Antibacterial activity of partitioned methanolic extract of Alstonia boonei (De Wild) against some medically important pathogens

J. O. Olanlokun¹ and O. M. David²*

¹Department of Biochemistry University of Ado-Ekiti, P. M. B. 5363, Ado-Ekiti, (Nigeria) ²Department of Microbiology University of Ado-Ekiti, P. M. B. 5363, Ado-Ekiti, (Nigeria)

ABSTRACT: Methanolic extract of Alstonia boonei (De Wild) has been reported to be very effective against bacterial pathogens. Four solvents (hexane, chloroform, ethyl acetate and distilled water) were used to partition the concentrated crude methanolic extract. The fractions were further diluted by dimethyl sulphuroxide (DMSO). The concentrations used were 100, 50 and 25 mg/ml. Standard method was used to test the antibacterial properties of the fractions against nine clinically important pathogens. Hexane fraction showed no inhibition on Enterococcus faecalis but inhibit other test organisms at 25 mg/ml. Staphylococcus aureus was resistant to aqueous fraction at a very low concentration (25 mg/ml). Shigella dysenteriae and Escherichia coli were most susceptible to aqueous fraction with zone of inhibition ranging between 18 and 5 mm. Chloroform fraction was the most effective out of the four fractions. Streptococcus sp, Staphylococcus aureus Proteus mirabilis and Escherichia coli were resistant to Ethyl acetate fraction at 25 mg/ml. Ethyl acetate had the least activity on the test organisms. The minimum inhibitory concentration (MIC) ranged between 0 and 25 mg/ml.

KEYWORDS: Alstonia boonei; methanolic extract; pathogens; partition fractions; zone of inhibition

[ HTML Full Text]