Physicochemical properties and biological activities of litchi glycans with different molecular weights

Summary In this study, three litchi glycans (Lzp1–Lzp3) with molecular weights (Mw) of 2.25 × 106 Da, 6.00 × 103 Da and 3.24 × 102 Da were purified, and their structural characteristics, biological activities and structure–activity relationships were investigated. The results showed that Lzp1–Lzp3 had similar inhibitory effects on Escherichia coli and Staphylococcus aureus, as evidenced by the fact that there were no significant correlations between the Mw, active groups, monosaccharide compositions of Lzp1–Lzp3 and their antimicrobial activities. Lzp1 consisted of more mannose, galactose and arabinose, and less ribose and xylose, thus leading to its higher antioxidant activities of DPPH, ABTS, hydroxyl and superoxide radical scavenging and ferric‐ion reducing with the values of 78.0%, 99.0%, 90.2%, 1.08 and 3.93 respectively. Lzp2 contained more sulphonic acid and uronic acid, and the least glucose possessed the best effect on the promotion of exopolysaccharide production (24.77 mg/mL) by Weissella confusa, and the proliferation of Weissella confusa, Lacticaseibacillus rhamnosus, Bifidobacterium bifidum and Bifidobacterium breve with the OD600 ranging from 0.278–1.082. This study can provide a reference for the preparation of litchi glycans possessed specific biological activity. Three litchi glycans (Lzp1–Lzp3) with different molecular weights were prepared, and their structural characteristics, biological activities and the structure–activity relationships were investigated.