Abstract:The polysaccharides from Gracilaria lemaneiformis were exacted using hot water, different acids, and enzymes. The effects of different methods on the extraction rate were compared, and the chemical composition and immunoregulatory activity of polysaccharides extracted using acids were evaluated. The results showed that the yield of the polysaccharides extracted using citric acid was the highest (27.66 ± 0.49%), which was 1.86 times those extracted using hot water. The amounts of total sugar, proteins, uronic acids, and sulfates of the polysaccharides exacted using citric acid were 62.24 ± 1.09%, 1.54 ± 0.15%, 6.25 ± 0.72%, and 16.74 ± 0.11%, respectively. No polyphenols were detected. In addition, the polysaccharides extracted using citric acid significantly promoted the proliferation of RAW 264.7 cells, and enhanced their pinocytic capability. G. lemaneiformis polysaccharide improved the thymus and spleen indices in photoaged mice, as well as reduced the concentration of interleukin-10 and increased tumor necrosis factor-α content in mouse serum. These findings suggest that G. lemaneiformis polysaccharides have a relatively high capacity to enhance the immune functions of mice and can alleviate immunosuppression during the photoaging process.
