Structural peculiarities of carrageenans from Far Eastern red seaweed Mazzaella parksii (Gigartinaceae)

The sulfated polysaccharides from cystocarpic plants of Mazzaella parksii were studied. Fractionation at a given KCl concentration allowed us to assume, and stepwise fractionation to prove, that these polysaccharides con-sisted of several carrageenans that differed in structure and molecular weight. As a result of stepwise fraction-ation with KCl, nine gelling (1-9) and one non-gelling (10) fractions were obtained. Using IR spectroscopy, it was shown that fractions 3, 4 and 5 were kappa/iota-, kappa-and kappa/beta-carrageenans, respectively. The structures of the main fractions 1, 2, 9 and 10 were investigated in more detail by methylation, NMR spec-troscopy and mass spectrometry. Fractions 1 and 2 were hybrid kappa/iota-carrageenans with kappa:iota ratio 79:21 and 63:37, respectively. At the same time, fraction 9 contained kappa-, iota-and small amounts of nu-carrageenans. The fraction 10 had complex structure and was built from kappa-, iota-, beta-, mu-and nu-carrageenans and included agar-like structure, which explained the inability of this fraction to gel at 15 % KCl. It was shown that isolated polysaccharides activated the classical pathway of complement system, increasing the concentration of C1 inhibitor of serine protease by 50 % compared with the negative control.

Automated summary

The sulfated polysaccharides from cystocarpic plants of Mazzaella parksii were fractionated and determined to consist of several carrageenans with different structures and molecular weights. Nine gelling fractions and one non-gelling fraction were obtained through stepwise fractionation with KCl. The structures of the main fractions were investigated in detail, and their ability to activate the complement system was also studied.