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Ciguatoxins are potent ichthyotoxins
1Southern Fisheries Centre, QDPI, Deception Bay, Qld, Australia.
Summary
Ciguatoxins are more potent than brevetoxins in fish and mammals. Their lethal effects in fish may limit toxin accumulation, potentially reducing human ciguatera poisoning risk.
Area of Science:
- Marine toxicology
- Natural product chemistry
Background:
- Ciguatoxins and brevetoxins are structurally similar lipid-soluble polyether compounds.
- Both toxin classes exhibit toxicity through interaction with voltage-dependent sodium channels.
Purpose of the Study:
- To compare the relative potencies of ciguatoxins and brevetoxins in fish.
- To investigate the accumulation and biotransformation of ciguatoxin-1 in fish.
- To assess the implications of fish toxicity for human ciguatera risk.
Main Methods:
- Exposure of Gambusia affinis to varying concentrations of ciguatoxin-1, ciguatoxin-2, and brevetoxin-2.
- Determination of lethal dose 50 (LD50) values in G. affinis.
- Measurement of ciguatoxin-1 accumulation in G. affinis.
Main Results:
- Ciguatoxins were up to 20-fold more potent than brevetoxins in G. affinis.
- LD50 values for ciguatoxin-1, ciguatoxin-2, and brevetoxin-2 were 0.5, 2.1, and 10 nmoles/litre, respectively.
- Only 3.4% of administered ciguatoxin-1 was accumulated by G. affinis, suggesting biotransformation.
Conclusions:
- Ciguatoxins exhibit higher acute toxicity to fish than brevetoxins.
- Fish biotransformation of ciguatoxins may limit bioaccumulation.
- This toxicity and limited accumulation could explain the lower incidence of severe human ciguatera poisoning.