Sulfate Modification and Evaluation of in vitro Anti‐HIV Activity of Lycium Barbarum Polysaccharides

Abstract

This study investigated the feasibility of sulfate modification of Lycium barbarum polysaccharides (LBPs) and their potential anti-HIV-1 application. LBPs with different molecular weights were prepared by fractional precipitation from crude LBP via aqueous extraction, ethanol precipitation, and deproteinization. The purified LBPs (G1, G2, and G3) were sulfated using the chlorosulfonic acid pyridine method to obtain sulfated LBPs (G1S1-G1S4, G2S1-G2S4, and G3S1-G3S4) with different sulfur degrees of substitution. The anti-HIV-1 activity in vitro was evaluated via the TD 50 from the cytotoxicity test and the IC 50 inhibitory activity. The cytotoxicity and inhibitory activity in vitro were carried out using the CCK-8 assay and MAGI test with Azidothymidine (AZT) as a positive control. The results show that the LBPs and the sulfated derivatives were not toxic towards CCK-8 cells with TD 50 > 100 μg/mL and they had strong anti-HIV-1 activity with IC 50 values of 0.02-0.12 μg/mL. Compared with the LBPs, the anti-HIV-1 activity of the sulfated LBPs increased with IC 50 values from 0.0924-0.1206 μg/mL to 0.0206-0.0722 μg/mL. Sulfate modification of LBPs can increase their anti-HIV pharmacological activity, the G1S4 (Mw = 2.13 × 10 4 Da and DS = 1.12) showed relatively good in vitro anti-HIV-1 activity with an IC 50 value near that of AZT (0.0200 μg/mL). The results suggest further detailed in vivo studies are warranted for these promising candidates with anti-HIV-1 activity.