Evaluation of improved biological properties of chemically modified exopolysaccharides from BR2.

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This work engrosses the production and further chemical modifications of EPS produced by BR2 and subsequent evaluation of their biological properties showed greater antioxidant properties for the derivatives compared to its native unmodified form. Of the three derivatives, acetylated EPS (a-EPS), carboxymethylated EPS (Cm-EPS), and sulphated EPS (s-EPS), a-EPS exhibited the highest DPPH radical scavenging and total antioxidant activity in a dose-dependent manner. At all tested concentrations, a-EPS showed higher scavenging activity, and a maximum activity of 73.81% at 2 mg/mL. Meanwhile, s-EPS showed the highest reducing power potential and hydroxyl radical scavenging activities. At 2 mg/mL concentration, the order of reducing power was observed to be s-EPS (41.39%) > a-EPS (37.43%) > Cm-EPS (24.02) > BR2 control EPS (16%) and the hydroxyl radical scavenging activity for the s-EPS was 54.43%. The highest reducing power activity exhibited by s-EPS is 2.6-fold higher and a 1.5-fold increase in the scavenging activity of native BR2 EPS after the sulphonyl group addition was observed. The increase in these activities is due to the addition of various functional groups that contributes largely to the scavenging abilities of different free radicals. The s-EPS and Cm-EPS derivatives also exhibited increased cholesterol-lowering activity of 40 and 34.5%, respectively, than the native EPS. Interestingly, there were hardly any inhibitions on cell growth and viability of normal L929 fibroblast cell lines upon treatment with these EPSes. The improved antioxidant properties resulting from chemical modification opened better avenues for EPS application in the food and pharma sectors. Thus, the potentiality of chemically modified EPS may be explored further in the development of functional foods.

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The online version contains supplementary material available at 10.1007/s13205-023-03718-5.