Characterization and in-vitro Alzheimer's properties of exopolysaccharide from Bacillus maritimus MSM1

Abstract

Four bacterial isolates were obtained from marine sediments collected from Sahl Hashish, Hurghada Red Sea, Egypt. This study was designed to search for promising anti-Alzheimer natural polysaccharide; therefore, four isolates were screened for exopolysaccharides (EPSs) production and acetylcholinesterase inhibition. The isolate S16 provided the highest EPS yield (7.51 g/L) and acetylcholinesterase inhibition. It was identified morphologically and genetically using 16S rRNA gene sequence analysis as Bacillus maritimus. A Physicochemical analysis of S16 exopolysaccharide (BMEPS) was estimated, which pointed to the presence of uronic acid and sulfate (24.7% and 18.3%, respectively). HPLC analysis indicated that mannuronic acid, glucuronic acid, glucose, and mannose are presented in a molar ratio of 0.8:1.0:2.8:2.3, respectively. Furthermore, FT-IR revealed an abundance of β-configurations. The GPC estimated the average molecular weight (Mw) as 4.31 × 10⁴ g/mol. BMEPS inhibited AChE (IC₅₀; 691.77 ± 8.65 μg/ ml), BChE (IC₅₀; 288.27 ± 10.50 μg/ ml), and tyrosinase (IC₅₀; 3.34 ± 0.09, 14.00 ± 0.14, and 22.96 ± 1.23 μg/ ml during incubation durations of 10, 20, and 40 min). It also demonstrated a selective anti-inflammatory action against COX-2 rather than COX-1. Moreover, BMEPS exhibited antioxidant capabilities as free radical and oxygen reactive species (ROS) scavenger, metal chelator, reductant agent, and lipid peroxidation suppressor. These activities are due to the distinct chemical composition. The findings of this study indicate that BMEPS could be considered as promising anti-disease Alzheimer's (AD) material in an in-vitro model, which qualifies it for advanced in-vivo studies in the discovery of alternative Alzheimer's treatment.

Figure 1

Colony morphology of Bacillus maritimus MSM1on solid marine medium (A) and Neighbor-joining Phylogenetic tree of strain based on 16S rRNA gene sequences (B).

Figure 2

The FTIR spectrum of BMEPS from Bacillus maritimus MSM1 (A) and molecular weight (B).

Figure 3

Reduction capability (A), metal chelation (B), and lipid peroxidation suppression (C) effects of BMEPS at different concentrations (100–1000 μg/ ml), compared to reference materials LAA and BHT. (LAA: L-Ascorbic acid and BHT: butylated hydroxytoluene). Data were presented as mean ± SE. ANOVA one-way was used for data analysis (n = 3, P ≤ 0.05). Data are followed with small letters; a means significant difference with Ascorbic Acid, b means significant difference with BHT.

Figure 4

Scavenging capacity of BMEPS; DPPH^• (A) and ABTS + (B), superoxide (C), and NO (D) at different concentrations (100–1000 μg/ ml), compared to reference materials; LAA and BHT. (NO: nitric oxide radical; LAA: L-Ascorbic acid; BHT: butylated hydroxytoluene; DPPH^.: 1,1diphenyl-2- picryl-hydrazyl free radical). Data presented as mean ± SE. ANOVA one-way was used for data analysis (n = 3, P < 0.05). Data are followed with small letter; a means significant difference with Ascorbic acid, b means significant difference with BHT.

Figure 5

COX- 1 (A) and COX-2 (B) inhibition activity of different concentrations (100–1000 μg/mL) of BMEPS and Celecoxib. Data presented as mean ± SE. ANOVA one-way was used for data analysis (n = 3, p < 0.05). Data are followed with a small letter, a means of significant difference with celecoxib.

Figure 6

Cholinesterase inhibitory effect of BMEPS at different concentrations (100–1000/ml), AChE (A) and BChE (B). Data were presented as mean ± SE. ANOVA one-way was used for data analysis (n = 3, P ≤ 0.05).

Figure 7

Tyrosinase inhibition activity of different concentrations (100–1000 μg/ ml) of BMEPS and reference materials Kojic acid. Data presented as mean ± SE. ANOVA one-way was used for data analysis (n = 3, P < 0.05). Data are followed with small letter; a means significant difference with Kojic acid.