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PubMed1985

Highly potent inhibition of prostaglandin 15-hydroxydehydrogenase in-vitro and of prostaglandin inactivation in perfused lung by the new azobenzene analogue, Ph CL 28A.

The new azobenzene analogue Ph CL 28A (2-hydroxy-5-(3,5-dimethoxycarbonyl-benzoyl)-benzene acetic acid) potently inhibited prostaglandin 15-hydroxydehydrogenase (PGDH) in the nanomolar range in-vitro and inhibited prostaglandin inactivation in rat perfused lung at similar concentrations, and is the most potent PGDH inhibitor yet available. It was synthesized because electronegative substituents in the B ring of homosalazine enhance PGDH inhibitory potency. Ph CL 28A inhibited human placental PGDH non-competitively with regard both to substrate PGF2 alpha (Ki = 18.7 +/- 0.9 nM) and the NAD+ cofactor (Ki = 57.6 +/- 2.9 nM); inhibition was greatly reduced at pH greater than or equal to 8.0. Ph CL 28A hydrolyses spontaneously in alkali (t1/2 at pH 9.0 = 45 h) to the less active dicarboxylic acid (IC50 human placental PGDH 1.6 microM versus 0.028 microM for Ph CL 28A). The new analogue is 1000 X more active than the parent compound sulphasalazine from which it derives. The IC50 values for five azobenzene analogues in rat perfused lung (Ph CL 28A = 72 nM) correlated strongly with those obtained using purified PGDH (r = 0.99), suggesting that they inhibit pulmonary prostaglandin degradation at the enzyme step rather than at the hypothetical carrier. The new compound will be a useful probe for PGDH structure and function.

Animals↗
PubMed1979

Detection by antihapten antibodies of liver-bound compounds related to azocarcinogens or their metabolites.

The localization of known azocarcinogens and metabolites such as p-aminoazobenzene and N-methyl-p-aminoazobenzene bound to components of liver cells of rats fed single or multiple doses of 3'-methyl-p-dimethylaminoazobenzene has been determined with the use of antibodies raised against p'-azo-p-aminoazobenzene and p'-azo-N-monomethyl-p-aminoazobenzene in the indirect fluorescent antibody procedure. These 2 antisera reacted with liver cells of rats fed 3'-methyl-p-dimethylaminoazobenzene, p'-amino-p-aminoazobenzene, p'-amino-N-monomethyl-p-aminoazobenzene and N-methyl-p-aminoazobenzene. The results obtained in this study suggest that both major and minor metabolites of azocarcinogens have common antigenic determinants.

Animals↗
PubMed2005

Synthesis of some new biologically active 1,3,4-oxadiazolyl nitroindoles and a modified Fischer indole synthesis of ethyl nitro indole-2-carboxylates.

An efficient and modified synthesis of ethyl-4-nitro/5-nitro/6-nitro and 7-nitroindole-2-carboxylates is described. Carbohydrazides of corresponding ethyl nitroindole-2-carboxylates underwent smooth one-step transformation to 1,3,4-oxadiazolyl nitroindoles (4a-l) on reaction with aromatic carboxylic acids in the presence of phosphorus oxychloride. An alternate method to synthesize 1,3,4-oxadiazolyl nitroindoles is also described. Among the newly synthesized 1,3,4-oxadiazolyl nitroindoles, a few compounds are studied for anti-inflammatory activity.

Animals↗
PubMed1979

Inhibitors for the mutagenicities of colon carcinogens, 1,2-dimethylhydrazine and azoxymethane, in the host-mediated assay.

Inhibitory effects of several chemicals on the mutagenicities of 1,2-dimethylhydrazine (DMH) and azoxymethane (AOM) for Salmonella typhimurium G46 in the host-mediated assay were investigated. They were carbon disulfide (CS2), tetraethylthiuram disulfide (disulfiram, DSF), sodium diethyldithiocarbamate (SDDC), ethylene-bis(dithiocarbamato) manganese (Maneb), pyrazole (PZ), aminoacetonitrile hydrogen sulfate (AAN), and sodium selenite (SE). All the compounds, except for SE, inhibited the mutagenicities of DMH and AOM.

Aminoacetonitrile↗
PubMed2003

Wavelength-dependent photochemistry of Diazo Meldrum's acid and its spirocyclic isomer, Diazirino Meldrum's acid: Wolff rearrangement versus isomerization.

Photoreaction of diazo Meldrum's acid (1) shows a unique wavelength selectivity. At 254 nm it results in efficient (phi(254) = 0.34) Wolff rearrangement, while irradiation with 355 nm light leads to a completely different process, isomerization into corresponding cyclic alpha,alpha"-dicarbonyl diazirine 2 (phi(350) = 0.024). UV photolysis of diazirine 2 is accompanied by two competing processes: loss of nitrogen followed by the Wolff rearrangement and isomerization into diazo compound 1. Thermal decomposition of 1 leads to clean Wolff rearrangement, while heating of 2 causes quantitative conversion into diazo isomer 1.

Azo Compounds↗
PubMed2005

Mixed-ligand Ru(II) complexes with 2,2'-bipyridine and aryldiazo-beta-diketonato auxillary ligands: synthesis, physico-chemical study and antitumour properties.

The complexes of Ru(II)-2,2'-bipyridyl with substituted diazopentane-2,4-diones (L1H-L5H) were synthesized and characterized by elemental analyses, conductance, FAB (fast atom bombardment) mass and spectral (IR, UV/Vis (UV/visible), NMR) studies. Molecular geometry optimization of the complexes was also made. None of the complexes luminesce. However, facilitated oxidation of Ru(II) to Ru(III) was evidenced from their lower reduction potential data. The ligands and their complexes were tested for their antitumour activity against a variety of tumour cell lines. Though activity is found to vary with the type of tumour cell lines used, yet complex 5 with naphtyldiazopentane-2,4-dione as co-ligand was found to be a potential compound as it showed in general significant activity against all cell lines studied.

2,2'-Dipyridyl↗
PubMed2006

Kinamycins A and C, bacterial metabolites that contain an unusual diazo group, as potential new anticancer agents: antiproliferative and cell cycle effects.

The cell growth and cell cycle inhibitory properties of the bacterial metabolites kinamycin A and kinamycin C were investigated in an attempt to determine their mechanism of action and to develop these or their analogs as anticancer agents. Both kinamycin A and kinamycin C have a highly unusual and potentially reactive diazo group. Even with short incubations, both the kinamycins were shown to have very potent cell growth inhibitory effects on either Chinese hamster ovary or K562 cells. Kinamycin C induced a rapid apoptotic response in K562 cells. The cell cycle analysis results in synchronized Chinese hamster ovary cells treated with kinamycin A revealed that they only displayed a G1/S phase block upon entry to the second cycle. Both kinamycins inhibited the catalytic decatenation activity of DNA topoisomerase IIalpha, but neither kinamycin acted as a topoisomerase II poison. Their inhibition of catalytic activity was not correlated with cell growth inhibitory effects. Pretreatment of the kinamycins with dithiothreitol protected the topoisomerase IIalpha activity, which suggested that they may be targeting critical protein sulfhydryl groups, either through reaction with the quinone or with an activated electrophilic diazo group. Neither kinamycin A nor kinamycin C intercalated into DNA, nor were they able to cross-link DNA. Although the cellular target(s) of the kinamycins has yet to be identified, the cluster map analysis, and the cell cycle and proapoptotic effects suggest that kinamycin C has a target different than other established anticancer compounds.

Adenosine Triphosphatases↗
PubMed1997

Stabilization of lignin peroxidases in white rot fungi by tryptophan.

Supplementation of various cultures of white rot fungi with tryptophan was found to have a large stimulatory effect on lignin peroxidase activity levels. This enhancement was greater than that observed in the presence of the lignin peroxidase recycling agent veratryl alcohol. Using reverse transcription-PCR, we found that tryptophan does not act to induce lignin peroxidase expression at the level of gene transcription. Instead, the activity enhancement observed is likely to result from the protective effect of tryptophan against H2O2 inactivation. In experiments using a partially purified lignin peroxidase preparation, tryptophan and its derivative indole were determined to function in the same way as veratryl alcohol in converting compound II, an oxidized form of lignin peroxidase, to ferric enzyme, thereby completing the catalytic cycle. Furthermore, tryptophan was found to be a better substrate for lignin peroxidase than veratryl alcohol. Inclusion of either tryptophan or indole enhanced the oxidation of the azo dyes methyl orange and Eriochrome blue black. Stimulation of azo dye oxidations by veratryl alcohol has previously been shown to be due to its enzyme recycling function. Our data allow us to propose that tryptophan stabilizes lignin peroxidase by acting as a reductant for the enzyme.

Azo Compounds↗
PubMed2002

Catechins and their oligomers linked by C4 --> C8 bonds are major cacao polyphenols and protect low-density lipoprotein from oxidation in vitro.

In vitro effects of catechins and their oligomers linked by C4 --> C8 bonds are major antioxidative components of chocolate and cocoa. Their effects on the susceptibility of human low-density lipoprotein (LDL) to oxidation were evaluated. The strength of the antioxidative activity was measured using copper ions as the radical generator as compared by weight varied in the following order: (+)-catechin > procyanidin B2 > or = (-)-epicatechin > or = procyanidin C1 > cinnamtannin A2. Using 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (MeO-AMVN) as the radical generator, the order was (-)-epicatechin > or = procyanidin B2 > or = procyanidin C1 > (+)-catechin > or = cinnamtannin A2. It is suggested that these compounds contribute to the activity of cacao products to protect LDL from oxidation.

Anthocyanins↗
PubMed1986

Demonstration of carboxyl and thiol protease activities in adult Schistosoma mansoni, Dirofilaria immitis, Angiostrongylus cantonensis and Ascaris suum.

Evidence has been presented showing two kinds of acidic protease activities in adult Schistosoma mansoni, Dirofilaria immitis, Angiostrongylus cantonensis and Ascaris suum. A haemoglobinolytic activity without adding any SH-containing compounds was maximal at pH 3.5, 2.5, 3.0 and 3.5 in S. mansoni, D. immitis, Angiostrongylus cantonensis and Ascaris suum respectively. The inhibitor studies demonstrated that this activity is ascribable to carboxyl protease(s). In the presence of dithiothreitol, activity on Azocoll (azo-dye coupled hide powder) was maximal at pH 4.6, 4.6, 3.5 and 5.6 in S. mansoni, D. immitis, Angiostrongylus cantonensis and Ascaris suum respectively. The effects of inhibitors demonstrated that this activity belongs to the thiol protease class. The intraspecific distribution of the protease activities was studied in some of the nematodes from which the organs could be anatomically separated. The distribution patterns of the haemoglobinolytic and azocollytic activities were quite different in An. cantonensis and much the same in As. suum. Based on the present results, acidic haemoglobinolytic activities reported in adult S. mansoni by other authors are thought to be due to carboxyl and thiol protease(s) respectively.

Angiostrongylus↗
PubMed1992

Nitriles in heterocyclic synthesis. Part III: New sulpha drugs related to cyanopyridine derivatives.

4-Hydroxyacetophenone (1) was reacted with cinnamonitrile derivatives (2-6) to give 3-cyano-4-(substituted phenyl)-6-(p-hydroxyphenyl)-pyridines (7-11). Interaction of compounds 7-9 with 4'-substituted heterocyclo-benzenesulphonyl diazonium chloride gave the corresponding 3-cyano-4-(substituted phenyl)-6-(3'-azobenzene sulphonamido-4'-hydroxyphenyl) pyridines (12-29). The corresponding iron (III) copper (II) and mercury (II) chelates were also prepared in a 1:2 metal-to-ligand ratio. All the synthesized compounds were characterized on the basis of microanalysis, IR and 1H-NMR spectrometry.

Anti-Bacterial Agents↗
PubMed1998

A pyridoxine cyclic phosphate and its 6-azoaryl derivative selectively potentiate and antagonize activation of P2X1 receptors.

Analogues of the P2 receptor antagonists pyridoxal-5'-phosphate and the 6-azophenyl-2',4'-disulfonate derivative (PPADS), in which the phosphate group was cyclized by esterification to a CH2OH group at the 4-position, were synthesized. The cyclic pyridoxine-alpha4, 5-monophosphate, compound 2 (MRS 2219), was found to be a selective potentiator of ATP-evoked responses at rat P2X1 receptors with an EC50 value of 5.9 +/- 1.8 microM, while the corresponding 6-azophenyl-2',5'-disulfonate derivative, compound 3 (MRS 2220), was a selective antagonist. The potency of compound 3 at the recombinant P2X1 receptor (IC50 10.2 +/- 2.6 microM) was lower than PPADS (IC50 98.5 +/- 5.5 nM) or iso-PPADS (IC50 42.5 +/- 17.5 nM), although unlike PPADS its effect was reversible with washout and surmountable. Compound 3 showed weak antagonistic activity at the rat P2X3 receptor (IC50 58.3 +/- 0.1 microM), while at recombinant rat P2X2 and P2X4 receptors no enhancing or antagonistic properties were evident. Compounds 2 and 3 were found to be inactive as either agonists or antagonists at the phospholipase C-coupled P2Y1 receptor of turkey erythrocytes, at recombinant human P2Y2 and P2Y4 receptors, and at recombinant rat P2Y6 receptors. Similarly, compounds 2 and 3 did not have measurable affinity at adenosine A1, A2A, or A3 receptors. The lack of an aldehyde group in these derivatives indicates that Schiff's base formation with the P2X1 receptor is not necessarily required for recognition of pyridoxal phosphate derivatives. Thus, compounds 2 and 3 are relatively selective pharmacological probes of P2X1 receptors, filling a long-standing need in the P2 receptor field, and are also important lead compounds for future studies.

Adenosine Triphosphate↗
PubMed1990

Diethyldithiocarbamate and dithizone augment the toxicity of kainic acid.

Male Fischer-344 rats were injected i.p. with diethyldithiocarbamate or dithizone 15 min after kainic acid (KA), s.c. Diethyldithiocarbamate and dithizone reduced both the number of wet dog shakes and the latency to onset of seizures induced by KA. Moreover, they increased the severity of seizures. These compounds may be useful tools for investigating the role of zinc in central nervous system excitatory transmission and/or convulsive phenomena.

Animals↗
PubMed2004

UV/Vis, IR and 1H NMR spectrophotometric studies of some bisazo-dianil compounds based on bis-(hydroxy, formyl) phenylazo phenylene and anthranilic acid.

The electronic absorption spectra of some bisazo-dianils are studied in organic solvents of different polarity and in buffer solutions of varied pH. The different absorption bands are assigned to the corresponding electronic transitions, the solvent effect on the CT band energy is also discussed. The spectral study in buffer solutions is utilized for the determination of the pKa of the phenolic OH-groups. The important bands in the IR spectra as well as the signals of the 1H NMR spectra are assigned and discussed in relation to molecular structure. The fluorescence spectra of the compounds are recorded. The fluorescence quantum yield and pK in the ground and excited states are determined.

Azo Compounds↗