Occurrence of a ciguatoxin-like substance in the Spanish mackerel (Scomberomorus commersoni).

A lipid-soluble toxin, similar to ciguatoxin as isolated by Scheuer et al. (1967), has been found in the flesh of the Spanish mackerel, Scomberomorus commersoni, caught in Queensland. The ciguatoxin-like substance was experimentally characterized by examination of specific biological and chromatographic properties of the lipid-soluble extract from a pooled sample of flesh from Spanish mackerel. Flesh from specimens known to have caused S. commersoni poisoning in humans was confirmed as toxic by cat bioassay. A toxin was extracted from S. commersoni which yielded, on partial purification, a clear, oily substance with an LD50 i.p. to mice of 0.72 mg/kg, and which had chromatographic properties similar to those of classical ciguatoxin. However, the Rf value on thin-layer chromatography plates was lower for S. commersoni toxin than for classical ciguatoxin. This is the first record of a ciguatoxin-like substance experimentally identified in S. commersoni, a pelagic fish that occurs throughout Queensland coastal waters. The majority of toxic S. commersoni are caught between latitudes 24 degrees and 26 degrees S.