Studies on bioactive potential of ethanolic leaf extract of spondias mombin on some baterial isolates obtained from stool samples of diarrhetic patients
The antibacterial activity of ethanolic extract of Spondias mombin leaf on some bacteria that were associated with diarrhoea was investigated. This was with a view to determining the phytochemicals, the extent and the rate of killing of the test isolates by the crude and various fractions of the extract. The leaves of Spondias mombin were harvested, dried in hot air oven at 45oC and ground into a fine powder. The powered leaf was cold extracted using ethanol and distilled water in ratio 3:2 (v/v). The crude extract obtained was concentrated in vacuo and lyophilized. The extract was screened for phytochemicals and antibacterial activity against selected bacterial isolates. The extract was partitioned into n-hexane, chloroform, ethyl acetate, butanol and aqueous fractions in order of their polarity. The antibacterial potentials, minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the crude extract and the fractions were determined using agar diffusion and agar dilution techniques, respectively. The antibacterial activities of the crude and active fractions (n-hexane, ethyl acetate and butanol fractions) were compared with standard antibiotics- ampicillin and streptomycin (1mg/mL). The time-kill assay of the various active fractions on the representative Gram negative (Escherichia coli) and Gram positive (Staphylococcus aureus) bacterial isolates was determined using standard method. The crude extract of the plant and various fractions obtained exhibited varying degree of antibacterial activities. The MIC of the crude extract ranged from 6.25 to 25.00 mg/mL while the MBC ranged from 12.50 to 25.00 mg/mL. The MIC and MBC of the active fractions against the isolates was 15.00 mg/mL. Phytochemical screening of the extract showed the presence of tannins, saponins, steroids, terpenes, alkaloids, flavonoids, and cardiac glycosides. The time-kill assay reveals a minimum of 4.3% death rate at 1 x MIC after 15 min contact time with the active fractions and minimum of 64.0% death rate after 120 min at the same concentration (1 x MIC). The rate of kill increased with increased concentration of the extract (active fractions) and time interval. The study concluded that the leaf of Spondias mombin investigated in the study area possessed antibacterial area possessed antibacterial property with broad spectrum of activity against both Gram negative and Gram positive test bacteria.