Antioxidant Activities of Exopolysaccharides Extracts from Two Endemic Fungi from Patagonia

A great number of free radicals have a negative impact on the human body, and an increased interest in the identification of new natural molecules with antioxidant properties has emerged due to concerns about synthetic antioxidants. Here, the antioxidant effect of four exo-polysaccharides (EPS) extracts obtained from submerged cultivation of Nothophellinus andinopatagonicus and Pseudoinonotus crustosus (N and P, respectively) in two culture media (M1 and M2) at 2 concentrations (100 and 250 µg/ml) was studied; then, its relation with the chemical composition of the EPS was evaluated. To assess the antioxidant activities of the extracts, several in vitro assays were performed: DPPH and ABTS radical scavenging, ferric-reducing antioxidant power, chelating ability on ferrous ions, and inhibition of the lipid peroxidation. The concentrations tested here were much lower than those reported in previous works. Despite variations in chemical composition and monosaccharide profiles among the extracts, all demonstrated antioxidant activity, although the type of activity differed; only P-M1 exhibited a good antioxidant activity across all assays. This extract contained the highest proportion of phenolic compounds, and also displayed the highest radical scavenging activity. Although the utilization of polysaccharides as functional food ingredients remains limited, we propose P-M1 as a promising candidate for a nutraceutical product. Additionally, a formulation could be made with a combination of extracts to create an antioxidant-rich supplement. Additional research is needed to confirm our findings in a cellular environment and to elucidate the mechanisms that drive their antioxidant activities, ultimately facilitating their development and utilization as nutraceutical products.