Faster ciguatoxin extraction methods for toxicity screening

Abstract

Ciguatera poisoning (CP) is a severe global public health problem caused by the consumption of seafood products contaminated with ciguatoxins (CTXs). The growing demand for seafood products requires high-throughput testing for CTX-susceptible seafood, however complex extraction and slow cleanup methods inhibit this goal. Herein, several methods for extracting CTXs from fish tissue were established and compared; these methods are sensitive, specific, and valid while achieving higher sample extraction throughput than currently established protocols. The trial fish material was generated from multiple species, with different physical conditions (wet and freeze-dried tissue), and naturally contaminated with various CTXs (i.e., CTX-1B, CTX-3C, and C-CTX-1), thus ensuring these methods are robust and broadly applicable. The extraction methods used were based on mechanical maceration with acetone or methanol or enzymatic digestion followed by acetone and ethyl acetate extraction. Crude extracts were investigated for CTX-like toxicity using an in vitro mouse neuroblastoma (N2a) cell-based assay (CBA). Among the three methods, there was no significant difference in toxin estimates (p = 0.219, two-way ANOVA), indicating their interchangeability. For speed (> 16 samples/day), accuracy (100%), and CTX analog retention confirmation by liquid chromatography-tandem mass spectrometry (LC‒MS/MS), the preferred extraction methods were both methanol and enzyme-based. All extraction methods post hoc confirmation of CTX analogs successfully met international seafood market-based CTX contaminant guidance. These methods can drastically increase global CTX screening capabilities and subsequently relieve sample processing bottlenecks, inhibiting environmental and human health-based CTX analysis.