Mechanisms of toxicity of 3-alkylpyridinium polymers from marine sponge Reniera sarai.

Polymeric 3-alkylpyridinium salts (poly-APS) present in the marine sponge Reniera sarai show a broad spectrum of biological activities. They are lytic to erythrocytes and various other mammalian cells, enabling the transfection of the latter with alien DNA. Furthermore, they show inhibitory effects to marine bacteria and can inhibit fouling of micro- and macroorganisms to submerged surfaces. Finally, poly-APS act as potent cholinesterase inhibitors. The kinetics of acetylcholinesterase inhibition by poly-APS in vitro is complex and comprises several successive phases ending in irreversible inhibition of the enzyme. The latter is accounted for by aggregation and precipitation of the enzyme-inhibitor complexes. Poly-APS are lethal to rats in concentrations above 2.7 mg/kg. Monitoring of the basic vital functions and histopathological analysis showed that the effects directly ascribable to acetylcholinesterase inhibition are only observed after application of lower concentrations of poly-APS. At higher concentrations, such effects were masked by other, more pronounced and faster developing lethal effects of the toxin, such as haemolysis and platelet aggregation.