Abstract
A strain of Bacillus cereus was isolated from the Saudi Red Sea coast and identified based on culture features, biochemical characteristics, and phylogenetic analysis of 16S rRNA sequences. EPSR3 was a major fraction of exopolysaccharides (EPS) containing no sulfate and had uronic acid (28.7%). The monosaccharide composition of these fractions is composed of glucose, galacturonic acid, and arabinose with a molar ratio of 2.0: 0.8: 1.0, respectively. EPSR3 was subjected to antioxidant, antitumor, and anti-inflammatory activities. The results revealed that the whole antioxidant activity was 90.4 ± 1.6% at 1500 µg/mL after 120 min. So, the IC50 value against DPPH radical found about 500 µg/mL after 60 min. While using H2O2, the scavenging activity was 75.1 ± 1.9% at 1500 µg/mL after 60 min. The IC50 value against H2O2 radical found about 1500 µg/mL after 15 min. EPSR3 anticytotoxic effect on the proliferation of (Bladder carcinoma cell line) (T-24), (human breast carcinoma cell line) (MCF-7), and (human prostate carcinoma cell line) (PC-3) cells. The calculated IC50 for cell line T-24 was 121 ± 4.1 µg/mL, while the IC50 for cell line MCF-7 was 55.7 ± 2.3 µg/mL, and PC-3 was 61.4 ± 2.6 µg/mL. Anti-inflammatory activity was determined for EPSR3 using different methods as Lipoxygenase (LOX) inhibitory assay gave IC50 12.9 ± 1.3 µg/mL. While cyclooxygenase (COX-2) inhibitory test showed 29.6 ± 0.89 µg /mL. EPSR3 showed potent inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci. The exposure times of EPSR3 for the complete inhibition of cell viability of methicillin resistant S. aureus was found to be 5% at 60 min. Membrane stabilization inhibitory gave 35.4 ± 0.67 µg/mL. EPSR3 has antitumor activity with a reasonable margin of safety. The antitumor activity of EPSR3 may be attributed to its content from uronic acids with potential for cellular antioxidant and anticancer functional properties.
Highlights
Bacterial exopolysaccharides are extracellular organic macromolecules that play a significant role in various bacterial cellular activities, including phage protection, bacterial cell clustering under osmatic stress, and surface adhesion [1]
This study aims to isolate and biochemically characterize EPS isolated from marine B. cereus and, further, to assay its in vitro antistaphylococci, antioxidant; anti-inflammatory; antitumor; and immunological activities
Antiinflammatory, and anticytotoxic effects of EPS from B. cereus AG3 isolated from a marine sediment source from the Red Sea as part of our search for novel bioactive metabolites from marine microorganisms and the antioxidant potential of bacterial extracts
Summary
Bacterial exopolysaccharides are extracellular organic macromolecules that play a significant role in various bacterial cellular activities, including phage protection, bacterial cell clustering under osmatic stress, and surface adhesion [1]. The exopolysaccharides (EPS) is made up of biofilm structural components engaged in preserving water and processing foreign organic compounds and inorganic ions to prevent cell desiccation [2]. PH, yeast, and sucrose extract supply are factors that impact the synthesis and generation of EPS [3]. The most well-known producers of EPS are Lactobacillus, Lactococcus, Bifidobacterium, Leuconostoc, Pediococcus, Streptococcus, Enterococcus and Weissella sp. Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Oenococcus, Pediococcus, Streptococcus, and Weissella, were reported to leave a significant impact in rapid industrialization [7]
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