Comparative Study on the Polysaccharide Contents and Antioxidant Activities of <em>Hippophae rhamnoides</em> subsp. <em>sinensis</em> and <em>Hippophae gyantsensis</em>

This paper reports a well-designed and in-depth comparative study on the polysaccharide yields, contents, and antioxidant activities of two Hippophae species of great research value, namely, Hippophae rhamnoides subsp. sinensis Rousi and Hippophae gyantsensis (Rousi) Y. S. Lian. The total polysaccharides of H.rhamnoides subsp. sinensis and H. gyantsensis were obtained through hot water extraction. Yields were compared, and polysaccharide contents were accurately determined through phenol-sulfuric acid colorimetry and compared. Meanwhile, the antioxidant activity of the polysaccharides was evaluated through 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging. Results showed that the polysaccharide yield (percentage of crude extract relative to the raw material) of H.rhamnoides subsp. sinensis (1.18% ± 0.02%) was significantly lower than that of H. gyantsensis (3.12% ± 0.06%) (P < 0.01). The polysaccharide content (defined as pure polysaccharides in the extract) of H.rhamnoides subsp. sinensis (352.97±1.07 mg/g) was significantly higher than that of H. gyantsensis (300.21 ± 1.49 mg/g) (P < 0.01). The half-inhibitory concentration of the DPPH free radical scavenging activity of H.rhamnoides subsp. sinensis polysaccharides (0.026 ± 0.004 mg/mL) was slightly lower than that of H. gyantsensis polysaccharides (0.021 ± 0.004 mg/mL). However, no significant difference was found between the two Hippophae species (P > 0.05). This experiment clarified the differences in polysaccharide yield, content, and antioxidant activity between H.rhamnoides subsp. sinensis and H. gyantsensis. This work can provide a scientific basis for the quality evaluation of sea buckthorn and the further development of polysaccharide active components.