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Alcohol metabolism's various processes create harmful compounds that contribute to cell and tissue damage. In particular, the enzyme cytochrome P450 2E1 (CYP2E1) plays a role in creating a harmful condition [...]

Substantial evidence now exists that intrinsic free-radical scavenging contributes to the receptor-independent neuroprotective effects of estrogens. This activity is inherently associated with the presence of a phenolic A-ring in the steroid. We report a previously unrecognized antioxidant cycle that maintains the 'chemical shield' raised by estrogens against the most harmful reactive oxygen species, the hydroxyl radical (*OH) produced by the Fenton reaction. In this cycle, the capture of *OH was shown to produce a nonphenolic quinol with no affinity to the estrogen receptors. This quinol is then rapidly converted back to the parent estrogen via an enzyme-catalyzed reduction by using NAD(P)H as a coenzyme (reductant) and, unlike redox cycling of catechol estrogens, without the production of reactive oxygen species. Due to this process, protection of neuronal cells against oxidative stress is also possible by quinols that essentially act as prodrugs for the active hormone. We have shown that the quinol obtained from a 17[beta]-estradiol derivative was, indeed, able to attenuate glutamate-induced oxidative stress in cultured hippocampus-derived HT-22 cells. Estrone quinol was also equipotent with its parent estrogen in reducing lesion volume in ovariectomized rats after transient middle carotid artery occlusion followed by a 24-h reperfusion. These findings may establish the foundation for a rational design of neuroprotective antioxidants focusing on steroidal quinols as unique molecular leads. hydroxyl radical | ischemia | prodrug

Research has been conducted on isolated light-harvesting proteins. The study of light-mediated degradation of these proteins and of oxygen free radicals involvement in the process has been carried out, and the results demonstrate that active oxygen is involved in light-harvesting protein degradation in these isolated subcomplexes.

Research has been conducted on peroxynitrite. The hypothesis that free radicals can be produced from this peroxynitrite has been tested, and the use of electron paramagnetic resonance spin trapping methodology in investigating interactions of peroxynitrite with human erythrocytes is described.

Experiments were designed to test whether nitric oxide (NO) and peroxynitrite trigger delayed coronary endothelial protection induced by preconditioning (PC) in rats. Prolonged ischemia reperfusion markedly reduced the response of isolated coronary arteries to acetylcholine, and this was prevented by PC performed 24 h earlier. The NO synthase (NOS) inhibitor [N.sup.G]-nitro-L-arginine methyl ester (L-NAME) administered during PC abolished its delayed endothelial protective effect, whereas the inducible NOS inhibitor N-(3(aminomethyl)benzyl) acetaminide had no effect. Delayed endothelial PC was also abolished by the peroxynitrite scavengers selenomethionine or uric acid given during PC. In parallel, the NO/peroxynitrite donor S-morpholinosydnonimine and authentic peroxynitrite, administered 24 h before prolonged ischemia-reperfusion mimicked endothelial PC, whereas the NO donor S-nitroso-N-acetylpencillamine had no effect. This suggests that peroxynitrite is an essential trigger of the delayed coronary endothelial protection induced by PC in rat hearts. delayed preconditioning; nitric oxide; free radicals

Research has been conducted on the stable sterically hindered nitroxyl radicals. The study of the radicals's reaction with allylic and benzylic substrates has been carried out and the details are presented.

Research has been conducted in murine proapoptotic proteins Bax which has been expressed in Kluyveromyces lactis. The role of this protein in cell survival and reactive oxygen species production has been investigated and the the results are reported.

Research has been conducted on Poria placenta wood degradation. The role of tropolone in this degradation has been investigated and the hypothesis that tropolone may act as a chelator, a chemical radical scavanger or as an antioxidant has been tested and discussed.

Research has been conducted on the chromium(III) and nickel(II) imino nitroxide complexes with different beta-diketonates. The synthesis, structural and magnetic characteristics and optical properties of these complexes have been examined and the details are presented.

Research has been conducted on 3-indolylacyl radicals. These radicals have been generated from phenyl selenoesters and their participation in the intermolecular addition reactions to carbon-carbon double bonds under nonreductive and reductive conditions has been investigated and discussed.

Research has been conducted on hydroxyalkyl radicals. The chiral auxiliary for these radicals has been developed and the effect of the ether linkage on this auxiliary which precludes its removal under mild conditions is described.

Research has been conducted on the 4,4'-(1,n-alkanediyl)bisbenzyl biradicals. The production of these compounds from the Norrish type-I reaction of [3,n]paracyclophan-2-ones in giving paracyclophans and the study of the biradicals' behavior are discussed.

Research has been conducted on the benzenethiol. The addition reaction of this compound to 1',2'-unsaturated uridine's glycan portion in the presence of Et (sub)3 N has been investigated and the results indicate the involvement of the thiolate's nucleophilic attack at the anomeric position.

Research has been conducted on the Lewis acids. The hypothesis that these acids can be used as promoters of the radical addition reactions and can affect the atom transfer processes has been tested and the details are reported.

Research has been conducted on the biomolecules' photooxidative damage. The effect of the UVA-irradiation on the photo-Fenton reagents has been investigated and the results indicate that this irradiation releases radicals inducing strand breaks.

Research has been conducted on the free radical cyclization reactions. Results indicate that tributylin hydride and tris(trimethylsilyl)silane are the promoters of the sequential or cascade free radical cyclization reactions of alkynes or dienoate tethered vinyliodides.

Research has been conducted on the supramolecular complexes. Results indicate that the photolysis of these complexes leads to the radical supramolecular complexes detected by CW-EPR spectroscopy and provides radicals' dynamics information.

Research has been conducted on the halogen atoms. The role of this atom as a leaving group in Bu (sub)3 SnH-mediated radical cyclization of N-(cyclohex-1-enyl) alpha-halo amides has been investigated and the details are reported.

Research has been conducted on the (+)-pinoresinol-forming dirigent protein. The characterization of this protein has been carried out via the use of the cross-linking agents and mass spectrometry in producing accurate molecular masses and the details are reported.

Research has been conducted on the 1,8-naphthalene diol and its 4-methoxy derivative. Results indicate that these compounds are the H-atom transfer compounds in terms of their rate constants for H-atom transfer or the antioxidants during inhibited styrene autoxidation.

Research has been conducted on the adamantylideneadamantane and sesquihomoadamantene. The behavior of these isomeric olefins, their steric differences and the molecular structures of their cation radicals have been investigated and are discussed.

Research has been conducted on the models with the growing radical chains formed from diallylamine and diallylammonium monomers. The results of the radical cyclization reactions of these models investigated via the use of the density functional theory are presented.

Research has been conducted on the paramagnetic pyridine derivatives. The structural and magnetic analyses of these compounds have been carried out and the results indicate that the lattice rearrangement temperature dependence can be affected by the evolution of magnetic properties.

Research has been conducted on the tetraoxygenated triarylmethyl radical and the tetrathiatriarylmethyl radicals. The syntheses of these radicals and the preparation of the key intermediate compounds have been carried out and discussed.

Research has been conducted on the gamma-irradiated CCl (sub)3 F/n-alkane solutions. The studies of these solutions carried out via the use of the electron paramagnetic resonance spectroscopy and gas chromatographic analysis after melting are discussed.

The authors review the publications on the chemical reactivity and biological activity of various functional groups. The topics of interest include the chemical reactivity of nitro, amino, olefinic, hydroxy and carboxaldehyde functional groups.

The authors review the publications on polyvalent iodine compounds' organic chemistry. The topics of interest include different classes of polyvalent iodine compound and their synthetic application.

Research has been conducted on the heterovinyl-substituted diradicals. The EPR-spectral data for these diradicals generated from the azoalkanes photochemically are reported.

Research has been conducted on the isomeric 5-, 6-, 7-, 8-hydroxyquinolines and 5-hydroxyisoquinoline. The results of the superelectrophilic activation of these compounds by their reaction with cyclohexane and benzene are presented.

Research has been conducted on the 1,2,3,4-tetraphenylcyclobutane and oxane cycloreversion. Results indicate that this cycloreversion can be achieved via the use of the electron-transfer photosensitizes, such as (thia)pyrylium salts.

Research has been conducted on the chlorophylls' Willstatter allomerization reaction. The free-radical allomerization mechanism developed with the help of (super)18 O-labeling and mass spectrometry is described.

Research has been conducted on the thianthrene cation radical salts. The addition of these salts to cycloalkenes in acetonitrile has led to the formation of mono- and bisadducts and the addition mechanisms are discussed.

Research has been conducted on the peptide acetals. The results of biocyclization of these acetals via the phenyl group's nucleophilic reaction with endocyclic acyliminium ion are described.

Research has been conducted on the diradicals. The thermodynamic stabilities of the diradicals' triplet states in which nonbonding electrons occupy delocalized pi orbital have been investigated and the details are reported.

The authors review the publications on rare-earth ions. The topics of interest include spin states of rare-earth ions and the nature of magnetic coupling which involves gadolinium(III).

The mechanism by which the iron-binding protein, Dpr, confers oxygen tolerance on Streptococcus mutans is elucidated. Results suggest that Dpr in a ferritin-like iron-binding protein fashion may facilitate catalase- and heme-peroxidase-deficient bacterium grow under air by limiting Fenton reaction.

Research has been conducted on the acetone and ketodiester alpha-cleavage and decarbonylation reactions. The thermochemical analysis of these reactions has been carried out via the use of the density functional method and the radical-stabilizing abilities of the ketone substituents have been investigated.

Research has been conducted on the free radical cyclization and the ring-closing metathesis reaction. The analysis of these reactions has been carried out to synthesize enantiomerically pure medium-sized carbocycles from carbohydrates and the details are reported.

Research has been conducted on the prostaglandins. The route to the F (sub)2t -isoprostanes has been developed via the use of C20 precursor's biomimetic radical cyclization and the results demonstrate the formation of (15R)- and (15S)-F (sub)2t -isoprostane diastereoisomers.

Research has been conducted on the ribonucleotide reductase which catalyzes deoxyribonucleotide biosynthesis. Results suggest that sulfinyl radicals are important intermediates in the ribonucleotide reductase radical chemistry.

Research has been conducted on the beta-(phosphatoxy)alkyl rearrangement. The mechanism of the 4-phenyl-2-phenoxy-2-oxo-1,3,2-dioxophosphorinan-5-yl radical ring contraction has been investigated via stereochemical, (super)17 O-labeling and kinetic studies and the details are reported.

Research has been conducted on the ciguatoxin's (E)FGN ring system. The convergent synthetic route to this system has been developed and the results indicate that the synthesis involves convergent coupling used in producing dioxane acetal and the ring-closing metathesis used in producing hexahydrooxonine ring F.

Research has been conducted on the substituted epoxy ethers. The results of the intramolecular radical cyclization of these ethers carried out via the use of bis(cyclopentadienyl)titanium(III) chloride as the radical source are presented.

Research has been conducted on the enaminone esters. The aryl radical cyclization in these esters has been investigated and the results indicate that this cyclization has not occurred in N-phenyl enaminones.

Research has been conducted on the tyrosyl radicals generated via the prostaglandin H synthase-1 reaction with ethyl hydrogen peroxide. The study of these radicals carried out by the use of high-field/high frequency EPR spectroscopy is presented.