Inhibition of complement activation by water-soluble polysaccharides of some far-eastern brown seaweeds.

Fucoidans and laminarans from Laminaria cichorioides, Laminaria japonica, Fucus evanescens, laminaran from Laminaria gurjanovae, other beta-D-glucans (translam, pustulan and zymosan) and lambda-carrageenan from Chondrus armatus were used to study the effect of water-soluble polysaccharides from seaweeds on the alternative pathway of complement (APC). beta-D-Glucans and fucoidans under study differed appreciably from each other by structural characteristics, and also by degree of purification. beta-D-glucans, on ability to bind complement, ranked in a line according to a degree of their purification. Highly purified beta-D-glucans under study did not reveal an ability to bind complement. The fucoidans were divided conventionally into three groups according to their action on APC. Highly sulfated alpha-L-fucan from L. cichorioides with the greatest activity toward APC and caused 50% inhibition of reaction of activation (RA) of APC in a concentration of 0.5-0.7 mg/ml. Opposite 50% of inhibition of lysis of erythrocytes by sulfated heterogeneous fucoidan from L. japonica was achieved with 20 mg/ml. All other fucoidans and lambda-carrageenan have activity at 6-10 mg/ml concentration. Decreasing the sulfate content from 36% up to 9% in sample fucoidans under study was not reflected practically in the 50% inhibition concentration. Apparently, the degree of sulfating of fucoidans did not influence their action on APC. But the positive influence of fucose in structure of polysaccharide was obvious.