Abstract

Methanol and ethanol cold percolation leaf extracts of  Antidesma venosum and Lanneabarteri were screened for their in vitro antibacterial activity against Staphylococcus aureus, Escherichia coli, Proteus vulgaris, Salmonella typhi, Streptococcus lactis and Shigella sp. using the agar well diffusion method. Methanol extracts gave higher filtrate of 16.57 and 9.44 g for A. venosum and L. barteri, respectively, while ethanol extract gave 13.52 and 7.10 g, respectively, from 500 g ground leaves extracted with 500 ml of each solvent. Both solvent extracts of A. venosum showed activity against all the clinical test organisms, with zone of inhibition range of 11 to 21 mm diameter except against S. aureus. S. lactis and Shigella sp. were the least susceptible to both solvent extracts of L. barteri. The minimum bactericidal concentration (MBC) range for A. venosum methanol leaf extracts against the clinical test organisms was 6.25 to 50 mg/ml, while for ethanol leaf extract, MBC range was 6.25 to 12.5 mg/ml. MBC range for L. barteri methanol and ethanol leaf extracts were 6.25 to 50 mg/ml and 6.25 to 12.5 mg/ml, respectively. The MBC killing rate of A. venosum methanol leaf extract shows that S. typhi was the most rapidly killed at a rate of 1.88 x 10⁶ CFU/min, while S. aureus was the most rapidly killed by L. barteri methanol leaf extract MBC at a rate of 1.45 x 10⁶ CFU/min.

Key words: Antibacterial, extract, inhibitory, bactericidal, susceptibility.