| The antimicrobial activity of the methanol extracts of Kappaphycus alvarezii, Kappaphycus cottoni,Eucheuma spinosum, Eucheuma cottoni and Sargassum binderi were evaluated against five bacteria (Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia colij, and one yeast (Candida maltosaj. The diffusion method on agar dishes was applied to determine the antimicrobial activity.MIC was determined in the extracts that showed some efficacy against the tested microorganisms. Ampicillin (10/jg/disc) against Bacillus subtilis and Staphylococcus aureus, Ampicillin (50 ijg/disc) against Escherichia coli, Gentamycin sulfate (25 /jg/disc) against Pseudomonas aeruginosa and nystatin (50 /jg/disc) against Candida maltosa were used as positive controls. The methanol extract showed a higher activity against B. Subtilis with inhibition diameter of 22 and 20 mm compared to Ampicyllin (23 mm), respectively, and Eucheuma spinosum showed weak activity against B. Subtilis with inhibition diameter of 12 mm, whereas Eucheuma cottoni and Sargassum binderi showed no inhibition against all of test microbes. Moreover methanol extract of Algae sp were also tested on the cytotoxicity of six methanol extracts from a marine algae used in folk medicine, to human bladder carcinoma (5637) cell lines. After 72-h incubation of human bladder carcinoma (5637) cell lines with varying concentrations of extracts (0.343, 1.029, 3.086, 9.259,27.78, 83.33 and 250 ug/ml), cytotoxicity was determined by the neutral red assay and reported in terms of cell viability. The methanol extract of Eucheuma spinosum, had a significant cytotoxicity against 5637cells with ICso values of 6.5 ug/ml compared to etoposide (5.3 ug/ml). This in vitro study corroborated the antimicrobial activity of the Kappaphycus alvarezii, Kappaphycus cottoni, were effective against only one of the pathogenic microorganisms. This study showed that Kappaphycus alvarezii and Kappaphycus cottoni CDC could be potential sources of new antimicrobial agents against Bacillus subtilis. |