Hemagglutinins in brown seaweeds

Twenty-eight brown seaweeds contain agglutinins that show activity against animal and human erythrocytes. Three brown seaweeds are described whose hemagglutinic activity has not been previously reported: Ectocarpus confervoides, Giffordia granulosa and Cutleria multifida. Hemagglutinic activity against different erythrocytes is as follows: rabbit, 100%; sheep, 71%; chicken, 64%; guinea-pig, 39%; human, 38%; horse, 25% and calf, 21%. The highest agglutinic activity was found with rabbit erythrocytes, with maximum titres of: Fucus serratus (218), Laminaria saccharina (217) and Himanthalia elongata (217). The species Giffordia granulosa showed certain specificity against human erythrocytes. In general, the hemagglutinic activity of these brown seaweeds seems to be of a polyphenolic nature. Agglutinic activity of some of these brown seaweeds can be used as a taxonomic index.