Optimization of the extraction of polysaccharides from the shells of Camellia oleifera and evaluation on the antioxidant potential in vitro and in vivo

The fruit shells of Camellia oleifera are a by-product on the Camellia oleifera industry without sufficient utilization. In this work, the ultrasound-assistant extraction process was optimized by response surface methodology. Then the physicochemical properties and antioxidant potential were evaluated. The results showed that the highest yield of polysaccharides was 12.94 ± 0.10% under the optimal condition. The polysaccharides of these fruit shells (CFP) contained 88.04 ± 1.46% of polysaccharides and the molecular weight was 8.74 × 104 Da mainly composed by xylose, mannose, glucose and galactose with the ratio of 43.54: 6.83: 34.94: 14.19. Moreover, CFP could well scavenge free radicals, and protect cells against oxidative damage induced by H2O2. In addition, CFP also increased the survival of Caenorhabditis elegans under thermal stress by activating DAF-16 transcription factor then stimulating the expression of superoxide dismutase. The results in this work elucidated CFP possessed a strong antioxidant potential in vitro and in vivo. Considering the big development trend of Camellia oleifera industry in China, thousands of tons of shells are produced therefore, they can be developed into a promising natural antioxidant, extending the industrial chain.