100 mg/ml of the ethanol extract. Meanwhile, only C. albicans showed MLC to the aqueous extract at 100 mg/ml. In addition, the phytochemical screening revealed the presence of flavonoids, alkaloids, tannin, saponins, oxalates and glycosides. The results of this work suggest further exploitation of the fruit pulp of D. guineense to possibly unveil its potential use for the treatment of diseases.   Key words: Dialium guineense, antimicrobial activity, phytochemical screening, microbial isolates, fruit pulp.