Toxinology of Venomous Marine Worms; A Review

Although the widespread distribution of venomous marine worms around the world, the structural and toxinologcal studies of their toxins are still limited.This study was aimed to evaluate the toxicity of poisonous marine worms. Touching the cilium of Chloeia flava and Sipuncula marine worms cause painful inflammation of the skin. Many species of nemertines prey their victims by a flexible proboscis and dense mucus on the surface of the skin. They have recently been classified into three groups of the Palaeonmertea, Pilidiophora, and Hoplonemertea. Their toxins comprise the three main groups of peptides, pyridine alkaloids, and tetradotoxin and their derivatives. The nicotinoide amphiporine compound, anabaseine and its derivatives, Nemertelline, and anabasine are as alkaloid toxins. They are selectively stimulated the  nicotinic receptors, in particular the type of α-7 receptors. Nemerteans are produced a variety of peptide toxins.The hemolytic activity is the most prominent activity of the cerebratulus toxins A-I to A-IV. Cytotoxin A-III, by forming tetrameric forms in the membranes of many different cells, and creating large pores, makes them very permeable. The toxin inhibits the protein kinase C and the selective cationic sodium and calcium channels of the voltage-gate in the nervous and cardiovascular systems at low lytic concentrations. From four main proteins "Cerebratulus toxins- B-II to B-IV", the toxin B-II performed to be the most toxic compound.The assessment of the Lineus extract showed that they are actually more toxic than Cerebratulus extracts. The neurotoxins α- and β-nemertides, respectively, belong to the family of three and six kilodaltons. The nemertide α-1 is highly potent toxin against the VGSC. Dose-dependent injections have caused permanent paralysis to death. Many toxin genes have been predicted or discovered in the genomes and transcriptoms of nemerteans. The most prominent of the toxin genes were the Plancitoxin-1 sequence, Stichodactyla toxin peptide (Shk toxin), Se-Cephalotoxin, β pore-forming toxin aerolysin, and several neurotoxin-related sequences, such as delta-actitoxin-Amc1a, Perivitellin-2, Mu-theraphotoxin Hhn2a 4 and turripeptide Gsg9.2, different α-, β-nemertides (B-neurotoxins analogs), and Parborlysin. Most likely, the Parborlysins belong to the same family of cytotoxins AI-AIV. Study on these marine organism toxins can provide useful probes for examining receptors, ion channels, and even innate immunity mechanisms against infectious viruses, parasites, and other microbes.