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Anti-inflammatory activity of 2-acyl-5(3)-hydroxytetrahydro-1H-pyrazole derivatives.

The anti-inflammatory effects of five pyrazolidine derivatives on white mice and laboratory rats were studied using models of thermal aseptic inflammation and inflammation induced by injection of carragenin and histamine, as well as models of "cotton-ball granuloma" and epinephrine (adrenaline)-induced pulmonary edema. These effects were compared with those of the most commonly used non-steroid anti-inflammatory drugs, such as phenylbutazone (CAS 50-33-9) and diclofenac (CAS 15307-79-6). It was found that the pyrazolidine compounds studied induced a pronounced anti-inflammatory effect by inhibiting both the proliferative and exudative phases of inflammation. At the same time, as compared to natural non-steroid anti-inflammatory drugs, these compounds had a lower toxicity and induced neither gastric ulcers nor suppression of hemopoiesis.

Animals↗

Pyrazoles as inhibitors of alcohol oxidation and as important tools in alcohol research: an approach to therapy against methanol poisoning.

4-Methylpyrazole, in a dose producing inhibition of alcohol dehydrogenase (alcohol:NAD(+) oxidoreductase, EC 1.1.1.1), was given alone or together with ethanol (10%) as sole drinking fluid to growing rats for up to 38 weeks. Their weight curves remained normal. Electron microscopy of liver, kidney, and heart revealed no changes related to treatment. Hematologic analysis showed normal values for blood and bone marrow. Several clinical chemical parameters showed no impairment of liver or kidney function, except for an enhancement of the microsomal drug-metabolizing activity after concurrent administration of 4-methylpyrazole and ethanol. A study on rats receiving 4-methylpyrazole and ethanol indicated a mutual interaction of the two compounds or the metabolites, leading to increased concentration in the blood of the compounds and reduced formation of 4-hydroxymethylpyrazole, the primary metabolite of 4-methylpyrazole. In monkeys, elimination of 4-methylpyrazole followed a linear course. 4-Hydroxymethylpyrazole accumulated to a level of at most 10% of that of 4-methylpyrazole. Concurrent administration of methanol inhibited the elimination of 4-methylpyrazole about 25%, and 4-methylpyrazole produced a profound inhibition of the oxidation of methanol. 4-Methylpyrazole, at a level in the plasma of more than 10 muM, prevented accumulation of the toxic metabolite formic acid in methanol-poisoned monkeys, and repeated injections of 4-methylpyrazole abolished methanol toxicity in monkeys receiving lethal doses of methanol. The present investigation indicates that 4-methylpyrazole, with its low toxicity and strong inhibition of alcohol oxidation, is a valuable tool for experimental studies of alcohol metabolism and its effects. It illustrates the usefulness of the monkey as a model to study 4-methylpyrazole activity and toxicity in light of its possible use for treating methanol poisoning in human beings.

Alcoholism↗

Antiparasitic activity of nine pyrazole derivatives against Trichomonas vaginalis, Entamoeba invadens and Plasmodium berghei.

Nine nitropyrazole derivatives were prepared and tested against Trichomonas vaginalis in vitro and in vivo, Entamoeba invadens in vitro and Plasmodium berghei in vivo. Three of the compounds, 4-4-nitropyrazole, 1-methyl-4-nitropyrazole and 4,4'-dinitro-1,1'-methylenedipyrazole, have an activity similar to that of metronidazole (used as the reference compound) against T. vaginalis and E. invadens after 48 hours of incubation. All the compounds tested were inactive against P. berghei.

Animals↗

Alteration of the response of platelets to surface stimuli by pyrazole compounds.

Sulfinpyrazone and phenylbutazone block the aggregating action of collagen, antigen-antibody complexes, and gamma globulin-coated surfaces on blood platelets. These drugs do not block the action of ADP or thrombin. Inhibition of surface-induced aggregation appears to be the result of a decreased response of the platelets to surface stimuli, giving rise to diminished release of platelet constituents, such as ADP and serotonin. The intravenous infusion of these drugs produced results similar to those found in the in vitro experiments. Administration of phenylbutazone in doses sufficient to produce marked suppression of the platelet-collagen reaction impaired hemostatic plug formation at the ends of transected mesenteric vessels in rabbits. Since platelet function is considered a factor influencing platelet survival, the effect of phenylbutazone on platelet survival was examined. It was found that phenylbutazone prolonged platelet survival to more than twice the normal time and reduced platelet turnover by nearly 50%. These studies show that drugs which suppress platelet response to surface stimuli alter platelet function in vivo.

Adenine Nucleotides↗

Synthesis and molecular modelling of novel substituted-4,5-dihydro-(1H)-pyrazole derivatives as potent and highly selective monoamine oxidase-A inhibitors.

This report describes novel pyrazoline derivatives investigated for their ability to selectively inhibit the activity of the A and B isoforms of monoamine oxidase. These new synthetic compounds proved to be reversible, potent, and selective inhibitors of monoamine oxidase-A rather than of monoamine oxidase-B, and are promising candidates to further advance drug discovery efforts. The most active compounds show inhibitory activity on monoamine oxidase-A in the 1.0x10(-8)-8.6x10(-9) M range. Moreover, it should be pointed out that for some compounds a high IC50>or=10(-9) M value is associated with a high A-selectivity (Selectivity Index monoamine oxidase-B/monoamine oxidase-A in the 10,000-12,500 range). Further insight to understand enzyme-inhibitor molecular interaction was obtained by docking experiments with the monoamine oxidase-A and monoamine oxidase-B isoforms.

Dose-Response Relationship, Drug↗