Conversion of arachidonic acid into 12-oxo derivatives in human platelets. A pathway possibly involving the heme-catalysed transformation of 12-hydroperoxy-eicosatetraenoic acid.
Analysis of arachidonic acid metabolites in human platelets by reverse-phase HPLC with radioactivity and UV detection revealed, besides Thromboxane B2 (TXB2), 12-hydroxy-heptadecatrienoic acid (HHT) and 12-hydroxy-eicosatetraenoic acid (12-HETE) previously described, two peaks of unidentified material absorbing at 280 nm. This material was purified by straight-phase HPLC and characterized by UV spectroscopy and gas chromatography-mass spectrometry. Three carbonyl compounds were identified: 12-keto-5,8,10,14-eicosatetraenoic acid and two geometric isomers of 12-oxo-5,8,10-dodecatrienoic acid. In a 5 min incubation at 37 degrees C in the presence of 9 microM arachidonic acid, the yield was of 0.5 to 1% of added arachidonic acid for the ketonic compound and of 4 to 7% for the sum of the two isomeric fatty acid aldehydes in comparison to 10 to 13% and 25 to 28% for TXB2 and 12-HETE, respectively. Because the three compounds carry a carbonyl group at position 12, their relationship with the 12-lipoxygenase pathway was investigated. It was found that the three compounds were formed when 12-hydroperoxy-eicosatetraenoic acid (12-HPETE) was incubated with intact or heat denaturated platelets or hemoproteins, strongly suggesting that these carbonyl compounds are products of a heme-catalysed transformation of 12-HPETE.
D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood*; D001792:Blood Platelets / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D015289:Leukotrienes; D013056:Spectrophotometry, Ultraviolet
D001095:Arachidonic Acids; D015289:Leukotrienes; D016718:Arachidonic Acid; C021201:12-HPETE