Antioxidant and antimicrobial evaluation of carboxymethylated and hydroxamated degraded polysaccharides from Sargassum fusiforme

In order to improve the bioactivity of the polysaccharide from Sargassum fusiforme (PSF), the degraded polysaccharide (DPSF) was modified by carboxymethylation, yielding carboxymethylated degraded polysaccharides (CDPSF), which were further modified to generate hydroxamated derivatives (HCDPSF). Both CDPSF and HCDPSF were characterized by Fourier transform infrared spectroscopy. The molecular weight of CDPSF and HCDPSF was found to be 354 kDa and 375 kDa, respectively. The in vitro antioxidant activity of CDPSF and HCDPSF was evaluated by determining the radical scavenging ability and total antioxidant activity. The results indicated that the antioxidant activity of CDPSF and HCDPSF was significantly improved when compared to those of DPSF. Antimicrobial assays indicated that both CDPSF and HCDPSF possessed a marked antimicrobial ability, while DPSF did not exhibit such effects under the same conditions. Such polysaccharide derivatives have potentials in the pharmaceutical and food industries. •Carboxymethylated and hydroxamated polysaccharides from S. fusiform were prepared.•The antioxidant activity of the modified polysaccharides was greatly improved.•Both hydroxamated and carboxymethylated polysaccharides showed antibacterial activity.