Detection of 8-epi prostaglandin F2alpha in an extract of epidermal secretion of the catfish from the Arabian Gulf.

We provide herein mass spectrometric evidence for the existence of F2 isoprostanes in an epidermal secretion of the catfish from the Arabian Gulf. The compounds were extracted, purified by thin layer chromatography (TLC) and derivatized into the pentafluorobenzyl trimethylsilyl (PFB-TMSi) derivatives and quantified using SIM-negative ion gas chromatography-mass spectrometry based on the addition of tetradeuterated 8-epi PGF2alpha as internal standard prior to sample workup. Freshly collected secretions from the male catfish contained 5.63 and 4.17 ng/ml (two determinations) and from the female catfish 3.60 and 3.81 ng/ml (two determinations) of free 8-epi PGF2alpha. The level of these compounds increases approximately 8-fold upon storage of the extract at -20 degrees. In view of the potent reported actions of F2 isoprostanes on vasoconstriction and as thromboxane receptor antagonists, the presence of isoprostanes in the catfish secretions may contribute to the reported ulcer healing properties of these secretions.