Toxinology of Cephalopods: A Review Article

Most cephalopods are venomous organisms whose major venom constituents include protein toxins, small toxic molecules, enzymes, and amines. Neurotoxic cephalotoxins are protein toxins that were first isolated from this family. They are categorized into SE-cephalotoxins, α-cephalotoxins, and β-cephalotoxins. The SE-cephalotoxin compound is roughly a thousand-fold more toxic than other members of the group. Among the small toxic molecules, tetrodotoxins and tachykinins can be mentioned. Salivary tachykinins of cephalopods can cause severe hypotension and contraction of gastrointestinal muscles in vertebrates. The peptide derivatives of tachykinins in the cephalopod brains have more toxic effects than the simple tachykinins. Chitinases, phospholipases and acetylcholinesterase are the most important integral components of the cephalopod venom. Phospholipase A2 plays an important role in fat metabolism, in the progression of some diseases, as well as the neurotoxic and myotoxic effects of the venom. Acetylcholinesterase inhibits the stimulation of muscarinic receptors. In addition to epinephrine, norepinephrine, dopamine, serotonin, and histamine, one of the most abundant amines found in octopus saliva is "octapamine". The inks of many species of cephalopods contain significant amounts of melanin, which, in addition to biotechnological applications, have antifungal, antibacterial and anti-cancer effects. Insoluble globules of the complex skin system of cephalopods contain proteins called "reflectin", which are responsible for producing a wide range of colors. Reflectins are exclusively found in cephalopods. In fact, the existing toxinological and biotechnological studies of the venom of this marine life are not commensurate with their diversity as well as their unique composition, and more efforts are needed to succeed in this field.