Identification of slow and fast-acting toxins in a highly ciguatoxic barracuda (Sphyraena barracuda) by HPLC/MS and radiolabelled ligand binding.
A barracuda implicated in ciguatera fish poisoning in Guadeloupe was estimated to have an overall flesh toxicity of 15 MUg/g using mouse bioassay. A lipid soluble extract was separated into two toxic fractions, FrA and FrB, on a LH20 Sephadex column eluted with dichloromethane/methanol (1:1). When intraperitoneal injected into mice, FrA provoked symptoms characteristic of slow-acting ciguatoxins, whereas FrB produced symptoms indicative of fast-acting toxins (FAT). High performance liquid chromatography/mass spectrometry/radio-ligand binding (HPLC/MS/RLB) analysis confirmed the two fractions were distinct, because only a weak overlap of some compounds was observed. HPLC/MS/RLB analysis revealed C-CTX-1 as the potent toxin present in FrA, and two coeluting active compounds at m/z 809.43 and 857.42 in FrB, all displaying the characteristic pattern of ion formation for hydroxy-polyethers. Other C-CTX congeners and putative hydroxy-polyether-like compounds were detected in both fractions, however, the RLB found them inactive. C-CTX-1 accounted for > 90% of total toxicity in this barracuda and was confirmed to be a competitive inhibitor of brevetoxin binding to voltage-sensitive sodium channels (VSSCs) with a potency two-times lower than P-CTX-1. However, FAT active on VSSCs and < 900 Da were suspected to contribute to the overall toxicity.
Laboratoire de Microbiologie Alimentaire USC INRA, Universite de Caen, Esplanade de la Paix, Caen 14032, France.
Ivannah
I
Pottier
Brett
B
Hamilton
Alun
A
Jones
Richard J
RJ
Lewis
Jean Paul
JP
Vernoux
D000818:Animals; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid; D036841:Ciguatera Poisoning / Q000209:etiology; D002922:Ciguatoxins / Q000302:isolation & purification* / Q000633:toxicity; D006801:Humans; D008297:Male; D008387:Marine Toxins / Q000302:isolation & purification* / Q000633:toxicity; D013058:Mass Spectrometry; D051379:Mice; D018482:Muscle, Skeletal / Q000737:chemistry*; D010473:Perciformes / Q000378:metabolism*; D011869:Radioligand Assay; D018675:Toxicity Tests
D008387:Marine Toxins; D002922:Ciguatoxins