New Insights into the Structure of Kappa/Beta-Carrageenan: A Novel Potential Inhibitor of HIV-1

New insights into the structure of the hybrid kappa/beta-carrageenan (kappa/beta-CRG) of the red alga Tichocarpus crinitus have been obtained. Carrageenan oligosaccharides were prepared through the chemical and enzymatic depolymerization of kappa/beta-CRG with kappa-carrageenase and its the enzyme-resistant fraction. The composition and distribution of the repetition units of kappa/beta- CRG were investigated by using the negative ion tandem MALDI-TOFMS and ESIMS method, which made it possible to prove and characterize the hybrid structure of this polysaccharide. An analysis revealed the blockwise distribution of the long beta-blocks along the polysaccharide chain, with the inclusion of kappa/beta, mu/nu-blocks and some iota-blocks. Furthermore, the desulfated kappa/beta-CRG was shown to contain of -G-D- repeating units up to 3.5 kDa. Previous studies have demonstrated that CRGs suppress the replication of several viruses. Here, we established that kappa/beta-CRG and its oligosaccharides significantly inhibit the transduction efficiency of replication-defective lentiviral particles pseudotyped with the envelope proteins of three different viruses. We found that the polysaccharide and its oligosaccharides strongly reduced the transduction efficiency of lentiviral particles pseudotyped with GP160-the envelope protein of the human immunodeficiency virus HIV-1-when added to T-lymphocyte Jurkat cells. The CRG oligosaccharides displayed significantly higher antiviral activity.

Automated summary

New insights into the hybrid structure of kappa/beta-carrageenan in the red alga Tichocarpus crinitus have been obtained, demonstrating its potential to inhibit the replication of various viruses, particularly the human immunodeficiency virus. The study revealed the antiviral activity of carrageenan oligosaccharides against lentiviral particles pseudotyped with different envelope proteins, with CRG oligosaccharides showing significantly higher activity.