Suggested mechanism for the formation of 15-hydroxyeicosatrienoic acid by rat epidermal microsomes.
We have previously demonstrated that rat epidermal microsomes NADPH-dependently convert 15(S)-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) into 15-hydroxy-5,8,11-eicosatrienoic acid (15-HETrE). The present study examines the mechanism of this reductive conversion. Rat epidermal microsomes were incubated with [1-14C]15-HPETE in the presence and absence of NADPH. Major reaction products were purified by high performance liquid chromatography (HPLC) and analyzed by gas chromatography-mass spectrometry (GC-MS), UV spectroscopy and/or cochromatography with standard products. In the presence of NADPH, 15-HPETE was transformed to 13-hydroxy-14,15-epoxy-5,8,11-eicosatrienoic acid (13-HEpETrE), 15(S)-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE), 15-keto-5,8,11-eicosatrienoic acid (15-KETrE) and 15-hydroxy-5,8,11-eicosatrienoic acid (15-HETrE). In the absence of NADPH, the microsomes reacted with 15-HPETE to form 13-HEpETrE, 15-keto-5,8,11,13-eicosatetraenoic acid (15-KETE) and 15-HETE. Furthermore, when supplemented with NADPH, epidermal microsomes converted 15-KETE to 15-KETrE, which was subsequently reduced to 15-HETrE. These data suggest that rat epidermal microsomes are capable of metabolizing 15-HPETE to 15-HETrE via the following reaction steps: conversion of HPETE to KETE, NADPH-dependent double bond saturation in KETE to KETrE and keto-reduction of the latter compound to HETrE.
Van Wauwe
J
J
Janssen Research Foundation, Beerse, Belgium.
Coene
M C
MC
Van Nyen
G
G
Cools
W
W
Le Jeune
L
L
Lauwers
W
W
D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004817:Epidermis / Q000378:metabolism*; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism*; D066298:In Vitro Techniques; D015289:Leukotrienes / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D006893:Hydroxyeicosatetraenoic Acids; D015289:Leukotrienes; D008054:Lipid Peroxides; C080037:15-hydroxy-5,8,11-eicosatrienoic acid; C025086:15-hydroperoxy-5,8,11,13-eicosatetraenoic acid; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D015126:8,11,14-Eicosatrienoic Acid