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PubMed1984

Mutagenicity of benzidine and benzidine-congener dyes and selected monoazo dyes in a modified Salmonella assay.

We have evaluated the mutagenic activity of a series of diazo compounds derived from benzidine and its congeners o-tolidine, o-dianisidine and 3,3'-dichlorobenzidine as well as several monoazo compounds. The test system used was a modification of the standard Ames Salmonella assay in which FMN, hamster liver S9 and a preincubation step are used to facilitate azo reduction and detection of the resulting mutagenic aromatic amines. All of the benzidine and o-tolidine dyes tested were clearly mutagenic. The o-dianisidine dyes except for Direct Blue 218 were also mutagenic. Direct Blue 218 is a copper complex of the mutagenic o-dianisidine dye Direct Blue 15. Pigment Yellow 12, which is derived from 3,3'-dichlorobenzidine, could not be detected as mutagenic, presumably because of its lack of solubility in the test reaction mixture. Of the monoazo dyes tested, methyl orange was clearly mutagenic, while C.I. Acid Red 26 and Acid Dye (C.I. 16155; often referred to as Ponceau 3R) had marginal to weak mutagenic activity. Several commercial dye samples had greater mutagenic activity with the modified test protocol than did equimolar quantities of their mutagenic aromatic amine reduction products. Investigation of this phenomenon for Direct Black 38 and trypan blue showed that it was due to the presence of mutagenic impurities in these samples. The modified method used appears to be suitable for testing the mutagenicity of azo dyes, and it may also be useful for monitoring the presence of mutagenic or potentially carcinogenic impurities in otherwise nonmutagenic azo dyes.

3,3'-Dichlorobenzidine↗
PubMed1987

In vitro oxidation of alpha-tocopherol (vitamin E) in human platelets upon incubation with unsaturated fatty acids, diamide and superoxide.

Incubation of human blood platelets in vitro in Tyrode solution with unsaturated fatty acids, diamide or superoxide (generated in situ) resulted in the oxidation of tocopherol in the platelets. Arachidonate concentrations of (3-5).10(-4) M caused a 50% decrease in platelet alpha-tocopherol. The addition of saturated fatty acids or platelet-active substances such as ADP, dibutyryl cyclic AMP, and some prostaglandins, or peroxidizing agents such as hydrogen peroxide and tert-butylhydroperoxide to the incubation medium did not cause any change in platelet tocopherol content. During incubations of platelets with arachidonate, malonaldehyde as well as alpha-tocopherolquinone were produced. The latter was also produced during incubations with diamide or superoxide. The oxidation of tocopherol induced by unsaturated fatty acids may be one factor responsible for the well-known increase in dietary vitamin E requirements induced by polyunsaturated fatty acids. The oxidative consumption of tocopherol in the membranes could be expected to take place during localized release of oxidants such as superoxide and polyunsaturated fatty acids during normal biological function (e.g., phagocytosis) or pathological processes (e.g., ischemia). Tocopherol utilization is kept low probably by the regeneration of the compound by vitamin C and/or the preferential utilization of the other biological antioxidants.

Adenosine Diphosphate↗
PubMed2000

Inhibition of formation of protease-resistant prion protein by Trypan Blue, Sirius Red and other Congo Red analogs.

Five compounds related to Congo Red were found to inhibit generation of protease-resistant prion protein in a cell-free system. In this assay Trypan Blue, Evans Blue, Sirius Red F3B, Primuline and Thioflavin-S were all more inhibitory than Congo Red itself. In scrapie-infected mouse neuroblastoma cells one compound, Sirius Red F3B, was capable of blocking the formation of protease-resistant prion protein to a similar extent as Congo Red; however, the other four compounds were less effective. Some of these compounds should be considered for testing in TSE disease models in live animals.

Animals↗
PubMed1986

Aurintricarboxylic acid and Evans Blue represent two different classes of anionic compounds which selectively inhibit the cytopathogenicity of human T-cell lymphotropic virus type III/lymphadenopathy-associated virus.

Aurintricarboxylic acid, an anionic triphenylmethane dye, and Evans Blue, an anionic compound structurally related to suramin, are, like suramin itself, inhibitors of human T-cell lymphotropic virus type III (HTLV-III)/-lymphadenopathy-associated virus (LAV) in vitro. These compounds may be targeted, at least in part, at the HTLV-III/LAV reverse transcriptase. The lack of any appreciable cytostatic action of aurintricarboxylic acid, Evans Blue and suramin against several murine and human cell lines, their inability to inhibit cellular DNA, RNA and protein synthesis, and their high lethal dose-50 (greater than or equal to 0.340 g/kg) for NMRI mice point to the selectivity of the compounds as inhibitors of HTLV-III/LAV.

Animals↗
PubMed1980

Dose response of 1,2-dimethylhydrazine and methylazoxymethanol acetate in the F 344 rat.

Weanling male and female F 344 rats were given various doses of 1,2-dimethylhydrazine (DMH) or methylazoxymethyl acetate (MAMAc), and were then held for 46-64 weeks in an effort to determine a dose response and establish a dose level which would produce a low level of intestinal neoplasia with a minimal number of tumors in other organs. DMH proved superior to MAM in this respect, although liver lesions were still observed with both compounds at the lowest carcinogenic intestinal dose.

Animals↗
PubMed1991

Muscarinic cholinergic agonists and antagonists of the 3-(3-alkyl-1,2,4-oxadiazol-5-yl)-1,2,5,6-tetrahydropyridine type. Synthesis and structure-activity relationships.

A series of 3-(3-alkyl-1,2,4-oxadiazol-5-yl)-1,2,5,6-tetrahydro-1-methylpyr idines (2a-q) were synthesized and tested for central muscarinic cholinergic receptor binding affinity by using [3H]oxotremorine-M and [3H]QNB as ligands and in a functional assay using guinea pig ileum. The analogues with unbranched C1-8-alkyl substituents (2a-g) were agonists, whereas the compounds with branched or cyclic substituents (2h-m) were antagonists. The alkyl ether analogues (2o-q) were also agonists but had lower receptor binding affinity than the corresponding alkyl analogues. The 3-(5-alkyl-1,2,4-oxadiazol-3-yl)-1,2,5,6-tetrahydro-1-methylpyridi ne analogues had only ver low affinity for the central muscarinic receptors and were weak antagonists in the ileum assay. A few 3-(3-butyl-1,2,4-oxadiazol-5-yl)-1,2,5,6-tetrahydro-1-methylpyr idines substituted with methyl or hydrogen in the 1-, 5-, or 6-position were synthesized and tested. N-Desmethyl analogue 7 was a potent muscarinic agonist, whereas N-desmethyl-5-methyl analogue 11 and N-methyl-6-methyl analogue 13 both were antagonists with lower muscarinic receptor affinity. The 3-(3-butyl-1,2,4-oxadiazol-5-yl)quinuclidine (17) and tropane (15) analogues were both very potent antagonists with high affinity for central muscarinic receptors. The ratio [IC50(QNB)/IC50(Oxo-M)] x 0.162 proved to be a good indicator of the efficacy of the compounds in the guinea pig ileum assay.

Animals↗
PubMed1994

Interaction of anionic compounds with gelatin. I: Binding studies.

Even though gelatin is the most widely used polymeric excipient in pharmaceutical products, scant attention has been paid to its interaction with small organic molecules. The present work deals with the interaction of gelatin and four monosulfonated or monocarboxylated azo dyes having hydrocarbon moieties of different sizes. These dyes were used as models for anionic drugs, which make up a significant percentage of all new drugs. Most binding studies used ultrafiltration to separate free from bound dye, followed by spectrophotometric dye assays. One binding study was based on the shift in pH when a dye was added to gelatin solutions. All binding isotherms consisted of two linear segments. The initial segments, which start at the origin, represent the partitioning of the dyes between the dissolved gelatin and the aqueous buffer solution. They changed abruptly to horizontal plateaus, which represent the binding limit. Increases in pH from 5.00 to 7.00 reduced the binding of the sulfonated dyes but increased the binding of the carboxylated dye. At pH > or = 7.00, where even the carboxylic acid groups are fully ionized, the carboxylated dye and its sulfonated analog were bound to gelatin to the same extent. The binding of all dyes decreased with increasing temperature (i.e., the standard enthalpy of binding was negative), with a change of the solvent medium from water to 0.15 M ammonium acetate, and with decreasing size of the hydrocarbon moieties of the dyes. The binding of the dyes to gelatin was always reversible and the standard entropy change associated with it was negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Anions↗
PubMed2006

Preparation and characterization of a self-emulsifying pellet formulation.

The purpose of the current study is to investigate the feasibility of producing solid self-emulsifying pellets using the extrusion/spheronization technique. Pellets were made from a mixture of C18 partial glycerides, Solutol HS15 and microcrystalline cellulose. Pellets with good physical properties (size, shape, friability) and self-emulsifying properties were produced. The pellets were, in contrast to pellets lacking Solutol, able to transfer a lipophilic dye and a spin probe into the aqueous media. The release kinetics and the microenvironment of the pellets during the release process were assessed using electron spin resonance (ESR) spectroscopy. The ESR results showed that the hydrophobic spin probe was localized mainly in the lipid environment all over the release time. Furthermore, the formulation was capable of accelerating the release of the drug diazepam and achieving a diazepam concentration above its saturation solubility. In conclusion, spherical pellets with low friability and self-emulsifying properties can be produced by the standard extrusion/spheronization technique. The pellets are capable of transfering lipophilic compounds into the aqueous phase and have a high potential to increase the bioavailability of lipophilic drugs.

Azo Compounds↗
PubMed1988

Antioxidant activity of carnosine, homocarnosine, and anserine present in muscle and brain.

Carnosine, homocarnosine, and anserine are present in high concentrations in the muscle and brain of many animals and humans. However, their exact function is not clear. The antioxidant activity of these compounds has been examined by testing their peroxyl radical-trapping ability at physiological concentrations. Carnosine, homocarnosine, anserine, and other histidine derivatives all showed antioxidant activity. All of these compounds showing peroxyl radical-trapping activity were also electrochemically active as reducing agents in cyclic voltammetric measurements. Furthermore, carnosine inhibited the oxidative hydroxylation of deoxyguanosine induced by ascorbic acid and copper ions. Other roles of carnosine, such as chelation of metal ions, quenching of singlet oxygen, and binding of hydroperoxides, are also discussed. The data suggest a role for these histidine-related compounds as endogenous antioxidants in brain and muscle.

Amidines↗
PubMed2004

Implications of the use of semicarbazide as a metabolic target of nitrofurazone contamination in coated products.

Data from the Brazilian Agricultural Ministry show that before the implementation of the Brazilian programme of nitrofuran control in February 2003, the cases of contamination of Brazilian chicken by nitrofurans were almost exclusively due to furaltadone. After May 2003, such cases decreased until no more reports of Brazilian chicken contamination with this nitrofuran were reported. Curiously, after April 2003, an increase was observed in the numbers of contaminated samples by semicarbazide, the target metabolite of nitrofurazone. Most Brazilian chicken found to be contaminated with semicarbazide has been covered with flour, salt and spices. For this reason, the authors' laboratory initialized a programme for tracing possible sources of food contamination by semicarbazide. After several semicarbazide positives in flour of controlled origin (results varying between 2.2 and 5.2 microg kg(-1)), the different additives used in the cereal industry as flour improvement agents were studied. The results indicate that the compound azodicarbonamide was responsible for the source of the contaminant semicarbazide.

Animals↗