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PubMed1997

Comparison of the base pairing properties of a series of nitroazole nucleobase analogs in the oligodeoxyribonucleotide sequence 5'-d(CGCXAATTYGCG)-3'.

The nucleoside analogs 1-(2'-deoxy-beta-D-ribofuranosyl)- 3-nitropyrrole (9), 1-(2'-deoxy-beta-D-ribofuranosyl)-4-nitropyrazole (10), 1-(2'-deoxy-beta-D-ribofuranosyl)-4-nitroimidazole (11) and 1-(2'-deoxy-beta-D-ribofuranosyl)-5-nitroindole (21) were incorporated into the oligonucleotide 5'-d(CGCXAATTYGCG)-3'in the fourth position from the 5'-end. Procedures for synthesis of two of the nitroazole nucleosides, 10 and 11, were developed for this study. Each of the nitroazoles was converted into a 3'-phosphoramidite for oligonucleotide synthesis by conventional automated protocols. Four oligonucleotides were synthesized for each modified nucleoside in order to obtain duplexes in which each of the four natural bases was placed opposite (position 9) the nitroazole. In order to assess the role of the nitro group on base stacking interaction, sequences were also synthesized in which the fourth base was 1-(2'-deoxy-beta-D-ribofuranosyl)pyrazole. Corresponding sequences containing an abasic site, as well as sequences containing inosine, were synthesized for comparison. Thermal melting studies yielded T m values and thermodynamic parameters. Each nucleoside analog displayed a unique pattern of base pairing preferences. The least discriminating analog was 3-nitropyrrole, for which T m values differed by 5 degrees C and Delta G 25 degrees C ranged from -6.1 to -6.5 kcal/mol. 5-Nitroindole gave duplexes with significantly higher thermal stability, with Tm values varying from 35.0 to 46.5 degrees C and -Delta G 25 degrees C ranging from 7.7 to 8.5 kcal/mol. Deoxyinosine (22), a natural analog which has found extensive use as a universal nucleoside, is far less non-discriminating than any of the nitroazole derivatives. Tm values ranged from 35.4 degrees C when paired with G to 62.3 degrees C when paired with C. The significance of the nitro substituent was determined by comparison of the base pairing properties of a simple azole nucleoside, 1-(2'-deoxy-beta-D-ribofuranosyl)pyrazole (12). The pyrazole-containing sequences melt at 10-20 degrees C lower than the corresponding nitropyrazole-containing sequences. On average, the pyrazole-containing sequences were equivalent in stability (average Delta G = -4.8 kcal/mol) to the sequences containing an abasic site (average Delta G = -4.7 kcal/mol).

Base Composition↗
PubMedDate not supplied

[Induction of cytochrome P450 2A5 in transplanted mouse hepatoma].

We have studied selective induction in vivo isoform of cytochrome P4502A in mouse hepatomas. Activity of coumarin 7-hydroxylase was increased in hepatoma 61 following pyrazole and cobalt chloride treatment. Microsomes isolated from hepatoma 61 transplanted to mice treated with either pyrazole or cobalt chloride catalyzed oxidation of coumarin and 7-ethoxycoumarin at rates 2-2.5-fold higher than in saline controls. Western blot analysis of hepatoma microsomes showed that the increase in functional activity of coumarin 7-hydroxylase was due to induction of CYP2A5 (cytochrome P450 isoenzyme catalysing coumarin 7-hydroxylation). Pyrazole or cobalt chloride induced the enzyme activity in hepatoma 61, whereas we did not measure induction of CYP2A5 in hepatoma 60. The changes in the amount of CYP2A5 in liver were more pronounced after pyrazole treatment than that after cobalt. It is suggested that hepatomas 60 and 61 are originated through initiation of hepatocytes which are localized within different regions of liver lobule.

Animals↗
PubMedDate not supplied

Oxidation of ethylene glycol to formaldehyde by rat liver microsomes. Role of cytochrome P-450 and reactive oxygen species.

Rat liver microsomes oxidized ethylene glycol to formaldehyde in a NADPH-dependent, carbon monoxide-sensitive manner. Formaldehyde production was inhibited by substrates and ligands for cytochrome P-450 such as aniline, p-nitrophenol, pyrazole, and 4-methylpyrazole, and inhibitors such as tryptamine, cimetidine, and miconazole. The apparent Km for ethylene glycol was about 25 mM and the apparent Vmax was about 6 nmol/min/mg protein. Microsomes isolated from rats treated with pyrazole or 4-methylpyrazole to induce cytochrome P-450IIE1 oxidized ethylene glycol at rates which were about twice those found with control microsomes or microsomes isolated from rats treated with phenobarbital or 3-methylcholanthrene, although significant rates were found with all microsomal preparations. Antibody raised against the pyrazole-induced P-450IIE1 inhibited formaldehyde production from ethylene glycol in microsomes from pyrazole-treated rats. H2O2 itself did not oxidize ethylene glycol to formaldehyde; however, the microsomal reaction was inhibited by catalase or glutathione plus glutathione peroxidase and was stimulated by added H2O2 in the presence of NADPH. Nonheme iron also appeared to be required for ethylene glycol oxidation in view of the inhibition of formaldehyde production by desferrioxamine, EDTA, and DTPA. Microsomal oxidation of ethylene glycol was not sensitive to superoxide dismutase, hydroxyl radical scavengers, or Trolox, suggesting that the oxidant derived from H2O2 and iron and responsible for the production of formaldehyde from ethylene glycol was not superoxide, hydroxyl radical, or lipid hydroperoxide. These results suggest that ethylene glycol is oxidized to formaldehyde by an oxidant derived from H2O2 and nonheme iron, and that cytochrome P-450 may function to generate the H2O2 and to catalyze reduction of the nonheme iron.

Animals↗
PubMed2003

Design and synthesis of some substituted 1H-pyrazolyl-oxazolidines or 1H-pyrazolyl-thiazolidines as anti-inflammatory-antimicrobial agents.

Four series of 1 H-pyrazole derivatives have been synthesized. The first series was synthesized starting with the reaction of 3-(5-bromo-2-thienyl)-1-phenyl-1 H-pyrazole-4-carboxaldehyde 1 with L-serine, L-cysteine, or L-penicillamine, followed by N-protection using (Boc)(2)O to provide compounds 2. The latter compounds could be N-deprotected by 4N HCl/dioxane to afford the second series 3 or reacted with NH(4)OH in the presence of DCC/HOBt to give the corresponding amides 4 followed by N-deprotection giving rise to compounds 5. The newly synthesized compounds were evaluated for their anti-inflammatory-antimicrobial activities. In addition, the ulcerogenic and acute toxicity profiles were determined. Compound 5b (2RS, 4R)-2-[3-(5-bromo-2-thienyl)-1-phenyl-1H-pyrazol-4-yl]-5-methylthiazolidine-4-carboxamide, proved to be the most active anti-inflammatory-antimicrobial agent in the present study with a good safety margin and no ulcerogenic effect.

Animals↗
PubMed2006

Synthesis and biological evaluation of some hydroxypyrazole derivatives as anti-inflammatory-antimicrobial agents.

Some hydroxypyrazole derivatives 2-7 were synthesized by cyclocondensation of the keto-ester 1 with hydrazines hydrate or substituted hydrazines followed by reduction and acylation with acetic anhydride or trifluoroacetic anhydride. The newly synthesized compounds were evaluated for their anti-inflammatory, antimicrobial activities. In addition, the ulcerogenic and acute toxicity profiles were determined. Compounds N-(4-(5-hydroxy-1-trifluoroacetyl-1H-pyrazol-3-yl)phenyl) trifluoroacetamide 4b, 3-(4-nitrophenyl)-1-(4-methoxyphenyl)-1H-pyrazol-5-ol 5b, and N-(4-(5-hydroxy-1-methyl-1H-pyrazol-3-yl)phenyl)trifluoroacetamide 7b were proved to be the most active anti-inflammatory, antimicrobial agents in the present study with a good safety margin and minimal or no ulcerogenic effect.

Animals↗
PubMed1990

Synthesis of 2-[1,2-dihydropyrazol-4-yl]-1,3,4-thiadiazole derivatives as potential antimicrobial agents.

The synthesis of some 2-[1,2-dihydropyrazol-4-yl]-1,3,4-thiadiazole derivatives is performed by reacting 4-dithiocarboxylic acid hydrazides of 3-amino-1,2-dihydro-5H-pyrazol-5-one and 3-amino-1,2-dihydro-1-methyl-5H-pyrazol-5-one with carboxylic acid derivatives. The unusual behaviour of 3-amino-1,2-dihydro-1-methyl-5H-pyrazol-5-one towards acetylating agents is described. The antimicrobial activity of some 2-[1,2-dihydropyrazol-4-yl]-1,3,4-thiadiazole derivatives is tested in a preliminary screening.

Anti-Bacterial Agents↗
PubMed1978

Changes in the hepatic copper conent after treatment with foreign compounds.

The effects of dimercaprol, CaNa2EDTA, D-penicillamine, diethyldithiocarbamate, disulfiram, pyrazole and phenobarbital on the hepatic copper content were studied. Adult male albino rats were given these compounds subcutaneously or intragastrically for 4 or 7 days, and the copper content in the hepatic crude homogenate was measured with an atomic absorption spectrophotometer. The metal chelating compounds dimercaprol, D-penicillamine and diethyldithiocarbamate only slightly decreased the level of copper in the liver. CaNa2 EDTA caused no change in the copper content. A slight decrease was found also after phenobarbital treatment. On the contrary, disulfiram and pyrazole increased the copper content 3- and 2-fold, respectively. It is suggested that the accumulation of copper in the liver is due to the cholestatic action of disulfiram and pyrazole.

Animals↗
PubMed2004

Cutaneous metabolism of glycol ethers.

The toxicity of glycol ethers is associated with their oxidation to the corresponding aldehyde and alkoxyacetic acid by cytosolic alcohol dehydrogenase (ADH; EC 1.1.1.1.) and aldehyde dehydrogenase (ALDH; 1.2.1.3). Dermal exposure to these compounds can result in localised or systemic toxicity including skin sensitisation and irritancy, reproductive, developmental and haemotological effects. It has previously been shown that skin has the capacity for local metabolism of applied chemicals. Therefore, there is a requirement to consider metabolism during dermal absorption of these compounds in risk assessment for humans. Cytosolic fractions were prepared from rat liver, and whole and dermatomed skin by differential centrifugation. Rat skin cytosolic fractions were also prepared following multiple dermal exposure to dexamethasone, ethanol or 2-butoxyethanol (2-BE). The rate of ethanol, 2-ethoxyethanol (2-EE), ethylene glycol, 2-phenoxyethanol (2-PE) and 2-BE conversion to alkoxyacetic acid by ADH/ALDH in these fractions was continuously monitored by UV spectrophotometry via the conversion of NAD+ to NADH at 340 nm. Rates of ADH oxidation by rat liver cytosol were greatest for ethanol followed by 2-EE >ethylene glycol >2-PE >2-BE. However, the order of metabolism changed to 2-BE >2-PE >ethylene glycol >2-EE >ethanol using whole and dermatomed rat skin cytosolic fractions, with approximately twice the specific activity in dermatomed skin cytosol relative to whole rat skin. This suggests that ADH and ALDH are localised in the epidermis that constitutes more of the protein in dermatomed skin than whole skin cytosol. Inhibition of ADH oxidation in rat liver cytosol by pyrazole was greatest for ethanol followed by 2-EE >ethylene glycol >2-PE >2-BE, but it only inhibited ethanol metabolism by 40% in skin cytosol. Disulfiram completely inhibited alcohol and glycol ether metabolism in the liver and skin cytosolic fractions. Although ADH1, ADH2 and ADH3 are expressed at the protein level in rat liver, only ADH1 and ADH2 are selectively inhibited by pyrazole and they constitute the predominant isoforms that metabolise short-chain alcohols in preference to intermediate chain-length alcohols. However, ADH1, ADH3 and ADH4 predominate in rat skin, demonstrate different sensitivities to pyrazole, and are responsible for metabolising glycol ethers. ALDH1 is the predominant isoform in rat liver and skin cytosolic fractions that is selectively inhibited by disulfiram and responds to the amount of aldehyde formed by the ADH isoforms expressed in these tissues. Thus, the different affinity of ADH and ALDH for alcohols and glycol ethers of different carbon-chain length may reflect the relative isoform expression in rat liver and skin. Following multiple topical exposure, ethanol metabolism increased the most following ethanol treatment, and 2-BE metabolism increased the most following 2-BE treatment. Ethanol and 2-BE may induce specific ADH and ALDH isoforms that preferentially metabolise short-chain alcohols (i.e. ADH1, ALDH1) and longer chain alcohols (i.e. ADH3, ADH4, ALDH1), respectively. Treatment with a general inducing agent such as dexamethasone enhanced ethanol and 2-BE metabolism suggesting induction of multiple ADH isoforms.

Alcohol Dehydrogenase↗
PubMed2005

Antagonism of discriminative stimulus effects of delta(9)-THC and (R)-methanandamide in rats.

RATIONALE: In previous drug discrimination studies we observed surmountable antagonism by Delta(9)-tetrahydrocannabinol (THC) in the presence of constant doses of SR-141716 [N-(piperidin-1-yl)-5-(4-chloro-phenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide] (0.3 and 1 mg/kg), but there was only marginal evidence for surmountable antagonism with combinations of SR-141716 and (R)-methanandamide, a chiral analog of the endocannabioid anandamide. OBJECTIVE: Here we examine antagonism where the cannabinoid CB1 receptor agonist [Delta(9)-THC and (R)-methanandamide] dose is held constant (i.e., the training dose) and the antagonist {i.e., SR-141716 and AM-251 [N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide; 2 ml/kg]} dose varied. We also tested the cannabinoid CB2 receptor antagonist SR-144528 {N-[(1S)-endo-1,3,3-trimethylbicyclo(2.2.1)heptan-2-yl]5-(4-chloro-3-methyl-phenyl)-1-(4-methylbenzyl)pyrazole-3-carboxamide}. METHODS: Different groups of rats were trained to discriminate between vehicle and three different doses of Delta(9)-THC (1.8, 3, and 5.6 mg/kg, presumably reflecting different efficacy demands) as well as 10 mg/kg (R)-methanandamide. Dose-generalization tests involved different doses of the cannabinoid CB1 receptor agonists. Antagonist tests varied the dose of the antagonist (range: 0.1 and 3 mg/kg for SR-141716 and AM-251, and 1 to 10 mg/kg for SR-144528). RESULTS: SR-141716 and AM-251 doses dependently blocked the agonist-induced discriminative stimulus effects. SR-141716 tended to be slightly more potent than AM-251. The effective dose 50 (ED(50)) of SR-141716 was higher in the 5.6 mg/kg Delta(9)-THC-trained group relative to the two other Delta(9)-THC-trained groups. The cannabinoid CB2 receptor antagonist SR-144528 combined with the training dose of 1.8 mg/kg Delta(9)-THC, as well as when combined with the training dose of 10 mg/kg (R)-methanandamide, did not markedly change drug-appropriate (agonist) responses. CONCLUSION: Data support that the discriminative stimulus effects of (R)-methanandamide and its overlap with the Delta(9)-THC cue are, indeed, CB1 receptor mediated events as revealed in antagonism tests with the selective central CB1 receptor antagonists SR-141716 and AM-251. The activation of cannabinoid CB2 receptors appears to be insignificant for these discriminations.

Animals↗
PubMed1990

Oxidation of glycerol to formaldehyde by rat liver microsomes. Effects of cytochrome P-450 inducing agents.

Glycerol was shown recently to be metabolized to formaldehyde by microsomes from chowfed control rats (Winters et al., Biochem Biophys Res Commun 153: 612-617, 1988). In the present study, experiments were carried out to evaluate the oxidation of glycerol by microsomes isolated from rats treated with inducers of different isozymes of cytochrome P-450. The oxidation of glycerol to formaldehyde was increased in microsomes from rats treated with pyrazole, ethanol or acetone relative to their respective controls, but not after treatment with phenobarbital or 3-methylcholanthrene. This reaction was sensitive to inhibition by carbon monoxide and was inhibited by compounds known to be effective substrates for P-450j, e.g. aniline, ethanol, pyrazole and 4-methylpyrazole. Treatment with pyrazole caused an increase in Vmax for glycerol oxidation but did not affect affect the Km (about 15 mM) for glycerol, as compared to saline controls. Evidence that the product of glycerol metabolism is formaldehyde was provided by the observation that this product served as a substrate for the glutathione-dependent formaldehyde dehydrogenase, and the amount of formaldehyde detected was identical to that detected by the Nash reaction. By utilizing [14C]glycerol, and coupling the formaldehyde dehydrogenase reaction to the formate dehydrogenase reaction, 14CO2 could be detected, indicating that the formaldehyde produced was derived from the added glycerol. These results suggest that that glycerol is not metabolically inert when added to microsomes but serves as an effective substrate for the cytochrome P-450j isozyme, extending the alcohol substrate specificity of this enzyme to poly-ols. The production of formaldehyde from glycerol may require caution since glycerol is often present in microsomal or reconstituted systems.

Acetone↗
PubMed2005

Synthesis of some novel pyrazolo[3,4-d]pyrimidine derivatives as potential antimicrobial agents.

The reaction of 4-hydrazino-8-(trifluoromethyl)quinoline (2) with ethoxymethylenecyanoacetate afforded ethyl 5-amino-1-[8-(trifluoromethyl)quinolin-4-yl]-1H-pyrazole-4-carboxylate (3) and that with ethoxymethylenemalononitrile afforded 5-amino-1-[8-(trifluoromethyl)quinolin-4-yl]-1H-pyrazole-4-carbonitrile (5). Compounds 3 and 5 were hydrolyzed to get 5-amino-1-[8-(trifluoromethyl)quinolin-4-yl]-1H-pyrazole-4-carboxylic acid and then reacted with acetic anhydride to afford 6-methyl-1-[8-(trifluoromethyl)quinolin-4-yl]pyrazolo[3,4-d]oxazin-4-one (6), which was condensed with different aromatic amines to give a series of 5-substituted 6-methyl-1-[8-(trifluoromethyl)quinolin-4-yl]-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-ones (7). Compounds 3 and 5 also reacted with formamide, urea, and thiourea affording the corresponding pyrazolo[3,4-d]pyrimidines (8-13), respectively. Structures of the products have been determined by chemical reactions and spectral studies. All compounds of the series have been screened for their antibacterial and antifungal activity studies. The results are summarized in Tables 1 and 2.

Anti-Infective Agents↗
PubMed2004

Isolation, synthesis and characterization of impurities in celecoxib, a COX-2 inhibitor.

During the impurity profile of Celecoxib, four polar impurities (impurity I, II, III and IV) and one non-polar impurity (impurity V) with respect to Celecoxib were detected by HPLC. LC-MS has been employed in this impurity profile study. The three polar impurities (I, II and III) were found to be process related while impurities (IV and V) turned out to be isomers. The impurities III, IV and V were isolated with the help of preparative HPLC. The structure of impurities III, IV (ortho-isomer) and V (regio-isomer) were confirmed as [5-(4-methylphenyl)-3-trifluoromethyl-1H-pyrazole], 4-[5-(2'-methyl phenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzenesulfonamide, and 4-[4-(4'-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]-benzenesulfonamide, respectively. The structures of impurities I, II, III and IV were confirmed by synthesis and structural characterization using spectral data. However, the impurity V was not synthesized.

Celecoxib↗
PubMed2003

4-substituted 1,5-diarylpyrazole, analogues of celecoxib: synthesis and preliminary evaluation of biological properties.

A number of 5-aryl-1-[4-(methylsulfonyl)-phenyl]-1H-pyrazoles and 4-(5-aryl-1H-pyrazol-1-yl)benzenesulfonamides 3, 4, 5, 6, analogues of the COX-2 selective inhibitor celecoxib (celebrex), were synthesized. In order to verify the effects on the biological properties of certain substituents put on position 4 of the pyrazole nucleus, some of these compounds were screened in vivo for their anti-inflammatory and analgesic activities. Moreover, sodium salts of carboxylic acids 4 were tested in vitro for their platelet anti-aggregating properties. The results of these preliminary biological assays showed that new derivatives are not endowed with improved anti-inflammatory and analgesic properties, in comparison with celecoxib. In addition, docking studies were carried out on the most significative compounds to evaluate their interaction mode at the active site of both COX-1 and COX-2. Some remarks about the SAR of this class of COX-inhibitors are drown out.

Analgesics↗
PubMed1999

Novel structural templates for estrogen-receptor ligands and prospects for combinatorial synthesis of estrogens.

BACKGROUND: The development of estrogen pharmaceutical agents with appropriate tissue-selectivity profiles has not yet benefited substantially from the application of combinatorial synthetic approaches to the preparation of structural classes that are known to be ligands for the estrogen receptor (ER). We have developed an estrogen pharmacophore that consists of a simple heterocyclic core scaffold, amenable to construction by combinatorial methods, onto which are appended 3-4 peripheral substituents that embody substructural motifs commonly found in nonsteroidal estrogens. The issue addressed here is whether these heterocyclic core structures can be used to prepare ligands with good affinity for the ER. RESULTS: We prepared representative members of various azole core structures. Although members of the imidazole, thiazole or isoxazole classes generally have weak binding for the ER, several members of the pyrazole class show good binding affinity. The high-affinity pyrazoles bear close conformational relationship to the nonsteroidal ligand raloxifene, and they can be fitted into the ligand-binding pocket of the ER-raloxifene X-ray structure. CONCLUSIONS: Compounds such as these pyrazoles, which are novel ER ligands, are well suited for combinatorial synthesis using solid-phase methods.

Binding Sites↗
PubMed1983

Resonance Raman spectra of copper(II)-substituted liver alcohol dehydrogenase: a type 1 copper analogue.

Liver alcohol dehydrogenase (LADH) with copper in place of the catalytic zinc has recently been proposed to contain a type 1 site analogous to that in "blue" copper proteins. Resonance Raman spectra for the copper-substituted enzyme, Cu(II) X LADH, and its binary complexes with reduced nicotinamide adenine dinucleotide (NADH) and pyrazole support this viewpoint. These spectra have two dominant features: a sharp peak at approximately 415 cm-1, which is believed to be associated with vibration of the single histidine ligand, and a broader, asymmetric band at approximately 350 cm-1, whose components are assigned predominantly to vibrational modes of the two cysteinate ligands. The high frequency of these transitions, which is reminiscent of the blue copper proteins, is ascribed to the tetrahedral nature of the metal site that produces unusually short Cu-S bonds and coupled vibrational modes. Solvent exchange with H218O reveals no contribution to the resonance Raman spectrum of the water molecule, which is a metal ligand in free Cu(II) X LADH; however, the spectrum of the binary complex with pyrazole has several new peaks attributable, in part, to pyrazole ligation. The strong similarity among the vibrational spectra demonstrates that the Cu(II) environment in alcohol dehydrogenase maintains its near-tetrahedral geometry in the various enzyme derivatives. The resonance Raman spectrum of Ni(II) X LADH is close to that of Cu(II) X LADH and suggests a similar tetrahedral site. The Raman spectra presented here together with available optical and EPR data indicate that Cu(II) X LADH belongs to the type 1 copper classification and, thus, can provide new insights into this unusual coordination geometry.

Alcohol Dehydrogenase↗
PubMed2006

Phototransformation of the insecticide fipronil: identification of novel photoproducts and evidence for an alternative pathway of photodegradation.

Fipronil is a recently discovered insecticide of the phenylpyrazole series. It has a highly selective biochemical mode of action, which has led to its use in a large number of important agronomical, household, and veterinary applications. Previous studies have shown that, during exposure to light, fipronil is converted into a desulfurated derivative (desulfinyl-fipronil), which has slightly reduced insecticidal activity. In this study, the photodegradation of fipronil was studied in solution at low light intensities (sunlight or UV lamp). In addition to desulfinyl-fipronil, a large number of minor photoproducts were observed, including diversely substituted phenylpyrazole derivatives and aniline derivatives that had lost the pyrazole ring. Desulfinylfipronil itself was shown to be relatively stable under both UV light and sunlight, with only limited changes occurring in the substitution of the aromatic ring. Since this compound accumulated to levels corresponding to only 30-55% of the amount of fipronil degraded, it was concluded that one or more alternative pathways of photodegradation must be operating. On the basis of the structurally identified photoproducts, it is proposed that fipronil photodegradation occurs via at least two distinct pathways, one of which involves desulfuration at the 4-position of the pyrazole ring giving the desulfinyl derivative and the other of which involves a different modification of the 4-substituent, leading to cleavage of the pyrazole ring and the formation of aniline derivatives. The latter compounds do not accumulate to high levels and may, therefore, be degraded further. The ecological significance of these results is discussed, particularly with regard to the insecticidal activity of the photoproducts.

Aedes↗
PubMed1976

Synthesis and structure-activity relationships of heterocyclic compounds containing a trimethoxyarene function.

Pyrazole-, isoxazole-, and pyrazolone-containing systems were prepared from 3,4-dihydro-5,6,7-trimethoxy-1(2H)-naphthalenone, 3,4-dihydro-6,7,8-trimethoxy-1(2H)-naphthalenone, and 3,4-dihydro-6,7,8-trimethoxy-1(2H)-phenanthrone. Primarily, the pyrazoles displayed inhibition of growth in the microbial screens and in tissue culture. Correlation of the heteroatom distances between the oxygen atoms of two methoxy groups and a nitrogen atom in the pyrazole function with the percent plating efficiency on KB cell growth suggests increased inhibition as the (OA-N)/(OB-N) ratio deviates from one. No trend was observed in relating the OA-N-OB angle and activity for the examples studied.

Bacillus subtilis↗
PubMed2001

A novel approach for the development of selective Cdk4 inhibitors: library design based on locations of Cdk4 specific amino acid residues.

Identification of a selective inhibitor for a particular protein kinase without inhibition of other kinases is critical for use as a biological tool or drug. However, this is very difficult because there are hundreds of homologous kinases and their kinase domains including the ATP binding pocket have a common folding pattern. To address this issue, we applied the following structure-based approach for designing selective Cdk4 inhibitors: (1) identification of specifically altered amino acid residues around the ATP binding pocket in Cdk4 by comparison of 390 representative kinases, (2) prediction of appropriate positions to introduce substituents in lead compounds based on the locations of the altered amino acid residues and the binding modes of lead compounds, and (3) library design to interact with the altered amino acid residues supported by de novo design programs. Accordingly, Asp99, Thr102, and Gln98 of Cdk4, which are located in the p16 binding region, were selected as first target residues for specific interactions with Cdk4. Subsequently, the 5-position of the pyrazole ring in the pyrazol-3-ylurea class of lead compound (2a) was predicted to be a suitable position to introduce substituents. We then designed a chemical library of pyrazol-3-ylurea substituted with alkylaminomethyl groups based on the output structures of de novo design programs. Thus we identified a highly selective and potent Cdk4 inhibitor, 15b, substituted with a 5-chloroindan-2-ylaminomethyl group. Compound 15b showed higher selectivity on Cdk4 over those on not only Cdk1/2 (780-fold/190-fold) but also many other kinases (>430-fold) that have been tested thus far. The structural basis for Cdk4 selective inhibition by 15b was analyzed by combining molecular modeling and the X-ray analysis of the Cdk4 mimic Cdk2-inhibitor complex. The results suggest that the hydrogen bond with the carboxyl group of Asp99 and hydrophobic van der Waals contact with the side chains of Thr102 and Gln98 are important. Compound 15b was found to cause cell cycle arrest of the Rb(+) cancer cell line in the G(1) phase, indicating that it is a good biological tool.

Adenosine Triphosphate↗