Pratheepa V, Vasconcelos Vitor
CIIMAR, Marine and Environmental Research Center, Porto University, Rua dos Bragas, 289, 4050-123 Porto, Portugal.
Mini Rev Med Chem. 2017;17(4):320-327.
Tetrodotoxin (TTX) found in diverse variety of animals including puffer fishes, some newts, frogs and limited number of non-vertebrate species (6 different phyla). The saxitoxin (STX) and the TTX are small molecules composed of 7,8,9 guanidinium and 1,2,3 guanidinium groups, respectively in their structures. These groups provide positive charge to the molecules and are believed to interact with negatively charged Glu755 and Asp400 residues in domain II and I of the sodium channel strongly. The pharmacokinetic studies (absorption, distribution and accumulation) reported on Takifugu rubripes, Takifugu pardalis, Takifugu niphobles, Takifugu vermicularis, Takifugu snyderi, etc. revealed that higher concentration of TTX is accumulated in liver than in the skin or other tissues. Although TTX is also accumulated in the skin of various marine species (secretory glands) and the excess of TTX are emitted through skin which acts as a defence agent for those species. STX showed high toxicity on crab and other animals, due to its accumulation in the tissues and resistance to the sodium channel proteins. It concluded that TTX and STX based toxicities are developed on the species by the absorption, distribution and accumulation of toxins in tissues. Also the ingestion of these species (marine species) as food may allow transferring toxin to the human being.
河豚毒素（TTX）存在于多种动物中，包括河豚、一些蝾螈、青蛙以及数量有限的非脊椎动物物种（6个不同的门）。石房蛤毒素（STX）和河豚毒素在结构上分别是由7、8、9个胍基和1、2、3个胍基组成的小分子。这些基团为分子提供正电荷，并被认为与钠通道结构域II和I中带负电荷的Glu755和Asp400残基强烈相互作用。对红鳍东方鲀、豹纹东方鲀、菊黄东方鲀、蠕虫状东方鲀、星点东方鲀等进行的药代动力学研究（吸收、分布和积累）表明，河豚毒素在肝脏中的积累浓度高于皮肤或其他组织。尽管河豚毒素也会在各种海洋物种的皮肤（分泌腺）中积累，并且过量的河豚毒素会通过皮肤排出，皮肤起到了这些物种防御剂的作用。石房蛤毒素由于在组织中的积累以及对钠通道蛋白的抗性，对螃蟹和其他动物表现出高毒性。得出的结论是，基于河豚毒素和石房蛤毒素的毒性是通过毒素在组织中的吸收、分布和积累在这些物种中产生的。此外，食用这些物种（海洋物种）作为食物可能会使毒素转移到人类身上。
