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

Irina Yermak,Anna Kravchenko,Valery Glazunov,Pavel Spirin,Andrey Shulgin,William Helbert,Stanislav Anastyuk,Vladimir Prassolov

doi:10.3390/ijms222312905

Abstract

New insights into the structure of the hybrid κ/β-carrageenan (κ/β-CRG) of the red alga Tichocarpus crinitus have been obtained. Carrageenan oligosaccharides were prepared through the chemical and enzymatic depolymerization of κ/β-CRG with κ-carrageenase and its the enzyme-resistant fraction. The composition and distribution of the repetition units of κ/β- 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 β-blocks along the polysaccharide chain, with the inclusion of κ/β, μ/ν-blocks and some ι-blocks. Furthermore, the desulfated κ/β-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 κ/β-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.

Highlights

Carrageenans (CRGs) are a family of water-soluble linear sulfated galactans extracted from red algae
The structure of the gelling polysaccharide was studied by 13 C nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FT-IR), and the obtained spectra were compared with the spectra of polysaccharides isolated from T. crinitus earlier by our group [9]
According to data obtained by spectroscopy, the KCl-insoluble polysaccharide from T. crinitus featured a hybrid κ/β-CRG structure

Summary

Introduction

Carrageenans (CRGs) are a family of water-soluble linear sulfated galactans extracted from red algae They are appreciated for their structural diversity, which is associated with a large panel of physico-chemical properties and biological activities. To describe the complex CRG structure, a uniform letter code nomenclature has been developed [1] Based on this nomenclature, the three-linked β-D-galactopyranose is the G unit, while four-linked α-D-galactopyranose D-unit or DA-units, respectively. A new type of CRG, in which the three-linked residues are not sulphated and the four-linked units lack sulphate at C-2, was first reported by Greer and Yaphe [3]. This type was called β-CRG, or furcelaran, since it was extracted from Furcellaria lumbricalis.

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