New cell surface bound lectins with complex carbohydrate specificity from members of green algae

Lectins, algal in particular, have immense potential for biomedical applications such as anti-HIV, antitumoral, antimicrobial, anti-inflammatory and antinociceptive activities. In this context, there is a growing interest among researchers on agglutinins from green algae. Here, we have made an attempt to catalogue lectins from various unexplored green algae species. Chlorophyceae members (Chlorella vulgaris, Chlorococcum infusiformis, Desmodesmus dimorphus, D. subspicatus and Scenedesmus quadricauda) were screened for lectin activity using human, pig, sheep, goat and rabbit erythrocytes. All of them showed surface bound lectin activity with highest agglutination titre towards human blood type B erythrocytes and rabbit erythrocytes. Neuraminidase and protease treatment to human blood type B erythrocytes considerably enhanced the agglutination titre of lectins from S. quadricauda, C. vulgaris and D. subspicatus. However, protease treatment of erythrocytes showed no effect on C. infusiformis lectin activity, and decreased the lectin activity of D. dimorphus. Lectins of members of chlorophyceae have shown unique glycoprotein binding specificities as their lectin activity was specifically inhibited by glycoproteins exhibiting complex O-glycans, such as bovine submaxillary mucin, porcine stomach mucin and fetuin. All the algal cultures expressed maximum lectin activity during stationary phase of growth except S. quadricauda which expressed maximum lectin activity during mid-log to stationary phase of cultivation. Possibly, it is a new report on cell surface bound lectins from unexplored members of chlorophyceae for lectin activity.