Abstract

This study addresses for the first time the chemistry and biological activity of polysaccharides isolated from Didymosphenia geminata. Fourier-transform infrared spectroscopy (FTIR) and high-performance thin-layer chromatography (HPTLC) techniques were used to characterize the crude and acidic polysaccharides of D. geminata; galactose and xylose were found to be the main monomer components. The antioxidant activity as well as the effect on the expression of IL-6 and TNF-α in RAW 264.7 murine cell lines were determined for both types of polysaccharides. The antioxidant activity of crude polysaccharides proved to be stronger than acidic polysaccharides by means of quenching experiments of ABTS·+ and Trolox equivalent antioxidant capacity (TEAC) (p < 0.05). Crude polysaccharides induced an increase in both IL-6 and TNF-α contents. Acidic polysaccharides produced a similar effect on these cytokines, but to a lesser extent. These results suggest that polysaccharides from D. geminata could be explored as natural antioxidant and immunomodulatory agents in medicine and the nutraceutical industry. This investigation suggests an opportunity to turn the invasive mats of D. geminata, which currently cause environmental problems, into a source of polysaccharides with nutraceutical application.