Okadaic acid
OA
White solid
Fixed
144-146 ° C
Insoluble in water
Risk
192 ug · kg -1 ( LD50, mouse, ip)
Template: Infobox chemical / molecular formula search available
Okadaic acid accumulates in mussels and causes food poisoning. The molecular formula is C44H68O13.
Occurrence
The name derives from the okadaic acid was occurring at the Japanese marine sponge Halichondria okadai Pacific coast, from which okadaic acid was isolated for the first time. It has also been isolated from occurring in the Caribbean sponge H. malanodocia as a cytotoxin. Originally okadaic acid of the Dinophytes ( dinoflagellates ) scoring marine algae is produced, such as Dinophysis sp. or Prorocentrum sp., which produce okadaic acid into a harmless precursor for them, the so-called dinophysistoxin -4. The dinophysistoxin -4 is released into the Dinophytes to the surrounding medium or exits at their death and is hydrolyzed in the medium to Okadasäurediolester.
Properties
Okadasäurediolester is fat soluble, so that can happen biomembranes and thus penetrate into cells of other organisms where the Okadasäurediolester is further hydrolyzed to the actual, toxic effect okadaic acid.
Toxicology
The toxicity of okadaic acid based on the inhibition of Serin-/Threonin-spezifischen protein phosphatases type 1 (PP1 ), 2a ( PP2A ) and 2b ( PP2B ), followed by the classification of okadaic acid based as hepatotoxin and as a tumor promoter. The inhibitory effect is concentration dependent on the individual phosphatase types. Is most inhibits phosphatase type 2, which is inhibited with an okadaic acid concentrations in the range of 1 nM to 50% (IC50). The IC50 for PP1 is 0.3 to 1 uM, and for PP2B in about 1 uM. For example, okadaic acid induces a long-lasting muscle contraction, since the dephosphorylation of the protein involved in the contraction of myosin by the Serin-/Threonin-spezifischen protein phosphatases can no longer take place.
The lethal concentration of okadaic acid in mice ( LD50) is 192 micrograms / kg, ip. ( intraperitoneal)