Abstract
We characterized the inhibitory activity of several acetylenic and olefinic compounds on cytochrome P450 (CYP)-derived arachidonic acid ω-hydroxylation and epoxidation using rat renal cortical microsomes and recombinant CYP proteins. Among the acetylenic compounds, 6-(2-propargyloxyphenyl)hexanoic acid (PPOH) and N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide were found to be potent and selective inhibitors of microsomal epoxidation with IC50 values of 9 and 13 μM, respectively. On the other hand, 17-octadecynoic acid inhibited both ω-hydroxylation and epoxidation of arachidonic acid with IC50 values of 7 and 5 μM, respectively. The olefinic compounds N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS) and 12,12-dibromododec-11-enoic acid (DBDD) exhibited a high degree of selectivity inhibiting microsomal ω-hydroxylation with an IC50 value of 2 μM, whereas the IC50 values for epoxidation were 60 and 51 μM for DDMS and DBDD, respectively. Studies using recombinant rat CYP4A isoforms showed that PPOH caused a concentration-dependent inhibition of ω-hydroxylation and 11,12-epoxidation by CYP4A3 or CYP4A2 but had no effect on CYP4A1-catalyzed ω-hydroxylase activity. On the other hand, DDMS inhibited both CYP4A1- and CYP4A3- or CYP4A2-catalyzed arachidonic acid oxidations. Inhibition of microsomal activity by PPOH, but not DDMS, was time- and NADPH-dependent, a result characteristic of a mechanism-based irreversible inhibitor. These studies provide information useful for evaluating the role of the CYP-derived arachidonic acid metabolites in the regulation of renal function and blood pressure.
Footnotes
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Send reprint requests to: Dr. Michal Laniado Schwartzman, Department of Pharmacology, New York Medical College, Valhalla, NY 10595.
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↵1 Supported by NIH grants HLPO134300 and EY06513 (M.L.S.) and DK38226 (J.R.F.) and by a Grant-in-Aid (M.H.W.) from the American Heart Association (#970104).
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↵2 Mong-Heng Wang and Elimor Brand-Schieber contributed equally to the development of this research paper.
- Abbreviations:
- CYP
- cytochrome P450
- EET
- epoxyeicosatrienoic acid
- 20-HETE
- 20-hydroxyeicosatrienoic acid
- 17-ODYA
- 17-octadecynoic acid
- PPOH
- 6-(2-propargyloxyphenyl)hexanoic acid
- MS-PPOH
- N-methanesulfonyl-6-(2-propargyloxyphenyl)hexanamide
- DDMS
- N-methylsulfonyl-12,12-dibromododec-11-enamide
- DBDD
- 12-12-dibromododec-11-enoic acid
- DPMS
- N-methylsulfonyl-15,15-dibromopentadec-14-enamide
- SHR
- spontaneously hypertensive rat
- COX
- cyclooxygenase
- Received July 31, 1997.
- Accepted November 7, 1997.
- The American Society for Pharmacology and Experimental Therapeutics
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