Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

Two streptomyces strains were isolated from soil samples and the sequence of ~ 1500 nucleotides of their 16S rDNA showed 99% identity to streptomyces sp. HV10 and 100% identity to streptomyces chattanoogensis respectively. These newly isolated Streptomyces strains produced extracellular polysaccharides (EPS) named MOE6-EPS and MOE7-EPS respectively. The two EPS were characterized by various spectroscopic techniques including fourier transform infrared (FTIR), HPLC, 1HNMR as well as UV visible spectroscopy. MOE6-EPS composed of 71±1% carbohydrate by weight, 3.6±0.1% uronic acid and 0.78±0.1% protein, while MOE7-EPS composed of 98±0.5% carbohydrate by weight, 0.2±0.1% uronic acid and 0.3±0.1% protein. MOE6-EPS and MOE7-EPS showed antioxidant activities by scavenging the hydroxyl free radical scavenging activity and 2,2-diphenyl-2-picryl-hydrazyl (DPPH) radicals. In addition, MOE6-EPS showed high ferrous ion (Fe2+) chelation activity which is another antioxidant activity. Interestingly, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays that were colorimetric assays for NAD(P)H-dependent cellular oxidoreductases and a proxy of the number of viable cells, showed that MOE6-EPS and MOE7-EPS inhibited the proliferation of the human breast cancer cells (MDA-MB-231). Moreover, the scratch wound assay showed that MOE6-EPS and MOE7-EPS reduced the migration of human breast cancer cells (MDA-MB-231) in EPS concentration dependent manner

Issued also as CD