Tetrodotoxins of the starfish Astropecten vappa collected from western Taiwan

It is well known that tetrodotoxin (TTX) is a potent neurotoxin widely distributed in marine animals. Food poisoning incidents due to ingestion of puffer, gastropod, and goby were reported in Taiwan. 1–4 In July 2000, a TTX food poisoning due to ingestion of gastropod Polinices didamy occurred in Chiayi County, western Taiwan. 5 It is supposed that TTX-bearers become toxic through the food chain with TTX transferred from lower to higher strata animals, such as starfish to gastropod. 6 Judging from this, it is indicated that the source of TTX in Chiayi County might be abundant. To elucidate the food chain of toxin in the toxic gastropods, the benthos collected from the same coastal waters of western Taiwan were analyzed by using TTX bioassay. In contrast, three species of starfish A. scoparius, A. latespinosus and A. polyacanthus were found to contain TTX, 6,7 and one species, Asterias amurensis, contained paralytic shellfish poisons (PSP) in Japan. 8 In the previous paper, the toxin of starfish A. scoparius collected from Tungkang, southern Taiwan, was mainly composed of TTX (88%) along with minor PSP (12%), and the toxicity in viscera was higher than in the other part. 9 In this study, we examined the toxin and seasonal variation of toxicity in the starfish A. vappa in western Taiwan. The starfish Astropecten vappa were seasonally captured by local fishing boats along the coastal waters of Chiayi County from April 2001 to December 2001. The specimens were kept alive, transported to the laboratory, and immediately dissected into viscera and other parts. Each part was weighed, homogenized, extracted with three volumes of 0.1% acetic acid, and examined for toxicity by TTX mouse assay. 10 After bioassay, the specimens of A. vappa were combined and extracted with three volumes of 1% acetic acid in methanol. The crude toxin extracts (8500 MU) were then purified by defatted with dichloromethane, filtered through a Diaflo YM-1 membrane (Amicon, Beverly, MA, USA), and eluted through a Bio-Gel P-2 column (2 ¥ 94 cm; Bio-Rad, Hercules, CA, USA). Toxic fractions were combined, freeze-dried, dissolved in a small amount of water, and submitted to high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) analyses, as described previously. 11,12