Sulfated modification and anti-HIV activity evaluation of Lycium barbarum polysaccharides

BACKGROUND: Lycium barbarum polysaccharides (LBPs) belong to a very important class of biological macromolecules from Lycium barbarum berries in nature, and have received much attention due to their various biological activities. Since sulfated polysaccharides have antiviral activity in vitro, there is no published research on the sulfated modification of LBPs. RESULTS: The objective of this study was to investigate the feasibility of sulfated modification of LBPs and their potential application in inhibiting HIV-1. The LBPs with different molecular weight were prepared by fractional precipitation from crude LBP through aqueous extraction, ethanol precipitation and deproteinization. The purified LBPs (G1, G2 and G3) were sulfated by chlorosulfonic acid pyridine method to give rise to the sulfated LBPs (G1S1-G1S4, G2S1-G2S4 and G3S1-G3S4) with different degrees of substitution. The anti-HIV-1activities were evaluated by TD 50 of the cytotoxicity and IC 50 of inhibitory activity using the CCK-8 and Magi test with Azidothymidine (AZT) as positive control. The results showed that LBPs and sulfated LBPs showed non-toxicity with the TD 50 >100 μg/mL. Compared with the LBPs, the inhibition of anti-HIV-1 activity of sulfated LBPs was increased significantly with the IC 50 value from 0.0924-0.1206 μg/mL to 0.0206-0.0722 μg/mL. The G1S4 (Mw=2.13×10 4 Da and DS=1.12) showed excellent anti-HIV-1 activity with the IC 50 value near to that of AZT (0.0200μg/mL), which would make it possible to become a candidate compound with anti-HIV-1 activity. CONCLUSION: The outcome of the study indicated that sulfated modification of LBPs was feasible and sulfated LBPs had good potential as an anti-HIV drug.