Abstract

O. A. Ogundare

Methanol extract of Senna podocarpa leaf was obtained using the cold extraction method. The extract was tested for antimicrobial activity against ten organisms, namely Pseudomonas aeruginosa, Streptococcus feacalis, Klebsiella pneumoniae, Shigella dysenteriae, Staphyloccoccus aureus, Escherichia coli, Microccoccus leutus, Salmonella typhi, Bacillus cereus, and Candida albicans. The agar well diffusion method was used to carry out this test. Antimicrobial activity was indicated by appearance of zones of inhibition around wells. Results showed that the extract inhibited the growth of all the organisms except E. coli, with zones of inhibition ranging from 3 mm in S. aureus and M. leutus, to 28 mm in C. albicans. The Minimum inhibitory concentration was also determined using four different concentrations of the extract (30, 25, 20, 15 mg/ml). The death rate of the susceptible microorganism by 30 mg/ml concentration of the extract was investigated, whereby P. aeruginosa, K. pnuemoniae and S. typhi continually reduced from 420, 350 and 600 cfu/ml respectively to zero after 12, 9 and 8 h of respective interaction between them and the extract. However, S. feacalis reduced gradually from 550 cfu/ml to zero at the 10th h. Mechanism of action of the extract on the organism inhibited was also carried out. Results showed that potassium ions were continuously leaked throughout the time of interaction (24 h) between the extract and the susceptible organisms. Result of the phytochemical screening showed the presence of saponins, tanins anthraquinone, phlobatanin, and alkaloids. The percentage yield of the plant as recorded is 4.6%.