Sulfated modification of lycium barbarum polysaccharide under microwave irradiation and their anti-HIV activities

The sulfated Lycium barbarum polysaccharide (LBP) were prepared by chlorosulfonic acid–pyridine (Py-SO₃) method according to orthogonal L₉(3)⁴ test under microwave irradiation. Eight sulfated sLBP, with various degrees of sulfate (DS) and the number average molecular weight (M_w), were obtained and their anti-HIV activities were compared by MTT and ELISA assay.  The results indicated that when DS within the scope of 0.2–0.5 and the M_w in the range of 40–50 kDa, sLBP exhibited significantly strong inhibition of HIV activity, and it was confirmed by real-time biomolecular interaction analysis (BIAcore). The optimum sulfation conditions were reaction temperature of 45°C, the molar ratio of Py-SO₃ to LBP of 2:1 and the reaction time of 6 min at the microwave power of 45W in DMF.