Tetrodotoxin and Its Analogues in the Pufferfish Arothron hispidus and A. nigropunctatus from the Solomon Islands: A Comparison of Their Toxin Profiles with the Same Species from Okinawa, Japan.

Clyde Puilingi,Keiichi Konoki,Yuta Kudo,Yuko Cho,Mari Yotsu-Yamashita

doi:10.3390/toxins7093436

Abstract

Pufferfish poisoning has not been well documented in the South Pacific, although fish and other seafood are sources of protein in these island nations. In this study, tetrodotoxin (TTX) and its analogues in each organ of the pufferfish Arothron hispidus and A. nigropunctatus collected in the Solomon Islands were investigated using high resolution LC-MS. The toxin profiles of the same two species of pufferfish from Okinawa, Japan were also examined for comparison. TTXs concentrations were higher in the skin of both species from both regions, and relatively lower in the liver, ovary, testis, stomach, intestine, and flesh. Due to higher TTX concentrations (51.0 and 28.7 µg/g at highest) detected in the skin of the two species from the Solomon Islands (saxitoxin was <0.02 µg/g), these species should be banned from consumption. Similar results were obtained from fish collected in Okinawa, Japan: TTX in the skin of A. hispidus and A. nigropunctatus were 12.7 and 255 µg/g, respectively, at highest, and saxitoxin was also detected in the skin (2.80 µg/g at highest) and ovary of A. hispidus. TTX, 5,6,11-trideoxyTTX (with its 4-epi form), and its anhydro forms were the most abundant, and 11-oxoTTX was commonly detected in the skin.

Highlights

Tetrodotoxin (TTX) is a well-studied neurotoxin known for its distribution in pufferfish [1] and marine invertebrates such as snails [2], crabs [3], starfish [4], blue-ringed octopus [5], and sea slugs [6].Recently, TTX was detected in bivalve mollusks: New Zealand clams [7], mussels and oysters in England [8], and in Greek shellfish [9]
Certain TTX and its analogues might be hydrolyzed to tetrodonic acid (Figure 1) type compounds [16,40], which are detectable using liquid chromatography-fluorescent detection (LC-FLD) for TTXs [41,42] without specific pre-purification
TTXs in the ethanolic solution used to soak the skin of A. hispidus, and in the skin soaked in this ethanolic solution were both analyzed by LC-FLD

Summary

Introduction

Tetrodotoxin (TTX) is a well-studied neurotoxin known for its distribution in pufferfish [1] and marine invertebrates such as snails [2], crabs [3], starfish [4], blue-ringed octopus [5], and sea slugs [6]. TTX was detected in bivalve mollusks: New Zealand clams [7], mussels and oysters in England [8], and in Greek shellfish [9]. TTX, as the primary agent of pufferfish poisoning, is reported to be produced by marine bacteria and accumulated in the pufferfish via the food chain [12,13]. We have found various TTX analogues (Figure 1) which can be further classified into (1) hemilactal type analogues, (2) 5-deoxy-10,7-lactone type analogues, (3) 4,9- and 4,4a-anhydro type analogues and (4) tetrodonic acid type analogue [16,17]

Results

Discussion

Conclusion