Seasonal variations in a polysaccharide composition of Far Eastern red seaweed Ahnfeltiopsis flabelliformis (Phyllophoraceae)

The quantitative and qualitative composition of polysaccharides from red alga Ahnfeltiopsis flabelliformis collected in the Amur Bay (Sea of Japan) from February to December 2009, depending on the water temperature and daily dose of photosynthetically active radiation (PAR), was analyzed. The highest content of polysaccharides was observed in February and November-December at low water temperature and daily PAR dose. The polysaccharide amount produced by the seaweed significantly decreased from March to September and increased from September to November. The main components of the polysaccharides were galactose and 3,6-anhydrogalactose containing sulfate groups. The galactose content was high throughout the studied period (28-42%), 3,6-anhydrogalactose ones in the summer (17.4%) and did not depend on environmental factors. The sulfate group amount was high in April-May and July-August. A statistically significant positive correlation was found between the sulfate group amount in the polysaccharide and the average daily PAR dose in the habitat of seaweed. The dynamics of dry weight accumulation during the year was similar to the polysaccharides. According to IR spectroscopy, the polysaccharides mainly contained disaccharide units of kappa-carrageenans and iota-carrageenans. The polysaccharide from A. flabelliformis collected in June had more regular structure than that in other months.