The study was conducted to screen in-vitro antibacterial activity of crude ethanol and aqueous extracts of Garcinia kola seed against some selected bacterial isolates composing of Gram positive and Gram negative organisms namely Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The disc diffusion method was employed to determine the inhibitory effects of the seed extract on the test micro-organisms. The ethanol and aqueous extract of the seed at concentration of 4g/40ml were diluted at the concentration of 0.1g/ml, O.2g/ml, 0.4g/ml, 0.6g/ml and 0.8g/ml, then impregnated into a sterile filter paper disc. Also ethanol alone was impregnated into the sterile filter paper disc and used as control. The zones of inhibition obtained for ethanol extract (4g/40ml) of Garcinia kola seed ranged between 12mm-15mm. The zone of inhibition obtained for diluted ethanol extract (4g/40ml) of Garcinia kola seed at concentration 0.1g/ml, 0.2g/ml, 0.4g/ml, 0.6g/ml and 0.8glml ranged from 8mm-15mm also the zone of inhibition obtained for ethanol extract (40g/80ml) of Garcinia kola seed ranged between 12mm-16mm, the zone of inhibition obtained for diluted ethanol extract (40g/80ml) of Garcinia kola seed at concentration 0.1g/ml, 0.2g/ml, 0.4g/ml, 0.6g/ml and 0.8g/ml ranged from 7mm-15mm. the aqueous extract (4g/40ml and 40g/80ml) of Garcinia kola seed and the diluted aqueous extract were all resistant to Staphylococcus aureus, Escherichia Coli and Pseudomonas aeruginosa. The zone of inhibition of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa at concentration of 4g/40ml, 40g/80ml, 0.1g/ml, 0.2g/ml, 0.4g/ml and 0.8g/ml ranged from 9mm-16mm, 8mm-13mm, 17mm-12mm respectively, the zone of inhibition of ethanol alone ranged between 8mm-10mm. This investigations shows that Garcinia kola is effective only when used in organic solvent at higher concentration.

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