The oxidation of 12-hydroxylauric acid methyl ester (12-OH-L-Me) and of ω-hydroxy-prostaglandins (ω-OH-PGs) such as 20-OH-PGB1 and 20-OH-PGE1, was demonstrated with liver cytosol from rat, rabbit, and guinea pig in the presence of NAD; however, NADP did not support this oxidation. (ω-1)-Hydroxy-compounds (11-OH-laurate and 19-OH-PGB1) and PGE1, PGF1α, and PGB1, all lacking the terminal (ω)-hydroxyl, did not reduce NAD. However, at pH 10, PGE1 slightly enhanced NAD reduction, suggesting that at this pH PGE1, could be a substrate for 15-hydroxy-PG dehydrogenase (PGDH). The oxidation products from incubations of 12-OH-L-Me, 20-OH-PGB1-Me, and 20-OH-PGE1 with guinea pig liver cytosol were isolated and identified by gas chromatography/mass fragmentation spectrometry as being the corresponding dicarboxylic acids. In contrast to the liver cytosol, guinea pig kidney cytosol had only a minimal effect on NAD reduction by 12-OH-L-Me but nevertheless did support the stimulation of NAD reduction by PGE1, and PGF1α, but not by PGB1, indicating the participation of kidney cytosolic PGDH in PGE1 and PGF1α oxidation and demonstrating that the oxidation of ω-OH to the carboxylic acid is not mediated by PGDH. Though the in vivo rate of oxidation of ω-OH-PGs has not been established, these results suggest that the urinary dicarboxylic-PG metabolites involve a multiple sequentialstep oxidation of PGs involving ω-hydroxylation by an NADPH-cytochrome P-450 system in the endoplasmic reticulum and the subsequent oxidation of the ω-OH by an NAD-dependent dehydrogenase in the cytosol.
ASJC Scopus subject areas
- Molecular Biology