Immunological effects of Chondrus armatus carrageenans and their low molecular weight degradation products

Abstract Ability of high molecular weight (HMW) κ‐ and λ‐carrageenans of the red marine algae Chondrus armatus and their low molecular weight degradation products (LMWDPs) (0.7–20 and 10–170 kDa respectively) to influence functional properties (motility and phagocytosis) of murine peritoneal macrophages was assessed in this study as an in vitro and a weeklong feeding experiment. We demonstrated that, with an exception of one, all carrageenan samples at 100 μg/ml increased cellular motility and dose‐dependently decreased phagocytic activity; LMWDPs of λ‐carrageenan suppressed motility and had no effect on phagocytosis. Oral administration of all the carrageenan samples at 100 μg/kg/day for 7 days to mice had no effect on their clinical appearance, body weight, weight of their liver, spleen or thymus or development of noticeable changes to their inner organs. All samples induced a shift of the cell composition of the peritoneal cavity towards macrophages. Consumption of LMWDPs of κ‐carrageenan resulted in development of leukopenia, however, no changes to relative WBC count were introduced by either of the samples. All samples decreased murine peritoneal macrophages phagocytic activity, with λ‐samples possessing higher efficacy than their κ‐counterparts; all LMWDPs stimulated peritoneal macrophages motility, with κ‐samples possessing higher efficacy than their λ‐counterparts In conclusion, we have shown that κ‐ and λ‐carrageenans of the C. armatus and their LMWDPs suppress phagocytotic activity of peritoneal macrophages under both in vitro and in vivo conditions. This allows them to be viewed as pharmacologically active substances andpropagates the need for their further investigation as such.