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PubMed1984

Increased microsomal oxidation of alcohols after pyrazole treatment and its similarities to the induction by ethanol consumption.

Microsomes isolated from rats treated for 3 days with 200 mg/kg body wt. per day of pyrazole, a potent inhibitor of alcohol dehydrogenase, catalyzed the oxidation of ethanol and 2-butanol at rates 2-3-fold higher than saline controls. This increase was blocked by carbon monoxide, and was not associated with an increase in the oxidation of aminopyrine or in the content of cytochrome P-450, suggesting the possibility of an induction of an alcohol-preferring cytochrome P-450 by pyrazole. Microsomes from the pyrazole-treated rats displayed a stereochemical preference for the oxidation of the (+)-2-butanol isomer over the (-)-2-butanol isomer, which was blocked by carbon monoxide, and also displayed a type-2 binding spectrum with dimethylsulfoxide or 2-butanol. No such spectrum was found with the saline controls. These properties are similar to those which are observed with microsomes from chronic ethanol-fed rats. These similarities suggest the possibility that pyrazole treatment may induce a cytochrome P-450 isozyme with properties similar to the ethanol-inducible cytochrome P-450.

1-Butanol↗

PubMed1991

Increased catalytic activity of cytochrome P-450IIE1 in pericentral hepatocytes compared to periportal hepatocytes isolated from pyrazole-treated rats.

Cytochrome P-450IIE1 is induced by a variety of agents, including acetone, ethanol and pyrazole. Recent studies employing immunohistochemical methods have shown that P-450IIE1 was expressed primarily in the pericentral zone of the liver. In order to evaluate whether catalytic activity of P-450IIE1 is preferentially localized in the pericentral zone of the liver acinus, the oxidation of aniline and p-nitrophenol, two effective substrates for P-450IIE1, by periportal and pericentral hepatocytes isolated from pyrazole-treated rats was determined. Periportal and pericentral hepatocytes were prepared by a digitonin-collagenase procedure; the marker enzymes glutamine synthetase and gamma-glutamyl transpeptidase indicated reasonable separation of the two cell populations. Viability, yield and total cytochrome P-450 content were similar for the periportal and pericentral hepatocytes. Pericentral hepatocytes oxidized aniline and p-nitrophenol at rates that were 2-4-fold greater than periportal hepatocytes under a variety of conditions. Carbon monoxide inhibited the oxidation of the substrates with both preparations and abolished the increased oxidation found with the pericentral hepatocytes. Pyrazole or 4-methylpyrazole, added in vitro, effectively inhibited the oxidation of aniline and p-nitrophenol and prevented the augmented rate of oxidation by the pericentral hepatocytes. Western blots carried out using isolated microsomes revealed a more than 2-fold increase in immunochemical staining with microsomes isolated from the pericentral hepatocytes, which correlated to the 2-4-fold increase in the rate of oxidation of aniline or p-nitrophenol by the pericentral hepatocytes. These results suggest that functional catalytic activity of cytochrome P-450IIE1 is preferentially localized in the pericentral zone of the liver acinus, and that most of the induction by pyrazole of P-450IIE1 appears to occur within the pericentral zone.

Aniline Compounds↗

PubMed2004

Design, synthesis and anti-microbial activity of 1H-pyrazole carboxylates.

In a SAR study, we have synthesized a few 1H-pyrazole carboxylate related microbicides using Vilsmeier reagent. The anti-microbial screening results of 1H-pyrazole-3-carboxylate are reported here for the first time. The effect of 1H-pyrazole carboxylates on the mycelial growth of plant pathogenic fungi is revealed. The first X-ray structure in the family of microbicidal 1H-pyrazole-4-carboxylates is presented.

Anti-Bacterial Agents↗

PubMed2005

Synthesis and leishmanicidal activities of 1-(4-X-phenyl)-N'-[(4-Y-phenyl)methylene]-1H-pyrazole-4-carbohydrazides.

1H-pyrazole-4-carbohydrazides were synthesized and their leishmanicidal in vitro activities and cytotoxic effects were investigated. The drugs prototypes of these new compounds (ketoconazole, benznidazole, allopurinol and pentamidine) were also tested. It was found that among all the 1H-pyrazole-4-carbohydrazides derivatives examined, the most active compounds were those with X = Br, Y = NO2 (27) and X = NO2, Y = Cl (15) derivatives which showed to be most effective on promastigotes forms of L. amazonensis than on L. chagasi and L. braziliensis species. When tested against murine peritoneal macrophages as mammalian host cell controls of toxicity, 1-(4-Br-phenyl)-N'-[(4-NO(2)-phenyl)methylene]-1H-pyrazole-4-carbohydrazides (27) (EC50 = 50 microM l(-1)) and 1-(4-NO2-phenyl)-N'-[(4-Cl-phenyl)methylene]-1H-pyrazole-4-carbohydrazides (15) EC50 = 80 microM l(-1))] was reasonably toxic. However, both compounds were less toxic than pentamidine and ketoconazole. These results provide new perspectives on the development of drugs with activities against Leishmania parasite.

Animals↗

PubMed2005

Synthesis, spectroscopy (IR, multinuclear NMR, ESI-MS), diffraction, density functional study and in vitro antiproliferative activity of pyrazole-beta-diketone dihalotin(IV) compounds on 5 melanoma cell lines.

Novel 4-acylpyrazolon-5-ato-dihalotin(IV) complexes, [Q2SnX2], (X = F, Cl, Br or I); HQ = HQ(CHPh2) (1,2-dihydro-3-methyl-1-phenyl-4-(2,2-diphenylacetyl)pyrazol-5-one), HQ(Bn) (1,2-dihydro-3-methyl-1-phenyl-4-(2-phenylacetyl)pyrazol-5-one) or HQ(CF3,py) (4-(2,2,2-trifluoroacetyl)-1,2-dihydro-3-methyl-1-(pyridin-2-yl)pyrazol-5-one) have been synthesized and characterized by spectroscopic (IR, 1H, 13C, 19F and 119Sn NMR, electrospray ionisation mass spectrometry (ESI-MS)), analytical and structural methods (X-ray and density functional theory). 119Sn chemical shifts depend on the nature of the halides bonded to tin. Isomer conversion, detected in solution by NMR spectroscopy, is related to the acyl moiety bulkiness while the cis(Cl)-cis(acyl)-trans(pyrazolonato) scheme is found in the solid state. The in vitro antiproliferative tests of three derivatives on three human melanoma cell lines (JR8, SK-MEL-5, MEL501) and two melanoma cell clones (2/21 and 2/60) show dose-dependent decrease of cell proliferation in all cell lines. The activity correlates with the nature of the substituent on position 1 of pyrazole, decreasing in the order pyridyl>Ph>>methyl. The activity for (Q(CF3,py))2SnCl2 on the SK-MEL-5 cell line is IC50 = 50 microM.

Animals↗

PubMed2006

Comparative studies on the mechanism of cytotoxic action of novel platinum II complexes with pyrazole ligands.

In search for new platinum-based anticancer drugs, four cisplatin analogues, which contain pyrazole rings as non-leaving ligands, have been synthesized: cis-PtCl(2)(3,5-DM HMPz)(2), cis-PtCl(2)(Pz)(2), cis-PtCl(2)(ClMPz)(2), and cis-PtCl(2)(HMPz)(2), where Pz=pyrazole, H=hydroxyl, M=methyl. We tested their cytotoxicity, apoptosis induction ability, DNA damaging and modification properties comparing them in respect to the parent compound. The cytotoxic activity of these platinum pyrazole complexes toward the murine leukemia cell line was 2.9-3.8 times lower than actvity of cisplatin. The tested compounds varied in their mechanism of action by producing different DNA lesions. The most interesting compound seems to be the complex with chloromethyl groups at N1 of pyrazole rings, which exhibited the highest ability to form bifunctional adducts with DNA in vitro.

Animals↗

PubMed2000

Isolation and identification of the intermediates during pyrazole formation of some carbohydrate hydrazone derivatives.

Reaction of the oxidation product of L-ascorbic acid, dehydro-L-ascorbic acid, with o-phenylenediamine, followed by 2,4,6-trichlorophenylhydrazine (3) afforded 3-[1-(2,4,6-trichlorophenylhydrazono)-L-threo-2,3,4-trihydroxybut-1-yl]quinoxalin-2(1H)one (4), whose structure was deduced from studying its periodate oxidation, which gave the glyoxal derivative 3-[1-(2,4,6-trichlorophenylhydrazono)glyoxal-1-yl]quinoxalin-2(1H)one (5) that upon reduction afforded 3-[1-(2,4,6-trichlorophenylhydrazono)-2-hydroxyethy-1-yl]quinoxalin-2(1H)one (6). The reaction of 5 with 3 afforded the bishydrazone 3-[1,2-bis(2,4,6-trichlorophenylhydrazono)glyoxal-1-yl]quinoxalin-2(1H)one. The reaction of 5 with acetic anhydride in pyridine afforded the 2,3-dihydrofuro[2,3-b]quinoxaline derivative 2-acetoxy-3-[2-acetyl-2-(2,4,6-trichlorophenyl)hydrazono)]-2,3-dihydrofuro[2,3-b]quinoxaline. Acetylation of 4 with acetic anhydride in pyridine afforded the acyclic diacetate intermediate 3-[3,4-di-O-acetyl-2-deoxy-1-(2,4,6-trichlorophenylhydra-zono)but-2-en-1-yl]quinoxalin-2(1H)one (12), which was also obtained from the reaction of 4 with boiling acetic anhydride. Compound 12 rearranged under the reaction conditions to give the pyrazole derivatives 3-[5-(ace-toxymethyl)-1-(2,4,6-trichlorophenyl)pyrazol-3-yl]quinoxalin-2(1H)one (14) and 2-acetoxy-3-[5-(acetoxymethyl)-1-(2,4,6-trichlorophenyl)pyrazol-3-yl)]quinoxaline (15), as well as the 2,3-dihydrofuro[2,3-b]quinoxaline derivative 2-(2-acetoxyethen-2-yl)-3-[2-(2,4,6-trichlorophenyl)hydrazono]-2,3-dihydrofuro[2,3-b]quinoxaline. Acetylation of 3-[5-(hydroxymethyl)-l-(2,4,6-trichlorophenyl)pyrazol-3-yl]quinoxalin-2(1H)one (16) with acetic anhydride in pyridine or 12 with boiling acetic anhydride afforded 15 and 16, respectively. Treatment of 4 with diluted sodium hydroxide afforded the pyrazolo[2,3-b]quinoxaline (flavazole) derivative 1-(2,4,6-trichlorophenyl)-3-(L-threo-glycerol-1-yl)pyrazolo[2,3-b]quinoxaline whose acetylation afforded the acetyl derivative 3-(2,3,4-tri-O-acetyl-L-threo-glycerol-1-yl)-1-(2,4,6-trichlorophenyl)pyrazolo[2,3-b]quinoxaline. The assigned structures were based on spectral analysis. The activity of compound 4 against hepatitis B virus has been studied.

Carbohydrates↗

PubMed1994

Leukotriene B4 (LTB4) receptor antagonists: a series of (hydroxyphenyl)pyrazoles.

A series of (hydroxyphenyl)pyrazoles was designed by molecular modeling comparison with the LTB4 structure and prepared for evaluation as LTB4 receptor antagonists, culminating in 4-ethyl-5-[[6-methyl-6-(1H-tetrazol-5-yl)heptyl]oxy]-2-(1H-pyrazol -3- yl)phenol (2). Using an assay for inhibition of specific [3H]LTB4 binding to human PMN, it was found that the pyrazole ring could be methylated at N(1) with little loss of activity while methylation at N(2) reduced activity significantly. The structure-activity relationship of the terminal acid group was investigated. Good activity was found with o- and m-phenylalkanoic acids, chromane carboxylic acid, and tetrazole groups. The best in vitro activity was realized with the pyrazole nitrogen unsubstituted and with a six-carbon chain linking the phenyl ether oxygen to the tetrazole group. Compound 2, having an IC50 of 6.4 +/- 0.8 nM in the binding assay, was selected for further preclinical evaluation.

Animals↗

PubMed1984

Studies on heterocyclic compounds. 6. Synthesis and analgesic and antiinflammatory activities of 3,4-dimethylpyrano[2,3-c]pyrazol-6-one derivatives.

A series of new 1- and 2-substituted 3,4-dimethylpyrano[2,3-c]pyrazol-6-one derivatives and 1-substituted 1,6-dihydro-4-methyl-6-oxopyrano[2,3-c]pyrazole-3-acetic acids were synthesized and examined for their analgesic and antiinflammatory activities. Most of these compounds showed more prominent analgesic activities than antiinflammatory activities, and this result was similar to that of aminopyrine. Among these compounds, 1,3,4-trimethylpyrano[2,3-c]pyrazol-6(1H)-one and 2,3,4-trimethylpyrano[2,3-c]pyrazol-6(2H)-one showed more potent analgesic activity than aminopyrine.

Analgesia↗

PubMed2004

Synthesis and antibacterial activity of a novel series of potent DNA gyrase inhibitors. Pyrazole derivatives.

We have previously found that a pyrazole derivative 1 possesses antibacterial activity and inhibitory activity against DNA gyrase and topoisomerase IV. Here, we synthesized new pyrazole derivatives and found that 5-[(E)-2-(5-chloroindol-3-yl)vinyl]pyrazole 16 possesses potent antibacterial activity and selective inhibitory activity against bacterial topoisomerases. Many of the synthesized pyrazole derivatives were potent against clinically isolated quinolone- or coumarin-resistant Gram-positive strains and had minimal inhibitory concentration values against these strains equivalent to those against susceptible strains.

Anti-Bacterial Agents↗

PubMed2003

Pyrazole derivatives as partial agonists for the nicotinic acid receptor.

Nicotinic acid as a hypolipidemic agent appears unique due to its potential to increase HDL cholesterol levels to a greater extent than other drugs. However, it has some side effects, among which severe skin flushing is the most frequent and often limits patients' compliance. In a search for novel agonists for the recently identified and cloned G protein-coupled nicotinic acid receptor, we synthesized a series of substituted pyrazole-3-carboxylic acids that proved to have substantial affinity for this receptor. The affinities were measured by inhibition of [(3)H]nicotinic acid binding to rat spleen membranes. Potencies and intrinsic activities relative to nicotinic acid were determined by their effects on [(35)S]GTPgammaS binding to rat adipocyte and spleen membranes. Interestingly, most compounds were partial agonists. In particular, 2-diazabicyclo[3,3,0(4,8)]octa-3,8-diene-3-carboxylic acid (4c) and 5-propylpyrazole-3-carboxylic acid (4f) proved active with K(i) values of approximately 0.15 microM and EC(50) values of approximately 6 microM, while their intrinsic activity was only approximately 50% when compared to nicotinic acid. Even slightly more active was 5-butylpyrazole-3-carboxylic acid (4g) with a K(i) value of 0.072 microM, an EC(50) value of 4.12 microM, and a relative intrinsic activity of 75%. Of the aralkyl derivatives, 4q (5-(3-chlorobenzyl)pyrazole-3-carboxylic acid) was the most active with a relatively low intrinsic activity of 39%. Partial agonism of the pyrazole derivatives was confirmed by inhibition of G protein activation in response to nicotinic acid by these compounds. The pyrazoles both inhibited the maximum effect elicited by 100 microM nicotinic acid and concentration dependently shifted nicotinic acid concentration-response curves to the right, pointing to a competitive mechanism of action.

Adipocytes↗

PubMed2004

4,5-dihydro-1H-pyrazole derivatives with inhibitory nNOS activity in rat brain: synthesis and structure-activity relationships.

In an attempt to find new compounds with neuroprotective activity, we have designed, synthesized and characterized 19 new nNOS inhibitors with a 4,5-dihydro-1H-pyrazole structure. Compounds 11r [1-cyclopropanecarbonyl-3-(2-amino-5-chlorophenyl)-4,5-dihydro-1H-pyrazole] and 11e [1-cyclopropanecarbonyl-3-(2-amino-5-methoxyphenyl)- 4,5-dihydro-1H-pyrazole] show the highest activities with inhibition percentages of 70% and 62%, respectively. A structure-activity relationship for the nNOS inhibition can be established from the structural comparison of these new pyrazole derivatives and the described synthetic kynurenines 10.

Aniline Compounds↗

PubMed1999

Structure-activity relationships of pyrazole derivatives as cannabinoid receptor antagonists.

As a potent, specific antagonist for the brain cannabinoid receptor (CB1), the biarylpyrazole N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2, 4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR141716A; 1) was the lead compound for initiating studies designed to examine the structure-activity relationships of related compounds and to search for more selective and potent cannabimimetic ligands. A series of pyrazole derivatives was designed and synthesized to aid in the characterization of the cannabinoid receptor binding sites and also to serve as potentially useful pharmacological probes. Therapeutically, such compounds may have the ability to antagonize harmful side effects of cannabinoids and cannabimimetic agents. Structural requirements for potent and selective brain cannabinoid CB1 receptor antagonistic activity included (a) a para-substituted phenyl ring at the 5-position, (b) a carboxamido group at the 3-position, and (c) a 2,4-dichlorophenyl substituent at the 1-position of the pyrazole ring. The most potent compound of this series contained a p-iodophenyl group at the 5-position, a piperidinyl carboxamide at the 3-position, and a 2,4-dichlorophenyl group at the 1-position of the pyrazole ring. The iodinated nature of this compound offers additional utility as a gamma-enriching SPECT (single photon emission computed tomography) ligand that may be useful in characterizing brain CB1 receptor binding in vivo.

Animals↗

PubMed2002

Sequential functionalization of pyrazole 1-oxides via regioselective metalation: synthesis of 3,4,5-trisubstituted 1-hydroxypyrazoles.

A range of 3,5-diarylated and 3,4,5-triarylated 2-(4-methoxybenzyl)pyrazole 1-oxides have been prepared by regioselective deprotonation at C-5 or bromine-magnesium exchange at C-3 or C-4 followed by transmetalation with ZnCl(2) and palladium(0)-catalyzed cross-coupling. Furthermore, the metalated pyrazole 1-oxides could be trapped with electrophiles. The sequential metalation/functionalization of the pyrazole 1-oxides may follow the order C-5, C-3, C-4, or alternatively the order C-3, C-5, C-4. The 4-methoxybenzyl group of the functionalized 2-(4-methoxybenzyl)pyrazole 1-oxides could be removed by treatment with TFA and i-Pr(3)SiH in CH(2)Cl(2), providing the corresponding functionalized 1-hydroxypyrazoles.

Magnesium↗

PubMed2004

Design and synthesis of two pyrazole libraries based on o-hydroxyacetophenones.

Two new solid-phase syntheses of substituted pyrazoles are described. The first includes supporting an o-hydroxyacetophenone on Merrifield resin, Vilsmeier-Haack formylation on the methyl group and cyclization with a substituted hydrazine to afford a pyrazole ring with two diversity centers. The second starts from o-hydroxyacetophenone supported on Wang resin, which undergoes a Claisen condensation with a carboxylic acid ester to yield a 1,3-dicarbonyl compound that cyclizes to a pyrazole using a hydrazine. Both methods have been used to synthesize two small pyrazole libraries.

Acetophenones↗

PubMed2005

Self-assembled meso-helicates of linear trinuclear nickel(II)-radical complexes with triple pyrazolate bridges.

Complexation of 3-nitronyl-nitroxide-substituted pyrazolate (pzNN) and 3-imino-nitroxide-substituted pyrazolate (pzIN) with nickel(II) gave [Ni3(pzNN)6] and [Ni3(pzIN)6], respectively. They were practically isomorphous and characterized as a linear trinuclear structure with neighboring nickel ions triply bridged by pyrazolate moieties. The space groups were P2(1)/n but the molecules have a pseudo three-fold axis. We found polymorphs in the crystals of [Ni3(pzIN)6] depending on the solvate molecules; another space group was a cubic Pa3[combining macron]. The opposite chirality around the inversion center at the central nickel(II) ion leads to a meso-helical symmetry in the whole molecule. The radical oxygen atoms participate in the 6-membered chelation at the terminal nickel(II) ions. Antiferromagnetic couplings were observed in both complexes, which are ascribable to interactions between the nickel and radical spins and between the nickel spins across the pyrazolate bridges.

Crystallography, X-Ray↗

PubMed1992

Effect of pyrazole, cobalt and phenobarbital on mouse liver cytochrome P-450 2a-4/5 (Cyp2a-4/5) expression.

Pyrazole, cobalt and phenobarbital increase the activity of coumarin 7-hydroxylase (COH) in mouse liver. To study the mechanism of this increase, we measured the expression of the cytochrome P-450 2a-4/5 (Cyp2a-4/5) complex, which mediates testosterone 15 alpha-hydroxylase and COH activities, as a function of dose and time after the treatment of C57BL/6 (B6) and DBA/2 (D2) male mice with the inducers. COH activity and Cyp2a-4/5 steady-state mRNA levels were increased in both strains in response to the inducers. No marked effect occurred with testosterone 15 alpha-hydroxylase or activities associated with Cyp1a-1 or Cyp2e-1. A 2-7-fold increase in response to the inducers was seen in the amount of P-450Coh (cytochrome P-450 isoenzyme catalysing coumarin 7-hydroxylation) protein in Western immunoblots. PCR amplification of a 1 kb region in Cyp2a-4/5-mRNA-derived cDNA, followed by cutting at the diagnostic PstI site, showed that most of the steady-state mRNA consisted of Cyp2a-5, which is also the form most affected by pyrazole. Nuclear run-off analysis revealed no increase in the transcription rate of Cyp2a-4/5 after pyrazole or cobalt treatment, whereas a 2-3-fold increase occurred after phenobarbital pretreatment in B6 mice. Together with previous reports [Aida & Negishi (1991) Biochemistry 30, 8041-8045], the current data suggest that both pyrazole and cobalt increase COH catalytic activity by affecting Cyp2a-5 by post-transcriptional mechanisms in mice.

Animals↗

PubMed2005

Synthesis of 3-aminoimidazo[4,5-c]pyrazole nucleoside via the N-N bond formation strategy as a [5:5] fused analog of adenosine.

3-Amino-6-(beta-D-ribofuranosyl)imidazo[4,5-c]pyrazole (2) was synthesized via an N-N bond formation strategy by a mononuclear heterocyclic rearrangement (MHR). A series of 5-amino-1-(5-O-tert-butyldimethylsilysilyl-2,3-O-isopropylidene-beta-D-ribofuranosyl)-4-(1,2,4-oxadiazol-3-yl)imidazoles (6a-d), with different substituents at the 5-position of the 1,2,4-oxadiazole, were synthesized from 5-amino-1-(beta-D-ribofuranosyl)imidazole-4-carboxamide (AICA Ribose, 3). It was found that 5-amino-1-(5-O-tert-butyldimethylsilyl-2,3-O-isopropylidene-beta-D-ribofuranosyl)-4-(5-methyl-1,2,4-oxadiazol-3-yl)imidazole (6a) underwent the MHR with sodium hydride in DMF or DMSO to afford the corresponding 3-acetamidoimidazo[4,5-c]pyrazole nucleoside(s) (7b and/or 7a) in good yields. A direct removal of the acetyl group from 3-acetamidoimidazo[4,5-c]pyrazoles under numerous conditions was unsuccessful. Subsequent protecting group manipulations afforded the desired 3-amino-6-(beta-D-ribofuranosyl)imidazo[4,5-c]pyrazole (2) as a 5:5 fused analog of adenosine (1).

Adenosine↗