Polysaccharide structure of tetrasporic red seaweed Tichocarpus crinitus.

Sulfated polysaccharide isolated from tetrasporic plants of Tichocarpus crinitus was investigated. The polysaccharide was isolated by two methods: with water extraction at 80 °C (HT) and with a mild alkaline extraction (AE). The extracted polysaccharides were presented by non-gelling ones only, while galactose and 3,6-AG were the main monosaccharides, at the same time amount of 3,6-AG in AE polysaccharides was the similar to that of HT. According to methods of spectroscopy and mass spectrometry, the polysaccharide from tetrasporic T. crinitus contains main blocks of 1,3-linked ß-D-galactopyranosyl-2,4-disulfates and 1,4-linked 3,6-anhydro-α-D-galactopyranosyl while 6-sulfated 4-linked galactopyranosyl resudies are randomly distributed along the polysaccharide chain. The alkaline treatment of HT polysaccharide results in obtaining polysaccharide with regular structure that composed of alternating 1,3-linked ß-D-galactopyranosyl-2,4-disulfates and 1,4-linked 3,6-anhydro-α-D-galactopyranosyl residues. Native polysaccharide (HT) possessed both high anticoagulant and antiplatelet activity measured by fibrin clotting and platelet aggregation induced by collagen. This activity could be connected with peculiar chemical structure of HT polysaccharide which has high sulfation degree and contains also 3,6-anhydrogalactose in the polymer chain.

Atomic force microscopy imaging of carrageenans from red algae of Gigartinaceae and Tichocarpaceae families.

In the present article, the atomic force microscopy was applied to investigate macromolecular structures of various carrageenan types including hybrid polysaccharides (κ-, κ/ß-, κ/ι-, λ-, and X-carrageenans) depending on polysaccharide concentration. The structures dependence on a polysaccharide concentration also was focused. κ-Carrageenan forms both single and two stranded structures at a low concentration. At high concentrations κ-, κ/ß-, and κ/ι-carrageenans form fibrous network-like structures by a side-by-side association type at the same time for κ/ι-carrageenan end-to-end association type also was found. Comparably to κ-carrageenan, κ/ß-carrageenan network was more open with coarser fibers while κ/ι-carrageenan structure is characterized with a more flexible network. Honeycombed structures due to end-to-end and side-by-side association types were observed for X-carrageenan, while λ-carrageenan formed honeycombed structures only at high concentrations. In order to investigate topographical parameters of the carrageenans macromolecular structure a new method of the autocorrelation function analysis was used for the first time.

Correlation between influence of polysaccharides on hydrolase activity and their antiviral effect in tobacco leaves.

The activities of hydrolases (acid phosphatase, RNase, and proteases) in healthy and tobacco mosaic virus-infected leaves of Nicotiana tabacum L. var. Samsun, both untreated and treated with polysaccharides (PS) (1,3;1,6-ß-D-glucan, fucoidan, and κ/ß-carrageenan), were determined. The PS lead to substantial increase in the hydrolase level. The percentage of viral particles undergoing destructive change also increases in leaves treated with PS 24 h before infection. We suppose that the PS-mediated hydrolase activation promotes intracellular destruction of the viral particles and, thus, comprises one of the PS-induced protective mechanisms limiting intracellular viral accumulation.

In vitro and ex vivo studies of antioxidant activity of carrageenans, sulfated polysaccharides from red algae.

Antioxidant properties of structurally different sulfated polysaccharides (carrageenans) were studied in vitro and ex vivo. Ferric reducing antioxidant activity of carrageenans and their inhibitory effects on hydroxyl radicals and superoxide anion radicals were demonstrated in vitro. Activity of carrageenans depends on the polysaccharide structure. Carrageenans stimulate catalytic activity of SOD from donor erythrocyte.

[Inhibitory effect of kappa/beta-carrageenan from red alga Tichocarpus crinitus on the development of a potato virus X infection in leaves of Datura stramonium L].

The effect of kappa/beta-carrageenan from red alda Tichocarpus crinitus on the development of a potato virus X (PVX) infection in the leaves of Datura stramonium L. has been studied. The treatment of leaves with carrageenan stimulates a protein synthesis in the cells, causing an increase in the size of nucleoli and in the number of mitochondria and membranes of the granular endoplasmic reticulum. At the same time, such treatment slightly stimulates lytic processes, causing an increase in the number of agranular endoplasmic reticulum cisterns, dictyosomes, and cytoplasmic vacuoles and the formation of cytoplasmic zones, transparent to electron microscopy. The carrageenan-induced stimulation of lytic processes results in the destruction of viral particles and can be considered as one of the defense mechanisms, preventing the intracellular accumulation of viruses. The carrageenan-stimulated formation of PVX-specific laminar structures, able to bind viral particles and, therefore, prevent their intracellular translocation and reproduction, represents another carrageenan-induced mechanism of the antiviral defense in plant cells.

[Influence of kappa/beta-carrageenan from red alga Tichocarpus crinitus on development of local infection induced by tobacco mosaic virus in Xanthi-nc tobacco leaves].

The influence of kappa/beta-carrageenan from red marine alga Tichocarpus crinitus on the development of tobacco mosaic virus (TMV) infection in Xanthi-nc tobacco leaves was studied. It was shown that the number of necrotic lesions on the leaves inoculated with the mixture of TMV (2 microg/ml) and carrageenan (1 mg/ml) was reduced by 87%, compared to the leaves inoculated with the virus only. The suppression of virus infection was also observed when leaves were treated with carrageenan 24 h before or 24 h after leaf inoculation with TMV; however, in these cases, suppression was less evident than after inoculation with the virus-polysaccharide mixture. It is supposed that the antiviral activity of carrageenan applied together with TMV may be explained by its action not only on the plant but also on the virus itself. The inhibitory effect of carrageenan pretreatment can be explained by its favorable effect on tissue resistance to infection. The suppression of this resistance by actinomycin D indicates that carrageenan functions via its action on the cell genome.

Natural polysaccharide carrageenan inhibits toxic effect of gram-negative bacterial endotoxins.

The protective effect of polysaccharide carrageenan on the damaging effect of endotoxins of gram-negative bacteria was studied in vivo and in vitro. Carrageenan increased mouse resistance to the toxic effect of LPS. The degree of protection depended on polysaccharide concentration and administration time and route. Pretreatment of donor platelets with carrageenan reduced their aggregation activity caused by cooperative effect of LPS and ADP.

Comparative study of carrageenans from reproductive and sterile forms of Tichocarpus crinitus (Gmel.) Rupr (Rhodophyta, Tichocarpaceae).

A comparative study of the structure and properties of the sulfated polysaccharides (carrageenans) isolated from the vegetative and reproductive forms of the red alga Tichocarpus crinitus was performed. The polysaccharides were separated into the gelling (KCl-insoluble) and non-gelling (KCl-soluble) fractions by precipitation with 4% KCl. The total content of polysaccharides extracted from the reproductive form of the alga was 1.8-fold more than that extracted from the vegetative form, and in the first case, the gelling polysaccharides mostly accumulated. The gelling polysaccharides from the vegetative form have the highest molecular weight (354 kD). According to the results of FT-IR and 13C-NMR spectroscopy, the gelling polysaccharide fractions from both forms are kappa/beta carrageenans. The differences concern the content of the kappa- and beta-disaccharide units and the presence of a small content of the sulfated disaccharide segments (precursors of the kappa-carrageenans) in the polysaccharide from the reproductive form of the alga. The non-gelling polysaccharide fractions from both forms of the plant are mixtures of sulfated galactans with a low content of 3,6-anhydrogalactose.