Detection of Cyclic Imines (CIs) Toxins in Whole Body of Shellfishes: First Monitoring Report of CIs in South Korea Shellfishes

Abstract

Cyclic imines (CIs) produced by microalgal species that accumulate in the food chains of marine organisms are novel biotoxins that do not belong to the classic group of marine biotoxins. In the past, CIs were found only in limited areas; however, in recent years, rapid changes in marine ecosystems have led to widespread CIs and increased exposure to toxic risks. In this study, we analyzed seven CI toxins, GYM-A, SPX (13-desmethyl spirolide C, 13, 19-dideMe spirolide C, 20-methyl spirolide G), and PnTX-E, F, and G, using LC/MRM-MS. Shellfish samples were purchased from a domestic Korean fish market (67 samples in 2021 and 216 samples in 2022). The entire body of the shellfish was ground and extracted with 50% methanol, followed by lipophilic-specific SPE. Only GYM-A, PnTX-G, and 13-desmethyl spirolide C were detected in all analyzed samples. The maximum concentrations of GYM-A is maximum 179 ppt (ng/kg) in Crassostrea nippona (March 2022), PnTX-G is maximum 7 ppt in Anadara broughtonii (April 2022), 13-desmethyl SPX C is maximum 58 ppt in Crassostrea nippona (April 2022). The southern coast exhibited the highest frequency of detection of these toxins, which was attributed to elevated sea-surface temperatures, aligned with conducive conditions for toxin-producing phytoplankton. According to the monitoring results, there were no significant CI toxins in the shellfish; however, it is important to monitor CI toxin accumulation in shellfish because of their high risk of toxicity.