Production, structural and biochemical characterization relevant to antitumor property of acidic exopolysaccharide produced from Bacillus sp. NRC5.

This study targeted the production of exopolysaccharide from Bacillus sp. NRC5 grown in Egyptian seawater to use it as natural antitumor therapy. The biological activities of selected exopolysaccharide (BEPS) as an antioxidant, anti-inflammatory and anticancer have been studied. BEPS was evaluated as an anti-inflammatory in vitro against cyclooxygenase (COX-1 and COX-2) and evaluated as an anticancer on human breast and prostate cancer cell lines (MCF-7 and PC3). In addition, BEPS antitumor activity was tested against the Ehrlich Ascites Carcinoma (EAC) model. The BEPS presented potent antioxidant activities, consisted of glucose, mannose, and mannuronic acid in a molar ratio of 1.0:1.7:0.8 with a molecular weight of 3.59 × 105 g/mol. BEPS showed a promising COX-2 inhibitory effect in comparison with the reference drug celecoxib. BEPS appeared efficient anticancer property, where it killed 64.20 and 70.20% of MCF-7 and PC3 cells at 100 µg/ml, respectively (IC50, 76.70, and 70.40 µg/ml, respectively). BEPS exhibited antitumor ability as it prolonged the lifespan of mice to reach 75 days instead of 20 days in the tumor control, reduced viable cancer cells count, tumor volume and weight, modulated blood components, and white blood cells differentiation. BEPS produced from Bacillus sp. NRC5 showed its antioxidant and anti-inflammatory abilities and antitumor abilities, which may all be attributed to its unique composition containing sulfated moieties and uronic acids.