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PubMed1987

Mode of action of nitro-heterocyclic compounds on Escherichia coli.

The inhibitory and bactericidal activities of several different nitro-heterocyclic compounds, such as nitrofuran, nitronaphthofuran, nitrobenzofuran, nitroimidazole and nitrothiazole, were assessed in vitro. All these substances except nitroimidazole were active against Escherichia coli, though to different degrees. Under anaerobic test conditions the antibacterial activity increased slightly. Nitroreductase-deficient mutants, however, were highly resistant to all nitro-compounds, indicating that only when the nitro-group is reduced to these agents get into an active antibacterial form. SOS repair-deficient strains were much more susceptible to the nitro-containing substances than repair-proficient counterparts, indicating that damage to bacterial DNA is the essential mechanism of antibacterial activity of all nitro-heterocyclic compounds.

Escherichia coli↗
PubMed2002

Construction of heterocyclic compounds by use of alpha-diazophosphonates: new one-pot syntheses of indoles and isocoumarins.

[reaction: see text] alpha-Diazophosphonates, which have extremely useful properties from a synthetic point of view, are disclosed as 1,1-ambiphilic one-carbon building blocks for one-pot construction of various heterocyclic compounds. They are easily prepared and have higher stability by the effect of the phosphoryl group than corresponding alpha-diazocarbonyl compounds. Using this synthon, we have developed a novel, mild, and efficient synthetic method of 2,3-disubstituted indoles and 3,4-disubstituted isocoumarins.

Catalysis↗
PubMed2000

LC-MS for the identification of oxygen heterocyclic compounds in citrus essential oils.

The oxygen heterocyclic compounds (coumarins, psoralens and polymethoxylated flavones) present in the nonvolatile residue of the essential oils of Mandarin, Sweet Orange, Bitter Orange, Bergamot and Grapefruit were analysed with an HPLC/API/MS system equipped with an APcI probe in positive mode. The use of hyphenated techniques, such as LC/MS provides a great information about the content and nature of constituents of natural complex matrices, such as essential oils. In this work, MS spectra were recorded at different voltages, to obtain structural information in addition to molecular weight information. The different response of the compounds identified has been also evaluated. The method allowed the confirmation of the identification of the main components of the fraction, previously reported for the different oils. MS characteristics of coumarins, psoralens and polymethoxylated flavones with different substitution patterns were determined on the basis of the response obtained with the APcI interface. Interface parameters were optimised to obtain a contemporaneous response for all the three classes of components.

Chromatography, High Pressure Liquid↗
PubMed2002

Metabolic response against sulfur-containing heterocyclic compounds by the lignin-degrading basidiomycete Coriolus versicolor.

The fungal conversions of sulfur-containing heterocyclic compounds were investigated using the lignin-degrading basidiomycete Coriolus versicolor. The fungus metabolized a series of sulfur compounds--25 structurally related thiophene derivatives--via several different pathways. Under primary metabolic conditions, C. versicolor utilized thiophenes, such as 2-hydroxymethyl-, 2-formyl-, and 2-carboxyl-thiophenes, as a nutrient sulfur source for growth; thus, the fungus degraded these compounds more effectively in a non-sulfur-containing medium than in conventional medium. The product analysis revealed that several redox reactions, decarboxylation reactions, and C-S cleavage reactions were involved in the fungal conversion of non-aromatic thiophenes. On the other hand, benzothiophene (BT) and dibenzothiophene (DBT) skeletons were converted to water-soluble products. All the products and metabolic intermediates were more hydrophilic than the starting substrates. These metabolic actions seemed to be a chemical stress response against exogenously added xenobiotics. These metabolic reactions were optimized under ligninolytic conditions, also suggesting the occurrence of a fungal xenobiotic response. Furthermore, the fungus converted a series of BTs and DBTs via several different pathways, which seemed to be controlled by the chemical structure of the substrates. DBT, 4-methylDBT, 4, 6-dimethylDBT, 2-methylBT, and 7-methylBT were immediately oxidized to their S-oxides. BTs and DBTs with the hydroxymethyl substituent were converted to their xylosides without S-oxidation. Those with carboxyl and formyl substituents were reduced to form a hydroxymethyl group, then xylosidated. These observations strongly suggested the involvement of a fungal substrate-recognition and metabolic response mechanism in the metabolism of sulfur-containing heterocyclic compounds by C. versicolor.

Benzaldehydes↗
PubMed2002

Method for determining nitrogenous heterocycle compounds in wine.

Qualitative and quantitative analyses of N-heterocycle compounds were conducted by using a liquid-liquid extraction followed by additional chemical silica gel purification and injection into a gas chromatographic (GC) column coupled to a nitrogen-phosphorus detector (NPD). The purified extract fraction was investigated by GC-NPD and by GC-mass spectrometry. The compounds identified and quantified in wines were 2,4,5-trimethyloxazole, 2,4-dimethylthiazole, and 4-methylthiazole by GC-NPD and both 2-acetylthiazole and 2-acetyl-2-thiazoline by GC-MS. The procedure was used to analyze different wines and gave reliable and reproducible results.

Chromatography, Gas↗
PubMed2006

Anti-HIV activity of stilbene-related heterocyclic compounds.

Viral transcription has not been routinely targeted in the development of new antiviral drugs. This crucial step of the viral cycle depends on the concerted action of cellular and viral proteins such as NF-kappaB and Tat. In the present study, stilbene-related heterocyclic compounds including benzalphthalide, phthalazinone, imidazoindole and pyrimidoisoindole derivatives are tested for their anti-HIV activity. Original assays based on recombinant viruses were used to evaluate HIV replication inhibition and stably transfected cell lines were used to evaluate inhibition of Tat and NF-kappaB proteins. Some of the stilbene-related heterocyclic compounds analysed displayed anti-HIV activity through interference with NF-kappaB and Tat function. Moreover, compounds inhibiting both targets displayed a stronger activity on viral replication.

Anti-HIV Agents↗
PubMed2002

Syntheses of fused heterocyclic compounds and their inhibitory activities for squalene synthase.

A variety of fused heterocyclic compounds (2-11) were synthesized as a modification of the lead compound 1a and evaluated for their inhibition of squalene synthase. 4,1-Benzothiazepine derivative 2, 1,4-benzodiazepine derivative 6, 1,3-benzodiazepine derivative 7, 1-benzazepine derivative 9, and 4,1-benzoxazocine derivative 10 potently inhibited squalene synthase activity, whereas the 4,1-benzoxazepine derivatives 1 was the most potent inhibitor. 4,1-Benzothiazepine S-oxide derivative 4, 1,4-benzodiazepine derivative 5, 1,3,4-benzotriazepine derivative 8, and 1,2,3,4-tetrahydroquinoline derivative 11 were found to be weakly active. Comparison of the X-ray structures of these compounds (1a, 2, 4, 5, 7 and 10) suggests that orientation of the 5- (or 6)-phenyl group is important for activity.

Animals↗
PubMed2002

Heterocyclic compounds as inflammation inhibitors.

Clinical use of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with significant toxicity particularly in the gastrointestinal tract and kidney. Various approaches such as formulation co-administration (of agents to protect the stomach), chemical manipulation and synthesis of new safer anti-inflammatory drugs reported in the literature to overcome the toxicity of NSAIDs have been summarized. As far as synthesis of new more effective and safer anti-inflammatory drugs is concerned, we have reported recent findings in the area of synthesis of heterocyclic compounds such as pyrimidines, imidazole, benzimidazole, thiazole, thiazolidine, acridine, thiourea, alkanoic acid derivatives and other related heterocyclic compounds and their role as inflammation inhibitors.

Acridines↗
PubMed1998

Molecular modelling and footprinting studies of DNA minor groove binders: bisquaternary ammonium heterocyclic compounds.

We report new quantitative footprinting data which reveal differences in binding constants of bisquaternary ammonium heterocyclic compounds (BQA) with AT-rich DNA sites depending on the ligand structure and on the size and sequence of the DNA binding site. In an attempt to understand the dependence of binding affinity on the ligand structure we have performed quantum-chemical AM1 calculations on the BQA compounds and on subunits to explore the conformational space and to calculate the electronic and structural features of individual ligand conformations. Due to the properties of the rotatable backbone bonds, there is a large number of possible conformations with almost equal energy. We present a new method for the calculation of the radius of curvature of molecular structures. Assuming that strong binders should have a shape complementary to the DNA minor groove, this measure is used to select the optimum conformations for DNA-drug binding. The approach yields the correct ligand conformation for SN6999, for which an X-ray DNA-drug structure is known. The curvature of the optimum conformations of all ligands is compared with the experimental binding constants. A correlation is found between curvature and binding constant provided other structural factors do not vary. Therefore, we conclude that within structurally similar BQA compounds the extent of curvature is the relevant quantity which modulates the binding affinity.

DNA↗
PubMed1998

Combinatorial chemistry: from peptides and peptidomimetics to small organic and heterocyclic compounds.

Modified dipeptides have been used successfully for the generation of a variety of small organic and heterocyclic combinatorial libraries, including linear urea, polyamine, hydantoin, thiohydantoin, cyclic urea, cyclic thiourea and bicyclic guanidine. The synthesis and screening results for a number of these libraries are described. The solid phase synthesis of heterocyclic compounds such as diazepine and thiomorpholinone are also described.

Chemistry, Organic↗
PubMed1998

Differential detection of N-heterocyclic compounds and their N-methylated derivatives by immunoanalysis.

Competitive enzyme-linked immunosorbent assay (ELISA) systems are proposed for the indirect monitoring of formaldehyde by the parallel detection of its N-methylated precursors and the corresponding demethylated compounds. As an example for such immunoanalytical differentiation between an N-heterocyclic compound and its N-methylated derivative, the quantitative detection of the systemic triazole fungicide, myclobutanil, is discussed. Antibodies recognizing the non-zwitterionic structure of 2-(4-chlorophenyl)-2-[(1,2,4-triazol-1-yl)-methyl]-hexanonitril e (myclobutanil) showed only minor binding to corresponding N-alkylated derivatives of myclobutanil. And vice versa, literature data indicate that antibodies raised against the pyridilium ionic structure of the herbicide paraquat, displayed only mediocre reactivity towards the corresponding dealkylated derivatives. Thus, both experimental and literature data suggest that immunoanalytical methods for differential detection of N-methylated heterocycles (potentially including formaldehyde precursors) and their non-methylated counterparts are possible to develop.

Antibody Affinity↗
PubMed1984

Abiotic synthesis of purines and other heterocyclic compounds by the action of electrical discharges.

The synthesis of purines and pyrimidines using Oparin-Urey-type primitive Earth atmospheres has been demonstrated by reacting methane, ethane, and ammonia in electrical discharges. Adenine, guanine, 4-aminoimidazole-5-carboxamide (AICA), and isocytosine have been identified by UV spectrometry and paper chromatography as the products of the reaction. The total yields of the identified heterocyclic compounds are 0.0023%. It is concluded that adenine synthesis occurs at a much lower concentration of hydrogen cyanide than has been shown by earlier studies. Pathways for the synthesis of purines from hydrogen cyanide are discussed, and a comparison of the heterocyclic compounds that have been identified in meteorites and in prebiotic reactions is presented.

Biological Evolution↗
PubMed2006

A novel kind of nitrogen heterocycle compound induces apoptosis of human chronic myelogenous leukemia K562 cells.

The effects of a novel kind of nitrogen heterocycle compound, which was synthesized in our laboratory previously, on human chronic myelogenous leukemia K562 cells were investigated. The morphological changes were observed by Acridine orange (AO) staining. The screened results through DNA fragmentation and the Annexin V-FITC/PI staining assay showed that compound 8 blocked cell cycles at G(1) phase which led to apoptosis. The increase of caspase-3, 8, and 9 was detected, indicating that both of death-receptor and mitochondria-pathways were activated. Compound 8 induced a biphasic alteration in mitochondrial membrane potential of K562 cells. A dramatic elevation of Ca(2+) was also observed. In addition, a transient increase of ROS was also involved in the process. This study showed that compound 8 might be a potential chemopreventive agent for chronic myelogenous leukemia. It would guide our future work to synthesize more compounds derived from compound 8, which might have better effect, and to determine the target protein. Moreover, it might also provide a background mechanism for the introduction of this new type of promising therapeutic agent.

Apoptosis↗