Preparation and potential in vivo anti-influenza virus activity of low molecular-weight κ-carrageenans and their derivatives



Degradation of native κ-carrageenan was performed using acid hydrolysis aided with microwave heating. Combined with nonofiltration membrane (cut-off molecular weight 250 Da) separation, 1. 400 Da - 50 kDa low-molecular-weight (LMW) κ-carrageenans were obtained. Narrow molecular weight distribution of LMW κ-carrageenans could be prepared under pH 2.18 during the microwave power range investigated. The in vivo anti-influenza virus (IV) activity of three kinds of LMW κ-carrageenans (3, 5, and 10 kDa), their acetylated derivatives (acetylation degree of 1.5), as well as an acetylated and sulfated derivative of 3 kDa carrageenan (acetylation degree of 1.0 and sulfation degree of 2.4), were investigated using FM1-induced pulmonary oedema model. These LMW κ-carrageenans showed significant inhibition against FM1-induced pulmonary oedema as compared with the virus control, although their activities were inferior to that of positive control, Rabivirin. Introduction of acetyl groups greatly increased their anti-IV activity. The acetylated 3-kDa κ-carrageenan exhibited comparative activity with Rabivirin at both doses of 6 and 30 2. mg/kg·d, and the acetylated and sulfated derivative of 3 kDa carrageenan displayed higher activity than Rabivirin at the dose of 30 mg/kg·d. These results disclosed that 3 kDa κ-carrageenan with proper acetylation degree and sulfation degree was a potential candidate against influenza virus. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013