Polysaccharide structure of tetrasporic red seaweed Tichocarpus crinitus

•Sulfated polysaccharide from tetrasporic plants of Tichocarpus crinitus was investigated.•The extracted polysaccharides were presented by non-gelling ones only.•Instrumental methods showed T. crinitus contains main blocks of –G(2,4)S-(1,3)-DA–.•6-sulfated 4-linked Galp resudies are randomly located along polysaccharide chain. 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 β-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 β-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.