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At least 19 recordsLinked to original sources
PubMed2026

Ampyrone is a direct agonist of human tyrosinase and a potential therapeutic for hypopigmentation disorders.

Significant loss of pigmentation can increase visual disability, skin cancer risk, and psychosocial stress. Tyrosinase (TYR) catalyzes the first and rate-limiting step of melanin synthesis. Inhibitors of TYR are well established and are currently used in clinical settings; however, there is a dearth of direct activators of TYR. Here, using a human TYR construct, we developed high-throughput screening methods, in cell confirmatory assays employing 13C-tyrosine tracing, and computational analysis techniques, and identified ampyrone (4-aminoantipyrine) as a TYR activator. Ampyrone increased the in vitro catalytic activity of the human recombinant intramelanosomal domain of TYR (hTYR) and its hypomorphic variant, Pro406Leu (P406L), a cause of oculocutaneous albinism type 1B (OCA1B). Moreover, ampyrone induced melanin synthesis in both WT and OCA1B human melanocytes, mouse OCA2 melanocytes, as well as 3-dimensional (3D) human skin cultures. Computational studies provided additional insight into the effects of direct TYR agonists on enzyme activity. Our results identify ampyrone as a lead candidate for TYR activation, potentially supporting the development of therapies for patients with genetic and acquired diseases of hypopigmentation.

Humans↗
PubMed1979

Fourier transform carbon-13 NMR spectra of ampyrone and aminopyrine.

The natural abundance 13C-NMR spectra of ampyrone and aminopyrine were obtained using the pulse Fourier transform technique. The chemical shifts were assigned with the help of the chemical shift theory, multiplicity generated in single-frequency off-resonance decoupled spectra, relaxation time, and comparison with structurally related compounds.

Aminopyrine↗
PubMed1981

A new enzymatic method for the demonstration of choline in human seminal stains.

A new, simple method for the identification of seminal stains based on the reaction of choline oxidase with choline is presented. The key reaction is the production of hydrogen peroxide by the oxidase action on choline, whereby hydrogen peroxide reacts with N-ethyl-N-(3-methylphenyl)-N'-acetylethylenediamine and 4-aminoantipyrine (ampyrone) in the presence of peroxidase to produce a purple color so that seminal fluid can be identified. Some data are presented on the sensitivity, stability, and specificity of the present method.

Alcohol Oxidoreductases↗
PubMed1996

Optimization studies of components in enzymatic cholesterol reagents containing cholesterol oxidase from Nocardia erythropolis, Streptomyces sp, or Pseudomonas fluorescens.

Although enzymatic methods for serum cholesterol determination are widely used in clinical laboratories, little is known about the optimization of each component in enzymatic reagents. We investigated the optimal components in the reagents containing cholesterol oxidase isolated from Nocardia erythropolis, Streptomyces sp, or Pseudomonas fluorescens. The optimal components in the reagents are: cholesterol oxidase 250 (Nocardia erythropolis), 250 (Streptomyces sp), or 300 (Pseudomonas fluorescens) U/L, cholesterol esterase 200 U/L, peroxidase 10,000 U/L, sodium cholate 3 mmol/L, 4-aminoantipyrine 0.5 mmol/L, phenol 20 mmol/L, Triton X-100 2 mL/L, and phosphate buffer, pH 7.0. Lower reaction sensitivity and lower cholesterol linearity, < 18.1 mmol/L (700 mg/dL), could be obtained by using lower components than those suggested above. Pseudomonas fluorescens were an improper source for cholesterol oxidase; either Nocardia erythropolis or Streptomyces was suitable cholesterol oxidase. We prefer using Streptomyces sp cholesterol oxidase because of its economical cost and longest reagent stability. Sodium cholate must be included in the enzymatic reagent to prevent turbidity. However, sodium cholate of > 5 mmol/ L will suppress the reaction resulting in low cholesterol linearity.

Ampyrone↗
PubMed1994

[In vivo nitrosation of methimazole in humans].

Monitoring the excretion of the non-carcinogenic nitroso-methylaminoantipyrine (NMAA) after peroral applications of the analgesic drug metamizole is a useful procedure for evaluating endogenous nitrosation, also in man. The outstanding nitrosatibility of this drug led to high amounts of excreted NMAA, easily detected without derivatisation by HPLC. By nitrate ingestion considered as normal dietary intake the nitrosation is scarcely modified by ascorbic acid, sodium-bicarbonate or sodium-bicarbonate plus metronidazole. These results are an other indication of a third, cell-mediated path of endogeneous nitrosation in man.

Ampyrone↗
PubMed1990

Zymographic screening of plant peroxidase isoenzymes oxidizing 4-hydroxystilbenes.

A zymographic assay is described for the detection of peroxidase isoenzymes oxidizing 4-hydroxystilbene following isoelectric focusing. The assay is based on coupling intermediate products of the oxidation of 4-hydroxystilbene with 4-aminoantipyrine, with resultant formation of dye complexes. Control experiments in the absence of 4-hydroxystilbene and hydrogen peroxide demonstrate the peroxidative nature of the 4-hydroxystilbene-dependent dye reaction.

Ampyrone↗
PubMed1997

Inhibition of acyl-CoA oxidase by phenol and its implication in measurement of the enzyme activity via the peroxidase-coupled assay system.

Yeast (Candida tropicalis) acyl-CoA oxidase catalyzes the oxidation of a variety of acyl-CoA substrates to their corresponding alpha-beta enoyl-CoA products, with concomitant reduction of the buffer-dissolved O2 to H2O2. By utilizing indolepropionyl-CoA as a chromogenic substrate, we could measure the enzyme activity either directly by monitoring formation of the reaction product indoleacryloyl-CoA (lambda(max) = 367 nm) or indirectly by measuring the formation of H2O2 via the oxidative-coupled assay system, involving 4-aminoantipyrine, phenol, and horseradish peroxidase. We compared the rates of the enzyme catalysis by the above two methods. The experimental data revealed that the rate measured via the direct method was about twofold higher than that measured by the coupled-assay system. The above difference was found to be due to the inhibition of the enzyme by phenol, one of the reagents of the coupled assay system. The inhibitory role of phenol is not unique for indolepropionyl-CoA as substrate, but is also evident with aliphatic acyl-CoA substrates of varied chain lengths. Since the magnitude of inhibition is dependent on the nature of the acyl-CoA substrate, it is suggested that the coupled-reaction conditions must be carefully standardized with individual substrates. Some tips on standardizing the reaction conditions for quantitative measurement of the acyl-CoA oxidase-catalyzed reaction are offered.

Acyl Coenzyme A↗
PubMed1992

Formation and excretion of dipyrone metabolites in man.

The formation and urinary excretion of the dipyrone metabolites, methylaminoantipyrine (MAA), aminoantipyrine (AA), formylaminoantipyrine (FAA) and acetylaminoantipyrine (AAA) were determined following administration of a single oral 1.0 g dose of dipyrone to 12 healthy volunteers. The AAA/AA plasma ratio showed that 3 subjects were slow and 9 were rapid acetylators. Pharmacokinetic parameters were determined separately for each group. A good correlation was found between the plasma and urine AAA/AA ratios. The renal clearance of the four metabolites was similar for both phenotypes. A significant difference in the rate of formation of dipyrone metabolites was found for AA, 0.25 (slow) vs 0.1 ml.min-1.kg-1 (rapid), and for AAA 0.75 (slow) vs 7.53 ml.min-1.kg-1 (rapid). There were comparable differences between slow and rapid acetylators in the AUC and the urinary excretion extrapolated to infinity for AA and AAA. The present results show that the kinetics of dipyrone metabolites in plasma and urine can provide a useful measure of the activity of the enzymes involved in their production.

Administration, Oral↗
PubMed1990

Pharmacokinetics of metamizol metabolites in healthy subjects after a single oral dose of metamizol sodium.

The linearity of the pharmacokinetics of the metamizol metabolites 4-methyl-amino-antipyrine (4-MAA), 4-amino-antipyrine (4-AA), 4-formyl-aminoantipyrine (4-FAA), and 4-acetyl-amino-antipyrine (4-AcAA) has been studied after administration to 15 healthy male volunteers of single oral doses of 750, 1500, and 3000 mg metamizol. The trial was open, randomized, and cross-over, with a one-week interval between dosing days. Metabolite concentrations in serum and urine were measured using reverse-phase HPLC. The mean Cmax of 4-MAA increased linearly with dose whereas its AUC was not proportional to dose after administration of 1500 and 3000 mg. With 4-AA, the increase in mean Cmax was linear, but the increase in AUC was not. The increases in mean Cmax and AUC for 4-FAA after doses of 1500 and 3000 mg were not proportional to the dose. The increases in mean Cmax and AUC for 4-AcAA were roughly proportional to the increase in dose. There were no significant differences in renal clearance between doses for any of the four metabolites. The observed non-linearities reflect the saturability of metabolic pathways. However, although they were statistically significant, the deviations from linearity were marginal and should not be of clinical relevance to the analgesic efficacy of metamizol in the dose range tested.

Administration, Oral↗
PubMed1993

The kinetics of metamizol and its metabolites in critical-care patients with acute renal dysfunction.

We have studied the clearance of monomethylaminoantipyrine (MMAAP), the pharmacologically active form of metamizol, in 46 patients in surgical intensive care with different degrees of renal dysfunction. In 23 patients without any renal impairment, mean clearance was 2.8 ml.min-1 x kg-1. Twenty-one patients with acute renal impairment had a significantly reduced clearance of MMAAP (0.83 ml.min-1 x kg-1). There was also reduced clearance in four patients with septic shock (1.0 ml.min-1 x kg-1). Kinetics of the metabolites of MMAAP (N-formylaminoantipyrine (FAAP), aminoantipyrine (AAP), and its secondary product N-acetylaminoantipyrine (AcAAP)) were calculated. FAAP and AcAAP showed delayed invasion, which can be explained by reduced hepatic metabolic activity. The product of N-demethylation, AAP, was not significantly altered. The delayed elimination of monomethylaminoantipyrine can be explained by reduced hepatic function in parallel with acute renal failure due to disturbed cardiovascular function caused by septic shock. This may also lead to disturbed hepatic macro- and microperfusion associated with altered oxygen supply and oxygen consumption.

Acute Kidney Injury↗
PubMed1985

Plasma protein binding of dipyrone metabolites in man.

Four metabolites of dipyrone, 4-methylaminoantipyrine (MAA), 4-aminoantipyrine (AA), 4-formylaminoantipyrine (FAA) and 4-acetylaminoantipyrine (AAA) can be identified in human plasma after its oral administration. The plasma protein binding of the metabolites in samples from 20 healthy volunteers was determined by ultrafiltration. None of the metabolites were found to be extensively bound to plasma proteins. The binding of MAA and AA was relatively higher than of FAA and AAA, as expected from their chemical structure. The mean percentage plasma protein binding was 57.6% for MAA, 47.9 for AA, 17.8 for FAA and 14.2% for AAA. The correlation between the unbound concentration in plasma and the total concentrations of MAA, AA, FAA and AAA was linear. No association was evident between the total protein plasma concentration and the extent of binding. The possible therapeutic implications related to protein binding of several analgesic and non-steroidal anti-inflammatory drugs are discussed.

Acetaminophen↗
PubMed1984

Plasma kinetics of dipyrone metabolites in rapid and slow acetylators.

The pharmacokinetics of the dipyrone metabolites 4-methylaminoantipyrine (MAA), 4-aminoantipyrine (AA), 4-formylaminoantipyrine (FAA) and 4-acetylaminoantipyrine (AAA) were evaluated following the administration of a single oral 1.0 g dose of dipyrone to 23 healthy volunteers. Twelve were slow and 11 were rapid acetylators as previously determined by dapsone phenotyping. For MAA and FAA the mean peak plasma concentrations were 10.5 +/- 2.8 micrograms/ml and 2.1 +/- 0.8 micrograms/ml and the half-lives were 3.3 +/- 1.0 and 10.1 +/- 1.8 h, respectively. No significant difference was found between rapid and slow acetylators in MAA and FAA kinetics. For AA, the mean peak plasma concentrations were 2.7 +/- 0.6 and 1.6 +/- 0.7 micrograms/ml (p less than 0.01), the peak times 6.7 +/- 2.1 and 3.1 +/- 1.1 h (p less than 0.01) and the half-lives were 5.5 +/- 1.0 and 3.8 +/- 1.2 h in slow and rapid acetylators, respectively. For AAA, the mean peak plasma concentrations were 1.6 +/- 0.4 and 4.4 +/- 1.1 micrograms/ml (p less than 0.01) and the peak time 16.1 +/- 5.1 and 10.0 +/- 2.6 h (p less than 0.01) in slow and rapid acetylators, respectively. There was no difference in the elimination half-life between the two groups (10.6 +/- 2.2 h). Thus, it has been demonstrated that the AAA/AA ratio is an indicator of the acetylation phenotype, as it is closely correlated with that determined by dapsone (r = 0.895, p less than 0.0005).

Acetylation↗
PubMedDate not supplied

Dose-dependent pharmacokinetics of metabolites of dipyrone in saliva.

Metabolites of dipyrone have been determined in the saliva of 18 volunteers following the oral intake of 0.5 g, 1.0 g, 1.5 g, 2.0 g and 2.5 g dipyrone. High concentrations were measured for N-methyl-aminoantipyrine (MAA), the other analgetic active metabolite, 4-aminoantipyrine was found in minor quantities only. N-formyl-antipyrine was not present in the saliva of some volunteers after low doses but could be determined following the intake of doses from 1.5 g - 2.5 g in saliva of all volunteers. N-acetyl-antipyrine appears late in saliva, acetylation rates varied greatly interindividually. Concentrations of the metabolites in saliva mimic the respective non-protein bound fraction in plasma found by other authors.

Adult↗
PubMed2002

Determination of polyphenols in wines by reaction with 4-aminoantipyrine and photometric flow-injection analysis.

A new flow-injection analytical procedure is proposed for the determination of the total amount of polyphenols in wines; the method is based on the formation of a colored complex between 4-aminoantipyrine and phenols, in the presence of an oxidizing reagent. The oxidizing agents hexacyanoferrate(III), peroxodisulfate, and tetroxoiodate(VII) were tested. Batch trials were first performed to select appropriate oxidizing agents, pH, and concentration ratios of reagents, on the basis of their effect on the stability of the colored complex. Conditions selected as a result of these trials were implemented in a flow-injection analytical system in which the influence of injection volume, flow rate, and reaction-coil length, was evaluated. Under the optimum conditions the total amount of polyphenols, expressed as gallic acid, could be determined within a concentration range of 36 to 544 mg L(-1), and with a sensitivity of 344 L mol(-1) cm(-1) and an RSD <1.1%. The reproducibility of analytical readings was indicative of standard deviations <2%. Interference from sugars, tartaric acid, ascorbic acid, methanol, ammonium sulfate, and potassium chloride was negligible. The proposed system was applied to the determination of total polyphenols in red wines, and enabled analysis of approximately 55 samples h(-1). Results were usually precise and accurate; the RSD was <3.9% and relative errors, by the Folin-Ciocalteu method, <5.1%.

Ampyrone↗