Microalgae Exopolysaccharides: Postbiotic with Anti-Adhesive Properties

BACKGROUND AND OBJECTIVESThe development of antibiotic resistance in Helicobacter pylori has emerged as a significant issue in recent times. Using non-biocidal surface-active compounds to prevent bacterial pathogens from adhering and aggregating is a promising alternative to antibiotic treatments. Some anti-adhesive compounds, such as capsular polysaccharides released by different microalgae, have been identified for this purpose. The present study aimed to determine if the sulfated exopolysaccharides extracted from chlorella sp. strain N۴ have any anti-adhesive effects against H. pylori.MATERIALS AND METHODSThe sulfated exopolysaccharides were extracted using acid (۰.۰۷%) at ۹۰°C for ۴ hours. The total carbohydrates and sulfate content of exopolysaccharides were analyzed by the phenol-sulfuric acid and BaCl۲ gelatin method respectively. The inhibitory effect of extracted polysaccharides on H. pylori attachment to gastric adenocarcinoma (AGS) cell lines was investigated in vitro using AGS-coated microtiter plates.RESULTS AND DISCUSSIONThe results implied that sulfated exopolysaccharides extracted from chlorella sp. strain N۴ have a ۰.۴۱ sulfate/ sugar ratio. The extracted exopolysaccharides could effectively protect AGS cells against H. pylori. In addition, a competitive binding assay showed that the antiadhesive activity of exopolysaccharides was higher than heparin. While heparin at the concentration of ۲۵۰ μg/mL reduced attachment of H. pylori to AGS cells by approximately ۵۲.۵±۳.۰۷%, the extracted polysaccharides caused ۷۱.۳۵±۳.۴۷% reduction in adhesion at the same concentration. The observed anti-adhesive properties are likely due to a combination of factors, such as the sulfate content and its binding site, the monosaccharide residues, and the glycoside bonds. These elements are involved in the bioactivity of the polysaccharide.CONCLUSIONAccording to the findings, the sulfated exopolysaccharide extracted from chlorella sp. strain N۴ demonstrated a strong ability to prevent adhesion of H. pylori cells in vitro. So, they have remarkable potential in H. pylori eradication therapy by inhibition of gastric colonization.