Biomedical and therapeutic potential of marine-derived Pseudomonas sp. strain AHG22 exopolysaccharide: A novel bioactive microbial metabolite

Abstract

Microbial exopolysaccharides (EPSs) are gaining interest as alternatives to chemical antioxidants and pharmaceuticals. This study mines the promising biomedical and antimicrobial potential of a marine bacterium, a prolific EPS producer, isolated from the Red Sea. Pseudomonas sp. strain AHG22 generated an EPS weighing 6.98 g·L−1, coded EPSF8, subjected to FT-IR and HPLC chemical analysis. EPSF8 was then investigated for antioxidant assessment by 2,2-diphenyl-1-picrylhydrazyl (DPPH), H2O2, ABTS˙+, nitric oxide, total antioxidant capacity (TAC), and ferric reducing antioxidant power (FRAP). EPSF8 had an IC50 of 46.99 μg·mL−1 in the DPPH antioxidant assay and antioxidant capacities of 219.45 μg·mg−1 ascorbic acid equivalent (AAE) in the TAC assay and 54.15 μg·mg−1 AAE in the FRAP assay. The in vitro anti-inflammatory effect of EPSF8 was tested against 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) enzymes and compared with the drugs ibuprofen and celecoxib used as controls. The IC50 values of 5-LOX, COX-2, ibuprofen, and celecoxib were found to be 14.82, 15.49, 1.5, and 0.28 μg·mL−1, respectively. Additionally, EPSF8 revealed antidiabetic activity toward α-amylase and α-glucosidase, and the IC50 values were 93.1 and 127.28 μg·mL−1, compared to those of acarbose (50.93 and 4.13 μg·mL−1, respectively). Anti-obesity activity of EPSF8 by lipase inhibition revealed IC50 = 56.12 μg·mL−1 compared to orlistat (IC50 = 20.08 μg·mL−1) as a control. EPSF8 displayed antibiofilm and bactericidal activity against Gram-positive (G +ve) and Gram-negative (G −ve) ATCC pathogenic bacterial strains. It had a minimum bactericidal concentration/minimum inhibitory concentration ratio ≤2, indicating a broad bactericidal spectrum. Furthermore, EPSF8 is evidenced to have a promising anti-butyrylcholinesterase activity for the control of Alzheimer’s disease. The findings of the present analysis suggest that the isolated Pseudomonas sp. strain AHG22 EPS can potentially be explored as a promising green therapeutic compound.

Keywords

• antioxidant
• anti-inflammatory
• antidiabetic
• anti-obesity
• antibiofilm
• anti-alzheimer