scholarly journals Kinetic basis for selective inhibition of cyclo-oxygenases

1999 ◽  
Vol 339 (3) ◽  
pp. 607-614 ◽  
Author(s):  
James K. GIERSE ◽  
Carol M. KOBOLDT ◽  
Mark C. WALKER ◽  
Karen SEIBERT ◽  
Peter C. ISAKSON
Keyword(s):  
Inhibitory Activity ◽  
Tight Binding ◽  
Selective Inhibition ◽  
Time Dependent ◽  
Experimental Conditions ◽  
Kinetic Behaviour ◽  
Competitive Kinetics ◽  
Binding Time ◽  
Cox 2 ◽  
Cox 1

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit the formation of prostaglandins by cyclo-oxygenases (COX). The discovery of a second COX isoform (COX-2) associated with inflammation led to agents that selectively inhibit COX-2, e.g. celecoxib. We evaluated the kinetics of inhibition of celecoxib and several NSAIDs. Celecoxib displays classic competitive kinetics on COX-1 (Ki = 10-16 μM). An initial competitive interaction with COX-2 can also be discerned with celecoxib (Ki = 11-15 μM), followed by a time-dependent interaction leading to potent inhibition, characterized as inactivation (Kinact = 0.03-0.5 s-1). Half-maximal inhibition (IC50) using end-point assays reflects the competitive component on COX-1 (IC50 = 4-19 μM) and the inactivation component on COX-2 (IC50 = 0.003-0.006 μM). NSAIDs exhibit four distinct modes of COX inhibition based on kinetic behaviour: (1) competitive, e.g. ibuprofen; (2) weak binding, time-dependent, e.g. naproxen, oxicams; (3) tight binding, time-dependent, e.g. indomethacin; (4) covalent, e.g. aspirin. In addition, most NSAIDs display different kinetic behaviour for each isoform. Weakly binding inhibitors show variable behaviour in enzyme assays, with apparent inhibitory activity being markedly influenced by experimental conditions; determination of kinetic constants with this class is unreliable and IC50 values are strongly dependent on assay conditions. Although IC50 determinations are useful for structure/activity analyses, the complex and distinct mechanisms of enzyme inhibition of each COX isoform by the NSAIDs renders comparison of inhibitory activity on COX-1 and COX-2 using IC50 ratios of questionable validity.

A three-step kinetic mechanism for selective inhibition of cyclo-oxygenase-2 by diarylheterocyclic inhibitors

2001 ◽  
Vol 357 (3) ◽  
pp. 709-718 ◽  
Author(s):  
Mark C. WALKER ◽  
Ravi G. KURUMBAIL ◽  
James R. KIEFER ◽  
Kirby T. MORELAND ◽  
Carol M. KOBOLDT ◽  
...  
Keyword(s):  
Selective Inhibition ◽  
Kinetic Mechanism ◽  
Time Dependent ◽  
Irreversible Inhibition ◽  
Inhibitory Mechanisms ◽  
Dependent Inhibition ◽  
Inflammatory Drugs ◽  
Cox 2 ◽  
Time Dependent Inhibition ◽  
Cox 1

Cyclo-oxygenase (COX) enzymes are the targets for non-steroidal anti-inflammatory drugs (NSAIDs). These drugs demonstrate a variety of inhibitory mechanisms, which include simple competitive, as well as slow binding and irreversible inhibition. In general, most NSAIDs inhibit COX-1 and −2 by similar mechanisms. A unique class of diarylheterocyclic inhibitors has been developed that is highly selective for COX-2 by virtue of distinct inhibitory mechanisms for each isoenzyme. Several of these inhibitors, with varying selectivity, have been utilized to probe the mechanisms of COX inhibition. Results from analysis of both steady-state and time-dependent inhibition were compared. A generalized mechanism for inhibition, consisting of three sequential reversible steps, can account for the various types of kinetic behaviour observed with these inhibitors.

New indomethacin analogs as selective COX‐2 inhibitors: Synthesis, COX‐1/2 inhibitory activity, anti‐inflammatory, ulcerogenicity, histopathological, and docking studies

2020 ◽  
Author(s):  
Khaled R. A. Abdellatif ◽  
Eman K. A. Abdelall ◽  
Heba A. H. Elshemy ◽  
El‐Shaymaa El‐Nahass ◽  
Maha M. Abdel‐Fattah ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Docking Studies ◽  
Cox 2 ◽  
Anti Inflammatory ◽  
Cox 2 Inhibitors ◽  
Cox 1

Sa1096 SELECTIVE INHIBITION OF COX-1, BUT NOT COX-2, DECREASED THE COLONIC EPITHELIAL INTEGRITY IN THE TNBS-INDUCED COLITIS IN RATS.

2020 ◽  
Vol 158 (6) ◽  
pp. S-274
Author(s):  
Humberto B. da Costa ◽  
Thiago M. Sales ◽  
Suliana M. Paula ◽  
Rodrigo C. Mourão ◽  
Maria Klayre A. Sousa ◽  
...  
Keyword(s):  
Selective Inhibition ◽  
Epithelial Integrity ◽  
Cox 2 ◽  
Cox 1

A role for cyclooxygenase-2 in lipopolysaccharide-induced anorexia in rats

2002 ◽  
Vol 283 (4) ◽  
pp. R862-R868 ◽  
Author(s):  
F. Lugarini ◽  
B. J. Hrupka ◽  
G. J. Schwartz ◽  
C. R. Plata-Salaman ◽  
W. Langhans
Keyword(s):  
Cerebrospinal Fluid ◽  
Cyclooxygenase 2 ◽  
Major Metabolite ◽  
Time Dependent ◽  
Selective Inhibitors ◽  
Cox 2 ◽  
Cox 1

Because nonselective cycloooxygenase (COX) inhibition attenuated anorexia after lipopolysaccharide (LPS) administration, we tested the ability of resveratrol (2.5, 10, and 40 mg/kg) and NS-398 (2.5, 10, and 40 mg/kg), selective inhibitors of the two COX isoforms COX-1 and -2, respectively, to attenuate LPS (100 μg/kg ip)-induced anorexia. NS-398 (10 and 40 mg/kg) administered with LPS at lights out attenuated LPS-induced anorexia, whereas resveratrol at all doses tested did not. Because prostaglandin (PG) E2 is considered the major metabolite synthesized by COX, we measured plasma and cerebrospinal fluid (CSF) PGE2levels after LPS administration. LPS induced a time-dependent increase of PGE2 in CSF but not in plasma. NS-398 (5, 10, and 40 mg/kg) blocked the LPS-induced increase in CSF PGE2, whereas resveratrol (10 mg/kg) did not. These results support a role of COX-2 in mediating the anorectic response to peripheral LPS and point at PGE2 as a potential neuromodulator involved in this response.

In vitro COX-1, COX-2 and 5-LOX inhibitory activity of plant family Ranunculaceae

Planta Medica ◽  
2011 ◽  
Vol 77 (12) ◽  
Author(s):  
J Malik ◽  
P Landa ◽  
Z Kutil ◽  
P Marsik ◽  
L Kokoska
Keyword(s):  
Inhibitory Activity ◽  
Plant Family ◽  
Cox 2 ◽  
Cox 1

Selectivity of cyclooxygenase isoform activity and prostanoid production in normal and diseased Han:SPRD-cy rat kidneys

2006 ◽  
Vol 290 (4) ◽  
pp. F897-F904 ◽  
Author(s):  
Lori Warford-Woolgar ◽  
Claudia Yu-Chen Peng ◽  
Jamie Shuhyta ◽  
Andrew Wakefield ◽  
Deepa Sankaran ◽  
...  
Keyword(s):  
Selective Inhibition ◽  
Relative Difference ◽  
Prostaglandin E ◽  
Mrna Levels ◽  
Relative Contribution ◽  
Prostanoid Production ◽  
Prostaglandin F ◽  
Cox 2 ◽  
Cox 1

Renal prostanoids are important regulators of normal renal function and maintenance of renal homeostasis. In diseased kidneys, renal cylooxygenase (COX) expression and prostanoid formation are altered. With the use of the Han:Sprague-Dawley- cy rat, the aim of this study was to determine the relative contribution of renal COX isoforms (protein, gene expression, and activity) on renal prostanoid production [thromboxane B2 (TXB2, stable metabolite of TXA2), prostaglandin E2 (PGE2), and 6-keto-prostaglandin F1α (6-keto-PGF1α, stable metabolite of PGI2)] in normal and diseased kidneys. In diseased kidneys, COX-1-immunoreactive protein and mRNA levels were higher and COX-2 levels were lower compared with normal kidneys. In contrast, COX activities were higher in diseased compared with normal kidneys for both COX-1 [0.05 ± 0.02 vs. 0.45 ± 0.11 ng prostanoids·min−1·mg protein−1 ( P < 0.001)] and COX-2 [0.64 ± 0.10 vs. 2.32 ± 0.22 ng prostanoids·min−1·mg protein−1 ( P < 0.001)]. As the relative difference in activity was greater for COX-1, the ratio of COX-1/COX-2 was higher in diseased compared with normal kidneys, although the predominant activity was still due to the COX-2 isoform in both genotypes. Endogenous and steady-state in vitro levels of prostanoids were ∼2–10 times higher in diseased compared with normal kidneys. The differences between normal and diseased kidney prostanoids were in the order of TXB2 > 6-keto-PGF1α > PGE2, as determined by higher renal prostanoid levels and COX activity ratios of TXB2/6-keto-PGF1α, TXB2/PGE2, and 6-keto-PGF1α/PGE2. This specificity in both the COX isoform type and for the prostanoids produced has implications for normal and diseased kidneys in treatments involving selective inhibition of COX isoforms.

scholarly journals Differential contribution of COX-1 and COX-2 derived prostanoids to cortical spreading depression—Evoked cerebral oligemia

2016 ◽  
Vol 37 (3) ◽  
pp. 1060-1068 ◽  
Author(s):  
Helaine Gariepy ◽  
Jun Zhao ◽  
Dan Levy
Keyword(s):  
Cortical Spreading Depression ◽  
Spreading Depression ◽  
Selective Inhibition ◽  
Doppler Flowmetry ◽  
Relative Contribution ◽  
Cox Inhibitor ◽  
Cox 2 ◽  
Synthase Inhibitor ◽  
Later Phase ◽  
Cox 1

Cortical spreading depression (CSD) is considered a significant phenomenon for human neurological conditions and one of its key signatures is the development of persistent cortical oligemia. The factors underlying this reduction in cerebral blood flow (CBF) remain incompletely understood but may involve locally elaborated vasoconstricting eicosanoids. We employed laser Doppler flowmetry in urethane-anesthetized rats, together with a local pharmacological blockade approach, to test the relative contribution of cyclooxygenase (COX)-derived prostanoids to the oligemic response following CSD. Administration of the non-selective COX inhibitor naproxen completely inhibited the oligemic response. Selective inhibition of COX-1 with SC-560 preferentially reduced the early reduction in CBF while selective COX-2 inhibition with NS-398 affected only the later response. Blocking the action of thromboxane A2 (TXA2), using the selective thromboxane synthase inhibitor ozagrel, reduced only the initial CBF decrease, while inhibition of prostaglandin F2alpha action, using the selective FP receptor antagonist AL-8810, blocked the later phase of the oligemia. Our results suggest that the long-lasting oligemia following CSD consists of at least two distinct temporal phases, mediated by preferential actions of COX-1- and COX-2-derived prostanoids: an initial phase mediated by COX-1 that involves TXA2 followed by a later phase, mediated by COX-2 and PGF2alpha.

Flavonoids and Stilbenoids with COX-1 and COX-2 Inhibitory Activity fromDracaena loureiri

Planta Medica ◽  
2002 ◽  
Vol 68 (9) ◽  
pp. 841-843 ◽  
Author(s):  
Kittisak Likhitwitayawuid ◽  
Kanokporn Sawasdee ◽  
Kanyawim Kirtikara
Keyword(s):  
Inhibitory Activity ◽  
Cox 2 ◽  
Cox 1

PGE2 reduces arachidonic acid release in murine podocytes: evidence for an autocrine feedback loop

2003 ◽  
Vol 284 (2) ◽  
pp. C302-C309 ◽  
Author(s):  
Lyne I. Lemieux ◽  
Sherine S. Rahal ◽  
Chris R. J. Kennedy
Keyword(s):  
Arachidonic Acid ◽  
Cell Line ◽  
Selective Inhibition ◽  
Renal Diseases ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
Glomerular Function ◽  
Cox 2 ◽  
Regulatory Loop ◽  
Cox 1

Increased glomerular prostaglandin E2 (PGE2) production is associated with the progression of diseases such as membranous nephropathy, nephrotic syndrome, and anti-Thy1 nephritis. We investigated the signaling pathways that regulate the synthesis and actions of PGE2 in glomerular podocytes. To study its actions, we assessed the ability of PGE2 to regulate the production of its own precursor, arachidonic acid (AA), in a mouse podocyte cell line. PGE2 dose-dependently reduced phorbol ester (PMA)-mediated AA release. Inhibition of PMA-stimulated AA release by PGE2 was found to be cAMP/PKA-dependent, because PGE2 significantly increased levels of this second messenger, whereas the inhibitory actions of PGE2 were reversed by PKA inhibition and reproduced by the cAMP-elevating agents forskolin and IBMX. PGE2 synthesis in this podocyte cell line increased fourfold at 60 min in response to PMA, coinciding with upregulation of cyclooxygenase (COX)-2 but not COX-1 levels. However, PGE2 synthesis was significantly reduced by COX-1-selective inhibition, yet to a lesser extent by COX-2-selective inhibition. Our findings suggest that PMA-stimulated PGE2 synthesis in mouse podocytes requires both basal COX-1 activity and induced COX-2 expression, and that PGE2 reduces PMA-stimulated AA release in a cAMP/PKA-dependent manner. Such an autocrine regulatory loop might have important consequences for podocyte and glomerular function in the context of renal diseases involving PGE2 synthesis.

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