Lysis of red blood cells by extracts from benthic dinoflagellates

Samples of the cultured benthic dinoflagellates Gambierdiscus toxicus and Ostreopsis lenticularis, both isolated from a shallow back reef habitat in southwestern Puerto Rico, were extracted in methanol, dried and resuspended in distilled water. After centrifugation, aliquots of the supernatant, or dilutions thereof, were added to suspensions of washed human and mouse red blood cells and incubated at different temperatures for different time periods. Further spectrophotometrical examinations of the samples showed a hemolytic activity against mouse and human red blood cells. The hemolytic activity of G. toxicus extract was 3 to 4 times greater than that of O. lenticularis and was less temperature-dependent. Such findings suggest that these two dinoflagellates produce chemically different hemolysins.