Pacific Ciguatoxin-1 (P-CTX-1) in a Moray eel (Gymnothorax javanicus) Responsible for Ciguatera in Khanh Hoa Province, Viet Nam

Abstract

On 5 November 2020, a poisoning event involving four people by the consumption of moray eel occurred in Khanh Hoa Province, Viet Nam, with signs indicative of ciguatera. The remaining moray portion was confiscated for identification of causative species and responsible toxins. The phylogenetic study based on COX1 identified the moray as Gymnothorax javanicus Bleeker (1859). Out of 17 marine lipophilic toxins (MLPs) that were analyzed using LC-MS/MS, only Pacific ciguatoxin-1 (P-CTX-1) was detected in the moray’s flesh at 1.30 ± 0.004 ng/g ww, while no toxin was found in the skin. The N2a assay’s ciguatoxicities in the skin and flesh were 0.69 ± 0.075 and 2.49 ± 0.216 ng P-CTX-1/g ww equivalent, respectively. In the N2a assay, the P-CTX-1 amount in the moray flesh was 1.9 times greater than that determined by LC-MS/MS, indicating the presence of additional sodium channel activators or a matrix effect. The P-CTX-1 amount in the moray flesh was at a level that generates major ciguatera poisoning (CP) symptoms in humans (1.0 ng/g P-CTX-1), makes sense given that four consumers experienced the onset of poisoning symptoms. This study is significant for the management of seafood safety since it is the first scientific report on the species and toxin in a moray causing ciguatera in Viet Nam.