RESUMO
Xylaria nigripes, a local rare medicinal fungus, has multi-antioxidant activities owing to its water extraction as shown by previous research. However, the main indicator causing the antioxidant effect was not clear, so this research focused on the antioxidant activities from different sources of X. nigripes such as fruiting body polysaccharides, mycelium intracellular polysaccharides, mycelium extracellular polysaccharides, and their deproteinization products. The mycelium intracellular polysaccharide (XnIPS-1) from X. nigripes showed the highest reducing power of antioxidant activity, since it revealed the lowest IC50 values in all the assayed methodologies. The IC50 values of chelating ferrous ion ability, ABTS radical scavenging activity, and DPPH free radical scavenging were 1412, 174.25, and 351.56 µg/mL, respectively. In addition to these results, this research also explored the mechanism between polysaccharides and antioxidants compared by FT-IR analysis. The spectrum shows that the X. nigripes polysaccharide structure changed after the proteins were removed.