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PubMed1993

Endonuclease-sensitive DNA modifications induced by acetone and acetophenone as photosensitizers.

Repair endonucleases, viz. endonuclease III, formamidopyrimidine-DNA glycosylase (FPG protein), endonuclease IV, exonuclease III and UV endonuclease, were used to analyse the modifications induced in bacteriophage PM2 DNA by 333 nm laser irradiation in the presence of acetone or acetophenone. In addition to pyrimidine dimers sensitive to UV endonuclease, 5,6-dihydropyrimidines (sensitive to endonuclease III) and base modifications sensitive to FPG protein were generated. The level of the last in the case of acetone was 50% and in the case of acetophenone 9% of the level of pyrimidine dimers. HPLC analysis of the bases excised by FPG protein revealed that least some of them were 8-hydroxyguanine (7,8-dihydro-8-oxoguanine). In the damage induced by direct excitation of DNA at 254 nm, which was analysed for comparison, the number of FPG protein-sensitive base modifications was only 0.6% of that of the pyrimidine dimers. Mechanistic studies demonstrated that the formation of FPG protein-sensitive modifications did not involve singlet oxygen, as the damage was not increased in D2O as solvent. Hydroxyl radicals, superoxide and H2O2 were also not involved, since the relative number of single strand breaks and of sites of base loss (AP sites) was much lower than in the case of DNA damage induced by hydroxyl radicals and since the presence of SOD or catalase had no effect on the extent of the damage. However, the mechanism did involve an intermediate that was much more efficiently quenched by azide ions than the triplet excited carbonyl compounds and which was possibly a purine radical. Together, the data indicate that excited triplet carbonyl compounds react with DNA not only by triplet-triplet energy transfer yielding pyrimidine dimers, but also by electron transfer yielding preferentially base modifications sensitive to FPG protein, which include 8-hydroxyguanine.

Acetone↗
PubMed2001

Structure-dependent reactivity of oxyfunctionalized acetophenones in the photooxidation of DNA: base oxidation and strand breaks through photolytic radical formation (spin trapping, EPR spectroscopy, transient kinetics) versus photosensitization (electron transfer, hydrogen-atom abstraction).

The photooxidative damage of DNA, specifically guanine oxidation and strand-break formation, by sidechain-oxyfunctionalized acetophenones (hydroxy, methoxy, tert-butoxy and acetoxy derivatives), has been examined. The involvement of triplet-excited ketones and their reactivity towards DNA has been determined by time-resolved laser-flash spectroscopy. The generation of carbon-centered radical species upon Norrish-type I cleavage has been assessed by spin-trapping experiments with 5,5-dimethyl-1-pyrroline N-oxide, coupled with electron paramagnetic resonance spectroscopy. The observed DNA-base oxidation and strand-break formation is discussed in terms of the peroxyl radicals derived from the triplet-excited ketones by alpha cleavage and molecular oxygen trapping, as well as direct interaction of the excited states by electron transfer and hydrogen-atom abstraction. It is concluded that acetophenone derivatives, which produce radicals upon photolysis, in particular the hydroxy (AP-OH) and tert-butoxy (AP-O(t)Bu) derivatives, are more effective in oxidizing DNA.

Acetophenones↗
PubMed2002

Antifungal evaluation of bis Mannich bases derived from acetophenones and their corresponding piperidinols and stability studies.

The development of resistance to current antifungal therapeutics drives the search for effective new agents. The fact that some acetophenone-derived Mannich bases had shown antifungal activities in our previous studies led us to design and synthesize acetophenone-derived bis Mannich bases, B1-B5, bis(beta-aroylethyl)methylamine hydrochlorides, to evaluate their antifungal activity. These bis Mannich bases were then converted to the corresponding piperidinols, C1-C5, which are structural isomers of bis derivatives, 3-aroyl-4-aryl-1-methyl-4-piperidinol hydrochlorides, to see alterations in biological activity. A stability study of B1 and Cl was also carried out to estimate whether they alkylate the thiols. All compounds studied have shown antifungal activity, especially against dermatophytes (Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton tonsurans, and Microsporum canis), in the concentration range studied (2-128 microng/ml). The activity was especially apparent against T. tonsurans. All compounds had at least equal antifungal activity compared with the reference compound amphotericin-B against T. tonsurans. Bis Mannich bases were generally found to be more potent compounds than their structural isomer piperidinols. The results of our stability studies suggest that thiol alkylation may contribute to the antifungal activity of the Mannich bases synthesized. Even though all compounds showed antifungal activity against dermatophytes, bis Mannich bases B1, B2, B4, and B5 appear to have potential for developing novel antifungal agents against dermatophytes.

Acetophenones↗
PubMed2005

Biotransformation of benzaldehyde-type and acetophenone-type derivatives by Pharbitis nil hairy roots.

The glucosylation of some coumarin and flavone derivatives on incubation with the hairy roots of morning glory (Pharbitis nil) was previously reported. We further studied the biotransformation of benzaldehyde- and acetophenone-type derivatives. Vanillin and isovanillin were reduced to alcoholic derivatives and glucosylated at the phenolic and the alcoholic hydroxyl groups. In the case of 3,4-dihydroxybenzaldehyde, the formyl group was reduced and the 3-hydroxyl or 4-hydroxyl groups were glucosylated to give monoglucosides. The 3-hydroxyl group was predominantly glucosylated to the 4-hydroxyl group. 4-beta-D-Glucopyranosyloxy-3-methoxybenzylalcohol was obtained in low yield. In time-course experiments with vanillin, it was found that the high-level reduction of the formyl group and glucosylation of the phenolic hydroxyl group occurred, and finally 4-O-beta-D-glucopyranosylvanillylalcohol was obtained as the main product. In the case of 3,4-dimethoxybenzaldehyde, 3,4,5-trimethoxybenzaldehyde, and salicylaldehyde, the formyl groups were reduced, and then the hydroxyl groups at the benyl position were glucosylated to give alcoholic glucosides in relatively high yields. In 4-hydroxy-3-methoxyacetophenone, the 4-hydroxyl group was glucosylated and two dimerized glucosides, biphenyl and biphenylether types, were obtained in low yields. In acetophenone, 1-beta-D-glucopyranosyloxy-1-phenylethane and 2-beta-D-glucopyranosyloxyacetophenone were obtained. As mentioned above P. nil hairy roots showed various biotransformative activities including glucosylation of phenolic and benzylic hydroxyl groups, reduction of the formyl group near the benzene ring, and phenol oxidation dimerization. The glucosylation reaction was especially interesting for the production of valuable glucosides.

Acetophenones↗
PubMed1986

Metabolic N-hydroxylation of substituted acetophenone imines. I. Evidence for formation of isomeric oximes.

A series of chemically stable substituted acetophenone imines and their potential N-hydroxylated metabolites (i.e., oximes) have been synthesized and characterized by spectroscopic methods. The enzymic N-hydroxylation of acetophenone imines in vitro has been demonstrated as a general metabolic pathway in several mammalian species including the guinea-pig. The oxime metabolites were formed as mixtures of two geometric isomers, Z (syn-phenyl) and E (anti-phenyl), wherein the phenyl and hydroxyl group are cis and trans to each other respectively. The E (anti-phenyl) isomer was the quantitatively predominant isomeric form metabolically produced by all species studied. The relative proportions of the E and Z isomers in metabolic mixtures were found to be species dependent.

Acetophenones↗
PubMed2000

Ring-hydrogen participation in the keto--enol isomerization of the acetophenone radical cation

Molecular ions obtained from acetophenone have been observed to undergo proton transfer reactions in competition with unimolecular blackbody dissociation in a Fourier transform ion cyclotron resonance spectrometer provided with an in situ high temperature blackbody source. The ionizing energy dependence of these two processes and generation of the enol molecular ion by fragmentation of butyrophenone reveal that the keto ion undergoes blackbody dissociation exclusively while the enol ion promotes fast proton transfer reactions and undergoes very slow blackbody induced dissociation. Experiments with labeled acetophenone either on the methyl group or on the ring reveal that the enol ions can transfer both H+ and D+ suggesting that the mechanism responsible for the tautomerization process of these radical cations may involve scrambling of the methyl and ring hydrogens, or more than one mechanism. Theoretical calculations at the B3LYP level predict that the most favorable pathway for unimolecular isomerization of the keto ion involves initial migration of an ortho hydrogen to the carbonyl. The subsequent rearrangement to the enol form is calculated to require enough internal energy that would allow hydrogen walk around the benzene ring in agreement with the experimental results. The possibility that isomerization may also occur by a direct 1,3-hydrogen migration is also explored in terms of possible excited electronic states of the ion.

Journal Article↗
PubMed2006

13C NMR chemical shifts of carbonyl groups in substituted benzaldehydes and acetophenones: substituent chemical shift increments.

13C NMR Substituent chemical shift (SCS) increments have been determined for the carbonyl carbon of a variety of substituted benzaldehydes and acetophenones. The 13C NMR chemical shift of the carbonyl carbon can be predicted for many di- and trisubstituted benzaldehydes and acetophenones through simple additivity of the SCS increments. The magnitude and sign of the SCS increments have been explored using Hartree-Fock 6-31G* calculations to determine the natural atomic charges of the carbonyl carbon. When a substituent capable of intermolecular hydrogen bonding is present, deviations from additivity on the order of 2 ppm are observed in dilution experiments; deviations of up to 6 ppm can result from intramolecular hydrogen bonding.

Journal Article↗
PubMed1997

Infrared Study of Substituted Acetophenones Adsorbed on Silica

Infrared spectra are reported of silica preheated at 873 K and exposed at 295 K to the vapors of four acetophenones (H, 4-Me, 4-OMe, and 4-NO2). Surface-adsorbate interactions involved hydrogen bonding between isolated silanol groups and carbonyl groups, the strength of the hydrogen bonds being related to the electronic effects of the acetophenone ring substituents. The 4-OMe compound also generated SiOH···OMe hydrogen bonds probably via a bridging structure involving two silanol groups perturbed simultaneously by each adsorbed molecule. The mode of adsorption of substituted benzene derivatives on silica is strongly dependent on the electronic effects of the substituents on each other and on the aromatic pi-electron charge density. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed2006

IR-spectroscopic characterization of acetophenone complexes with Fe+, Co+, and Ni+ using free-electron-laser IRMPD.

The gas-phase complexes M(+)(acet)(2), where M is Fe, Co, or Ni and acet is acetophenone, were studied spectroscopically by infrared multiple-photon dissociation (IRMPD) supported by density functional (DFT) computations. The FELIX free electron laser was used to give tunable radiation from approximately 500 to 2200 cm(-1). The spectra were interpreted to determine the metal-ion binding sites on the ligands (oxygen (O) or ring (R)) and to see if rearrangement of the ligand(s) to toluene plus CO occurred. For Ni(+), O binding was found to predominate (similar to the previously studied Cr(+) case), with less than approximately 10% of R-bound ligands in the population. For Co(+), a roughly equal mixture of R-bound and O-bound ligands was present; based on the computed thermochemistry, the OR complex was considered likely to predominate. Fe(+) complexes appeared largely O-bound, but with clear evidence for some R-binding. The exceptionally large extent of R binding for Co(+) highlights the special affinity of this metal ion for aromatic ring ligands. In contrast, the predominant O binding for Ni(+) emphasizes the especially high metal-ion affinity of the O site of acetophenone compared with other ligands such as anisole where R binding of Ni(+) predominates. The spectra did not indicate significant intracomplex rearrangement of ligands to toluene plus CO, and in particular for the Co(+) case the absence of a metal-bound C triple bond O stretching peak near 2100 cm(-1) strongly ruled out such a rearrangement.

Journal Article↗
PubMed2003

Palladium-catalyzed reaction of aryl iodides with acetic anhydride. A carbon monoxide-free synthesis of acetophenones.

[reaction: see text] The palladium-catalyzed reaction of aryl iodides with acetic anhydride provides a straightforward and experimentally simple carbon monoxide-free route to acetophenones. The reaction tolerates a wide range of functionalized aryl iodides. Acetophenones are isolated in excellent yield with a variety of neutral, slightly electron-rich, and slightly electron-poor aryl iodides, whereas moderate yields are obtained with aryl iodides containing strongly electron-withdrawing substituents.

Journal Article↗
PubMed2007

Glutathione transferase omega 1 catalyzes the reduction of S-(phenacyl)glutathiones to acetophenones.

S-(Phenacyl)glutathione reductase (SPG-R) plays a significant role in the biotransformation of reactive alpha-haloketones to nontoxic acetophenones. Comparison of the apparent subunit size, amino acid composition, and catalysis of the reduction of S-(phenacyl)glutathiones indicated that a previously described rat SPG-R (Kitada, M., McLenithan, J. C., and Anders, M. W. (1985) J. Biol. Chem. 260, 11749-11754) is homologous to the omega-class glutathione transferase GSTO1-1. The available data show that the SPG-R reaction is catalyzed by GSTO1-1 and not by other GSTs, including the closely related GSTO2-2 isoenzyme. In the proposed reaction mechanism, the active-site cysteine residue of GSTO1-1 reacts with the S-(phenacyl)glutathione substrate to give an acetophenone and a mixed disulfide with the active-site cysteine; a second thiol substrate (e.g., glutathione or 2-mercaptoethanol) reacts with the active-site disulfide to regenerate the catalytically active enzyme and to form a mixed disulfide. A new spectrophotometric assay was developed that allows the rapid determination of SPG-R activity and specific measurement of GSTO1-1 in the presence of other GSTs. This is the first specific reaction attributed to GSTO1-1, and these results demonstrate the catalytic diversity of GSTO1-1, which, in addition to SPG-R activity, catalyzes the reduction of dehydroascorbate and monomethylarsonate(V) and also possesses thioltransferase and GST activity.

Animals↗
PubMed1990

Bacterial degradation of ring-chlorinated acetophenones.

Two strains, Alcaligenes sp. strain ACA and Pseudomonas fluorescens ACB, isolated from acetophenone and 4'-hydroxyacetophenone enrichments, respectively, cometabolize a range of chlorinated acetophenones (CAs). A biological Baeyer-Villiger reaction converts the CA to chlorophenyl acetate. This is evident only in the presence of an esterase inhibitor, since the CA is normally rapidly hydrolyzed to a chlorophenol which has the same substitution pattern as the original ketone. The oxygenase that attacks the ketone uses NADPH in the incorporation of one atom of O(2) and is strongly inhibited by phenols that bear an ortho or meta chlorine or bromine, but much less by cresols or phenol itself. A feedback phenomenon may thus account for the inability of strain ACA to grow on CAs, which also fail to induce the cells for their own metabolism.

Journal Article↗
PubMed1998

Anticonvulsant activity of thioureido derivatives of acetophenone semicarbazone.

A series of thioureido derivatives of acetophenone semicarbazone were synthesized and evaluated for anticonvulsant activity. Some compounds provided significant protection against maximal electroshock (MES) and subcutaneous pentylenetetrazol (scPTZ) induced seizures. The compound (2e) was the most active compound in the series with a dose of 30 mg kg-1 and ED50 23.5 mg kg-1 and equipotent to phenytoin ED50 23.2 mg kg-1. The toxicity of the compounds was assessed by determination of their approximate TD50 and LD50 values in order to have a better assessment of their pharmacological profile and protective index.

Acetophenones↗
PubMed1984

Specific cation effect in the reaction of nitroprusside with cysteine, acetophenone and sulfite (Legal and Boedeker reaction).

The colour formation of cysteine (I), acetophenone (II) and sulfite (III) with the sodium and tetrabutylammonium (TBA) salt of nitroprusside (NP2-) in aqueous solution was studied. The intensity of colour formation depends strongly on the nature and concentration of the cations and increases in the order TBA less than Li less than Na less than K less than Rb less than Cs (in case of cysteine TBA and Li are interchanged). This specific cation effect was known for the Boedeker reaction (III) and is now also demonstrated for the Legal reaction (I and II). The adduct formation between NP2- and I to III is based on an anion-anion interaction. The role of the cation is to reduce the Coulombic repulsion between the reactants by ion-pair formation. The efficiency of ion-pair formation corresponds with the order given before except for TBA, which behaves divergently.

Acetophenones↗
PubMed1985

Aldose reductase inhibitors: flavonoids, alkaloids, acetophenones, benzophenones, and spirohydantoins of chroman.

The inhibitory activity of various compounds, including 12 flavonoids, 10 alkaloids, 15 benzophenones, 5 acetophenones, and 7 spirohydantoins of chroman, was tested on rabbit lens aldose reductase, an enzyme involved in complications of diabetes. Almost all compounds tested were found to inhibit the enzyme at low concentrations (10(-5) M). The most potent inhibitor was 2R,4S-6-chloro-2-methylspiro(chroman-4,4'-imidazo-lidine+ ++)-2',5'-dione with an I50 value of 4.7 x 10(-8) M; other spirohydantoins showed similar potency. Polyhydroxybenzophenones were also potent inhibitors with an I50 value of about 10(-7) M. The possible structure-inhibitory activity relationships of the compounds tested are discussed.

Acetophenones↗
PubMed1992

Alpha-(phenylselenenyl)acetophenone derivatives with glutathione peroxidase-like activity. A comparison with ebselen.

Here we describe a new class of organoselenium compounds possessing glutathione peroxidase-like activity. The parent compound, alpha-(phenylselenenyl)acetophenone (PSAP), increased the rate of reaction of glutathione with H2O2, tert-butylhydroperoxide, cumene hydroperoxide, linoleic acid hydroperoxide and dilinoleyl lecithin hydroperoxide by 7.0, 25.1, 34.1, 19.1 and 8.4-fold, respectively, as assessed by the oxidized glutathione (GSSG) reductase enzyme assay. Direct assay of the removal of hydrogen peroxide and glutathione from reaction mixtures confirmed the peroxidase-like activities of these selenoorganic compounds, but indicate that the conventional coupled GSSG reductase assay may be unsuitable for the assessment of the catalytic capacity of PSAP and Ebselen. One possible mechanism of catalysis by PSAP involves an initial oxidation at selenium. Thiol may then react with the selenoxide to yield a selenium (II) compound, H2O and a disulfide. Compounds derived from PSAP may provide potential selenium-based anti-inflammatory agents.

Acetophenones↗