In vitro effects of a natural marine algae polysaccharide (λ-carrageenan) on seabream erythrocytes, tumour cell lines and marine bacterial pathogens

Abstract

Carrageenan is a high molecular weight sulphated polysaccharide used to induce experimental inflammation in mammals. In addition, it possesses a wide variety of properties that have not yet been studied in fish. This study evaluated the hemagglutinating, hemolytic, cytotoxic, and antibacterial activities of λ-carrageenan. The results showed that λ-carrageenan has hemagglutinating and hemolytic activities on gilthead seabream erythrocytes, which were dose and time-dependent during the first 6 h of incubation. No significant effects on the haemolytic activity of erythrocytes were observed after incubation for 12 or 24 h with λ-carrageenan. The PLHC-1 cell line showed significant increases in cytotoxic activity after 6 or 12 h of incubation compared with control cells, and the highest doses of λ-carrageenan caused cytotoxicity in PLHC-1 cells after 24 h of incubation. The morphology of PLHC-1 cells incubated with the highest doses of λ-carrageenan for 12 or 24 h showed obvious cell death changes compared with control cells. Interestingly, no significant variations in cytotoxic activity were observed in SAF-1 cell line after incubation with λ-carrageenan. Furthermore, λ-carrageenan showed significant dose-dependent bactericidal activity against Photobacterium damselae but had no significant effect on the bactericidal activity of Vibrio harveyi, Vibrio anguillarum, and Tenacibaculum maritimum. The study suggests that λ-carrageenan has potential applications in aquaculture and aquatic pharmaceutical industries as a hemagglutinating, hemolytic, and antibacterial agent.