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Background: Exopolysaccharides are extremely powerful molecules with a wide range of uses in pharmaceuticals due to their structural and compositional complexity. Marine microorganisms often produce bioactive substances with novel functions and structures because of their special living conditions. Polysaccharides from marine microorganisms are of interest to new drug discovery. Results: The current research focused on the isolation of bacteria from Red Sea, Egypt, that have the ability to produce a new natural exopolysaccharide in order to be examined in treating Alzheimer's illness to obviate side effects of synthetic drugs. Properties of exopolysaccharide (EPS) produced by an isolated Streptomyces strain were investigated for its capability to play as anti-Alzheimer. This strain was identified morphologically, physiologically, and biochemically and actually was confirmed by molecularly 16S rRNA analysis as Streptomyces sp. NRCG4 with accession number MK850242. The produced EPS was fractionated by precipitation 1:4 volumes of chilled ethanol and the third major fraction (1:3) listed as NRCG4, and then the functional groups, MW, and chemical evaluation have been detected via Fourier-transform infrared (FTIR), high-performance gel permeation chromatography (HPGPC), and high-performance liquid chromatography (HPLC). The findings showed that NRCG4 was an acidic EPS composed of mannuronic acid, glucose, mannose, and rhamnose in a molar ratio of 1.2:1.5:2.8:1.0, respectively. NRCG4 Mw was determined to be 4.25 × 105 gmol−1 and the Mn to be 1.97 × 105 gmol−1. Also, the NRCG4 included uronic acid (16.0%) and sulfate (0.0%), but no protein was found. In addition, antioxidant and anti-inflammation activity was measured through various methods. This study confirmed that NRCG4 exopolysaccharide exerted anti-Alzheimer's characters via inhibition of cholinesterase and tyrosinase as well as anti-inflammatory and antioxidant abilities. Additionally, it occurred a potential role in the suppression of Alzheimer's disease risk factors through its antioxidant (metal chelation, radical scavenging capability), anti-tyrosinase and anti-inflammatory characteristics. The anti-Alzheimer's disease efficacy of NRCG4 exopolysaccharide may be assigned to its unique determined chemical composition. Conclusions: The present study highlighted those exopolysaccharides could be harnessed to improve pharmaceutical industry (anti-Alzheimer, anti-tyrosinase, anti-inflammatory, and antioxidant agents). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]