Paralytic shellfish toxins (PSTs) and tetrodotoxin (TTX) of Korean pufferfish

Abstract

Paralytic shellfish toxins (PSTs) and tetrodotoxin (TTX) are neurotoxins that display pharmacological activity that is similar to that of specific sodium channel blockers; they are the principle toxins involved in shellfish and puffer fish poisoning. In Korea, puffer fish is a very popular seafood, and several cases of accidental poisoning by TTX have been reported. Therefore, it is necessary to determine whether puffer fish poisoning incidents are caused by PSTs or by TTX. In this study, we used mouse bioassay (MBA) and liquid chromatograph-tandem mass spectrometry (LC-MS/MS) to determine the presence of PSTs and TTX in puffer fish from an area near Mireuk-do, Tong-Yeong on the southern coast of Korea from January through March, 2014. The toxicity of PSTs and TTX extracts prepared from three organs of each specimen was analyzed by MBA. Most of the extracts killed mice with typical signs of TTX and PSTs. The LC-MS/MS analysis of seven specimens of Takifugu pardalis and Takifugu niphobles, each divided into muscles, intestines, and liver, were examined for TTX. In T. pardalis, the TTX levels were within the range of 1.3–1.6 μg/g in the muscles, 18.8–49.8 μg/g in the intestines, and 23.3–96.8 μg/g in the liver. In T. niphobles, the TTX levels were within the range of 2.0–4.5 μg/g in the muscles, 23.9–71.5 μg/g in the intestines, and 28.1–114.8 μg/g in the liver. Additionally, the toxicity profile of the detected PSTs revealed that dcGTX3 was the major component in T. pardalis and T. niphobles. When PSTs were calculated as saxitoxin equivalents the levels were all less than 0.5 μg/g, which is below the permitted maximum standard of 0.8 μg/g. These findings indicate that the toxicity of T. pardalis and T. niphobles from the southern coast of Korea is due mainly to TTX and that PSTs do not exert an effect.