Structural elucidation and in vitro antioxidant activities of a new heteropolysaccharide from Litchi chinensis

Two polysaccharides, LCP70S-1 and LCP70W, were isolated from the pulp tissues of Litchi chinensis by anion-exchange chromatography and gel-filtration chromatography, while the structure of LCP70S-1 was elucidated and its physico-chemical properties was analyzed. The results demonstrated that LCP70S-1 is composed of L-rhamnose, L-arabinose and D-galactose in the ratio of 1.06:6.39:4.21, and the main chain of the heteropolysaccharide possess (1 -> 3,6)-linked galactopyranosyl branches at O-6. The three branches consist of (1. 3)-linked rhamnopyranosyl residues, (1 -> 3,6)-linked galactopyranosyl and (1 -> 5)-linked arabinopyranosyl residues, and terminated with (1 ->)-linked arabinopyranosyl residues, respectively. The two polysaccharides were further evaluated with 1,1-diphenyl-2picrylhydrazyl (DPPH) radical scavenging activities and their reducing power in vitro. The results showed that LCP70W and LCP70S-1 possessed significant antioxidant activities, especially for LCP70S-1. As such, LCP70S-1 could potentially serve as an antioxidant and would value further study for human healthcare.