Tetrodotoxin in several species of xanthid crabs in southern Taiwan

Tetrodotoxin was detected by tetrodotoxin (TTX) bioassay in 28 specimens of six species of xanthid crabs collected from Tunkang, southern Taiwan, in May 2004. The average toxicity of crab specimens was 347 ± 276 (means ± SD) mouse units (MU) for Demania cultripes, 59 ± 17 MU for Demania toxica, 324 ± 114 MU for Demania reynaudi, 214 ± 65 MU for Lophozozymus incisus, 184 ± 85 MU for Lophozozymus pictor and 611 ± 471 MU for Atergatopsis germaini. Each toxin of the six species of crabs was extracted with acidic methanol, cleansed using a C18 solid-phase extraction (SPE) column, filtered through a microcentrifuge filter and determined by LC-MS and GC-MS. The recovery of TTX was above 82.9% and the detection limit was 0.005 μg with LC-MS analysis. A linear equation was obtained between 0.03 and 3.0 μg of TTX. Analyses by LC-MS and GC-MS showed that these crab species all contained TTX. The paralytic shellfish poisons were not found. Among samples, D. cultripes, D. toxica and L. incisus are the first to be recorded as toxic in Taiwan.