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In this manuscript we report a critical evaluation of the ability of natural DNA to mediate the nitroaldol (Henry) reaction at physiological temperature in pure water. Under these conditions, no background reaction took place (i.e., control experiment without DNA). Both heteroaromatic aldehydes (e.g., 2-pyridinecarboxaldehyde) and aromatic aldehydes bearing strong or moderate electron-withdrawing groups reacted satisfactorily with nitromethane obeying first order kinetics and affording the corresponding β-nitroalcohols in good yields within 24 h. In contrast, aliphatic aldehydes and aromatic aldehydes having electron-donating groups either did not react or were poorly converted. Moreover, we discovered that a number of metal-free organic buffers efficiently promote the Henry reaction when they were used as reaction media without adding external catalysts. This constitutes an important observation because the influence of organic buffers in chemical processes has been traditionally underestimated, Financial assistant by Universität Regensburg and SINCHEM Program (Erasmus Mundus Action 1 FPA 2013-0037) are gratefully acknowledged. D.D.D. thanks J.J. Marrero-Tellado for helpful discussions and DFG for the Heisenberg Professorship Award.

A novel C1-symmetric dinitrogen ligand was synthesized in high yield from commercially available (1R,2R,3R,5S)-(−)-isopinocampheylamine and 1-methyl-2- imidazolecarboxaldehyde. In combination with Cu(OAc)2∙H2O, this new ligand promote the reaction between nitromethane and aliphatic aldehydes with high yields (up to 97%) and moderate enantioselectivities (up to 67% ee). The reactions with benzaldehyde required prolonged reaction time that resulted in diminished yields, but accompanied with ee-values in the 55%–76% range.

One approach to achieve fast and efficient separations in packed column liquid chromatography (LC) is to reduce eddy diffusion and mass transfer resistance in the mobile phase using short columns packed with small particles. In this study, efficiencies of columns packed with 1.5 and 3.0 microm nonporous and porous particles were compared in reversed-phase LC using nitromethane and a protein as analytes. Nonporous particles provided overall higher efficiency at high linear velocities when nitromethane was used as solute; however, the efficiency difference diminished significantly when the particle size was reduced from 3 to 1.5 microm. Efficiencies for 1.5 microm nonporous particles were considerably higher than those for 1.5 microm porous particles at high linear velocities when a protein, alpha-chymotrypsinogen A (MW 25,000), was used as solute. In addition, the average retention factor for amylbenzene in a column packed with ACQUITY C(18) porous particles was approximately 16 fold higher than for Micra C(18) nonporous particles for aqueous mobile phase compositions containing from 40 to 75% acetonitrile. Pressure drop, sample loading capacity, and separation power were also evaluated and compared for porous and nonporous particles under practical conditions.

Acid-catalysed methanolysis of 3,4,5,6-tetra- O -acetyl-1,2-dideoxy- l - arabino -hex-1-enitol proceeds via a cascade set of consecutive reactions resulting in its regiospecific conversion to a mixture of α- and β- C - l -arabinofuranosylmethanal dimethyl acetals and a mixed internal methyl acetal. Structures of the final products of the overall process provide unique evidence that a kinetically controlled, five-membered-ring closure precedes a six-membered-ring closure in reversible systems capable of giving both five-membered and six-membered all-sp 3 -atom rings. Determination of the reaction intermediate enabled extension of the Nef reaction to C -glycosylnitromethanes. Protonated aci -nitro forms of C -glycosylnitromethanes that are resistant to the Nef reaction in aqueous acidic media undergo a modified Nef reaction in acidified methanol, and the corresponding C -glycosylmethanal dimethyl acetals with α- l -arabinopyranosyl, β- d -glucopyranosyl, β- d -galactopyranosyl, β- d -mannopyranosyl and β- l -rhamnopyranosyl configurations were obtained in moderate yields.

The Henry reaction with the easily available alpha-d-xylo-pentodialdose afforded a diastereomeric mixture of nitroaldoses with the alpha-d-gluco- and beta-l-ido-configuration, respectively, in good yield. When n-BuLi was used as the base, the reaction afforded the alpha-d-gluco-nitroaldose as the only product. The reduction of the nitro group in the alpha-d-gluco- and beta-l-ido-nitroaldoses, removal of the protecting groups and intramolecular reductive cyclo-amination afforded the corresponding (2S,3R,4R,5R) and (2S,3R,4R,5S) tetrahydroxyazepanes.

A study of C-nucleophilic substitution at the C4-position on pyrimidine and C6-position on 2'-deoxyguanosine to produce novel nucleosides is presented with the spectroscopic properties of their respective substitution products. C4-(1,2,4-triazol-1-yl) pyrimidine nucleosides 1 were treated with nitroalkanes, malononitrile, acetylacetone, ethyl nitroacetate, acetoacetate and cyanoacetate at 100 degrees C in dioxane in the presence of DBU resulting in the production of novel nucleosides 2-11. To explore the application of this methodology to purine chemistry, this approach was used to produce novel analogs from 2'-deoxyguanosine. We found that the triazolo derivative 12 undergoes C-nucleophilic substitution with nitromethane, malononitrile, acetylacetone, ethyl nitroacetate and cyanoacetate in the presence of potassium carbonate (K2CO3) in DMF at 100 degrees C to give novel nucleosides 13-17.

It has been shown that oxidatively modified forms of proteins accumulate during oxidative stress, aging, and in some age-related diseases. One of the unique features of a wide variety of routes by which proteins are oxidized is the generation of carbonyl groups. This paper reports a method for the isolation of oxidized proteins, which involves (1) biotinylation of oxidized proteins with biotin hydrazide and (2) affinity enrichment using monomeric avidin affinity chromatography columns. The selectivity of the method was validated by adding in vitro oxidized biotinylated BSA to a yeast lysate and showing that the predominant protein recovered was BSA. This method was applied to the question of whether large doses of 2-nitropropane produce oxidized proteins. A study of rat liver homogenates showed that animals dosed with 2-nitropropane produced 17 times more oxidized protein than controls in 6 h. Tryptic digestion of these oxidized proteins followed by reversed-phase chromatography and tandem mass spectrometry led to the identification of 14 peptides and their parent proteins. Nine of the 14 identified peptides were found to carry 1 or 2 oxidation sites and 5 of the 9 peptides were biotinylated. The significance of this affinity method is that it allows the isolation of oxidized proteins from the rest of the proteome and facilitates their identification. In some cases, it is even possible to identify the site of oxidation.

First-principles calculations that are based on spin-unrestricted density functional theory and the generalized gradient approximation have been used to study the adsorption of nitromethane and 1,1-diamino-2,2-dinitroethylene molecules on the Al(111) surface. The calculations employ (3 x 3) aluminum slab geometries and three-dimensional periodic boundary conditions. On the basis of these calculations, we have determined that both dissociative and nondissociative adsorption mechanisms are possible, depending on the molecular orientation and the particular surface sites involved. In the case of dissociative chemisorption, O-atom ion by Al surface atoms has been determined to be the dominant mechanism. The dissociated O atom forms strong Al-O bonds with the neighboring Al sites around the dissociation sites. In addition, the radical species obtained as a result of O-atom elimination remains bonded to the surface. In some instances, both O atoms of the nitro group dissociate and oxidize the aluminum surface. Finally, for the case of nondissociative adsorption, various N-O-Al bridge-type bonding configurations can be formed. On the basis of the data provided from these studies, it can be concluded that oxidation of the aluminum surface readily occurs, either by partial or complete dissociation of the O atoms from the NO 2 group.

In alkaline solutions, nitroalkanes (RCH2NO2) undergo deprotonation and rearrange to an aci anion (RHC=NO2-), which may function as a spin trap. Using electron paramagnetic resonance (EPR) spectroscopy, we have investigated suitability of aci anions of a series of nitroalkanes (CH3NO2, CH3CH2NO2, CH3(CH2)2NO2, and CH3(CH2)3NO2) to spin trap nitric oxide (*NO). Based on the observed EPR spectra, the general structure of the adducts, formed by addition of *NO to RHC=NO2-, was identified as nitronitroso dianion radicals of general formula [RC(NO)NO2]*2- in strong base (0.5 M NaOH), and as a mono-anion radical [RCH(NO)NO2]*- in alkaline buffers, pH 10-13. The hyperfine splitting on 14N in the -NO2 moiety (11.2-12.48 G) is distinctly different from the splitting on 14N in the -NO moiety of the adducts (5.23-6.5 G). The structure of the adducts was verified using 15N-labeled *NO, which produced radicals, in which triplet due to splitting on 14N (I = 1) in 14NO/aci nitro adducts was replaced by a doublet due to 15N (I = 1/2) in 15NO/aci nitro adducts. EPR spectra of aci nitromethane/NO adduct recorded in NaOH and NaOD (0.5 M) showed that the hydrogen at alpha-carbon can be exchanged for deuterium, consistent with structures of the adducts being [CH(NO)NO2]*2- and [CD(NO)NO2]*2-, respectively. These results indicate that nitroalkanes could potentially be used as prototypes for development of *NO-specific spin traps suitable for EPR analysis.

Caloric restriction is a potent experimental manipulation that extends mean and maximum life span and delays the onset and progression of tumors in laboratory rodents. While caloric restriction (CR) clearly protects the genome from deleterious damage, the mechanism by which genomic stability is achieved remains unclear. We provide evidence that CR promotes genomic stability by increasing DNA repair capacity, specifically base excision repair (BER). CR completely reverses the age-related decline in BER capacity (P

A need exists for whole animal toxicity, mutagenesis, and carcinogenesis models that are alternative to the traditional rodent test models and that are economical, sensitive, and scientifically acceptable. Among small fish models, the Japanese medaka (Oryzias latipes) is preeminent for investigating effects of carcinogenic and/or toxic waterborne hazards to humans. The guppy (Poecilia reticulata ), although less widely used, is valuable as a comparison species. Both species are easy to maintain and handle in the laboratory and there is a large body of background information on their responsiveness to a range of classes of carcinogens. There are considerable data on the occurrence of background diseases and on spontaneous neoplastic lesions, both of which occur relatively rarely. With few modifications, the medaka and guppy are amenable to carcinogenicity testing under the rigid standards established by the National Toxicology Program (NTP) for rodent tests. The advantages of the small fish in carcinogenesis studies are best realized in long-term studies that involve environmentally realistic exposures. Studies to identify chronic effects can be conducted in about 12 months, near the life span of medaka in our laboratory. Practically, 9-month studies are optimal but shorter study cycles and a variety of exposure/growout and initiation/promotion scenarios are available. Studies on 3 compounds tested in medaka under NTP protocols are under review and preliminary analysis indicates that chronic carcinogenicity bioassays with medaka, guppy, and potentially with other small fish species are feasible and scientifically valid.

A series of novel multifunctional amino alcohols were prepared by tandem Michael–Henry reaction by reacting nitroalkanes such as 2-nitropropane with readily available α,β-unsaturated aldehydes. The dinitro compounds were further reduced by catalytic hydrogenation to obtain respective diamines. This synthetic route provides a very convenient method of preparing multifunctional amino alcohols.

Base excision repair (BER) is the DNA repair pathway primarily responsible for repairing small base modifications and abasic sites caused by normal cellular metabolism or environmental insult. Strong evidence supports the requirement of DNA polymerase beta (beta-pol) in the BER pathway involving single nucleotide gap filling DNA synthesis in mammalian systems. In this study, we examine the relationship between oxidative stress, cellular levels of beta-pol and BER to determine whether oxidizing agents can upregulate BER capacity in vivo. Intraperitoneal injection of 2-nitropropane (2-NP, 100 mg/kg), an oxidative stress-inducing agent, in C57BL/6 mice was found to generate 8-hydroxydeoxyguanosine (8-OHdG) in liver tissue (4-fold increase, P < 0.001). We also observed a 4-5-fold increase in levels of DNA single strand breaks in 2-NP treated animals. The protein level of the tumor suppressor gene, p53 was also induced in liver by 2-NP (2.1-fold, P < 0.01), indicating an induction of DNA damage. In addition, we observed a 2-3-fold increase in mutant frequency in the lacI gene after exposure to 2-NP. Interestingly, an increase in DNA damage upregulated the level of beta-pol as well as BER capacity (42%, P < 0.05). These results suggest that beta-pol and BER can be upregulated in response to oxidative stress in vivo. Furthermore, data show that heterozygous beta-pol knockout (beta-pol(+/-)) mice express higher levels of p53 in response to 2-NP as compared with wild-type littermates. While the knockout and wild-type mice display similar levels of 8-OHdG after 2-NP exposure, the beta-pol(+/-) mice exhibit a significant increase in DNA single strand breaks. These findings suggest that in mice, a reduction in beta-pol expression results in a higher accumulation of DNA damage by 2-NP, thus establishing the importance of the beta-pol-dependent BER pathway in repairing oxidative damage.

This study examined the response of the Eker rat to nephrotoxic compounds and to genotoxic nonrenal carcinogens. Groups of male Eker rats received either no treatment; a vehicle treatment; treatment with a noncarcinogeni c nephrotoxin (aluminum nitrilotriacetate, 2 mg/kg/day of aluminum, intraperitoneally, 3 days per week or cyclosporine A, 30 mg/kg/day, orally by gavage, 7 days/week); or treatment with a genotoxic nonrenal carcinogen (furan, 8 mg/kg/day, orally by gavage, 5 days/week or 2,4-diaminotoluene, 6.5 mg/kg/day, orally by gavage, 7 days/week or 2-nitropropane, 89 mg/kg/day, orally by gavage, 3 days/week). Duration of treatment was 4 and/or 6 months. Tissues from the Eker rats were evaluated microscopically and numbers of proliferative renal lesions were counted. Administration of nephrotoxic compounds (Al-NTA and cyclosporine) significantly increased the number of preneoplasti c and neoplasti c renal lesions in the Eker rat compared to concurrent vehicle controls. The genotoxi c nonrenal carcinogens had no consistent effect on numbers of preneoplastic or neoplastic renal lesions and did not produce neoplasms in the expected target organ (liver).

In the absence of a rapid serum methanol level estimation, it is difficult to assess the risk from unintentional childhood ingestion of model fuels containing methanol and nitromethane (MFNM). Previous reports have documented false elevations of serum creatinine from the nitromethane in these fuels, suggesting its utility as a readily available marker of significant methanol ingestion.We performed a 2-year retrospective chart review of cases of ingestion of MFNM in children, with both a methanol level and measured creatinine level.Seven children, ages 19 months to 3 years, ingested MFNM. All seven children were seen in a hospital and had measured methanol and creatinine levels. All blood samples for methanol and creatinine were drawn within 3 hours of ingestion with methanol estimation delayed up to 24 hours. Creatinine ranged from 0.39 (0.034 mmol/l) to 10.7 mg/dl (0.95 mmol/l). All methanol levels were10 mg/dl (0.31 mmol/l) or reported as negative. Fomepizole was initiated empirically in two patients due to delay in obtaining methanol analysis results.Transient elevations of creatinine occurred in five of the seven children. Blood urea nitrogen was within normal limits, and there was no history of renal impairment in these children, suggesting the elevated creatinine was mostly related to nitromethane ingestion. No child had a significantly elevated methanol level.Elevated creatinine level, as measured by Jaffe colorimetric method, is not a reliable marker for elevated methanol levels after unintentional ingestion of MFNM.

The intriguing decompositions of nitro-containing explosives have been attracting interest. While theoretical investigations have long been concentrated mainly on unimolecular decompositions, bimolecular reactions have received little theoretical attention. In this paper, we investigate theoretically the bimolecular reactions between nitromethane (CH3NO2)-the simplest nitro-containing explosive-and its decomposition products, such as NO2, NO and CO, that are abundant during the decomposition process of CH3NO2. The structures and potential energy surface (PES) were explored at B3LYP/6-31G(d), B3P86/6-31G(d) and MP2/6-311 + G(d,p) levels, and energies were refined using CCSD(T)/cc-pVTZ methods. Quantum chemistry calculations revealed that the title reactions possess small barriers that can be comparable to, or smaller than, that of the initial decomposition reactions of CH3NO2. Considering that their reactants are abundant in the decomposition process of CH3NO2, we consider bimolecular reactions also to be of great importance, and worthy of further investigation. Moreover, our calculations show that NO2 can be oxidized by CH3NO2 to NO3 radical, which confirms the conclusion reached formerly by Irikura and Johnson [(2006) J Phys Chem A 110:13974-13978] that NO3 radical can be formed during the decomposition of nitramine explosives.

(2-Nitroethyl)benzene was identified as a major component of the flower scent of the Japanese loquat Eriobotrya japonica [Rosales: Rosaceae], together with p-methoxybenzaldehyde and methyl p-methoxybenzoate. The corresponding volatiles from chopped leaves did not contain these three compounds. This is the first time that 1-nitro-2-phenyl-ethane has been demonstrated to be a natural product among Japanese plants, although two Japanese millipedes are known to possess the same aromatics.

The peak capacity of small columns packed with 2.7 μm core–shell particles and 1.8 μm fully porous particles were compared at high temperatures using very steep (fast) gradient conditions and quite high linear velocities using the same instrument configuration as used to transfer first dimension effluent to the second dimension column as done in on-line comprehensive two-dimensional liquid chromatography. The experimental peak capacities of small columns (2.1 mm × 30 mm) packed with both types of particles were measured with fast gradients (9 s to 2 min) at high temperature (95 °C) using both the same flow rate (1.75 mL/min) and then at different flow rates at the same pressure (400 bar). Equal or slightly better peak capacities were achieved with the core–shell particle columns as compared to the fully porous particle columns at the same backpressure or the same flow rate. However, core–shell particles offer a real advantage over the smaller, fully porous particles because they can be operated at higher flow rates thus gradient mixer flush out and column reequilibration can be done in less time thereby allowing a greater fraction of the second dimension cycle time to be dedicated to the gradient time.

(−)-Horsfiline and (−)-coerulescine were synthesized through three one-pot operations in 33 and 46 % overall yield, respectively. Key to the success was the efficient use of a diarylprolinol silyl ether to catalyze the asymmetric Michael addition of nitromethane to a 2-oxoindoline-3-ylidene acetaldehyde. This allowed the all-carbon quaternary, spirocyclic carbon stereocenter to be constructed in good yield with excellent enantioselectivity.

An effective and practical method has been developed for the diversity-oriented synthesis of fully substituted cyclohexene β-aminoester via a pseudo five-component reaction between nitromethane, aromatic aldehydes, and substituted cyanoacetate for the generation of a wide range of structurally relevant and highly functionalized compounds. The attractive range and features of the method, which enables the facile preparation of highly substituted cyclohexenes, are its simple and straightforward procedure, mild reaction conditions, and ideal yields. The mechanism involves a double Michael addition reaction followed by intramolecular ring closure. The fully substituted cyclohexene β-aminoesters with potential bioactivities could be of impact in medical chemistry.

Methylolated nitroparaffins, and in particular the simpler and least expensive exponent of their class, namely tris(hydroxymethyl)nitromethane (TN), function well as hardeners of a variety of tannin-based adhesives while affording considerable side advantages to the adhesive and to the bonded wood joint. In panel products, such as particleboard, medium density fiberboard and plywood, the joint performance which is obtained is of the exterior/ marine grade type, while a very advantageous and very considerable lengthening in glue-mix pot-life is obtained. Furthermore, the use of this hardener is coupled with such a marked reduction in formaldehyde emission from the bonded wood panel to reduce emission exclusively to the formaldehyde emitted by just heating the wood (and slightly less, thus functioning as a mild depressant of emission from the wood itself). Furthermore, TN can be mixed in any proportion with traditional formaldehyde-based hardeners for tannin adhesives, its proportional substitution of such hardeners inducing a proportionally marked decrease in the formaldehyde emission of the wood panel without affecting the exterior/marine grade performance of the panel. Medium density fibreboard (MDF) industrial plant trials confirmed all the properties reported above, and the trial conditions and results are reported. In the case of cold-setting adhesives for finger-jointing and glulam, tris(hydroxymethyl)nitromethane (TN) can be used to good effect only in radiofrequency curing of such joints, hence also by heat activation, its performance instead not coming up to the requirements of relevant standards in the case of ambient temperature curing due to higher temperature activation characteristics of this hardener.

The radiation-chemical transformations of Purex solvent, 30% TBP-n-dodecane-HNO3, arising from radiolysis of nitric acid were examined by gas chromatographic fingerprinting of the radiolyzed system. The present study describes a procedure for identifying diluent degradation products by gas chromatographic, infrared and gas chromatographic—mass spectrographic assay. The identified gas chromatographic signatures can be used to monitor the growth of diluent degradation products (DDP) like nitroparaffins, long chain alcohols, and paraffins in the Purex solvent before its recycling. The increase in the concentration profiles of these species with absorbed dose parallels the increase in the retention of Ru, Zr, and Pu by the diluent phases resolved (by the phosphoric acid equilibration method) from the radiolyzed solvent under recycling conditions.

In alkaline solutions at pH >10, peroxynitrite (ONOO(-)) rapidly and efficiently nitrates aci-nitroalkane anions, RCH=NO(2)(-) (R = H, CH(3), or CH(3)CH(2)), to give the radical dinitrodianions, RC(NO(2))(2)(2-). These anions have been characterized by EPR and have multiplets based on 1:2:3:2:1 pentets consistent with a hyperfine coupling with two equivalent (14)N nuclei of the nitro groups, and the following hyperfine coupling constants, in gauss: R = H, a(N) = 9.96 and a(H) = 1.85; R = CH(3), a(N) = 9.90 and a(H) = 3.22; and R = CH(3)CH(2), a(N) = 9.57 and a(H) = 4.01. Nitration is attributed to the trapping of nitrogen dioxide, formed by ONO-OCO(2)(-) homolysis for the carbon dioxide adduct of peroxynitrite, by the aci-nitroalkane anion. In air, the radical dinitrodianions are oxidized to the monoanions, and the kinetics of its formation is readily followed by UV/vis spectroscopy of the rise in absorption at 380 nm. This report represents the first successful spin trapping of nitrogen dioxide formed from peroxynitrite, and the method may be a useful one for preparing geminal dinitroalkanes.

Tissue slices are a useful biological system for lipid peroxidation studies but their use for DNA damage studies is not well characterized. Hence, the present study investigates DNA damage in rat liver slices, in comparison with isolated rat liver nuclei and HepG2 human hepatoma cells, incubated with ferric nitrilotriacetate (Fe(III)-NTA), bromotrichloromethane (BrCCl3), bromobenzene (BrB) or 2-nitropropane (2-NP) at 37°C for 2 hr. DNA damage was measured in slices, cells or nuclei after centrifugation as formation of as 8-hydroxy-2′-deoxyguanosine (8-OH-dGu) and loss of double-stranded (dsDNA) due to strand breakage using a fluorometric analysis of DNA unwinding (FADU). Lipid peroxidation was measured as thiobarbituric acid-reactive substances (TBARS) released into the medium. The results show that in liver slices and isolated nuclei, Fe/NTA (1 m m /4 m m ) induced high levels of TBARS but low levels of 8-OH-dGu, whereas the oxidant induced low levels of TBARS and no formation of 8-OH-dGu in HepG2 cells. In all three systems, inclusion of ascorbate caused dose-dependent formation of 8-OH-dGu, and the levels were similar between liver slices and HepG2 cells but were far higher in isolated nuclei. In liver slices the FADU assay was not applicable due to limited solubilization of DNA from the slice, whereas the assay detected significant loss of dsDNA in HepG2 cells and slight loss in isolated nuclei induced by Fe/NTA with or without ascorbate. Liver slices incubated with 1 mm BrCCl3, BrB or 2-NP had elevated TBARS but had little or no formation of 8-OH-dGu; none of these oxidants induced lipid peroxidation or DNA damage in HepG2 cells. When liver slices obtained from rats injected with diethylmaleate (to deplete GSH) were incubated with BrCCl3, BrB or 2-NP, levels of TBARS and 8-OH-dGu increased markedly. Similarly, HepG2 cells with decreased GSH showed marked elevation of TBARS and loss of dsDNA induced by these oxidants, although no formation of 8-OH-dGu was detected. The present study demonstrates the usefulness and limitations of liver slices for DNA damage studies and the importance of cellular GSH in the protection of DNA against environmental toxicants.

Nitroalkane oxidase catalyzes the oxidation of nitroalkanes to aldehydes or ketones with production of nitrite and hydrogen peroxide. pH and kinetic isotope effects with [1, 1-(2)H(2)]nitroethane have been used to study the mechanism of this enzyme. The V/K(ne) pH profile is bell-shaped. A group with a pK(a) value of about 7 must be unprotonated and one with a pK(a) value of 9.5 must be protonated for catalysis. The lower pK(a) value is seen also in the pK(is) profile for the competitive inhibitor valerate, indicating that nitroethane has no significant external commitments to catalysis. The (D)(V/K)(ne) value is pH-independent with a value of 7.5, whereas the (D)V(max) value increases from 1.4 at pH 8.2 to a limiting value of 7.4 below pH 5. The V(max) pH profile decreases at low and high pH, with pK(a) values of 6.6 and 9.5, respectively. Imidazole, which activates the enzyme, affects the V(max) but not the V/K(ne) pH profile. In the presence of imidazole at pH 7 the (D)V(max) value increases to a value close to the intrinsic value, consistent with cleavage of the carbon-hydrogen bond of the substrate being fully rate-limiting for catalysis in the presence of imidazole.

The synthesis of (R,S)-[4-11C]baclofen, the first 11C-labeled GABAB agonist, was demonstrated via Michael addition of nitro[11C]methane as a key step. A tetrabutylammonium fluoride promoted Michael addition of nitro[11C]methane to methyl p-chlorocinnamate, followed by the nitro-group reduction in the presence of NiCl2 and NaBH4 in aqueous MeOH and alkaline hydrolysis yielded (R,S)-[4-11C]baclofen in 36.4 ± 1.8% radiochemical conversion in three steps within 20 min.

A chiral phosphine catalyzes the addition of a carbon nucleophile to the gamma position of an electron-poor allene (amide-, ester-, or phosphonate-substituted), in preference to isomerization to a 1,3-diene, in good ee and yield. This strategy provides an attractive method for the catalytic asymmetric gamma functionalization of carbonyl (and related) compounds.

Samples of 30% tributyl phosphate (TBP)–n-dodecane–HNO3 undergoing gamma radiolysis with and without solvent cleanup have been examined by GLC and IR spectrometry. In order to assess the rate of buildup of various radiolytic species in the solvent, their relative hydrophobicities with respect to alkaline wash have been determined. The differences in the Pu extraction and retention behaviors of the two solvent systems with increasing dose are explained in terms of the formation of derivatives of nitroparaffins and high molecular weight organophosphates.

2-Nitropropane (2-NP) is a genotoxic hepatocarcinogen in rats. The genotoxicity of the compound has been attributed to a sulfotransferase-mediated formation of DNA-reactive species from the anionic form of 2-NP, propane 2-nitronate (P2N). Several observations have suggested that sulfotransferases (SULTs) 1A1 and/or 1C1 may be important in the activation of P2N to a genotoxicant in rat liver, but a definite proof is lacking. In order to identify the sulfotransferase(s) of rat liver that are capable of activating P2N, we have investigated the genotoxicity of P2N in various V79-derived cell lines engineered for expression of individual forms of rat hepatic sulfotransferases. Genotoxicity was assessed by measuring the induction of DNA repair synthesis. 1-Hydroxymethylpyrene (HMP), which is metabolically activated by most sulfotransferases, served as a positive control. Neither P2N nor HMP induced DNA repair in the parental V79-MZ cells, which do not show any sulfotransferase activity. P2N was also inactive in V79-rHSTa and V79-rHST20 cells, which express specific hydroxysteroid sulfotransferases. By contrast, a clear and concentration-dependent induction of repair synthesis by P2N was observed in V79-rPST-IV and V79-rST1C1 cells, which express rat SULT1A1 and SULT1C1, respectively. HMP was genotoxic in all sulfotransferase-expressing cell lines. Acetone oxime (AO), the tautomeric form of the first reduction product of 2-NP, 2-nitrosopropane, was inactive in all cell lines. The results corroborate the essential role of sulfotransferases in the metabolic activation of P2N to genotoxic products and identify two rat sulfotransferases which are capable of catalyzing the activation step.

The labelling synthesis of ethyl nitro[2-(11)C]acetate, a synthetic intermediate feasible for (11)C-labelled PET tracers, by C-carboxylation of [(11)C]MeNO(2) with 1-ethoxycarbonylbenzotriazole, and its simple application are presented.

The degree of lipid peroxidation (LPO) as indicated by the levels of thiobarbituric acid reactive substances, malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA), and the activity of sorbitol dehydrogenase (SDH) in serum as parameters of hepatotoxicity were studied in rats treated with a single intraperitoneal (i.p.) injection of the hepatocarcinogen 2-nitropropane (2-NP). Since melatonin, the main secretory product of the pineal gland, has been shown to protect against a number of toxic agents, it was given 30 min before 2-NP to test its protective effect against 2-NP toxicity. Significant increases in LPO in liver (P

The alleged cancer preventive effects of cruciferous vegetables could be related to protection from mutagenic oxidative DNA damage. We have studied the effects of Brussels sprouts, some non-cruciferous vegetables and isolated glucosinolates on spontaneous and induced oxidative DNA damage in terms of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in groups of 6-8 male Wistar rats. Excess oxidative DNA damage was induced by 2-nitropropane (2-NP 100 mg/kg). Four days oral administration of 3 g of cooked Brussels sprouts homogenate reduced the spontaneous urinary 8-oxodG excretion by 31% (p

The dichloro[(-)-sparteine-N,N']copper(II) complex provides Henry adducts with high enantioselectivities (73-97% ee) in Henry reaction between nitromethane and various aldehydes.

The reaction between pairs of enantiomeric cocrystals involving caffeine or theophylline and a chiral cocrystal former has been investigated by liquid-assisted grinding: we demonstrate two different outcomes for such cocrystal-cocrystal reactions.

Previously, the secondary nitroalkane 2-nitropropane, a strong hepatocarcinogen in rats, had been shown to induce the formation of 8-aminoguanine in both DNA and RNA of rat liver through a sulfotransferase-mediated pathway. This pathway was postulated to convert the carcinogen into an aminating species [Sodum, R. S., et al. (1994) Chem. Res. Toxicol. 7, 344-351]. To submit this postulate to further test, we examined liver proteins of rats treated with 2-nitropropane, other carcinogenic secondary nitroalkanes, or the related rat liver tumorigen acetoxime for the presence of 3-aminotyrosine, the expected product of tyrosine amination. Using ion-pair and/or cation-exchange high-performance liquid chromatography with electrochemical detection, we found that the liver cytosolic proteins of these animals contained 0.1-1.5 mol of 3-aminotyrosine/10(3) mol of tyrosine. Treatment with the noncarcinogenic primary nitroalkane 1-nitropropane or with other primary nitroalkanes did not produce an analogous increase in the aminated amino acid (level of detection estimated at approximately 0.01 mol/10(3) mol of tyrosine). To our knowledge, this is the first report of the modification of protein tyrosine in vivo by a carcinogen. In vitro studies with acetoxime-O-sulfonate and hydroxylamine-O-sulfonate showed that these proposed intermediates in the activation pathway of 2-nitropropane react with guanosine to give 8-aminoguanosine, N1-aminoguanosine, and 8-oxoguanosine and also react with tyrosine to give 3-aminotyrosine and 3-hydroxytyrosine. The in vitro amination and oxidation of guanosine at C8 were also produced by acetophenoxime-O-sulfonate and 2-heptanoxime-O-sulfonate. These results provide additional evidence for the production of a reactive species capable of aminating nucleic acids and proteins from 2-nitropropane and other carcinogenic secondary nitroalkanes by a pathway involving oxime- and hydroxylamine-O-sulfonates as intermediates.

We observed that pretreatment of male F344 rats with benzyl selenocyanate, a versatile organoselenium chemopreventive agent in several animal model systems, decreases the levels of DNA and RNA modifications produced in the liver by the hepatocarcinogen 2-nitropropane. To clarify the mechanisms involved, we pretreated male F344 rats with either benzyl selenocyanate, its sulfur analog benzyl thiocyanate, phenobarbital or cobalt protoporphyrin IX; the latter is a depletor of P450. We then determined (1) the ability of liver microsomes to denitrify 2-nitropropane, (2) effects on 2-nitropropane-induced liver DNA and RNA modifications and (3) amount of nitrate excreted in rat urine following administration of the carcinogen. Pretreatment with benzyl selenocyanate or phenobarbital increased the denitrification activity of liver microsomes by 217 and 765%, respectively, increased liver P4502B1 by 31- and 435-fold, respectively, decreased the levels of 2-nitropropane-induced modifications in liver DNA (29-70% and 17-30%, respectively) and RNA (67-85% and 30-50%, respectively), and increased the 24-h urinary excretion of nitrate by 157 and 209%, respectively. Pretreatment with benzyl thiocyanate had no significant effect on any of these parameters. Pretreatment with cobalt protoporphyrin IX decreased liver P4502B 1 by 87%, decreased the denitrification activity of liver microsomes by 76%, decreased the 24 h urinary excretion of nitrate by 88.5%, but increased the extent of 2-nitropropane-induced liver nucleic acid modifications by 17-67%. These results indicate that the metabolic sequence from 2-nitropropane to the reactive species causing DNA and RNA modifications does not involve the removal of the nitro group. Moreover, they suggest that benzyl selenocyanate inhibits 2-NP-induced liver nucleic acid modifications in part by increasing its detoxication through induction of denitrification, although it is evident that other mechanisms must also be involved.

Nucleoside analogues have played an important role in the viral decease and cancer therapy. To date, various nucleosides analogous have been investigated to improve their therapeutic effects and toxic properties. The modification of the sugar moiety has produced new active analogous. Especially, the design of furanose rings that include various heteroatoms has been one of the most useful approaches in the search for new nucleoside analogues with beneficial biological activity. Azanucleosides, in which the furanose oxygen atom is replaced by a nitrogen atom, have attracted interest because of possibility of their further modification through the nitrogen atom and structural similarity to the franose ring system. Considerable efforts have been dedicated to develop the efficient method for the synthesis of azanucleoside derivatives. Most of the synthetic strategies have been designed in order that N-glycosyl bond has been formed through an iminium ion intermediate. This process is necessary to incorporate a leaving group into the pyrrolidinyl precursor to generate the key reactive intermediate. However, access to such precursors requires a multi-step synthetic sequence, which includes cumbersome operations and harsh reaction condition. Indeed, this process often removes the opportunity of providing diverse azanucleosides based on further modification of the nitrogen atom. To address this challenge, we reasoned that direct and selective insertion of a nucleobase to the N-a position of prolinol moiety would avoid the redundant multi-step synthetic operation. We proposed that an electro-organic method might provide such an approach to overcome the challenge of direct introduction of a nucleobase into an unactivated pyrrolidine moiety. Previously, we have demonstrated the direct modification of pyrrolidine derivatives using LiClO4-CH3NO2 electrochemical oxidation system. This reaction system can accumulate desired iminium ion intermediates, anodically derived from N-protected pyrrolidine derivatives by C-H bound activation, enabling coupling with a variety of nucleophiles in one-pot reaction. In this conference, we report the electrochemical azanucleoside synthesis by coupling an unactivated prolinol derivative with a nucleobase through anodic oxidation using LiClO4-CH3NO2 solution system, and demonstrate the utility of this transformation by addition of various nucleophiles to readily available prolinol derivatives in a regioselective manner.

We report a detailed theoretical study of the structural, vibrational, and optical properties of solid nitromethane using first principles density functional calculations. The ground state properties were calculated using a plane wave pseudopotential code with either the local density approximation (LDA), the generalized gradient approximation (GGA), or with a correction to include van derWaals interactions. Our calculated equilibrium lattice parameters and volume using a dispersion correction are found to be in reasonable agreement with the experimental results. Also, our calculations reproduce the experimental trends in the structural properties at high pressure. It was found to be a discontinuity in the bond length, bond angles and also a weaking of hydrogen bond strength in the pressure range from 10 to 12 GPa, picturing the structural transition from phase I to Phase II. Moreover, we predict the elastic constants of solid nitromethane and found that the corresponding bulk modulus is in good agreement with experiments. The calculated elastic constants are showing an order of C11> C22 > C33, indicating that the material is more compressible along the c-axis. We also calculated the zone center vibrational frequencies and discuss the internal and external modes of this material under pressure. From this, we found the softing of lattice modes around 8 to 12 GPa. We have also attempt the quasiparticle band structure of solid nitromethane with the G0W0 approximation and found that nitromethane is an indirect band gap insulator with a value of the band gap of about 7.8 eV with G0W0 approximation. Finally, the optical properties of this material, namely the absorptive and dispersive part of the dielectric function, and the refractive index and absorption spectra are calculated and the contribution of different transition peaks of the absorption spectra are analyzed., 12 pages, 9 figures

Four solvates of an antifungal drug, griseofulvin (GF), were discovered. All the solvates were characterized by differential scanning calorimetry, thermogravimetric analysis, and their crystal structures were determined by single-crystal X-ray diffraction. The solvents that form the solvates are acetonitrile, nitromethane and nitroethane (2:1 and 1:1). It was found that all the solvates lose the solvent molecules from the crystal lattice between 343 and 383 K, and that the melting point of the desolvated materials matched the melting point of the solvent-free GF (493 K). The conformation of the GF molecule in solvent-free form was found to be significantly different from the conformations found in the solvates. Solution stability studies revealed that the GF–acetonitrile solvate transforms to GF and that GF–nitroethane (1:1) solvate transforms to GF–nitroethane (2:1) solvate. On the other hand, GF–nitromethane and GF–nitroethane (2:1) solvates were found to be stable in solution. Our results highlight the importance of the co-crystallization technique in the pharmaceutical drug development; it not only expands the solid form diversity but also creates new avenues for unraveling novel solvates.

N-nitrosodimethylamine (NDMA), as a new disinfection byproduct, is a potential carcinogen. In this study, we focused on the role of ozone in NDMA degradation. We characterized the removal efficiency, influencing factors and degradation mechanism. Our results demonstrated that ozonation was an efficient process for NDMA degradation. The removal efficiency was affected by initial NDMA concentration; higher NDMA dosing required higher ozone utilization. NDMA oxidation was favored at high ozone dosage and high pH. NDMA ozonation under various pH as well as hydroxyl radical (OH) inhibition experiments verified that OH generated from ozone dominated NDMA oxidation. The main products of NDMA ozonation were methylamine (MA), dimethylamine (DMA), nitromethane (NM) and ammonium (AM). Their yields changed with the amount of ozone provided. A NDMA ozonation mechanism was proposed. It is suggested that NDMA degradation is induced by OH attacking through any of four pathways, with oxygen involving in the oxidation process. MA generation was due to OH attacking on amine nitrogen and methyl group. DMA formation was related to OH attacking on nitrosyl nitrogen via a parallel pathway. We speculate that supersaturated dissolved oxygen by ozone decomposition is responsible for NM generation by further oxidation of MA and DMA. AM formation may be favored due to MA degradation under OH exposure.

No-carrier-added racemic [ 11 C]metaraminol was prepared by a selective condensation of [ 11 C]nitroethane with 3-hydroxy-benzaldehyde using tetrabutylammonium fluoride in tetrahydrofuran (THF) as a catalyst, followed by a reduction with Raney nickel in formic acid. [ 11 C]Metaraminol was produced in 30 to 45% decay-corrected yield from [ 11 C]nitroethane (13 to 20% decay corrected from [ 11 C]CO 2 ) within 45 to 55 min total synthesis time. Reversed phase high-performance liquid chromatography (HPLC) was used for the separation of the racemic erythro- and threo-forms of [ 11 C]metaraminol. The radiochemical purity was higher than 98%, and the specific radioactivity at the end of synthesis was 500 to 800 Ci/mmol (18 to 30 GBq/μmol). Positron emission tomography (PET) examination of racemic erythro-[ 11 C]metaraminol in a Cynomolgus monkey showed a high uptake of radioactivity in the heart. Following pretreatment with the selective norepinephrine reuptake inhibitor desipramine, the radioactivity uptake in the myocardium was markedly reduced (80%), demonstrating the specificity of erythro-[ 11 C]metaraminol for the norepinephrine reuptake system of the heart. Pretreatment with desipramine had no effect on radioactivity in lung. The metabolism was rapid for [ 11 C]metaraminol. The amounts of the total radioactivity representing [ 11 C]metaraminol in plasma, determined by HPLC, were 14% at 6 min and 8% at 34 min. The high specific uptake of racemic erythro-[ 11 C]metaraminol indicates that enantiomerically pure (R,S)-[ 11 C]metaraminol has potential for detailed mapping of the sympathetic innervation of the human myocardium.

We have undertaken electron paramagnetic resonance and spin trapping investigations of the photochemistry of kynurenine (KN), a natural component of the human eye and close analog of the principal chromophore in the young human lens 3-OH-kynurenine O-glucoside (3HKG). 5,5-Dimethyl-1-pyrroline N-oxide (DMPO) was employed as a spin trap. We found that upon UV irradiation (> 300 nm) KN photoreduces oxygen to superoxide radical (in DMSO) and nitromethane (CH3NO2) to a nitromethane radical anion (CH3NO2.-) (in air-free buffers, pH 7 and 9.5). KN also sensitized photooxidation of cysteine, NADH, EDTA, azide, and ascorbate; oxygen greatly accelerated this process. Oxidation of cysteine, NADH, and EDTA was accompanied by superoxide radical formation. Cysteinyl and azidyl radicals were detected as DMPO adducts. We also observed that KN undergoes photodegradation to a product(s) whose photosensitizing capacity is greater than that of KN itself. We postulate that: (i) 3HKG may be able to photoinitiate free radical reactions in vivo, and (ii) oxygen is an important factor determining the yields of free radical processes initiated by lenticular chromophores.

The high diastereoselectivity in the Michael addition of nitromethane to α,β-unsaturated γ-amino esters, crystal conformations of β-nitromethane substituted γ-amino acids and peptides are studied. Results suggest that the N-Boc protected amide NH, conformations of α,β-unsaturated γ-amino esters and alkyl side chains play a crucial role in dictating the high diastereoselectivity of nitromethane addition to E-vinylogous amino esters. Investigation of the crystal conformations of both α,β-unsaturated γ-amino esters and the Michael addition products suggests that an H-C(γ)-C(β)=C(α) eclipsed conformer of the unsaturated amino ester leads to the major (anti) product compared to that of an N-C(γ)-C(β)=C(α) eclipsed conformer. The major diastereomers were separated and subjected to the peptide synthesis. The single crystal analysis of the dipeptide containing β-nitromethane substituted γ-amino acids reveals a helical type of folded conformation with an isolated H-bond involving a nine-atom pseudocycle.

Male rats were given 2% green tea as their drinking water for 2 wk before a single ip injection of the carcinogen 2-nitropropane (2NP) (100mg/kg body weight) and liver nuclear 8-hydroxydeoxyguanosine (8-OHdG) levels and hepatotoxicity parameters were determined 6 or 15 hr thereafter. The increase of 8-OHdG adducts in liver nuclear DNA caused by 2NP was depressed 50% at both time points with the green tea pretreatment. The time-dependent elevations of serum aminotransferases and lactate dehydrogenase values by 2NP were also effectively prevented. However, green tea had no obvious effects on the falls in serum lipid peroxide and triglyceride levels associated with carcinogen exposure. Increases of hepatic lipid peroxide levels with 2NP were depressed 100 and 30%, at 6 and 15 hr, respectively, by green tea and the decrease in hepatic glycogen content at 6 hr was clearly alleviated. Histopathological examination revealed effective protection against induction of hepatic degenerative changes by 2NP at 15 hr. Drinking crude catechin extract solution with the same concentration of (-)epigallocalechin gallate as green tea provided protection at 6 hr, but with only half the effectiveness. These findings demonstrate that green tea can effectively block oxidative DNA damage to the liver as well as hepatotoxicity in rats treated with 2NP.

A relationship has been derived between the activation energies E a of low-temperature non-autocatalyzed thermolysis of nitroparaffins and their oxygen balances. An analogous relationship has also been found for pre-exponents of log A of this thermolysis. The direct relationship existing between E a values and the impact sensitivity of the nitrocompounds in a condensed state is confirmed by the first relationship. From these two relationships, the molecular-structural dependences of the thermal reactivity of nitroparaffins in both gaseous and liquid states are discussed. For the thermolysis of mononitromethane in the liquid state, primary homolytic pseudo-monomolecular fragmentation decomposition is hypothesized.

We report 13C NMR measurements of the flux through aldose reductase in isolated rat sciatic nerve, and its inhibition by an aldose reductase inhibitor of the sulphonylnitromethane class. [1-13C] galactose was used as substrate, and the rate of production of [1-13C] dulcitol was measured. Quantitation required the use both of internal extracellular, and external, standards. The mean net forward flux (+/- SD) was 20 +/- 11 nmol/(mL nerve water)/min (n = 10). In the presence of the inhibitor, flux was reduced significantly (p < 0.001) to 13% of control. Since dulcitol is symmetrical, an estimate of the backward flux, to [6-13C] galactose, is also possible; under our conditions, this was negligible.

A simple means of measuring of 8-hydroxyguanine (8-OHGua) levels in urine was developed. Rat and human urine samples were purified by means of strong cation exchange chromatography (Amberlite CG-120), followed by cellulose partition chromatography (Whatman CF-11). Thereafter, 8-OHGua was determined by means of high performance liquid chromatography (HPLC) using an electro-chemical detector. The level of 8-OHGua in rat urine increased by a factor of 2 to 4 after an intraperitoneal administration of 2-nitropropane (25 mg/kg), paraquat (11.3 mg/kg), or hydroquinone (11 mg/kg). On the other hand, the urine of smokers and persons exposed to air polluted with car exhaust also contained 1.9 and 3.8 fold more 8-OHGua, respectively, than that of control nonsmokers. These results indicated that the amount of 8-OHGua in urine is useful marker for monitoring the level of in vivo oxidative stress.

Highly stereoselective and rapid (1 min) addition reactions to the imine double bond of 2-(methylimino)acetate complexes [L(4)Co(O(2)CCH=NCH(3))](2+) [L(4) = (en)(2) (7), (tren) (11)] were achieved in aqueous solution with nitromethane, ethyl 3-oxobutanoate or diethyl malonate. The molecular structures of two product complexes, rac-(Δ*-R(C)*-S(N)*)-[Co(en)(2)(O(2)CCH[CH(2)NO(2)]NHCH(3))]ZnCl(4) and rac-(Δ*-R(C)*-S(N)*)-[Co(en)(2)(O(2)CCH[CH(2)COCH(3)]NHCH(3))]ZnCl(4), were established by X-ray diffraction.