Biological Activities of Extracts from Several Species of Rohdomelaceae from Fujian Coasts of China

Abstract

Five species of Rhodomelaceae (Rhodophyta) were screened for antibacterial and antifungal activities and examined for agglutinating activities with different animal and human erythrocytes. Among three extracts (lipid, polysaccharide and protein), only lipid extracts from four species of these algae were active against the bacteria and fungi tested. Furthermore, agglutinating activities of protein extracts from all five algal species were detected using erythrocytes from sheep, rabbit, chicken and human A, B, 0 and AB blood cell groups. In agglutination assay, extracts from four of the five algal species were found to agglutinate two or more types of erythrocytes. Of all the erythrocytes used, the rabbit erythrocytes showed the highest sensitivity of agglutination to protein extracts. This sensitivity was, however, inhibited by the presence of sugars. Agglutinations of rabbit erythrocytes by protein extracts from Laurencia japonica and L. okamurai were inhibited by both lactose and D-fructose, whereas agglutination by extracts from L. okamurai and Polysiphonia savatieri was inhibited by maltose. Inhibition of agglutination by these sugars has not been previously reported. These agglutinating activities were also found to be tolerant of high temperature (<95 degreesC).