Monoamine oxidase inhibition and neuroprotection by N1‐propargylphenelzine

The ability of N¹‐propargylphenelzine and related N¹‐propargylhydrazines to inhibit monoamine oxidase‐A (MAO‐A) and ‐B (MAO‐B) and to prevent N‐(2‐chloroethyl)‐N‐ethyl‐2‐bromobenzylamine (DSP‐4)‐induced noradrenergic neurotoxicity was examined. N¹‐Propargylphenelzine strongly inhibited MAO‐A and MAO‐B in in vitro assays using rat brain or liver as the enzyme source. In ex vivo studies in rats, both intraperitoneal and oral administration of N¹‐propargylphenelzine strongly inhibited brain and liver MAO‐A and MAO‐B. The extent of ex vivo MAO inhibition and increased levels of noradrenaline and 5‐hydroxytryptamine by N¹‐propargylphenelzine was comparable to that of phenelzine. Unlike phenelzine, however, N¹‐propargylphenelzine did not elevate γ‐aminobutryic acid (GABA) concentrations in rat brain. A single intraperitoneal administration of N¹‐propargylphenelzine to mice, 1 week prior to sacrifice, reduced DSP‐4‐induced depletion of noradrenaline in the hippocampus. The brains of N¹‐propargylphenelzine‐treated mice from the DSP‐4 neurotoxicity experiments had normal MAO‐B activity, but MAO‐A was significantly inhibited; this was in contrast to animals that had received (–)‐deprenyl, who showed normal MAO‐A activity but a decrease of MAO‐B. The present results indicate that N¹‐propargylphenelzine may be a useful neuroprotective compound with a long‐term in vivo propensity to inhibit MAO‐A. Drug Dev. Res. 53:15–21, 2001. © 2001 Wiley‐Liss, Inc.     

MAO‐B Inhibition by a Single Dose of l‐Deprenyl or Lazabemide Does Not Prevent Neuronal Damage Following Focal Cerebral Ischaemia in Rats

The present study investigated the effect of postischaemic infusion of an irreversible monoamine oxidase B (MAO‐B) inhibitor, l‐deprenyl, an equipotent dose of a reversible MAO‐B inhibitor, lazabemide, or 0.9% NaCl on infarct volumes following focal cerebral ischaemia in rats. The drug doses (0.3 mg/kg) were selected to induce selective MAO‐B inhibition (45–55%), but not MAO‐A inhibition. The infarct volumes in the cortex or in the striatum did not differ between the experimental groups 72 hr after transient occlusion of the middle cerebral artery, which suggests that during ischaemia/reperfusion, suppressed oxidative stress by partial MAO‐B inhibition or MAO‐B independent mechanisms such as induction of trophic factors, does not protect against ischaemia/reperfusion damage.     

Inhibition of MAO‐A Activity Enhances Behavioural Activity of Rats Assessed Using Water Maze and Open Arena Tasks

Abstract: To determine if the inhibition of MAO‐A and/or MAO‐B activities can influence cognitive processes in adult rats, we analysed whether chronic treatment with clorgyline, l‐deprenyl and pargyline could modify the performance of adult rats in a modified version of the water maze task. The effects of these treatments on locomotor activity and enzyme activities were also assessed. Rats were treated for 24 days with clorgyline (0.2 mg/kg), l‐deprenyl (0.25 mg/kg) and pargyline (1 or 10 mg/kg). The treatments were started two weeks before the water maze experiment and continued until the end of testing. The rats were trained to find a submerged platform (6 days:1 trial/day; 7 th day: probe trial). Over the next three days, locomotor activity was assessed in an open arena. Treatments with clorgyline (MAO‐A inhibitor), l‐deprenyl (MAO‐B inhibitor) and pargyline (non‐selective MAO inhibitor) did not improve the finding of the hidden platform, when compared to treatment with saline, but significantly increased the swimming speed of the rats. The different treatments, when compared to saline, failed to modify the distance covered and the number of groomings performed in the open arena. However, clorgyline and pargyline, 10 mg/kg, increased the number of faecal boli and clorgyline enhanced the number of rearings made when compared to saline, l‐deprenyl and pargyline, 10 mg/kg. These results indicate that near total inhibition of MAO‐A by clorgyline and pargyline as assessed by MAO activity measurement induces an increase in locomotor activity but that inhibition of MAO‐A or MAO‐B, either alone or combined, does not facilitate spatial learning in adult rats.     

A rapid, sensitive electron-capture gas chromatographic procedure for analysis of metabolites of N-methyl,N-propargylphenylethylamine, a potential neuroprotective agent

INTRODUCTION: N-Methyl,N-propargyphenylethylamine (MPPE) is a novel analog of (-)-deprenyl, a drug prescribed for Parkinson's disease and shown to have neuroprotective and neurorescue properties in a wide variety of in vitro and in vivo models. MPPE is also neuroprotective, but has the advantage over (-)-deprenyl of not being metabolized to amphetamine or N-methylamphetamine. METHOD: In this paper, extractive derivatization with pentafluorobenzenesulfonyl chloride (PFBSC) followed by electron-capture gas chromatography was utilized to study the metabolism of MPPE. RESULTS: The procedure is rapid and reproducible, giving derivatives with excellent chromatographic properties. Using this procedure, it has now been shown that beta-phenylethylamine (PEA), N-methylphenylethylamine (N-methylPEA) and N-propargylphenylethylamine (N-propargylPEA) are formed from MPPE during incubation of this drug with human liver microsomes. Levels of all three metabolites were shown to increase with increasing time of incubation with the microsomes. DISCUSSION: Extractive derivatization with PFBSC followed by electron-capture gas chromatography represents an efficient means of separating and quantitating the metabolites of MPPE, a novel neuroprotective agent.     

Evaluation of Natural and Synthetic 1,4‐naphthoquinones as Inhibitors of Monoamine Oxidase

Previous reports have documented that 1,4‐naphthoquinones act as inhibitors of the monoamine oxidase (MAO) enzymes. In particular, fractionation of the extracts of cured tobacco leafs has led to the characterization of 2,3,6‐trimethyl‐1,4‐naphthoquinone, a non‐selective MAO inhibitor. To derive structure–activity relationships for MAO inhibition by the 1,4‐naphthoquinone class of compounds, this study investigates the human MAO inhibitory activities of fourteen structurally diverse 1,4‐naphthoquinones of natural and synthetic origin. Of these, 5,8‐dihydroxy‐1,4‐naphthoquinone was found to be the most potent inhibitor with an IC₅₀ value of 0.860 μm for the inhibition of MAO‐B. A related compound, shikonin, inhibits both the MAO‐A and MAO‐B isoforms with IC₅₀ values of 1.50 and 1.01 μm , respectively. It is further shown that MAO‐A and MAO‐B inhibition by these compounds is reversible by dialysis. In this respect, kinetic analysis suggests that the modes of MAO inhibition are competitive. This study contributes to the discovery of novel MAO inhibitors, which may be useful in the treatment for disorders such as Parkinson's disease, depressive illness, congestive heart failure and cancer.     

Neuroprotective effects of a novel poly (ADP‐ribose) polymerase‐1 inhibitor,JPI‐289, in hypoxic rat cortical neurons

Excessive activation of poly (ADP‐ribose) polymerase‐1 (PARP‐1) is known to develop neuronal apoptosis, necrosis and inflammation after ischaemic brain injury. Therefore, PARP‐1 inhibition after ischaemic stroke has been attempted in successful animal studies. The purpose of present work was to develop a novel water soluble PARP‐1 inhibitor (JPI‐289) and explore its neuroprotective effect on ischaemic injury in an in vitro model. The half‐life of JPI‐289 after intravenous or oral administration in rats was relatively long (1.4‐1.5 hours) with 65.6% bioavailability. The inhibitor strongly inhibited PARP‐1 activity (IC₅₀=18.5 nmol/L) and cellular PAR formation (IC₅₀=10.7 nmol/L) in the nanomolar range. In rat cortical neuronal cells, JPI‐289 did not affect cell viability up to 1 mmol/L as assayed by Trypan blue staining (TBS) and lactate dehydrogenase (LDH) assay. Treatment of JPI‐289 for 2 hours after 2 hours of oxygen glucose deprived (OGD) rat cortical neuron attenuated PARP activity and restored ATP and NAD+ levels. Apoptosis‐associated molecules such as apoptosis inducing factor (AIF), cytochrome C and cleaved caspase‐3 were reduced after JPI‐289 treatment in the OGD model. The present findings suggest that the novel PARP‐1 inhibitor, JPI‐289, is a potential neuroprotective agent which could be useful as a treatment for acute ischaemic stroke.     

Synthesis and characterization of novel radiofluorinated probes for positron emission tomography imaging of monoamine oxidase B

Monoamine oxidase B (MAO‐B), predominantly expressed in glial cells, plays an important role in neurotransmitter regulation, and MAO‐B activity relates to several neuronal diseases. Here, we aimed to develop a radiofluorinated MAO‐B imaging probe based on the structure of a selective MAO‐B inhibitor, MD‐230254. We synthesized and evaluated a series of compounds in vitro and in vivo. A series of fluorinated analogs of MD‐230254 were synthesized and evaluated for inhibitory potency and selectivity toward MAO‐B. 5‐[4‐(2‐[¹⁸F]Fluorobenzyloxy)phenyl]‐3‐(2‐cyanoethyl)‐1,3,4‐oxadiazol‐2(3H)‐one (2‐[¹⁸F]FBPO) was synthesized from a corresponding tributylstannyl precursor and [¹⁸F]CH₃COOF. Biodistribution after intravenous injection of 2‐[¹⁸F]FBPO was evaluated in male ddY mice with or without pretreatment by inhibitors. Among the compounds synthesized and evaluated, 2‐FBPO showed high inhibitory potency and selectivity toward MAO‐B comparable with MD‐230254. 2‐[¹⁸F]FBPO was successfully synthesized by an electrophilic reaction with a high radiochemical purity of more than 99%. 2‐[¹⁸F]FBPO was efficiently taken up by the brain and showed rapid blood clearance, which provided a brain/blood radioactivity ratio of 3.7 at 90 minutes postinjection. The brain radioactivity was significantly decreased by pretreatment with an MAO‐B selective inhibitor. The great potential of 2‐[¹⁸F]FBPO as an MAO‐B imaging probe, applicable to a variety of diseases, is indicated.     

Avoidance Responding Following Amphetamine‐Induced Dopamine Depletion

The effect of an amphetamine‐induced depletion of striatal dopamine on active and passive avoidance responding of rats was examined. Sixteen animals received two sets of 4 injections each of 15 mg/kg d‐amphetamine, administered at 2 hr intervals with each set delivered one week apart. One week after the last injection, animals were given 50 consecutive active avoidance trials in a shuttle box. Animals treated with amphetamine exhibited a 50% depletion of striatal dopamine and showed a slower learning curve, as evidenced by significantly fewer avoidances and a slower escape latency during trials 21–30. Both groups demonstrated a 90% avoidance rate by trials 41–50. A separate group of rats was treated as above and trained for several weeks on the active avoidance procedure. Haloperidol (0.01–0.10 mg/kg intraperitoneally) dose‐dependently decreased avoidance number and increased avoidance and escape latency in both groups, an effect that was exaggerated in those animals previously treated with amphetamine. Finally, these animals were tested in the same apparatus using a passive avoidance procedure. The amphetamine treatment produced a significantly higher mean number of avoidances in this procedure compared to saline‐treated animals during trials 1–20. These results suggest that the impairment in conditioned avoidance following amphetamine treatment is due to a motoric, rather than a cognitive deficit.     

N‐acetylcysteine improves renal hemodynamics in rats with cisplatin‐induced nephrotoxicity

This work investigated the effect of N‐acetylcysteine (NAC), on renal hemodynamics in cisplatin (CP)‐induced nephrotoxicity in Wistar–Kyoto (WKY) rats. The animals were divided into four groups (n = 5 or 6). The first and second groups received normal saline (control) and intraperitoneal (i.p.) N‐acetylcysteine (500 mg kg^?1 per day for 9 days), respectively. The third and fourth groups were given a single intraperitoneal (i.p.) injection of CP (5 mg kg^?1) and an i.p. injection of CP (5 mg kg^?1) together with i.p. NAC (500 mg kg^?1 per day for 9 days), respectively. At the end of the experiment, rats were anesthetized and blood pressure and renal blood flow were monitored, followed by intravenous (i.v.) injection of norepinephrine (NE) for measurement of renal vasoconstrictor responses. CP caused a significant reduction in renal blood flow but did not affect NE‐induced renal vasoconstriction. In addition, CP significantly increased plasma concentrations of urea and creatinine and urinary N‐acetyl‐β‐D ‐glucosaminidase (NAG) activity and kidney relative weight. CP decreased body weight and creatinine clearance. Histopathologically, CP caused remarkable renal damage compared with control. NAC alone did not produce any significant change in any of the variables measured. However, NAC significantly ameliorated CP‐induced hemodynamic, biochemical and histopathological changes. The concentration of platinum in the kidneys of CP ? NAC treated rats was less than in CP‐treated rats by 37%. The results show that administration of i.p. NAC (500 mg kg^?1 per day for 9 days) reversed the renal hemodynamic changes as well as the biochemical and histopathological indices of CP‐induced nephrotoxicity in WKY rats. Copyright © 2009 John Wiley & Sons, Ltd.     

Attenuation of gentamicin‐induced nephrotoxicity: trimetazidine versus N‐acetyl cysteine

Gentamicin (G) is a highly nephrotoxic aminoglucoside. It was used to experimentally induce nephrotoxicity in male Wistar rats. To find a drug capable of protecting the nephron we assayed a cardioprotector (trimetazidine, TMZ) and a hepatoprotector (N‐acetyl cysteine, NAC). The rats were divided into six groups (n = 8): (A) control without drugs; (B) treated with 50 mg kg^?1 per day (i.p.) of G for 7 days; (C) diet supplemented with 20 mg kg^?1 per day of TMZ for 7 days; (D) treated with 10 mg kg^?1 per day (i.p.) of NAC for 7 days; (E) pretreated for 7 days with 20 mg kg^?1 per day of TMZ and during the following 7 days with G + TMZ; (F) pretreated for 7 days with 10 mg kg^?1 per day (i.p.) of NAC and during the following 7 days with G + NAC. Urea and creatinine as well as the excretion of urinary γ‐glutamyl transpeptidase (GGT_u) and urinary N‐acetyl‐glucosaminidase (NAG_u) were determined and structural and ultrastructural studies were carried out. Group B was used as a G‐induced nephrotoxicity control. Pretreatment with TMZ (E) showed a protector effect against induced nephrotoxicity, with no biochemical or functional changes nor alterations in histoarchitecture or ultrastructure. Pretreatment with NAC (F) showed no protector effect against G‐induced nephrotoxicity since no statistically significant differences were found with respect to the control group with G. We conclude that G‐induced nephrotoxicity is attenuated by the cytoprotective effect of TMZ. We may infer that TMZ inhibits the reabsorption and consequently the accumulation of G in the proximal tubule cell. Copyright © 2010 John Wiley & Sons, Ltd.     

Inhibition of human CYP1 enzymes by a classical inhibitor α‐naphthoflavone and a novel inhibitor N‐(3, 5‐dichlorophenyl)cyclopropanecarboxamide: An in vitro and in silico study

Enzymes in the cytochrome P450 family 1 (CYP1) catalyze metabolic activation of procarcinogens and deactivation of certain anticancer drugs. Inhibition of these enzymes is a potential approach for cancer chemoprevention and treatment of CYP1‐mediated drug resistance. We characterized inhibition of human CYP1A1, CYP1A2, and CYP1B1 enzymes by the novel inhibitor N‐(3,5‐dichlorophenyl)cyclopropanecarboxamide (DCPCC) and α‐naphthoflavone (ANF). Depending on substrate, IC₅₀ values of DCPCC for CYP1A1 or CYP1B1 were 10–95 times higher than for CYP1A2. IC₅₀ of DCPCC for CYP1A2 was 100‐fold lower than for enzymes in CYP2 and CYP3 families. DCPCC IC₅₀ values were 10–680 times higher than the ones of ANF. DCPCC was a mixed‐type inhibitor of CYP1A2. ANF was a competitive tight‐binding inhibitor of CYP1A1, CYP1A2, and CYP1B1. CYP1A1 oxidized DCPCC more rapidly than CYP1A2 or CYP1B1 to the same metabolite. Molecular dynamics simulations and binding free energy calculations explained the differences of binding of DCPCC and ANF to the active sites of all three CYP1 enzymes. We conclude that DCPCC is a more selective inhibitor for CYP1A2 than ANF. DCPCC is a candidate structure to modulate CYP1A2‐mediated metabolism of procarcinogens and anticancer drugs.     

Neuropharmacological, neuroprotective and amyloid precursor processing properties of selective MAO-B inhibitor antiparkinsonian drug, rasagiline

Rasagiline (N-propargyl-1R-aminoindan) is a novel, highly potent, irreversible monoamine oxidase (MAO)-B inhibitor designed for use as an antiparkinsonian drug. Unlike selegiline, rasagiline is not derived from amphetamine or metabolized to neurotoxic l-methamphetamine derivative, and it does not have sympathomimetic activity. Moreover, at selective MAO-B inhibitory dosage, it does not induce a "cheese reaction." Rasagiline is effective as monotherapy or as an adjunct to L-dopa for patients with early and late Parkinson's disease. Adverse events do not occur with greater frequency in subjects receiving rasagiline than in those on placebo. Its S-isomer, TVP1022, is more than a thousand times less potent as an MAO inhibitor. However, both drugs have neuroprotective activities in neuronal cell cultures in response to various neurotoxins, as well as in vivo (e.g., in response to global ischemia, neurotrauma, head injury, anoxia, etc.), indicating that MAO inhibition is not a prerequisite for neuroprotection. The neuroprotective activity of these drugs has been demonstrated to be associated with the propargylamine moiety, which protects mitochondrial viability and mitochondrial permeability transition pore by activating Bcl-2 and downregulating the Bax family of proteins. Rasagiline processes amyloid precursor protein (APP) into the neuroprotective-neurotrophic soluble APPalpha (sAPPalpha) by protein kinase C- and mitogen-activated protein kinase-dependent activation of alpha-secretase, and increases nerve growth factor, glial cell- derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) expression and proteins. Thus, rasagiline may induce neuroprotection, neuroplasticity and long-term potentiation. Rasagiline has therefore been chosen by the National Institutes of Health (NIH) to study its neuroprotective effects in neurodegenerative diseases. Long-term studies are required to evaluate the drug's disease-modifying prospects in Parkinson's and Alzheimer's diseases.     

Lesioning of Locus coeruleus Projections by DSP‐4 Neurotoxin Treatment: Effect on Amphetamine‐Induced Hyperlocomotion and Dopamine D2 Receptor Binding in Rats

DSP‐4 is a neurotoxin highly selective for the noradrenergic nerve terminals of the locus coeruleus projections. Data on the effect of DSP‐4 treatment on amphetamine‐induced hyperlocomotion are contradictory. In this study, DSP‐4 (50 mg/kg) caused reduction of noradrenaline levels by 70% in the cerebral cortex and by 79% in the cerebellum. This treatment resulted in upregulation of dopamine D₂ receptors in the striatum as evidenced by [³H]‐raclopride binding. In an open field test, DSP‐4 reduced locomotor activity. D ‐Amphetamine (1.5 mg/kg) caused a similar increase in locomotor activity in control and DSP‐4‐pretreated animals not familiar to the apparatus. However, when the rats were habituated to the test apparatus, the effect of amphetamine on horizontal activity was significantly larger in the DSP‐4‐pretreated animals. These data suggest that supersensitivity of D₂ receptors develops after locus coeruleus denervation, but that the enhanced efficacy of amphetamine in DSP‐4‐treated rats is masked by neophobia.     

Chemopreventive and anti‐angiogenic effects of dietary phenethyl isothiocyanate in an N‐methyl nitrosourea‐induced breast cancer animal model

The effect of phenethyl isothiocyanate (PEITC), a component of cruciferous vegetables, on the initiation and progression of cancer was investigated in a chemically induced estrogen‐dependent breast cancer model. Breast cancer was induced in female Sprague Dawley rats (8 weeks old) by the administration of N‐methyl nitrosourea (NMU). Animals were administered 50 or 150 µmol/kg oral PEITC and monitored for tumor appearance for 18 weeks. The PEITC treatment prolonged the tumor‐free survival time and decreased the tumor incidence and multiplicity. The time to the first palpable tumor was prolonged from 69 days in the control, to 84 and 88 days in the 50 and 150 µmol/kg PEITC‐treated groups. The tumor incidence in the control, 50 µmol/kg, and 150 µmol/kg PEITC‐treated groups was 56.6%, 25.0% and 17.2%, while the tumor multiplicity was 1.03, 0.25 and 0.21, respectively. Differences were statistically significant (p < 0.05) from the control, but there were no significant differences between the two dose levels. The intratumoral capillary density decreased from 4.21 ± 0.30 vessels per field in the controls to 2.46 ± 0.25 in the 50 µmol/kg and 2.36 ± 0.23 in the 150 µmol/kg PEITC‐treated animals. These studies indicate that supplementation with PEITC prolongs the tumor‐free survival, reduces tumor incidence and burden, and is chemoprotective in NMU‐induced estrogen‐dependent breast cancer in rats. For the first time, it is reported that PEITC has anti‐angiogenic effects in a chemically induced breast cancer animal model, representing a potentially significant mechanism contributing to its chemopreventive activity. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis of a 13C labeled N‐cyclopropylamine tetrahydropyridine derivative

The synthesis of 1‐(2‐¹³C)‐cyclopropyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (8) is reported. Attempts were first made to prepare labeled cyclopropylamine via a cyclopropanation/Curtius rearrangement sequence, but the yields were too modest to be suitable for the synthesis of a labeled compound. The preparation of 8 was achieved via cyclopropanation of the N‐formyl tetrahydropyridine derivative 21 using the Grignard reagent of ethyl bromide and Ti(O‐iPr)₄ as a catalyst. The synthesis proceeded in high yield (82%). The method has a wide potential for the synthesis of other cyclopropyl ring labeled and substituted cyclopropyl ring labeled tetrahydropyridine dervatives which can be used in Monoamine Oxidase (MAO) and Cyt P₄₅₀ enzymes mechanistic studies. Copyright © 2002 John Wiley & Sons, Ltd.     

Cytotoxic effects of psychotropic benzofuran derivatives,N‐methyl‐5‐(2‐aminopropyl)benzofuran and its N‐demethylated derivative,on isolated rat hepatocytes

The novel psychoactive compounds derived from amphetamine have been illegally abused as recreational drugs, some of which are known to be hepatotoxic in humans and experimental animals. The cytotoxic effects and mechanisms of 5‐(2‐aminopropyl)benzofuran (5‐APB) and N‐methyl‐5‐(2‐aminopropyl)benzofuran (5‐MAPB), both of which are benzofuran analogues of amphetamine, and 3,4‐methylenedioxy‐N‐methamphetamine (MDMA) were studied in freshly isolated rat hepatocytes. 5‐MAPB caused not only concentration‐dependent (0–4.0 mm ) and time‐dependent (0–3 h) cell death accompanied by the depletion of cellular ATP and reduced glutathione and protein thiol levels, but also accumulation of oxidized glutathione. Of the other analogues examined at a concentration of 4 mm , 5‐MAPB/5‐APB‐induced cytotoxicity with the production of reactive oxygen species and loss of mitochondrial membrane potential was greater than that induced by MDMA. In isolated rat liver mitochondria, the benzofurans resulted in a greater increase in the rate of state 4 oxygen consumption than did MDMA, with a decrease in the rate of state 3 oxygen consumption. Furthermore, the benzofurans caused more of a rapid mitochondrial swelling dependent on the mitochondrial permeability transition than MDMA. 5‐MAPB at a weakly toxic level (1 mm ) was metabolized slowly: levels of 5‐MAPB and 5‐APB were approximately 0.9 mm and 50 μm , respectively, after 3 h incubation. Taken collectively, these results indicate that mitochondria are target organelles for the benzofuran analogues and MDMA, which elicit cytotoxicity through mitochondrial failure, and the onset of cytotoxicity may depend on the initial and/or residual concentrations of 5‐MAPB rather than on those of its metabolite 5‐APB. Copyright © 2016 John Wiley & Sons, Ltd.     

Citral inhibits N‐nitrosodiethylamine‐induced hepatocellular carcinoma via modulation of antioxidants and xenobiotic‐metabolizing enzymes

Hepatocellular carcinoma (HCC) ranks the sixth position among various cancers worldwide. Recent research shows that natural and dietary compounds possess many therapeutic effects. Citral is a monoterpene aldehyde that contains geranial and neral. The present study was considered to study the role of citral against N‐nitrosodiethylamine (NDEA)‐induced HCC via modulation of antioxidants and xenobiotic‐metabolizing enzymes in vivo. NDEA‐alone‐administered group II animals profoundly showed increased tumor incidence, reactive oxygen species, liver marker enzyme levels, serum bilirubin levels, tumor markers of carcinoembryonic antigen, α‐fetoprotein, proliferative markers of argyrophilic nucleolar organizing regions, proliferating cell nuclear antigen (PCNA) expressions, phase I xenobiotic‐metabolic enzymes and simultaneously decreased antioxidants, and phase II enzymes levels. Citral (100 mg/kg b.w.) treatment significantly reverted the levels in group III cancer‐bearing animals when compared to group II cancer‐bearing animals. In group IV animals, citral‐alone administration did not produce any adverse effect during the experimental condition. Based on the results, citral significantly inhibits the hepatocellular carcinogenesis through restoring the antioxidants and phase II xenobiotic‐enzyme levels; thereby, it strongly proves as an antiproliferative agent against rat HCC.     

Increased expression of miR‐34a in mouse spleen one day after exposure to N‐ethyl‐N‐nitrosourea

MicroRNAs (miRNAs) are a class of single‐stranded small RNA molecules (~22 nucleotides) that are not translated into proteins and function as regulators of gene expression. Many miRNAs are involved in carcinogenesis. One of them, miR‐34a, is associated with various p53‐initiated biological processes and may act as a tumor suppressor miRNA. Its expression is generally down‐regulated in tumor tissues and up‐regulated in tissues exposed to carcinogens chronically or subchronically. However, the response of this miRNA to acute exposure of a genotoxic carcinogen is little known. In this study, miR‐34a expression was evaluated in spleen tissues of mice treated with a dose of 120 mg kg^?1 body weight N‐ethyl‐N‐nitrosourea (ENU), a potent mutagenic carcinogen. Real‐time PCR analysis showed that the ENU exposure resulted in a 5.5‐fold increase of miR‐34a expression over the control one day after the treatment. The result suggests that miR‐34a expression responds sensitively to genotoxic insults within a short period after exposure of the mutagen, and therefore, this gene has the potential to be used as an indicator for genotoxin exposure.     

Synthesis of labeled acrylamide and N‐methylolacrylamide (NMA): 15N‐acrylamide, 13C‐NMA, 15N‐NMA,and 13C,15N‐NMA

Labeled derivatives of N‐methylolacrylamide (NMA) including ¹⁵N‐NMA, ¹³C‐NMA, and ¹³C,¹⁵N‐NMA were synthesized and purified. A required chemical precursor, ¹⁵N‐acrylamide, was also prepared. Reported methods for synthesizing unlabeled analogs are noted, and modifications to these methods for achieving the labeled materials are specified. Monomers were examined via ¹H, ¹³C, and ¹⁵N nuclear magnetic resonance (NMR) spectroscopy. Peak assignments and coupling constants are reported for each compound. To our knowledge, this is the first reported publication on the preparation and characterization of ¹³C‐NMA, ¹⁵N‐NMA, ¹³C,¹⁵N‐NMA, and ¹⁵N‐acrylamide. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis of N‐methylmorpholine N‐(17O‐oxide) and N‐methylmorpholine 15N‐(17O‐oxide)

N‐Methylmorpholine N‐(¹⁷O‐oxide) and N‐methylmorpholine ¹⁵N‐(¹⁷O‐oxide) were prepared from N‐methylmorpholine and ¹⁵N‐methylmorpholine by oxidation with H₂ ¹⁷O₂. The facile one‐pot procedure provided yields of 82 and 76%, respectively. The labeled hydrogen peroxide was obtained by electrolysis of H₂ ¹⁷O followed by autoxidation of 2‐ethylanthraquinol with the molecular oxygen ¹⁷O₂ generated. The compounds serve for mechanistic studies into gold nanoparticle generation in NMMO solution. Copyright © 2009 John Wiley & Sons, Ltd.