Effect of copper-induced oxidative stress on sclerotial differentiation and antioxidant properties of Penicillium thomii PT95 strain.

Penicillium thomii PT95 strain was able to form abundant orange, sand-shaped sclerotia in which carotenoids were accumulated. The aim of this work was to determine the effects of copper-induced oxidative stress on the sclerotial differentiation and antioxidant properties of PT95 strain. The results showed that the time of exudates initiation, sclerotial initiation and sclerotial maturation of PT95 strain were advanced in 1-2 days under the copper-induced oxidative stress growth conditions. The analytical results of sclerotial biomass, carotenoids content in sclerotia showed that copper-induced oxidative stress favored the sclerotial differentiation and biosynthesis of carotenoids. Under the copper-induced oxidative stress growth conditions, the total phenolics content and DPPH free radical scavenging activity of sclerotia of this fungus were decreased as compared with the control. However, the oxidative stress induced by a lower amount of CuSO4 in media could enhance significantly the reducing power of sclerotia.

[Studies on the antioxidative activity of polysaccharides from radix Saposhnikoviae].

OBJECTIVE: To research the antioxidant activity of polysaccharides from Saposhnikovia divaricata (Turez.) Schischk. METHOD: Polysaccharides from Saposhnikovia divaricata (Turez.) Schischk were obtained through hot water extracting and ethanol precipitating method. Using CTAB as precipitant, Saposhnikovia polysaccharide was separated into acid Saposhnikovia polysaccharide (A-SPS) and neutral Saposhnikovia polysaccharide (N-SPS). The total reducing power, scavenging effect to superoixide anion (O2-*), hydroxyl radical (*OH), 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH*) and inhibiting effect to lipid-peroxidation induced by Fe2+ of different Saposhnikovia polysaccharides were measured in vitro chemical simulated systems for evaluating their antioxidant activity. RESULTS: Saposhnikovia polysaccharides had some functions of scavenging free radicals and inhibiting lipid peroxidation, and scavenging effects on DPPH* and OH* were especially significant. A-SPS had better effect among different Saposhnikovia polysaccharides, and the scavenging rate of DPPH* and OH* could approach to 70% when the experimental concentration was 8 mg/ml . CONCLUSION: A-SPS, potential main active ingredient of Saposhnikovia polysaccharide, has strong antioxidant activity and can be applied as a potential natural antioxidant in food and medicine industry.