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PubMedDate not supplied

Mutagenicity of mono-nitrobenzene derivatives in the Ames test and rec assay.

The mutagenicities of 37 mono-nitrobenzene derivatives, i.e. the ortho, meta, and para isomers of nitrotoluene, nitrophenol, nitroaniline, nitroanisole, nitrobenzaldehyde, nitrobenzyl chloride, nitrobenzonitrile, nitroacetophenone, nitrophenetol, nitrobenzoic acid, nitrophenylacetic acid, and nitrocinnamic acid and p-nitrothiophenol, were tested in the Ames test and rec assay. The rec assay gave more positive results than the Ames test. The para-substituted nitrobenzene derivatives were always positive in the rec assay as were all but 2 in the Ames test, while 5 out of 12 ortho and meta derivatives were mutagenic in the Ames test. The results of the present study, combined with those of the previous study, are discussed with special reference to the structure-mutagenicity relationships.

Acetophenones↗
PubMed2006

Synthesis and oxidation of carboxylate-bridged diiron(II) complexes with substrates tethered to primary alkyl amine ligands.

The synthesis and crystallographic characterization of a series of diiron(II) complexes with sterically hindered terphenyl carboxylate ligands and alkyl amine donors are presented. The compounds [Fe(2)(mu-O(2)CAr(Tol))(4)(L)(2)] (L=NH(2)(CH(2))(2)SBn (1); NH(2)(CH(2))(3)SMe (2); NH(2)(CH(2))(3)CCH (3)), where (-)O(2)CAr(Tol) is 2,6-di(p-tolyl)benzoate, and [Fe(2)(mu-O(2)CAr(Xyl))(2)(O(2)CAr(Xyl))(2)(L)(2)] (L=NH(2)(CH(2))(3)SMe (4); NH(2)(CH(2))(3)CCH (5)), where (-)O(2)CAr(Xyl) is 2,6-di(3,5-dimethylphenyl)benzoate, were prepared as small molecule mimics of the catalytic sites of carboxylate-bridged non-heme diiron enzymes. The compounds with the (-)O(2)CAr(Tol) carboxylate form tetrabridged structures, but those containing the more sterically demanding (-)O(2)CAr(Xyl) ligand have only two bridging ligands. The ancillary nitrogen ligands in these carboxylate-rich complexes incorporate potential substrates for the reactive metal centers. Their oxygenation chemistry was studied by product analysis of the organic fragments following decomposition. Compound 1 reacts with dioxygen to afford PhCHO in approximately 30% yield, attributed to oxidative dealkylation of the pendant benzyl group. Compound 3 decomposes to form Fe(II)Fe(III) and Fe(III)Fe(IV) mixed-valence species by established bimolecular pathways upon exposure to dioxygen at low temperatures. Upon decomposition, the alkyne-substituted amine ligand was recovered quantitatively. When the (-)O(2)CAr(Tol) carboxylate was replaced by the (-)O(2)CAr(Xyl) ligand in 5, different behavior was observed. The six-coordinate iron(III) complex with one bidentate and two monodentate carboxylate ligands, [Fe(O(2)CAr(Xyl))(3)(NH(2)(CH(2))(3)CCH)(2)] (6), was isolated from the reaction mixture following oxidation.

Amines↗
PubMed2002

Diastereoselective Diels-Alder reactions of alpha-fluorinated alpha,beta-unsaturated carbonyl compounds: chemical consequences of fluorine substitution. 2.

Two alpha-fluoro alpha,beta-unsaturated carbonyl compounds, i.e., benzyl 2-fluoroacrylate (3) and 2-fluorooct-1-en-3-one (4), as well as the corresponding nonfluorinated parent compounds, were synthesized and subjected to Diels-Alder reactions with cyclopentadiene. The cycloadditions were conducted thermally, microwave-assisted, and Lewis acid-mediated (TiCl(4)). The fluorinated dienophiles exhibited a lower reactivity and exo diastereoselectivity, while the corresponding nonfluorinated parent compounds reacted endo selectively. DFT calculations suggest that kinetic effects of fluorine determine the stereoselectivity rather than higher thermodynamic stability of the exo products.

Journal Article↗
PubMed1984

Synthesis of 3-hydroxy-2- and -4-pyridone nucleosides as potential antitumor agents.

The ribo- and arabinofuranosyl nucleosides of antitumor active 2- and 4-pyridones 1a and 2a were prepared by direct condensation of the silylated bases with either 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose (4a) or 2,3,5-tri-O-benzyl-1-p-nitrobenzoyl-D-arabinofuranose (7) in the presence of trimethylsilyl triflate (Me3SiOTf). In the case of the arabinofuranosyl nucleosides, separation of the alpha and beta anomers was accomplished at the stage of O-benzyl-protected compounds (8b + 9b, and 10b + 11b) after chemical functionalization of the 3-hydroxy group of the pyridone aglycons with acetyl and benzyl groups, respectively. Deblocking of the protected ribo- and arabinofuranosyl nucleosides was performed by the standard methods. In vitro activity against P-388 cells in culture indicated that the 4-pyridone riboside 6d was the most active member of the series with a twofold lower ID50 than the parent pyridone 2a. However, this and all the other compounds tested in this series showed no activity against the in vivo model system of murine P-388 leukemia at doses ranging from 25 to 400 mg/kg qd 1-5.

Animals↗
PubMed1974

Mechanism of inhibition of eukaryotic protein synthesis by trichothecene fungal toxins.

The 12,13-epoxytrichothecenes, a group of sesquiterpenoid fungal antibiotics, inhibit protein synthesis in eukaryotic cells but do not share a common mode of action. Trichodermin stabilizes polyribosomes, prevents their disaggregation by puromycin, and also prevents the release of nascent peptides from ribosomes by puromycin. Nivalenol, T-2 toxin, and verrucarin A cause rapid and almost quantitative breakdown of polyribosomes in H-HeLa cells, a process which is inhibited by anisomycin, cycloheximide, or trichodermin. Similar effects of trichodermin, nivalenol, and verrucarin A are also observed in yeast spheroplasts. We conclude that nivalenol, T-2 toxin, and verrucarin A are potent and highly selective inhibitors of polypeptide chain initiation in eukaryotes, whereas trichodermin inhibits chain elongation and (or) termination. We have compared the structural formulae of various trichothecenes and suggest that the presence of substituents on carbon-15 of the common trichothecene ring may be important in determining the precise modes of action of this group of compounds.

Acremonium↗
PubMed2006

Synthesis of furopyrazole analogs of 1-benzyl-3-(5-hydroxymethyl-2-furyl)indazole (YC-1) as novel anti-leukemia agents.

As part of our continuing search for potential anticancer drug candidates in YC-1 analogs, several 1-benzyl-3-(substituted aryl)-5-methylfuro[3,2-c]pyrazoles were synthesized and evaluated for their cytotoxicity against HL-60 cell line. Among these compounds, 1-benzyl-3-(5-hydroxymethyl-2-furyl)-5-methylfuro[3,2-c]pyrazole (1) showed more potency than YC-1. Through investigation of action mechanism, it was found that compound 1 induced terminal differentiation of HL-60 cells toward granulocyte lineage and promoted HL-60 cell differentiation by regulation of Bcl-2 and c-Myc proteins. Meanwhile, compound 1 also demonstrated apoptosis inducing effect. Such anti-leukemia mechanism of action is apparently different from that of YC-1 which mainly works by inducing apoptosis, but not cell differentiation. Therefore, compound 1 is identified here as a new lead compound of cell differentiating agent and apoptosis inducer for further development of new anti-leukemia agents.

Antineoplastic Agents↗
PubMed1997

Molecular rigidity and potency of bispyridinium type allosteric modulators at muscarinic M2-receptors.

Several bispyridinium compounds have been shown to be potent allosteric modulators of ligand binding to muscarinic M2-receptors. ,,Uno compounds" are benzyl derivatives of the bispyridinium "TMB4" (trimethylene-bis-[4-hydroxy-iminomethyl-pyridinium]). To gain more insight into structure activity relationships, eleven derivatives with varying structure of the oxime-linked aromatic substituent were tested for their ability to inhibit the equilibrium-binding of [3H]N-methylscopolamine ([3H]NMS) in guinea pig cardiac membranes and to retard [3H]NMS-dissociation allosterically. At a concentration of 3 microM, all compounds reduced [3H]NMS-binding to about 40 % of the control level, indicating a similar potency to inhibit the association of [3H]NMS. Allosteric retardation of [3H]NMS-dissociation required higher concentrations. Comparing the effects of the compounds at 30 and 300 microM, respectively, revealed considerable differences in potency. Therefore, the concentration-dependency of the delay of [3H]NMS-dissociation was determined for selected compounds. The results indicate that introduction of a benzyl-moiety into TMB4 leads to a 20-fold increase in allosteric potency. A further increment by a factor of 10 is obtained with the 2,6-dichlorobenzyl-substitution and with the naphthyl-derivative. The other compounds were less potent. An inverse correlation was found between the rotational freedom of the aromatic substituent and the allosteric potency. In conclusion, the aromatic moiety of non-symmetric bispyridinium-type modulators does not seem to be part of the pharmacophore involved in the inhibitory effect on the association of [3H]NMS. In contrast, a rigid aromatic lateral moiety appears to be essential for the interaction with the recognition site mediating the allosteric delay of [3H]NMS dissociation from muscarinic M2-receptors.

Allosteric Regulation↗
PubMedDate not supplied

Aspergillus nidulans as a test organism for chemical mutagens.

In the 3 strains of Aspergillus nidulans used, BC reduced survival most and 4HMB least. Similar trends were found when the effect on gene conversion was studied in a diploid strain and point mutation was scored in a haploid strain. None of the compounds had any effect on mitotic segregation.

Aspergillus nidulans↗