The analgesic effect profile of FR122047, a selective cyclooxygenase-1 inhibitor, in chemical nociceptive models

Differential roles of cyclooxygenase enzymes in the regulation of murine juvenile undifferentiated spermatogonia

BACKGROUND

Acetaminophen and ibuprofen are widely administered to babies due to their presumed safety as over-the-counter drugs. However, no reports exist on the effects of cyclooxygenase inhibitors on undifferentiated spermatogonia and spermatogonial stem cells. Infancy represents a critical period for spermatogonial stem cell formation and disrupting spermatogonial stem cells or their precursors may be associated with infertility and testicular cancer formation.

OBJECTIVES

The goal of this study was to examine the molecular and functional impact of cyclooxygenase inhibition and silencing on early steps of undifferentiated spermatogonia (u spg) and spermatogonial stem cell development, to assess the potential reproductive risk of pharmaceutical cyclooxygenase inhibitors.

METHODS

The effects of cyclooxygenase inhibition were assessed using the mouse C18-4 undifferentiated juvenile spermatogonial cell line model, previously shown to include cells with spermatogonial stem cell features, by measuring prostaglandins, cell proliferation, and differentiation, using cyclooxygenase 1- and cyclooxygenase 2-selective inhibitors NS398, celecoxib, and FR122047, acetaminophen, and ibuprofen. Cyclooxygenase 1 gene silencing was achieved using a stable short-hairpin RNA approach and clone selection, then assessing gene and protein expression in RNA sequencing, quantitative real-time polymerase chain reaction, and immunofluorescence studies.

RESULTS

Cyclooxygenase 2 inhibitors NS398 and celecoxib, as well as acetaminophen, but not ibuprofen, dose-dependently decreased retinoic acid-induced expression of the spg differentiation gene Stra8, while NS398 decreased the spg differentiation marker Kit, suggesting that cyclooxygenase 2 is positively associated with spg differentiation. In contrast, short-hairpin RNA-based cyclooxygenase 1 silencing in C18-4 cells altered cellular morphology and upregulated Stra8 and Kit, implying that cyclooxygenase 1 prevented spg differentiation. Furthermore, RNA sequencing analysis of cyclooxygenase 1 knockdown cells indicated the activation of several signaling pathways including the TGFb, Wnt, and Notch pathways, compared to control C18-4 cells. Notch pathway genes were upregulated by selective cyclooxygenase inhibitors, acetaminophen and ibuprofen.

CONCLUSION

We report that cyclooxygenase 1 and 2 differentially regulate undifferentiated spermatogonia/spermatogonial stem cell differentiation. Cyclooxygenases regulate Notch3 expression, with the Notch pathway targeted by PGD2. These data suggest an interaction between the eicosanoid and Notch signaling pathways that may be critical for the development of spermatogonial stem cells and subsequent spermatogenesis, cautioning about using cyclooxygenase inhibitors in infants.

A further pocket or conformational plasticity by mapping COX-1 catalytic site through modified-mofezolac structure-inhibitory activity relationships and their antiplatelet behavior

Cyclooxygenase enzymes have distinct roles in cardiovascular, neurological, and neurodegenerative disease. They are differently expressed in different type of cancers. Specific and selective COXs inhibitors are needed to be used alone or in combo-therapies. Fully understand the differences at the catalytic site of the two cyclooxygenase (COX) isoforms is still opened to investigation. Thus, two series of novel compounds were designed and synthesized in fair to good yields using the highly selective COX-1 inhibitor mofezolac as the lead compound to explore a COX-1 zone formed by the polar residues Q192, S353, H90 and Y355, as well as hydrophobic amino acids I523, F518 and L352. According to the structure of the COX-1:mofezolac complex, hydrophobic amino acids appear to have free volume eventually accessible to the more sterically hindering groups than the methoxy linked to the phenyl groups of mofezolac, in particular the methoxyphenyl at C4-mofezolac isoxazole. Mofezolac bears two methoxyphenyl groups linked to C3 and C4 of the isoxazole core ring. Thus, in the novel compounds, one or both methoxy groups were replaced by the higher homologous ethoxy, normal and isopropyl, normal and tertiary butyl, and phenyl and benzyl. Furthermore, a major difference between the two sets of compounds is the presence of either a methyl or acetic moiety at the C5 of the isoxazole. Among the C5-methyl series, 12 (direct precursor of mofezolac) (COX-1 IC50 = 0.076 μM and COX-2 IC50 = 0.35 μM) and 15a (ethoxy replacing the two methoxy groups in 12; COX-1 IC50 = 0.23 μM and COX-2 IC50 > 50 μM) were still active and with a Selectivity Index (SI = COX-2 IC50/COX-1 IC50) = 5 and 217, respectively. The other symmetrically substituted alkoxyphenyl moietis were inactive at 50 μM final concentration. Among the asymmetrically substituted, only the 16a (methoxyphenyl on C3-isoxazole and ethoxyphenyl on C4-isoxazole) and 16b (methoxyphenyl on C3-isoxazole and n-propoxyphenyl on C4-isoxazole) were active with SI = 1087 and 38, respectively. Among the set of compounds with the acetic moiety, structurally more similar to mofezolac (SI = 6329), SI ranged between 1.4 and 943. It is noteworthy that 17b (n-propoxyphenyl on both C3- and C4-isoxazole) were found to be a COX-2 slightly selective inhibitor with SI = 0.072 (COX-1 IC50 > 50 μM and COX-2 IC50 = 3.6 μM). Platelet aggregation induced by arachidonic acid (AA) can be in vitro suppressed by the synthesized compounds, without affecting of the secondary hemostasia, confirming the biological effect provided by the selective inhibition of COX-1. A positive profile of hemocompatibility in relation to erythrocyte and platelet toxicity was observed. Additionally, these compounds exhibited a positive profile of hemocompatibility and reduced cytotoxicity. Quantitative structure activity relationship (QSAR) models and molecular modelling (Ligand and Structure based virtual screening procedures) provide key information on the physicochemical and pharmacokinetic properties of the COX-1 inhibitors as well as new insights into the mechanisms of inhibition that will be used to guide the development of more effective and selective compounds. X-ray analysis was used to confirm the chemical structure of 14 (MSA17).

Lantana canescens (Kunth) inhibits inflammatory and hyperalgesic responses in murine models

ETHNOPHARMACOLOGICAL RELEVANCE

Lantana canescens is popularly known in Brazil as "cidreirinha" or "chumbinho-branco". It is found in Pantanal biome and its flowers and leaves are used in traditional medicine to treat pain and inflammation. Information about this species is limited to the activity of isolated essential oils. Studies with different extracts, composition, and biological properties are still scarce.

AIM OF THIS STUDY

The objective of this study was to evaluate the anti-inflammatory and anti-hyperalgesic activity of the hydroethanolic extract of L. canescens aerial parts.

MATERIALS AND METHODS

The hydroethanolic extract L. canescens aerial parts (HELc) was analyzed using HPLC-DAD-EM. Male and female Swiss mice weighing 18-25 g were used in the in vivo assays. Acute toxicity was assessed (2000 mg/kg); anti-inflammatory activity through paw edema, mast cell degranulation and peritonitis, and anti-hyperalgesic activity through abdominal writhing assays induced by acetic acid and formalin sensitization, were evaluated using the doses of 3, 30 and 300 mg/kg.

RESULTS

The phytochemical characterization of HELc confirmed the presence of glycosylated iridoids (theveside, theviridoside), verbascosides and flavonoids. The HELc did not present toxicity in the evaluated dose. HELc reduced formation of paw edema, degranulation of peritoneal mast cells and infiltration of polymorphonuclear cells into the animals peritoneal cavity. In addition, HELc decreased the number of abdominal writhing induced by acetic acid and the time of paw licking in the evaluation of formalin sensitization.

CONCLUSIONS

These results confirm the anti-inflammatory and anti-hyperalgesic effects of hydroethanolic extract of L. canescens, validating the use of this plant in folk medicine.

Learning from Nature: From a Marine Natural Product to Synthetic Cyclooxygenase-1 Inhibitors by Automated De Novo Design

The repertoire of natural products offers tremendous opportunities for chemical biology and drug discovery. Natural product-inspired synthetic molecules represent an ecologically and economically sustainable alternative to the direct utilization of natural products. De novo design with machine intelligence bridges the gap between the worlds of bioactive natural products and synthetic molecules. On employing the compound Marinopyrrole A from marine Streptomyces as a design template, the algorithm constructs innovative small molecules that can be synthesized in three steps, following the computationally suggested synthesis route. Computational activity prediction reveals cyclooxygenase (COX) as a putative target of both Marinopyrrole A and the de novo designs. The molecular designs are experimentally confirmed as selective COX-1 inhibitors with nanomolar potency. X-ray structure analysis reveals the binding of the most selective compound to COX-1. This molecular design approach provides a blueprint for natural product-inspired hit and lead identification for drug discovery with machine intelligence.

Synthesis and Antinociceptive Effect of Some Thiazole-Piperazine Derivatives: Involvement of Opioidergic System in the Activity

In this study, we aimed to design and synthesize novel molecules carrying both the thiazole and piperazine rings in their structures and to investigate their antinociceptive activity. Targeted compounds were obtained by reacting thiosemicarbazide derivative and appropriate 2-bromoacetophenone in ethanol. The structures of the obtained compounds were determined using data from various spectroscopic methods (IR, ¹H-NMR, ¹³C-NMR, and LCMSMS). Experimental data from in vivo tests showed that test compounds 3a–3c, 3f, and 3g (50 mg/kg) significantly prolonged reaction times of animals in tail-clip and hot-plate tests compared to the controls, indicating that these compounds possess centrally mediated antinociceptive activities. Furthermore, these compounds reduced the number of writhing behaviors in the acetic acid-induced writhing tests, showing that the compounds also possess peripheral antinociceptive activity. In the mechanistic studies, naloxone pre-treatments abolished the antinociceptive activities of compounds 3a–3c, 3f, and 3g, indicating that opioidergic mechanisms were involved in their antinociceptive effects. Molecular docking studies demonstrating significant interactions between the active compounds and µ- and δ-opioid receptor proteins supported the pharmacological findings. This study is the first showing that molecules designed to bear thiazole and piperazine moieties together on their structure exert centrally and peripherally mediated antinociceptive effects by activating the opioid system.

Structural and Chemical Biology of the Interaction of Cyclooxygenase with Substrates and Non-Steroidal Anti-Inflammatory Drugs

Cyclooxgenases are key enzymes of lipid signaling. They carry out the first step in the production of prostaglandins, important mediators of inflammation, pain, cardiovascular disease, and cancer, and they are the molecular targets for nonsteroidal anti-inflammatory drugs, which are among the oldest and most chemically diverse set of drugs known. Homodimeric proteins that behave as allosterically modulated, functional heterodimers, the cyclooxygenases exhibit complex kinetic behavior, requiring peroxide-dependent activation and undergoing suicide inactivation. Due to their important physiological and pathophysiological roles and keen interest on the part of the pharmaceutical industry, the cyclooxygenases have been the focus of a vast array of structural studies, leading to the publication of over 80 crystal structures of the enzymes in complex with substrates or inhibitors supported by a wealth of functional data generated by site-directed mutation experiments. In this review, we explore the chemical biology of the cyclooxygenases through the lens of this wealth of structural and functional information. We identify key structural features of the cyclooxygenases, break down their active site into regional binding pockets to facilitate comparisons between structures, and explore similarities and differences in the binding modes of the wide variety of ligands (both substrates and inhibitors) that have been characterized in complex with the enzymes. Throughout, we correlate structure with function whenever possible. Finally, we summarize what can and cannot be learned from the currently available structural data and discuss the critical intriguing questions that remain despite the wealth of information that has been amassed in this field.

Altered cyclooxygenase-1 and enhanced thromboxane receptor activities underlie attenuated endothelial dilatory capacity of omental arteries in obesity

AIMS

Obesity is a risk factor for endothelial dysfunction, the severity of which is likely to vary depending on extent and impact of adiposity on the vasculature. This study investigates the roles of cyclooxygenase isoforms and thromboxane receptor activities in the differential endothelial dilatory capacities of arteries derived from omental and subcutaneous adipose tissues in obesity.

MAIN METHODS

Small arteries were isolated from omental and subcutaneous adipose tissues obtained from consented morbidly obese patients (n = 65, BMI 45 ± 6 kg m^-2 [Mean ± SD]) undergoing bariatric surgery. Relaxation to acetylcholine was studied by wire myography in the absence or presence of indomethacin (10 μM, cyclooxygenase inhibitor), FR122047 (1 μM, cyclooxygenase-1 inhibitor), Celecoxib (4 μM, cyclooxygenase-2 inhibitor), Nω-Nitro-L-arginine methyl ester (L-NAME, 100 μM, nitric oxide synthase inhibitor) or combination of apamin (0.5 μM) and charybdotoxin (0.1 μM) that together inhibit endothelium-derived hyperpolarizing factor (EDHF). Contractions to U46619 (thromboxane A₂ mimetic) were also studied.

KEY FINDINGS

Acetylcholine relaxation was significantly attenuated in omental compared with subcutaneous arteries from same patients (p < 0.01). Indomethacin (p < 0.01) and FR122047 (p < 0.001) but not Celecoxib significantly improved the omental arteriolar relaxation. Cyclooxygenase-1 mRNA and U46619 contractions were both increased in omental compared with subcutaneous arteries (p < 0.05). L-NAME comparably inhibited acetylcholine relaxation in both arteries, while apamin+charybdotoxin were less effective in omental compared with subcutaneous arteries.

SIGNIFICANCE

The results show that the depot-specific reduction in endothelial dilatory capacity of omental compared with subcutaneous arteries in obesity is in large part due to altered cyclooxygenase-1 and enhanced thromboxane receptor activities, which cause EDHF deficiency.

The Adjuvant Effect of Squalene, an Active Ingredient of Functional Foods, on Doxorubicin-Treated Allograft Mice

Many functional foods or physiologically active ingredients derived from plants and animals are actively being investigated for their role in chronic disease prevention. Squalene (SQ) is found as active ingredient in the functional foods predominantly present in olive oil and shark liver oil. It is known that during chemotherapy anticancer drugs induce inflammation. SQ has been thought to prevent and suppress inflammation; however, there is little direct evidence available. We examined the adjuvant effect of SQ on tumor-transplanted mice along with anticancer drug doxorubicin (DOX). SQ significantly suppressed the DOX-induced increase in prostaglandin E₂ (PGE₂) concentration (P < 0.05) in plasma of tumor-bearing mice. SQ inhibited the numbers of writhing response (P < 0.05), formalin-induced pain and decreased COX-2 and substance P expression in the tumor tissue compared to control mice and also enhanced the antitumor efficacy of DOX in allograft mice. Thus, SQ reduces inflammation through modulation of PGE₂ production indicating its potential as an adjuvant during chemotherapy in tumor-bearing mice.

Cyclooxygenase-1 (COX-1) and COX-1 Inhibitors in Cancer: A Review of Oncology and Medicinal Chemistry Literature

Prostaglandins and thromboxane are lipid signaling molecules deriving from arachidonic acid by the action of the cyclooxygenase isoenzymes COX-1 and COX-2. The role of cyclooxygenases (particularly COX-2) and prostaglandins (particularly PGE₂) in cancer-related inflammation has been extensively investigated. In contrast, COX-1 has received less attention, although its expression increases in several human cancers and a pathogenetic role emerges from experimental models. COX-1 and COX-2 isoforms seem to operate in a coordinate manner in cancer pathophysiology, especially in the tumorigenesis process. However, in some cases, exemplified by the serous ovarian carcinoma, COX-1 plays a pivotal role, suggesting that other histopathological and molecular subtypes of cancer disease could share this feature. Importantly, the analysis of functional implications of COX-1-signaling, as well as of pharmacological action of COX-1-selective inhibitors, should not be restricted to the COX pathway and to the effects of prostaglandins already known for their ability of affecting the tumor phenotype. A knowledge-based choice of the most appropriate tumor cell models, and a major effort in investigating the COX-1 issue in the more general context of arachidonic acid metabolic network by using the systems biology approaches, should be strongly encouraged.

Design, synthesis and analgesic/anti-inflammatory evaluation of novel diarylthiazole and diarylimidazole derivatives towards selective COX-1 inhibitors with better gastric profile

The inhibition of gastric cyclooxygenase 1 (COX-1) enzyme was believed to be the major cause of non-steroidal anti-inflammatory drugs (NSAIDs)-induced gastric ulcer. Recent studies disproved this belief and showed that the gastric tissues vulnerability is not solely connected to COX-1 inhibition. This work aimed at exploring and rationalizing the differential analgesic and anti-inflammatory activities of novel selective COX-1 inhibitors with improved gastric profile. Two novel series of 4,5-diarylthiazole and diarylimidazole were designed, synthesized in analogy to selective COX-1 inhibitors (mofezolac and FR122047) which lack gastric damaging effects. The new compounds were evaluated in vitro for their COXs inhibitory activity and in vivo for their anti-inflammatory and analgesic potentials. Four compounds; diphenylthiazole glycine derivatives (15a, 15b) and diphenylimidazolo acetic acid derivatives (19a, 19b), which possess carboxylic acid group exhibited significant activity and selectivity against COX-1 over COX-2. Of these compounds, (4,5-bis(4-methoxyphenyl)thiazol-2-yl)glycine 15b was the most potent compound against COX-1 with an inhibitory half maximal concentration (IC₅₀) of 0.32μM and a selectivity index (COX-2 IC₅₀/COX-1 IC₅₀) of 28.84. Furthermore, an ulcerogenicity study was performed where the tested compounds demonstrated a significant gastric tolerance. Interestingly, the most selective COX-1 inhibitor showed higher analgesic activity in vivo as expected compared to their moderate anti-inflammatory activity. This study underscores the need for further design and development of novel analgesic agents with low tendency to cause gastric damage based on improving their COX-1 affinity and selectivity profile.

Arachidonic Acid Metabolite 19(S)-HETE Induces Vasorelaxation and Platelet Inhibition by Activating Prostacyclin (IP) Receptor

19(S)-hydroxy-eicosatetraenoic acid (19(S)-HETE) belongs to a family of arachidonic acid metabolites produced by cytochrome P450 enzymes, which play critical roles in the regulation of cardiovascular, renal and pulmonary functions. Although it has been known for a long time that 19(S)-HETE has vascular effects, its mechanism of action has remained unclear. In this study we show that 19(S)-HETE induces cAMP accumulation in the human megakaryoblastic leukemia cell line MEG-01. This effect was concentration-dependent with an EC₅₀ of 520 nM, insensitive to pharmacological inhibition of COX-1/2 and required the expression of the G-protein G_s. Systematic siRNA-mediated knock-down of each G-protein coupled receptor (GPCR) expressed in MEG-01 followed by functional analysis identified the prostacyclin receptor (IP) as the mediator of the effects of 19(S)-HETE, and the heterologously expressed IP receptor was also activated by 19(S)-HETE in a concentration-dependent manner with an EC₅₀ of 567 nM. Pretreatment of isolated murine platelets with 19(S)-HETE blocked thrombin-induced platelets aggregation, an effect not seen in platelets from mice lacking the IP receptor. Furthermore, 19(S)-HETE was able to relax mouse mesenteric artery- and thoracic aorta-derived vessel segments. While pharmacological inhibition of COX-1/2 enzymes had no effect on the vasodilatory activity of 19(S)-HETE these effects were not observed in vessels from mice lacking the IP receptor. These results identify a novel mechanism of action for the CYP450-dependent arachidonic acid metabolite 19(S)-HETE and point to the existence of a broader spectrum of naturally occurring prostanoid receptor agonists.

Role of cyclooxygenase-1 and -2 in endothelium-dependent contraction of atherosclerotic mouse abdominal aortas

The objective of this study was to determine the role of cyclooxygenase (COX)-1 or -2 in endothelium-dependent contraction under atherosclerotic conditions. Atherosclerosis was induced in apoE knockout (apoE(-/-)) mice and those with COX-1(-/-) (apoE(-/-)-COX-1(-/-)) by feeding with high fat and cholesterol food. Aortas (abdominal or the whole section) were isolated for functional and/or biochemical analyses. As in non-atherosclerotic conditions, the muscarinic receptor agonist acetylcholine (ACh) evoked an endothelium-dependent, COX-mediated contraction following NO synthase (NOS) inhibition in abdominal aortic rings from atherosclerotic apoE(-/-) mice. Interestingly, COX-1 inhibition not only abolished such a contraction in rings showing normal appearance, but also diminished that in rings with plaques. Accordingly, only a minor contraction (<30% that of apoE(-/-) counterparts) was evoked by ACh (following NOS inhibition) in abdominal aortic rings of atherosclerotic apoE(-/-)-COX-1(-/-) mice with plaques, and none was evoked in those showing normal appearance. Also, the contraction evoked by ACh in apoE(-/-)-COX-1(-/-) abdominal aortic rings with plaques was abolished by non-selective COX inhibition, thromboxane-prostanoid (TP) receptor antagonism, or endothelial denudation. Moreover, it was noted that ACh evoked a predominant production of the prostacyclin (PGI2, which mediates abdominal aortic contraction via TP receptors in mice) metabolite 6-keto-PGF1α, which was again sensitive to COX-1 inhibition or COX-1(-/-). Therefore, in atherosclerotic mouse abdominal aortas, COX-1 can still be the major isoform mediating endothelium-dependent contraction, which probably results largely from PGI2 synthesis as in non-atherosclerotic conditions. In contrast, COX-2 may have only a minor role in such response limited to areas of plaques under the same pathological condition.

A vasoconstrictor response to COX-1-mediated prostacyclin synthesis in young rat renal arteries that increases in prehypertensive conditions

This study aimed to determine whether prostacyclin (PGI2) functions as an endothelium-derived contracting factor (EDCF) in young rat renal arteries, and, if so, we wanted to examine the underlying mechanism(s) and how it changes in prehypertensive conditions. Vessels from Wistar-Kyoto (WKY) and prehypertensive spontaneously hypertensive rats (SHRs) of 25-28 days of age were isolated for functional and biochemical analyses. Result showed that following NO synthase (NOS) inhibition PGI2 and the thromboxane-prostanoid (TP) receptor agonist U-46619 evoked contractions in young WKY renal arteries that were similar to those in prehypertensive SHRs. Meanwhile, the endothelial muscarinic receptor agonist ACh evoked an endothelium-dependent contraction under NOS-inhibited conditions and a production of the PGI2 metabolite 6-keto-PGF1α; both were sensitive to cyclooxygenase (COX) and/or COX-1 inhibition but higher in prehypertensive SHRs than in young WKYs. Interestingly, in WKY renal arteries PGI2 did not evoke relaxation even after TP receptor antagonism that diminished the contraction evoked by the agonist. Indeed, PGI2 (IP) receptors were not detected in the vessel with Western blot. Moreover, we noted that treatment with the nonselective COX inhibitor indomethacin, which was started at the prehypertensive stage, blunted the elevation of systolic blood pressure and reduced the heart-to-body ratio in SHR within 2 mo of treatment. These results demonstrate that due to scarcity of IP receptors, PGI2, which is derived mainly from COX-1-mediated metabolism, acts as an EDCF in young WKY renal arteries, and it increases in prehypertensive conditions. Also, our data revealed that COX inhibition starting from the prehypertensive stage has an antihypertensive effect in young SHRs.

Vasomotor Reaction to Cyclooxygenase-1-Mediated Prostacyclin Synthesis in Carotid Arteries from Two-Kidney-One-Clip Hypertensive Mice

This study tested the hypothesis that in hypertensive arteries cyclooxygenase-1 (COX-1) remains as a major form, mediating prostacyclin (prostaglandin I2; PGI2) synthesis that may evoke a vasoconstrictor response in the presence of functional vasodilator PGI2 (IP) receptors. Two-kidney-one-clip (2K1C) hypertension was induced in wild-type (WT) mice and/or those with COX-1 deficiency (COX-1-/-). Carotid arteries were isolated for analyses 4 weeks after. Results showed that as in normotensive mice, the muscarinic receptor agonist ACh evoked a production of the PGI2 metabolite 6-keto-PGF1α and an endothelium-dependent vasoconstrictor response; both of them were abolished by COX-1 inhibition. At the same time, PGI2, which evokes contraction of hypertensive vessels, caused relaxation after thromboxane-prostanoid (TP) receptor antagonism that abolished the contraction evoked by ACh. Antagonizing IP receptors enhanced the contraction to the COX substrate arachidonic acid (AA). Also, COX-1-/- mice was noted to develop hypertension; however, their increase of blood pressure and/or heart mass was not to a level achieved with WT mice. In addition, we found that either the contraction in response to ACh or that evoked by AA was abolished in COX-1-/- hypertensive mice. These results demonstrate that as in normotensive conditions, COX-1 is a major contributor of PGI2 synthesis in 2K1C hypertensive carotid arteries, which leads to a vasoconstrictor response resulting from opposing dilator and vasoconstrictor activities of IP and TP receptors, respectively. Also, our data suggest that COX-1-/- attenuates the development of 2K1C hypertension in mice, reflecting a net adverse role yielded from all COX-1-mediated activities under the pathological condition.

Design of Fluorine-Containing 3,4-Diarylfuran-2(5H)-ones as Selective COX-1 Inhibitors

We report the design and synthesis of fluorine-containing cyclooxygenase-1 (COX-1)-selective inhibitors to serve as prototypes for the development of a COX-1-targeted imaging agent. Deletion of the SO2CH3 group of rofecoxib switches the compound from a COX-2- to a COX-1-selective inhibitor, providing a 3,4-diarylfuran-2(5H)-one scaffold for structure-activity relationship studies of COX-1 inhibition. A wide range of fluorine-containing 3,4-diarylfuran-2(5H)-ones were designed, synthesized, and tested for their ability to selectively inhibit COX-1 in purified protein and human cancer cell assays. Compounds containing a fluoro-substituent on the C-3 phenyl ring and a methoxy-substituent on the C-4 phenyl ring of the 3,4-diarylfuran-2(5H)-one scaffold were the best COX-1-selective agents of those evaluated, exhibiting IC50s in the submicromolar range. These compounds provide the foundation for development of an agent to facilitate radiologic imaging of ovarian cancer expressing elevated levels of COX-1.

Selective COX-1 inhibition as a target of theranostic novel diarylisoxazoles

Cyclooxygenase(COX)-1 role in some diseases is increasingly studied. 3-(5-Chlorofuran-2-yl)-5-methyl-4-phenylisoxazole (P6), a highly selective cyclooxygenase-1 inhibitor, was used as a "lead" to design new isoxazoles (2a-m), differently selective towards COX-1. Those isoxazoles might be useful as novel theranostic agents and also to better clarify COX-1 role in the human physiology and diseases. 2a-m were prepared in fair to good yields developing suitable synthetic strategies. They were evaluated in vitro for their COX-inhibitory activity and selectivity. Structure-activity relationship studies of the novel set of diarylisoxazoles allowed to identify new key determinants for COX-1 selectivity, and to uncover compounds appropriate for a deep pharmacokinetic and pharmacodynamic investigation. 3-(5-Chlorofuran-2yl)-4-phenylisoxazol-5-amine (2f) was the most active compound of the series, its inhibitory activity was assessed in purified enzyme (COX-1 IC₅₀ = 1.1 μM; COX-2 IC₅₀ > 50 μM) and in the ovarian cancer cell line (OVCAR-3) expressing only COX-1 (IC₅₀ = 0.58 μM). Furthermore, the high inhibitory potency of 2f was rationalized through docking simulations in terms of interactions with a crystallographic model of the COX-1 binding site. We found critical interactions between the inhibitor and constriction residues R120 and Y355 at the base of the active site, as well as with S530 at the top of the side pocket.

The Concise Guide to PHARMACOLOGY 2013/14: enzymes

The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Enzymes are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, nuclear hormone receptors, catalytic receptors and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.

Aspirin augments IgE-mediated histamine release from human peripheral basophils via Syk kinase activation

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs), especially aspirin, and food additives (FAs) may exacerbate allergic symptoms in patients with chronic idiopathic urticaria and food-dependent exercise-induced anaphylaxis (FDEIA). Augmentation of histamine release from human mast cells and basophils by those substances is speculated to be the cause of exacerbated allergic symptoms. We sought to investigate the mechanism of action of aspirin on IgE-mediated histamine release.

METHODS

The effects of NSAIDs, FAs or cyclooxygenase (COX) inhibitors on histamine release from human basophils concentrated by gravity separation were evaluated.

RESULTS

Benzoate and tartrazine, which have no COX inhibitory activity, augmented histamine release from basophils similar to aspirin. In contrast, ibuprofen, meloxicam, FR122047 and NS-398, which have COX inhibitory activity, did not affect histamine release. These results indicate that the augmentation of histamine release by aspirin is not due to COX inhibition. It was observed that aspirin augmented histamine release from human basophils only when specifically activated by anti-IgE antibodies, but not by A23187 or formyl-methionyl-leucyl-phenylalanine. When the IgE receptor signaling pathway was activated, aspirin increased the phosphorylation of Syk. Moreover, patients with chronic urticaria and FDEIA tended to be more sensitive to aspirin as regards the augmentation of histamine release, compared with healthy controls.

CONCLUSIONS

Aspirin enhanced histamine release from basophils via increased Syk kinase activation, and that the augmentation of histamine release by NSAIDs or FAs may be one possible cause of worsening symptoms in patients with chronic urticaria and FDEIA.

PGE2 maintains the tone of the guinea pig trachea through a balance between activation of contractile EP1 receptors and relaxant EP2 receptors

BACKGROUND AND PURPOSE

The guinea pig trachea (GPT) is commonly used in airway pharmacology. The aim of this study was to define the expression and function of EP receptors for PGE(2) in GPT as there has been ambiguity concerning their role.

EXPERIMENTAL APPROACH

Expression of mRNA for EP receptors and key enzymes in the PGE(2) pathway were assessed by real-time PCR using species-specific primers. Functional studies of GPT were performed in tissue organ baths.

KEY RESULTS

Expression of mRNA for the four EP receptors was found in airway smooth muscle. PGE(2) displayed a bell-shaped concentration-response curve, where the initial contraction was inhibited by the EP(1) receptor antagonist ONO-8130 and the subsequent relaxation by the EP(2) receptor antagonist PF-04418948. Neither EP(3) (ONO-AE5-599) nor EP(4) (ONO-AE3-208) selective receptor antagonists affected the response to PGE(2). Expression of COX-2 was greater than COX-1 in GPT, and the spontaneous tone was most effectively abolished by selective COX-2 inhibitors. Furthermore, ONO-8130 and a specific PGE(2) antibody eliminated the spontaneous tone, whereas the EP(2) antagonist PF-04418948 increased it. Antagonists of other prostanoid receptors had no effect on basal tension. The relaxant EP(2) response to PGE(2) was maintained after long-term culture, whereas the contractile EP(1) response showed homologous desensitization to PGE(2), which was prevented by COX-inhibitors.

CONCLUSIONS AND IMPLICATIONS

Endogenous PGE(2), synthesized predominantly by COX-2, maintains the spontaneous tone of GPT by a balance between contractile EP(1) receptors and relaxant EP(2) receptors. The model may be used to study interactions between EP receptors.

ASP6537, a novel highly selective cyclooxygenase-1 inhibitor, exerts potent antithrombotic effect without "aspirin dilemma"

INTRODUCTION

Aspirin inhibits both the cyclooxygenase (COX)-1-dependent production of thromboxane A2 (TXA2) in platelets and COX-2-dependent production of anti-aggregatory prostaglandin I2 (PGI2) in vessel walls, resulting in "aspirin dilemma." Our objective is to investigate whether ASP6537 can overcome aspirin dilemma and exert a potent antithrombotic effect without a concurrent ulcerogenic effect.

METHODS

We evaluated the inhibitory effects of ASP6537 on recombinant human COX-1 (rhCOX-1) and rhCOX-2 activities using a COX-1/2 selectivity test. To determine whether ASP6537 induces aspirin dilemma, we examined the effects of ASP6537 on in vitro TXA2 and PGI2 metabolite production from platelets and isolated aorta of guinea pigs, and on plasma concentrations of TXA2 and PGI2 metabolites in aged rats. Finally, we evaluated the antithrombotic effects and ulcerogenic activity of ASP6537 using an electrically induced carotid arterial thrombosis model and a gastric ulcer model in guinea pigs.

RESULTS

The IC50 ratios of rhCOX-2 to rhCOX-1 for ASP6537 and aspirin were >142,000 and 1.63 fold, respectively. ASP6537 inhibited TXA2 production more selectively than aspirin in in vitro and in vivo TXA2/PGI2 production studies. ASP6537 exerted a significant antithrombotic effect at ≥3 mg/kg, while aspirin tended to inhibit thrombosis at 300 mg/kg but it was not statistically significant. Further, ASP6537 did not induce ulcer formation at 100 mg/kg, whereas aspirin exhibited an ulcerogenic effect at doses of ≥100 mg/kg.

CONCLUSIONS

ASP6537 functions as a highly selective COX-1 inhibitor with a superior ability to aspirin for normalizing TXA2/PGI2 balance, and exerts antithrombotic effect without ulcerogenic effect.

Effect of celecoxib on cyclooxygenase-1-mediated prostacyclin synthesis and endothelium-dependent contraction in mouse arteries

This study aimed to determine whether a cyclooxygenase-2 (COX-2) inhibitor celecoxib influences endothelium-dependent contraction independent of its action on COX-2 and, if so, the underlying mechanism(s). Abdominal aortas and/or carotid arteries from C57BL/6 mice or those with genetic COX-2 deficiency (COX-2(-/-)) were isolated for functional and/or biochemical analyses. Result showed that following NO synthase inhibition celecoxib not only reduced the contraction evoked by acetylcholine in C57BL/6 abdominal aorta, but also that in COX-2 (-/-) mice showing a comparable magnitude. Notably, the IC(50) of celecoxib obtained in COX-2 (-/-) abdominal aorta was only ~0.364 μM. Also, celecoxib exhibited a similar effect on COX-2 (-/-) carotid arteries. Interestingly, celecoxib was not only found to inhibit the production of the prostacyclin (PGI(2)) metabolite 6-keto-PGF (1α) in COX-2 (-/-) aortas, but also caused a reduction in the contraction evoked by PGI(2), by the α(1)-adrenergic agonist phenylephrine, or by 30 mM K(+)-induced depolarization in COX-2 (-/-) and/or C57BL/6 abdominal aorta. Moreover, N-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide (NS398), another COX-2 inhibitor, also reduced the contraction evoked by acetylcholine or by 30 mM K(+)-induced depolarization in COX-2 (-/-) mice. These results demonstrate explicitly that in mouse arteries celecoxib not only inhibits COX-1-mediated synthesis of PGI(2) and probably some other prostanoids, but also causes a reduction in vessel contractility that is independent of either COX-2 or COX-1, leading to an inhibition of COX-1-mediated endothelium-dependent contraction with an IC(50) value far below that of it considered for COX-1 . Also, our data suggest that such effects of celecoxib could be possibly shared by some other COX-2 inhibitors, such as NS398.

Role of cyclooxygenase-1-mediated prostacyclin synthesis in endothelium-dependent vasoconstrictor activity of porcine interlobular renal arteries

This study aimed to determine whether PGI2 would be evoked by the endogenous endothelial B2 receptor agonist bradykinin (BK) in the porcine interlobular renal artery and, if so, to determine how it would influence the vasomotor reaction, and the specific cyclooxygenase (COX) isoform(s) involved in its synthesis. The production of the PGI2 metabolite 6-keto-PGF1α was analyzed with HPLC-mass spectroscopy, while vasomotor reaction to PGI2 or BK was determined with isometric force measurement. Results showed that BK evoked an increase in the production of 6-keto-PGF1α, which was abolished by endothelial denudation that removed COX-1 expression, or was reduced by COX-1 inhibition. Interestingly, PGI2 evoked a potent contraction, which was prevented by antagonizing thromboxane-prostanoid (TP) receptors and was not enhanced by antagonizing the vasodilator PGI2 (IP) receptors. The IP receptor agonists MRE-269 and iloprost did not induce any relaxation. Moreover, iloprost, which is also a PGI2 analog, caused a contraction, which was sensitive to TP receptor antagonism, but was to a significantly lesser extent than that of PGI2. Indeed, IP receptors were not detected by RT-PCR or Western blotting in the vessel. Following nitric oxide synthase (NOS) inhibition, BK also evoked an endothelium-dependent contraction, which was blocked by TP receptor antagonism. In addition, inhibition of COX-1 (but not COX-2) impeded the vasoconstrictor activity of BK and expedited the relaxation induced by the agonist in NOS-intact vessels. These results demonstrate that in the porcine interlobular renal artery BK evokes endothelial COX-1-mediated PGI2 synthesis, which mainly leads to the activation of TP receptors and a vasoconstrictor response, possibly due to a scarcity of vasodilator activity mediated by IP receptors. Also, our data suggested that the effect of a PGI2 analog on TP receptors could be reduced compared with that of PGI2 due to modified structure as with iloprost.

Concomitant activation of functionally opposing prostacyclin and thromboxane prostanoid receptors by cyclo-oxygenase-1-mediated prostacyclin synthesis in mouse arteries

This study aimed to determine whether cyclo-oxygenase-1 (COX-1) mediates dilatation of mouse arteries via synthesis of prostacyclin (PGI(2)) and, if so, how PGI(2) (IP) receptors contribute and whether thromboxane prostanoid (TP) receptors are implicated in the process. Mesenteric arteries were isolated from wild-type mice or mice with COX-1 deficiency (COX-1(-/-)). The vasomotor reaction to the COX substrate arachidonic acid (AA) was determined with isometric force measurement, while the in vitro production or the plasma level of the PGI(2) metabolite 6-keto-PGF(1α) was analysed with high-performance liquid chromatography-mass spectroscopy or enzyme immunoassay, respectively. Results showed that AA, which evoked endothelium-dependent 6-keto-PGF(1α) production, elicited relaxation that was inhibited or enhanced by antagonizing IP or TP receptors, respectively. Also, IP receptor blockade resulted in contraction in response to AA (following NO synthase inhibition), which was prevented by a concomitant TP receptor antagonism. Meanwhile, COX-1(-/-) or COX-1 inhibition abolished the in vitro 6-keto-PGF(1α) production and reduced the relaxation or contraction observed with AA. Real-time PCR showed that whereas TP receptor mRNAs were detected at similar levels, IP receptor mRNAs were present at higher levels in the branches than in the main stem of the mesenteric artery. In addition, antagonizing the IP receptors enhanced the contraction evoked by PGI(2) in the carotid artery. Also, we noted that COX-1(-/-) mice had a reduced basal plasma 6-keto-PGF(1α) level. These results demonstrate an explicit vasodilator role for COX-1-mediated endothelial PGI(2) synthesis and suggest that the functionally opposing IP and TP receptors concomitantly mediate the vasomotor reaction to PGI(2), with the dilator activity of IP receptors being compromised by the vasoconstrictor effect of TP receptors and vice versa.

Protection of protease-activated receptor 2 mediated vasodilatation against angiotensin II-induced vascular dysfunction in mice

Background

Under conditions of cardiovascular dysfunction, protease-activated receptor 2 (PAR2) agonists maintain vasodilatation activity, which has been attributed to increased cyclooxygenase-2, nitric oxide synthase and calcium-activated potassium channel (SK3.1) activities. Protease-activated receptor 2 agonist mediated vasodilatation is unknown under conditions of dysfunction caused by angiotensin II. The main purpose of our study was to determine whether PAR2-induced vasodilatation of resistance arteries was attenuated by prolonged angiotensin II treatment in mice. We compared the vasodilatation of resistance-type arteries (mesenteric) from angiotensin II-treated PAR2 wild-type mice (WT) induced by PAR2 agonist 2-furoyl-LIGRLO-amide (2fly) to the responses obtained in controls (saline treatment). We also investigated arterial vasodilatation in angiotensin II-treated PAR2 deficient (PAR2^-/-) mice.

Results

2fly-induced relaxations of untreated arteries from angiotensin II-treated WT were not different than saline-treated WT. Treatment of arteries with nitric oxide synthase inhibitor and SK3.1 inhibitor (L-NAME + TRAM-34) blocked 2fly in angiotensin II-treated WT. Protein and mRNA expression of cyclooxygenase-1 and -2 were increased, and cyclooxygenase activity increased the sensitivity of arteries to 2fly in only angiotensin II-treated WT. These protective vasodilatation mechanisms were selective for 2fly compared with acetylcholine- and nitroprusside-induced relaxations which were attenuated by angiotensin II; PAR2^-/- were protected against this attenuation of nitroprusside.

Conclusions

PAR2-mediated vasodilatation of resistance type arteries is protected against the negative effects of angiotensin II-induced vascular dysfunction in mice. In conditions of endothelial dysfunction, angiotensin II induction of cyclooxygenases increases sensitivity to PAR2 agonist and the preserved vasodilatation mechanism involves activation of SK3.1.

Antinociception produced by Thalassia testudinum extract BM-21 is mediated by the inhibition of acid sensing ionic channels by the phenolic compound thalassiolin B

Background

Acid-sensing ion channels (ASICs) have a significant role in the sensation of pain and constitute an important target for the search of new antinociceptive drugs. In this work we studied the antinociceptive properties of the BM-21 extract, obtained from the sea grass Thalassia testudinum, in chemical and thermal models of nociception in mice. The action of the BM-21 extract and the major phenolic component isolated from this extract, a sulphated flavone glycoside named thalassiolin B, was studied in the chemical nociception test and in the ASIC currents of the dorsal root ganglion (DRG) neurons obtained from Wistar rats.

Results

Behavioral antinociceptive experiments were made on male OF-1 mice. Single oral administration of BM-21 produced a significant inhibition of chemical nociception caused by acetic acid and formalin (specifically during its second phase), and increased the reaction time in the hot plate test. Thalassiolin B reduced the licking behavior during both the phasic and tonic phases in the formalin test. It was also found that BM-21 and thalassiolin B selectively inhibited the fast desensitizing (τ < 400 ms) ASIC currents in DRG neurons obtained from Wistar rats, with a nonsignificant action on ASIC currents with a slow desensitizing time-course. The action of thalassiolin B shows no pH or voltage dependence nor is it modified by steady-state ASIC desensitization or voltage. The high concentration of thalassiolin B in the extract may account for the antinociceptive action of BM-21.

Conclusions

To our knowledge, this is the first report of an ASIC-current inhibitor derived of a marine-plant extract, and in a phenolic compound. The antinociceptive effects of BM-21 and thalassiolin B may be partially because of this action on the ASICs. That the active components of the extract are able to cross the blood-brain barrier gives them an additional advantage for future uses as tools to study pain mechanisms with a potential therapeutic application.

Enhancement of antinociception by coadministration of minocycline and a non-steroidal anti-inflammatory drug indomethacin in naïve mice and murine models of LPS-induced thermal hyperalgesia and monoarthritis

BACKGROUND

Minocycline and a non-steroidal anti-inflammatory drug (NSAID) indomethacin, have anti-inflammatory activities and are both used in the management of rheumatoid arthritis. However, there are no reports on whether coadministration of these drugs could potentiate each other's activities in alleviating pain and weight bearing deficits during arthritis.

METHODS

LPS was injected to BALB/c mice intraperitoneally (i.p.) to induce thermal hyperalgesia. The hot plate test was used to study thermal nociception in naïve BALB/c and C57BL/6 mice and BALB/c mice with LPS-induced thermal hyperalgesia and to evaluate antinociceptive effects of drugs administered i.p. Monoarthritis was induced by injection of LPS intra-articularly into the right hind (RH) limb ankle joint of C57BL/6 mice. Weight bearing changes and the effect of i.p. drug administration were analyzed in freely moving mice using the video-based CatWalk gait analysis system.

RESULTS

In naïve mice indomethacin (5 to 50 mg/kg) had no significant activity, minocycline (25 to 100 mg/kg) produced hyperalgesia to thermal nociception, however, coadministration of minocycline 50 mg/kg with indomethacin 5 or 10 mg/kg produced significant antinociceptive effects in the hot plate test. A selective inhibitor of COX-1, FR122047 (10 mg/kg) and a selective COX-2 inhibitor, CAY10404 (10 mg/kg) had no significant antinociceptive activities to thermal nociception in naïve mice, however, coadministration of minocycline, with CAY10404 but not FR122047 produced significant antinociceptive effects. In mice with LPS-induced hyperalgesia vehicle, indomethacin (10 mg/kg) or minocycline (50 mg/kg) did not produce significant changes, however, coadministration of minocycline plus indomethacin resulted in antinociceptive activity. LPS-induced RH limb monoarthritis resulted in weight bearing (RH/left hind (LH) limb paw pressure ratios) and RH/LH print area ratios deficits. Treatment with indomethacin (1 mg/kg) or minocycline (50 mg/kg) had no effects on the weight bearing and print area ratios deficits of monoarthritic mice. However, combination of minocycline plus indomethacin restored weight bearing and paw print area ratios of monoarthritic mice similar to that observed in non-arthritic control mice.

CONCLUSIONS

Coadministration of indomethacin or a selective COX-2 inhibitor, CAY10404 with minocycline potentiates their effects and results in antinociception against thermal nociception, reduction of thermal hyperalgesia and alleviation of weight bearing deficits in monoarthritic mice at doses where either drug alone has no significant activity. Thus, the coadministration of lower doses of a NSAID or a selective COX-2 inhibitor plus minocycline could be useful in the management of inflammatory pain and arthritis.

Involvement of caspase-9 in autophagy-mediated cell survival pathway

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been considered for use in the prevention and treatment of cancer malignancy. FR122047 (FR) is known to have an anti-inflammatory effect, but the anticancer activity of the chemical has not yet been identified. In the present study, we could find that treatment of breast cancer MCF-7 cells with FR led to apoptosis accompanying with apparent activation of caspases. Treatment of caspase-specific inhibitors revealed that FR-induced apoptosis was caspase-8-dependent and inhibition of caspase-9 activity resulted in unexpected, marked enhancement of cell death. Knockdown of caspase-9 expression by specific siRNA caused increased susceptibility to FR-induced cell death, consistent with the results obtained with treatment of caspase-9 inhibitor. Inhibition of caspase-9 blocked the autophagic process by modulating lysosomal pH and acid-dependent cathepsin activities and augmented cell death due to blockage of cytoprotective autophagy. MCF-7 cells treated with sulforaphane, an autophagy-inducing drug, also showed marked accumulation of LC3-II, and co-treatment with caspase-9 inhibitor brought about increased susceptibility to sulforaphane-induced cell death. Different from the cases with FR or sulforaphane, etoposide- or doxorubicin-induced cell death was suppressed with co-treatment of caspase-9 inhibitor, and the drugs failed to induce significant autophagy in MCF-7 cells. Taken together, our data originally suggest that inhibition of caspase-9 may block the autophagic flux and enhance cell death due to blockage of cytoprotective autophagy.

Nicotinic acid- and monomethyl fumarate-induced flushing involves GPR109A expressed by keratinocytes and COX-2-dependent prostanoid formation in mice

The antidyslipidemic drug nicotinic acid and the antipsoriatic drug monomethyl fumarate induce cutaneous flushing through activation of G protein-coupled receptor 109A (GPR109A). Flushing is a troublesome side effect of nicotinic acid, but may be a direct reflection of the wanted effects of monomethyl fumarate. Here we analyzed the mechanisms underlying GPR109A-mediated flushing and show that both Langerhans cells and keratinocytes express GPR109A in mice. Using cell ablation approaches and transgenic cell type-specific GPR109A expression in Gpr109a-/- mice, we have provided evidence that the early phase of flushing depends on GPR109A expressed on Langerhans cells, whereas the late phase is mediated by GPR109A expressed on keratinocytes. Interestingly, the first phase of flushing was blocked by a selective cyclooxygenase-1 (COX-1) inhibitor, and the late phase was sensitive to a selective COX-2 inhibitor. Both monomethyl fumarate and nicotinic acid induced PGE2 formation in isolated keratinocytes through activation of GPR109A and COX-2. Thus, the early and late phases of the GPR109A-mediated cutaneous flushing reaction involve different epidermal cell types and prostanoid-forming enzymes. These data will help to guide new efficient approaches to mitigate nicotinic acid-induced flushing and may help to exploit the potential antipsoriatic effects of GPR109A agonists in the skin.

Prostaglandin modulation of airway inflammation and hyperresponsiveness in mice sensitized without adjuvant

As adjuvant during sensitization may cause unspecific immune reactions, the aim of the present study was to define the role of cyclooxygenase (COX) activity on airway inflammation and airway hyperresponsiveness (AHR) in an adjuvant-free allergic mouse model. Administration of diclofenac and indomethacin (non-selective COX inhibitors), FR122047 (COX-1 inhibitor) and lumiracoxib (selective COX-2 inhibitor) enhanced AHR. Only diclofenac and lumiracoxib reduced the inflammatory cell content of bronchoalveolar lavage (BAL). Moreover, levels of prostaglandins in BAL were reduced by indomethacin and FR122047 but were unaffected by lumiracoxib. However, compared with antigen controls, none of the COX inhibitors displayed major effects on the production of cytokines, smooth muscle mass, number of goblet cells and eosinophils, or collagen deposition in the airways. These data in mice sensitized without adjuvant support the fact that COX products have a general bronchoprotective role in allergic airway inflammation. Furthermore, the data suggest that COX-1 activity predominantly generates prostanoids in BAL, whereas COX-2 activity is associated with the accumulation of inflammatory cells in BAL. This study further supports that AHR on the one hand, and the inflammatory response and generation of prostanoids on the other, are dissociated and, at least in part, uncoupled events.

Analgesic activity of myricetin isolated from Myrica rubra Sieb. et Zucc. leaves

Myrica rubra Sieb. et Zucc. leaves are commonly used as an astringent, antidiarrheic, and analgesics in folk medicine in China. In the present study, the analgesic activity of myricetin, a major compound in Myrica rubra Sieb. et Zucc. leaves was evaluated in vivo. The analgesic effect of myricetin was tested by a serial of models, such as acetic acid-induced writhing response, formalin-induced paw licking and hot plate test. The sedative activity was evaluated by pentobarbital-induced sleep time. Platelet aggregation induced by collagen and arachidonic acid was also performed in vitro. Myricetin showed a significant inhibition on chemical nociceptive models such as the acetic acid-induced writhing response and the licking time on the late phase in the formalin test in a dose-dependent manner, but did not manifest a signicant effect in hot plate test. Myricetin was also not able to increase the sleeping time induced by pentobarbital, which further indicated that the analgesic effect of myricetin was unrelated to sedation. In addition, myricetin inhibited the content of PGE2 in the peritoneal fluid and platelet aggregation induced by collagen and arachidonic acid in vitro. These results collectively demonstrated that myricetin possessed potent analgesic activity, which was related with peripheral analgesia, but, not with the opioid system. Myricetin may be a potent COX-1 inhibitor with anti-platelet activity.

Effect of the oral absorption of benzenesulfonanilide-type cyclooxygenase-1 inhibitors on analgesic action and gastric ulcer formation

A benzensulfonanilide-type cyclooxygenase-1 (COX-1)-selective inhibitor, ZXX2-77: 4-amino-4'-chloro-N-methylbenzenesulfonanilide (4a), has been reported as a novel analgesic that does not cause gastric damage. This compound has a weak analgesic effect but has potent in vitro COX-1 inhibitory activity. Since the reason for the weak analgesic effect in vivo was thought to be the low rate of oral absorption, the blood concentration of ZXX2-77 (4a) was measured in rats. It was found that the C(max) value (1.2 microM) of ZXX2-77 (4a) at a dose of 30 mg/kg did not reach the COX-1 IC(50) value (3.2 microM). On the other hand, ZXX2-79 (4b) (SO(2)NH derivative of ZXX2-77 (4a); 4-amino-4'-chlorobenzenesulfonanilide), which shows less potent COX inhibitory activities (COX-1 IC(50) = 12 microM, COX-2 IC(50) = 150 microM) than those of ZXX2-77 (4a) in vitro, was found to be more absorbable (C(max) = 16 microM at a dose of 30 mg/kg in rats) than ZXX2-77 (4a). Furthermore, ZXX2-79 (4b) not only showed a potent analgesic effect in a formalin test but also caused little gastric damage. These findings indicate that demethylated sulfonamide compounds are more easily absorbed than are N-methylated sulfonamide compounds and suggest that COX-1-selective inhibitors will be useful as analgesics that do not cause gastric damage.

Critical role of COX-1 in prostacyclin production by human endothelial cells under modification of hydroperoxide tone

We aimed at evaluating the relative contribution of cyclooxygenase (COX) -1 and COX-2 to the synthesis of prostacyclin in endothelial cells under static conditions in the presence or absence of exogenous arachidonic acid and/or altered intracellular redox balance. Selective inhibitors of either COX-1 (SC560 and FR122047) or COX-2 (SC236) concentration dependently (1-300 nM) reduced basal and interleukin (IL) -1beta-induced prostacyclin production in human umbilical vein endothelial cells by 70% or more; compound selectivity was confirmed using a whole-blood assay (IC(50) COX-1/COX-2: 13 nM/930 nM for SC-560; 9 microM/457 nM for SC-236). The observed concomitant formation of isoprostane appeared to be associated with COX enzyme activity, while formation of COX-1/COX-2 heterodimers was detected by immunoprecipitation. In the presence of arachidonic acid and 12-hydroperoxy-eicosatetraenoic acid, either exogenous or provided by platelet activation, or after glutathione depletion, COX-1 inhibition but not COX-2 inhibition concentration dependently decreased prostacyclin production. Both isoforms appear to contribute to basal prostacyclin production by endothelial cells, with COX-2 providing the hydroperoxide tone required for COX-1 activity. Conversely, in the case of intracellular glutathione depletion or enhanced availability of arachidonic acid and hydroperoxides, selective COX-2 inhibition did not significantly affect the production of endothelial prostacyclin. These findings contribute to a better understanding of the effects of cyclooxygenase inhibitors on prostacyclin production.

Anti-apoptotic roles of prostaglandin E2 and F2alpha in bovine luteal steroidogenic cells

Production of prostaglandins (PGs) and expression of their receptors have been demonstrated in bovine corpus luteum (CL). The aim of the present study was to determine whether PGE2 and PGF2alpha have roles in bovine luteal steroidogenic cell (LSC) apoptosis. Cultured bovine LSCs obtained at the midluteal stage (Days 8-12 of the cycle) were treated for 24 h with PGE2 (0.001-1 microM) and PGF2alpha (0.001-1 microM). Prostaglandin E2 (1 microM) and PGF2alpha (1 microM) significantly stimulated progesterone (P4) production and reduced the levels of cell death in the cells cultured with or without tumor necrosis factor alpha (TNF)/interferon gamma (IFNG), in the presence and absence of FAS ligand (P < 0.05). Furthermore, DNA fragmentation induced by TNF/IFNG was observed to be suppressed by PGE2 and PGF2alpha. Prostaglandin E2 and PGF2alpha also attenuated mRNA expression of caspase 3 and caspase 8, as well as caspase 3 activity (P < 0.05) in TNF/IFNG-treated cells. FAS mRNA and protein expression were decreased only by PGF2alpha (P < 0.05). A specific P4 receptor antagonist (onapristone) attenuated the apoptosis-inhibitory effects of PGE2 and PGF2alpha in the absence of TNF/IFNG (P < 0.05). A PG synthesis inhibitor (indomethacin) reduced cell viability in PGE2- and PGF2alpha-treated cells (P < 0.05). A specific inhibitor of cyclooxygenase (PTGS), PTGS2 (NS-398), also reduced cell viability, whereas an inhibitor of PTGS1 (FR122047) did not affect it. The overall results suggest that PGE2 and PGF2alpha locally play luteoprotective roles in bovine CL by suppressing apoptosis of LSCs.

Cyclooxygenase-1-selective inhibitors are attractive candidates for analgesics that do not cause gastric damage. design and in vitro/in vivo evaluation of a benzamide-type cyclooxygenase-1 selective inhibitor

Although cyclooxygenase-1 (COX-1) inhibition is thought to be a major mechanism of gastric damage by nonsteroidal anti-inflammatory drugs (NSAIDs), some COX-1-selective inhibitors exhibit strong analgesic effects without causing gastric damage. However, it is not clear whether their analgesic effects are attributable to COX-1-inhibitory activity or other bioactivities. Here, we report that N-(5-amino-2-pyridinyl)-4-(trifluoromethyl)benzamide ( 18f, TFAP), which has a structure clearly different from those of currently available COX-1-selective inhibitors, is a potent COX-1-selective inhibitor (COX-1 IC 50 = 0.80 +/- 0.05 microM, COX-2 IC 50 = 210 +/- 10 microM). This compound causes little gastric damage in rats even at an oral dose of 300 mg/kg, though it has an analgesic effect at as low a dose as 10 mg/kg. Our results show that COX-1-selective inhibitors can be analgesic agents without causing gastric damage.

Analgesic, antipyretic and Ulcerogenic properties of an indigenous formulation--Kalpaamruthaa

A modified indigenous Siddha formulation Kalpaamruthaa (KA), containing Semecarpus anacardium nut milk extract (SA), dried powder of Emblica officinalis (EO) fruit and honey was evaluated for its analgesic, antipyretic and Ulcerogenic properties. Both SA and KA, at a dose of 150 mg/kg b. wt were compared with the standard drug diclofenac sodium. KA exhibited an enhanced effect on all properties compared with that found with sole SA treatment, and is likely to be due to synergistic and additive interactions within the complex mixture of phytochemicals present in KA.

Evidence that a prostanoid produced by cyclo-oxygenase-2 enhances contractile responses of the porcine isolated coronary artery following exposure to lipopolysaccharide

BACKGROUND

Prolonged incubation of porcine isolated coronary artery (PCA) to lipopolysaccharide (LPS) causes a moderate reduction in vessel constrictive responsiveness. This has been attributed mainly to the induction of nitric oxide synthase (NOS). We aimed to investigate the role of induction of cyclo-oxygenase (COX) and expression of endothelin receptor 1-A (ET1(A)) in modulating the vascular responses of PCA in vitro.

METHODS

Segments of PCA were exposed to 100 microg ml(-1) LPS overnight. L-Arginine 0.4 mM was included in the medium in some preparations to examine the influence of intracellular nitric oxide, and the influence of extracellular donor sodium nitroprusside (SNP) was also examined in separate experiments. After overnight incubation, the contractile function of the artery was evaluated by the isometric tension recording test. The non-selective NOS inhibitor (L-NAME), non-selective COX inhibitor (indomethacin), COX-1 inhibitor (FR 122047), COX-2 inhibitor (NS 398), and ET1(A) receptor antagonist (FR 139317) were added into the organ bath 30 min before eliciting contractile responses to KCl or U46619 separately or in combinations. Vascular relaxations to 10 nM Substance P (SP) were also assessed.

RESULTS

L-Arginine did not potentiate the effects of LPS. SNP caused a quantitatively larger reduction in the responsiveness to KCl and U46619 compared with 100 microg ml(-1) LPS. Post exposure to a combination of indomethacin and FR 139317, indomethacin or NS 398 alone enhanced the inhibitory effects of LPS, but FR 122047 or FR 139317 alone failed to modify the responses to LPS. L-NAME fully reversed the changes induced by LPS combined with indomethacin and NS398. In terms of the relaxation by SP, LPS failed to change the magnitude; none of the agents used affected the response except L-NAME which abolished it.

CONCLUSION

NOS and COX-2 are both activated by overnight exposure to LPS in vascular smooth muscle from PCA in vitro. The prostanoid produced by COX-2 functionally antagonizes the effects of induction of NOS.

Dual, but not selective, COX-1 and COX-2 inhibitors, attenuate acetic acid-evoked bladder irritation in the anaesthetised female cat

Non-selective cyclooxygenase (COX) inhibitors exert effects on lower urinary tract function in several species. The exact contributions of COX-1 and COX-2 isozymes have not been studied much. The present studies investigated the effects of non- and selective COX inhibitors on bladder irritation in the cat.Chloralose-anaesthetised female cats were catheterised through the bladder dome for cystometric evaluation of bladder responses to intravesical infusion of saline or acetic acid. Bladder capacity, voiding efficiency, threshold pressure, and reflex-evoked bladder contraction amplitude and duration were measured. The cat COX selectivity of the doses of inhibitors examined was determined using an in vitro whole-blood assay and analysis of plasma levels. Pretreatment with indomethacin or ketoprofen (non-selective COX inhibitors; 0.3 mg kg(-1) i.v.) inhibited acetic acid-evoked irritation (characterised by a decrease in bladder capacity in vehicle pretreated animals). FR-122047 (selective COX-1 inhibitor), NS-398 and nimesulide (selective COX-2 inhibitors; 1 and 3 mg kg(-1) i.v.) had no effects on bladder irritation. Analysis of plasma levels of the doses examined and determination of COX-1 and COX-2 inhibition in cat whole blood confirmed the reported selectivity of these compounds in this species. The present studies suggest that dual COX inhibition is required to attenuate acetic acid-evoked bladder irritation in the cat.

Analgesic agents without gastric damage: design and synthesis of structurally simple benzenesulfonanilide-type cyclooxygenase-1-selective inhibitors

In order to create novel analgesic agents without gastric disturbance, structurally simple cyclooxygenase-1 (COX-1) inhibitors with a benzenesulfonanilide skeleton were designed and synthesized. As a result, compounds 11f and 15a, which possess a p-amino group on the benzenesulfonyl moiety and p-chloro group on the anilino moiety, showed COX-1-selective inhibition. Moreover compound 11f, which is the most potent compound in this study showed more potent analgesic activity than that of aspirin at 30 mg/kg by po. The anti-inflammatory activity and gastric damage, however, were very weak or not detectably different from aspirin. Since the structure of our COX-1 inhibitors are very simple, they may be useful as lead compounds for superior COX-1 inhibitors as analgesic agents without gastric disturbance.