Demonstration of a liposoluble ciguateric toxin in Caranx bartholomaei caught in the French West Indies

This report deals with some of the biological and chemical properties of a liposoluble poison extracted from Caranx bartholomaei (yellow jack), a toxic fish from the French West Indies (St Barth's island). Within a single fish, poison concentration is higher in the viscera; toxicity level is uniform throughout the flesh. In the few specimens tested, liver toxicity variations parallel those of flesh. The poison is heat stable so that cooking does not impair the toxicity. It is soluble in acetone, diethyl ether, chloroform, benzene, methanol and ethanol, but insoluble in n. hexane. Crude toxin injection or ingestion induces ciguateric disease in cats, mice or newly born chicken. Crude toxin stability is good after 30 minutes at 90 degrees C in a 0,5 N solution of a weak acid but not of a weak base. In the same conditions, loss of activity is nearly complete with a strong acid or a strong base. Moreover, rapid alkali treatment at room temperature destroys more than 50 per cent of the toxicity. The toxin is eluted by chloroform-methanol (9:1) from a silicic acid column and by acetone-methanol (9,5:0,5) from a Florisil column. DEAE cellulose column chromatography clearly separates the toxin into two lethal components; but thin layer chromatography of crude or fractionated toxin indicates only one toxic band in three different solvent systems. As a conclusion, in spite of a few differences related to instability in alkalin medium and elution from DEAE cellulose, this poison is quite similar to those carried by ciguatoxic fishes from the Pacific area. The differences noted above could be accounted for either by a specific metabolism of the species studied or by differences in the causative agent due to geographical location, or both.