Preparation and anti-influenza A virus activity of κ-carrageenan oligosaccharide and its sulphated derivatives

Carrageenans, the sulphated galactans derived from red algae, are attracting increasing interest in developing potential anti-viral drugs. In this study, low molecular weight kappa-carrageenan oligosaccharides (KCO) and their sulphated derivatives (KCO-S) were prepared, and their anti-influenza A virus (IAV) properties were investigated. The results indicated that KCO and KCO-S could effectively inhibit IAV multiplication in MDCK cells in a dose-dependent manner. Furthermore, a structure-activity relationship study showed that the degree of sulphation and molecular weight were the main factors that influenced the anti-IAV activity of kappa-carrageenan oligosaccharide. The most active kappa-carrageenan oligosaccharide had a sulphate content of 0.8-1.0 mole/mole of disaccharide and a molecular weight of 1-3 kDa. In addition, KCO and KCO-S could significantly improve survival and decrease pulmonary viral titres in IAV-infected mice. Moreover, the antiviral effect of KCO and KCO-S does not seem to be dependent on the interferon system. In conclusion, carrageenan oligosaccharide and its sulphated derivative have good inhibitory actions on IAV replication in vitro and in vivo. (C) 2012 Elsevier Ltd. All rights reserved.