Acetaldehyde-induced cytotoxicity involves induction of spermine oxidase at the transcriptional level

Ethanol consumption causes serious liver injury including cirrhosis and hepatocellular carcinoma. Ethanol is metabolized mainly in the liver to acetic acid through acetaldehyde. We investigated the effect of ethanol and acetaldehyde on polyamine metabolism since polyamines are essential factors for normal cellular functions. We found that acetaldehyde induced spermine oxidase (SMO) at the transcriptional level in HepG2 cells. The levels and activities of ornithine decarboxylase (ODC) and spermidine/spermine acetyltransferase (SSAT) were not affected by acetaldehyde. Spermidine content was increased and spermine content was decreased by acetaldehyde treatment. Knockdown of SMO expression using siRNA reduced acetaldehyde toxicity. Acetaldehyde exposure increased free acrolein levels. An increase of acrolein by acetaldehyde was SMO dependent. Our results indicate that cytotoxicity of acetaldehyde involves, at least in part, oxidation of spermine to spermidine by SMO, which is induced by acetaldehyde.

Cigarette smoke component acrolein modulates chromatin assembly by inhibiting histone acetylation

Chromatin structure and gene expression are both regulated by nucleosome assembly. How environmental factors influence histone nuclear import and the nucleosome assembly pathway, leading to changes in chromatin organization and transcription, remains unknown. Acrolein (Acr) is an α,β-unsaturated aldehyde, which is abundant in the environment, especially in cigarette smoke. It has recently been implicated as a potential major carcinogen of smoking-related lung cancer. Here we show that Acr forms adducts with histone proteins in vitro and in vivo and preferentially reacts with free histones rather than with nucleosomal histones. Cellular fractionation analyses reveal that Acr exposure specifically inhibits acetylations of N-terminal tails of cytosolic histones H3 and H4, modifications that are important for nuclear import and chromatin assembly. Notably, Acr exposure compromises the delivery of histone H3 into chromatin and increases chromatin accessibility. Moreover, changes in nucleosome occupancy at several genomic loci are correlated with transcriptional responses to Acr exposure. Our data provide new insights into mechanisms whereby environmental factors interact with the genome and influence genome function.

Examination of the genome-wide transcriptional response of Escherichia coli O157:H7 to cinnamaldehyde exposure

Cinnamaldehyde is a natural antimicrobial that has been found to be effective against many food-borne pathogens, including Escherichia coli O157:H7. Although its antimicrobial effects have been well investigated, limited information is available on its effects at the molecular level. Sublethal treatment at 200 mg/liter cinnamaldehyde inhibited growth of E. coli O157:H7 at 37°C and for ≤2 h caused cell elongation, but from 2 to 4 h growth resumed and cells reverted to normal length. To understand this transient behavior, genome-wide transcriptional analysis of E. coli O157:H7 was performed at 2 and 4 h of exposure to cinnamaldehyde in conjunction with reverse-phase high-performance liquid chromatography (RP-HPLC) analysis for cinnamaldehyde and other cinnamic compounds. Drastically different gene expression profiles were obtained at 2 and 4 h. RP-HPLC analysis showed that cinnamaldehyde was structurally stable for at least 2 h. At 2 h of exposure, cinnamaldehyde induced expression of many oxidative stress-related genes and repressed expression of DNA, protein, O-antigen, and fimbrial synthetic genes. At 4 h, many cinnamaldehyde-induced repressive effects on E. coli O157:H7 gene expression were reversed, and cells became more motile and grew at a slightly higher rate. Data indicated that by 4 h, E. coli O157:H7 was able to convert cinnamaldehyde into the less toxic cinnamic alcohol using dehydrogenase/reductase enzymes (YqhD and DkgA). This is the first study to characterize the ability of E. coli O157:H7 to convert cinnamaldehyde into cinnamic alcohol which, in turn, showed that the antimicrobial activity of cinnamaldehyde is mainly attributable to its carbonyl aldehyde group.

Assays for the measurement of lipid peroxidation

Physical and emotional stress, metabolic alterations, carcinogenesis or inflammation are conditions that can trigger oxidative stress, which is defined as a balance shift of redox reactions towards oxidation, resulting in the increase of reactive oxygen species (ROS). ROS are continuously formed in small quantities during the normal metabolism of cell, however the overproduction of ROS is cytotoxic and damages macromolecules (DNA, proteins, sugars and lipids). Polyunsaturated fatty acids (PUFAs) that are esterified in membrane or storage lipids are subject to ROS-induced peroxidation resulting in the destruction of biomembranes. Final products of lipid peroxidation (LPO) are reactive aldehydes that are relatively stable and may diffuse far from the initial site of oxidative injury and act as second messengers or free radicals. The difference between physiological and pathological oxidative stress is often the occurrence of LPO and its final toxic products. In this chapter, two classes of methods for measurement of LPO are described. The first include assays for detection of LPO at the organismal level, while the second include molecular and cellular assays that reveal the mechanistic effects of LPO on the function, morphology and viability of the cells.

A comprehensive strategy to discover inhibitors of the translesion synthesis DNA polymerase κ

Human DNA polymerase kappa (pol κ) is a translesion synthesis (TLS) polymerase that catalyzes TLS past various minor groove lesions including N(2)-dG linked acrolein- and polycyclic aromatic hydrocarbon-derived adducts, as well as N(2)-dG DNA-DNA interstrand cross-links introduced by the chemotherapeutic agent mitomycin C. It also processes ultraviolet light-induced DNA lesions. Since pol κ TLS activity can reduce the cellular toxicity of chemotherapeutic agents and since gliomas overexpress pol κ, small molecule library screens targeting pol κ were conducted to initiate the first step in the development of new adjunct cancer therapeutics. A high-throughput, fluorescence-based DNA strand displacement assay was utilized to screen ∼16,000 bioactive compounds, and the 60 top hits were validated by primer extension assays using non-damaged DNAs. Candesartan cilexetil, manoalide, and MK-886 were selected as proof-of-principle compounds and further characterized for their specificity toward pol κ by primer extension assays using DNAs containing a site-specific acrolein-derived, ring-opened reduced form of γ-HOPdG. Furthermore, candesartan cilexetil could enhance ultraviolet light-induced cytotoxicity in xeroderma pigmentosum variant cells, suggesting its inhibitory effect against intracellular pol κ. In summary, this investigation represents the first high-throughput screening designed to identify inhibitors of pol κ, with the characterization of biochemical and biologically relevant endpoints as a consequence of pol κ inhibition. These approaches lay the foundation for the future discovery of compounds that can be applied to combination chemotherapy.

Biodegradable polymer (PLGA) coatings featuring cinnamaldehyde and carvacrol mitigate biofilm formation

Biofilm-associated infections are one of the leading causes of death in the United States. Although infections may be treated with antibiotics, the overuse of antibiotics has led to the spread of antibiotic resistance. Many natural antimicrobial compounds derived from edible plants are safe for human use and target bacteria nonspecifically. Therefore, they may impair biofilm formation with less evolutionary pressure on pathogens. Here, we explore the use of two natural antimicrobial compounds, cinnamaldehyde (CA, from cinnamon) and carvacrol (CARV, from oregano), for biofilm prevention. We have fabricated and characterized films that incorporate CA and CARV into the biodegradable, FDA-approved polymer poly(lactic-co-glycolic acid), PLGA. The addition of CA and CARV to PLGA films not only adds antimicrobial activity but also changes the surface properties of the films, making them more hydrophilic and therefore more resistant to bacterial attachment. An addition of 0.1% CA to a PLGA film significantly impairs biofilm development by Staphylococcus aureus, and 0.1% CARV in PLGA significantly decreases biofilm formation by both Escherichia coli and S. aureus. Pseudomonas aeruginosa, which is less susceptible to CA and CARV, was not affected by the addition of 0.1% CA or CARV to the PLGA coatings; however, P. aeruginosa biofilm was significantly reduced by 1.0% CA. These results indicate that both CA and CARV could potentially be used in low concentrations as natural additives in polymer coatings for indwelling devices to delay colonization by bacteria.

Reactive carbonyl species: their production from lipid peroxides, action in environmental stress, and the detoxification mechanism

Accumulation of lipid peroxide-derived aldehydes and ketones is a ubiquitous event in oxidative stress. The toxicity of these carbonyls, especially the α,β-unsaturated carbonyls (reactive carbonyls; RCS), in environmental-stressed plants has been demonstrated by several independent research groups, on the basis of the results that overexpression of different carbonyl-detoxifying enzymes commonly improved tolerance of the transgenic plants against environmental stresses. A positive correlation between the level of carbonyls and the stress-induced damage in these plants proves the cause-effect relationship between carbonyls and the cell injury. Comprehensive analysis of carbonyls has revealed that dozens of distinct RCS including highly toxic acrolein and 4-hydroxy-2-nonenal are contained at nmol/g fresh weight levels in the tissues of non-stressed plants. Stress treatments of plants increase the levels of these RCS, likely reaching a sub-mM order, but in the transgenic plants overproducing RCS-detoxifying enzymes, their increase is significantly suppressed. Immunological analyses have demonstrated that in non-stressed cells several proteins are modified by RCS and the extent of modification is increased on stresses. In heat-stressed leaves, the inactivation of the oxygen-evolving complex was associated with selective modification of OEC33 protein and photosystem II core proteins. RCS consume glutathione and inactivate various enzymes in chloroplasts and mitochondria, thereby accelerating oxidative stress status. Thus RCS, formed downstream of reactive oxygen species (ROS), act in a way biochemically distinct from that of ROS and play critical roles in the plant responses to oxidative stress.

Novel dehalogenase mechanism for 2,3-dichloro-1-propanol utilization in Pseudomonas putida strain MC4

A Pseudomonas putida strain (MC4) that can utilize 2,3-dichloro-1-propanol (DCP) and several aliphatic haloacids and haloalcohols as sole carbon and energy source for growth was isolated from contaminated soil. Degradation of DCP was found to start with oxidation and concomitant dehalogenation catalyzed by a 72-kDa monomeric protein (DppA) that was isolated from cell lysate. The dppA gene was cloned from a cosmid library and appeared to encode a protein equipped with a signal peptide and that possessed high similarity to quinohemoprotein alcohol dehydrogenases (ADHs), particularly ADH IIB and ADH IIG from Pseudomonas putida HK. This novel dehalogenating dehydrogenase has a broad substrate range, encompassing a number of nonhalogenated alcohols and haloalcohols. With DCP, DppA exhibited a k(cat) of 17 s(-1). (1)H nuclear magnetic resonance experiments indicated that DCP oxidation by DppA in the presence of 2,6-dichlorophenolindophenol (DCPIP) and potassium ferricyanide [K(3)Fe(CN)(6)] yielded 2-chloroacrolein, which was oxidized to 2-chloroacrylic acid.

Attenuation of mouse somatic and emotional inflammatory pain by hydralazine through scavenging acrolein and inhibiting neuronal activation

BACKGROUND

Acrolein signaling is important during spinal cord injury; whether it is involved in somatic and emotional pain is not clear. Hydralazine is a potent antihypertensive drug and can scavenge acrolein efficiently.

OBJECTIVE

We hypothesized that hydralazine decreases spinal level acrolein and renders analgesic effects with some side effects, which was tested in the current study.

STUDY DESIGN

Subcutaneous injection of formalin was used to induce somatic and emotional pain responses. The spinal neuronal activation (FOS expression) and acrolein expression were evaluated at 2 hours after subcutaneous formalin injection. The possible side effects of hydralazine on the murine central nervous system or cardiovascular system were evaluated at one hour after hydralazine injection with open field, elevated plus maze and rotarod tests, or telemetrical measurement of mean artery blood pressure and heart rate.

RESULTS

The subcutanous injection of formalin into the left hind paw induced significant somatic and emotional pain responses, evaluated by the biphasic spontaneous flinch/licking of the injected hind paw and interphase ultrasonic vocalizations during the one hour window after formalin injection. The spinal acrolein level was significantly increased and neurons were activated at 2 hours after formalin injection. Intraperitoneal injection of hydralazine (at 0.1, 1 or 10 mg/kg of body weight) at one hour before formalin challenging dose-dependently attenuated the formalin induced pain responses with an analgesic 50% effect dose ranging from 0.2 to 1 mg/kg of body weight. Furthermore, the neuronal activation and elevated acrolein expression were dose-dependently inhibited by hydralazine pretreatment. The side effects of intraperitoneal hydralazine on locomotion, anxiety, and motor coordination at one hour after hydralazine administration had negative results. The main side effects of hydralazine were an insignificant decrease of blood pressure and a significant increase of heart rates at high dose (10 mg/kg of body weight).

LIMITATIONS

This study is limited because the analgesic effect of hydralazine was tested on only one type of acute inflammatory pain model; however, its effect on chronic inflammatory or neuropathic pain needs to be further investigated.

CONCLUSIONS

Based on the above findings, hydralazine may find its new application of analgesia within a safe dose window (around one mg/kg of body weight) without causing severe side effects.

Thermotolerant cyclamen with reduced acrolein and methyl vinyl ketone

Reduced levels of trienoic fatty acids (TAs) in chloroplast membranes induce thermotolerance in several plant species, but the underlying mechanisms remain unclear. TA peroxidation in plant cell membranes generates cytotoxic, TA-derived compounds containing α,β-unsaturated carbonyl groups. The relationship between low TA levels and the amounts of cytotoxic TA-derived compounds was examined using thermotolerant transgenic cyclamen (Cyclamen persicum Mill.) with low TA contents. Changes in the levels of the cytotoxic TA-derived acrolein (ACR), methyl vinyl ketone (MVK), (E)-2-hexenal, 4-hydroxy-2-nonenal, and malondialdehyde were analysed in the leaf tissues of wild-type (WT) and thermotolerant transgenic cyclamen under heat stress. Levels of ACR and MVK in the WT increased in parallel with the occurrence of heat-induced tissue damage, whereas no such changes were observed in the thermotolerant transgenic lines. Furthermore, exogenous ACR and MVK infiltrated into leaves to concentrations similar to those observed in heat-stressed WT leaves caused similar disease symptoms. These results suggest that thermotolerance in transgenic cyclamen depends on reduced production rates of ACR and MVK under heat stress, due to the low level of TAs in these plants.

In vitro metabolic fate of alizapride: evidence for the formation of reactive metabolites based on liquid chromatography-tandem mass spectrometry

The study of the formation of reactive metabolites during drug metabolism is one of the major areas of research in drug development since the link between reactive metabolites and drug adverse effects was well recognized. In particular, it has been shown that acrolein, a reactive carbonyl species sharing carbonylating and alkylating properties, binds covalently to nucleophilic sites in proteins, causing cellular damage. Alizapride, (±)-6-methoxy-N-{[1-(prop-2-en-1-yl)-pyrrolidin-2-yl]methyl}-1H-benzotriazole-5-carboxamide, is a N-allyl containing dopamine antagonist with antiemetic properties for which no data concerning its metabolic fate are so far reported. The study of the in vitro metabolism of alizapride showed the formation of acrolein during the oxidative N-deallylation. Moreover, the formation of an epoxide metabolite has been also described suggesting its role as a putative structural alert. The reactivity of the acrolein and the epoxide generated in alizapride metabolism was demonstrated by the formation of the corresponding adducts with nucleophilic thiols. Overall, ten metabolites have been identified and characterized by electrospray ionization tandem mass spectrometry analysis allowing to propose an in vitro metabolic scheme for alizapride. At the best of our knowledge, this is the second case of a drug involved in the generation of acrolein during its metabolism being the first represented by cyclophosphamide.

Syringyl lignin is unaltered by severe sinapyl alcohol dehydrogenase suppression in tobacco

The manipulation of lignin could, in principle, facilitate efficient biofuel production from plant biomass. Despite intensive study of the lignin pathway, uncertainty exists about the enzyme catalyzing the last step in syringyl (S) monolignol biosynthesis, the reduction of sinapaldehyde to sinapyl alcohol. Traditional schemes of the pathway suggested that both guaiacyl (G) and S monolignols are produced by a single substrate-versatile enzyme, cinnamyl alcohol dehydrogenase (CAD). This was challenged by the discovery of a novel sinapyl alcohol dehydrogenase (SAD) that preferentially uses sinapaldehyde as a substrate and that was claimed to regulate S lignin biosynthesis in angiosperms. Consequently, most pathway schemes now show SAD (or SAD and CAD) at the sinapaldehyde reduction step, although functional evidence is lacking. We cloned SAD from tobacco (Nicotiana tabacum) and suppressed it in transgenic plants using RNA interference-inducing vectors. Characterization of lignin in the woody stems shows no change to content, composition, or structure, and S lignin is normal. By contrast, plants additionally suppressed in CAD have changes to lignin structure and S:G ratio and have increased sinapaldehyde in lignin, similar to plants suppressed in CAD alone. These data demonstrate that CAD, not SAD, is the enzyme responsible for S lignin biosynthesis in woody angiosperm xylem.

Distribution of lignin and its coniferyl alcohol and coniferyl aldehyde groups in Picea abies and Pinus sylvestris as observed by Raman imaging

Wood cell wall consists of several structural components, such as cellulose, hemicelluloses and lignin, whose concentrations vary throughout the cell wall. It is a composite where semicrystalline cellulose fibrils, acting as reinforcement, are bound together by amorphous hemicelluloses and lignin matrix. Understanding the distribution of these components and their functions within the cell wall can provide useful information on the biosynthesis of trees. Raman imaging enables us to study chemistry of cell wall without altering the structure by staining the sample or fractionating it. Raman imaging has been used to analyze distributions of lignin and cellulose, as well as the functional groups of lignin in wood. In our study, we observed the distribution of cellulose and lignin, as well as the amount of coniferyl alcohol and aldehyde groups compared to the total amount of lignin in pine (Pinus sylvestris) and spruce (Picea abies) wood samples. No significant differences could be seen in lignin and cellulose distribution between these samples, while clear distinction was observed in the distribution of coniferyl alcohols and coniferyl aldehyde in them. These results could provide valuable insight on how two similar wood species control biosynthesis of lignin differently during the differentiation of cell wall.

Acrolein-mediated injury in nervous system trauma and diseases

Acrolein, an α,β-unsaturated aldehyde, is a ubiquitous pollutant that is also produced endogenously through lipid peroxidation. This compound is hundreds of times more reactive than other aldehydes such as 4-hydroxynonenal, is produced at much higher concentrations, and persists in solution for much longer than better known free radicals. It has been implicated in disease states known to involve chronic oxidative stress, particularly spinal cord injury and multiple sclerosis. Acrolein may overwhelm the anti-oxidative systems of any cell by depleting glutathione reserves, preventing glutathione regeneration, and inactivating protective enzymes. On the cellular level, acrolein exposure can cause membrane damage, mitochondrial dysfunction, and myelin disruption. Such pathologies can be exacerbated by increased concentrations or duration of exposure, and can occur in normal tissue incubated with injured spinal cord, showing that acrolein can act as a diffusive agent, spreading secondary injury. Several chemical species are capable of binding and inactivating acrolein. Hydralazine in particular can reduce acrolein concentrations and inhibit acrolein-mediated pathologies in vivo. Acrolein scavenging appears to be a novel effective treatment, which is primed for rapid translation to the clinic.

Protein-conjugated acrolein as a biochemical marker of brain infarction

The relationship between acrolein (CH(2) =CH-CHO) and brain infarction is the focus of this review. It has been found that acrolein is produced mainly within cells from polyamines by polyamine oxidases (PAOs), especially from spermine by spermine oxidase during cell damage, and that acrolein is more toxic than reactive oxygen species (ROS) in a cell culture system. Thus, the possibility that acrolein and PAOs are good biochemical markers of stroke was tested because there are no other reliable biochemical markers at the early stage of stroke. Levels of protein-conjugated acrolein (PC-Acro) and PAOs (acrolein-producing enzymes) were significantly increased in the plasma of stroke patients. The multiplied value of PC-Acro by PAOs was nearly parallel with the size of stroke. Furthermore, when the combined measurements of PC-Acro, interleukin-6 (IL-6) and C-reactive protein (CRP) were evaluated along with age using a receiver operating characteristic (ROC) curve, even silent brain infarction (SBI), which is a small brain infarction, was indicated with approximately 84% sensitivity and specificity. These findings clearly indicate that acrolein is strongly correlated with cell damage during brain infarction.

Comparison of exposure to selected cigarette smoke constituents in adult smokers and nonsmokers in a European, multicenter, observational study

BACKGROUND

This multicenter, observational study was conducted in three European countries (Germany, Switzerland, and the United Kingdom) to determine the exposure of adult cigarette smokers and nonsmokers to selected cigarette smoke constituents: 1,3-butadiene, 2-naphthylamine, 4-aminobiphenyl, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), acrolein, benzene, carbon monoxide, nicotine, pyrene, and o-toluidine.

METHODS

Smokers were grouped by tar category (TC) according to the tar yield of their regular cigarette brand: TC1: ≤4 mg tar, TC2: 5-7 mg tar, and TC3: ≥8 mg tar [to the legal tar yield ceiling in the respective countries (10 or 12 mg tar)]. Levels of biomarkers of exposure to the aforementioned cigarette smoke constituents were compared between smokers and nonsmokers, and within smokers across tar categories.

RESULTS

The full population consisted of 1,631 subjects (1,223 smokers and 408 nonsmokers). Biomarkers of exposure were analyzed for 1,558 subjects (valid case population) as follows: 1,159 smokers (TC1: n = 402, TC2: n = 379, TC3: n = 378), and 399 nonsmokers. Exposure levels were higher in smokers than nonsmokers and increased with increasing tar yield and cigarette consumption. An association of tar category and exposure level was observed for all smoke constituents, except pyrene, 4-aminobiphenyl, and o-toluidine, whereas only NNK exposure was different in all three tar categories.

CONCLUSIONS

Smoking status and, among smokers, daily cigarette consumption and tar yield were observed to affect biomarker of exposure levels.

IMPACT

This research provides a comprehensive evaluation of smoke constituent exposure of adult cigarette smokers and nonsmokers in three European countries.

Aldose reductase (AKR1B3) regulates the accumulation of advanced glycosylation end products (AGEs) and the expression of AGE receptor (RAGE)

Diabetes results in enhanced chemical modification of proteins by advanced lipoxidation end products (ALEs) and advanced glycation end products (AGEs) precursors. These modifications have been linked to the development of several secondary diabetic complications. Our previous studies showed that aldose reductase (AR; AKR1B3) catalyzes the reduction of ALEs and AGEs precursors; however, the in vivo significance of this metabolic pathway during diabetes and obesity has not been fully assessed. Therefore we examined the role of AR in regulating ALEs and AGEs formation in murine models of diet-induced obesity and streptozotocin-induced diabetes. In comparison with wild-type (WT) and AR-null mice fed normal chow, mice fed a high-fat (HF) diet (42% kcal fat) showed increased accumulation of AGEs and protein-acrolein adducts in the plasma. AGEs and acrolein adducts were also increased in the epididymal fat of WT and AR-null mice fed a HF diet. Deletion of AR increased the accumulation of 4-hydroxy-trans-2-nonenal (HNE) protein adduct in the plasma and increased the expression of the AGE receptor (RAGE) in HF fed mice. No change in AGEs formation was observed in the kidneys of HF-fed mice. In comparison, renal tissue from AR-null mice treated with streptozotocin showed greater AGE accumulation than streptozotocin-treated WT mice. These data indicated that AR regulated the accumulation of lipid peroxidation derived aldehydes and AGEs under conditions of severe, but not mild, hyperglycemia and that deletion of AR increased RAGE-induction via mechanisms that were independent of AGEs accumulation.

Bioreduction of α,β-unsaturated ketones and aldehydes by non-conventional yeast (NCY) whole-cells

The bioreduction of α,β-unsaturated ketones (ketoisophorone, 2-methyl- and 3-methyl-cyclopentenone) and aldehydes [(S)-(-)-perillaldehyde and α-methyl-cinnamaldehyde] by 23 "non-conventional" yeasts (NCYs) belonging to 21 species of the genera Candida, Cryptococcus, Debaryomyces, Hanseniaspora, Kazachstania, Kluyveromyces, Lindnera, Nakaseomyces, Vanderwaltozyma, and Wickerhamomyces was reported. The results highlight the potential of NCYs as whole-cell biocatalysts for selective biotransformation of electron-poor alkenes. A few NCYs exhibited extremely high (>90%) or even total ketoisophorone and 2-methyl-cyclopentenone bioconversion yields via asymmetric reduction of the conjugated CC bond catalyzed by enoate reductases. Catalytic efficiency declined after switching from ketones to aldehydes. High chemoselectivity due to low competing carbonyl reductases was also sometimes observed.

Carnosine protects against the neurotoxic effects of a serotonin-derived melanoid

Anesthesia-related postoperative cognitive dysfunction (POCD) leads to morbidity in the elderly. Lipid peroxidative byproducts (i.e. acrolein) accumulate in aging and may play a role. Sevoflurane, an inhaled anesthetic, sequesters acrolein and enhances the formation of a serotonin-derived melanoid (SDM). SDM may be a biologically relevant polymeric melanoid that we previously showed exhibits redox activity and disrupts lipid bilayers. In this study, we examined the toxicity of SDM in cell culture and looked at protection using L-carnosine. SDM's toxic effects were tested on neuronal-like SH-SY5Y cells, causing an exponential decrease in viability, while human dermal fibroblasts were completely resistant to the toxic effects. SDM brought about morphological changes to differentiated SH-SY5Y cells, particularly to neuronal processes. Co- but not pre-treatment with L-carnosine protected differentiated SH-SY5Y cells exposed to SDM. Our mechanism suggests focal sevoflurane-induced sequestration of age-related acrolein leading to SDM synthesis and neuronal impairment, which is prevented by L-carnosine.

Uptake of methacrolein and methyl vinyl ketone by tree saplings and implications for forest atmosphere

Methacrolein (MACR) and methyl vinyl ketone (MVK) are oxygenates produced from isoprene which is abundantly emitted by trees. The uptake rate of these compounds by leaves of three different Quercus species, Q. acutissima, Q. myrsinaefolia, and Q. phillyraeoides, at typical concentrations within a forest (several part per billion by volume) were determined. The rates of uptake of croton aldehyde (CA) and methyl ethyl ketone (MEK) were also investigated for comparison. The rates of uptake of the two aldehydes MACR and CA were found to be higher than those of the two ketones. In particular, the rate of MEK uptake for Q. myrsinaefolia was exceptionally low. The ratio of intercellular to fumigated concentrations, Ci/Ca, for MACR and CA was found to be low (0-0.24), while the ratio for the two ketones was 0.22-0.90. To evaluate the contribution of tree uptake as a sink for the two isoprene-oxygenates within the forest canopy, loss rates of the compounds due to uptake by trees and by reactions with hydroxyl radicals (OH radicals) and O(3) were calculated. The loss rate by tree uptake was the highest, followed by the reaction with OH radicals, even at a high OH concentration (0.15 pptv) both for MACR and MVK, suggesting that tree uptake provides a significant sink.

Increased levels of 4-hydroxynonenal and acrolein in the brain in preclinical Alzheimer disease

Previous studies demonstrate increased levels of 4-hydroxynonenal (HNE) and acrolein in vulnerable brain regions of subjects with mild cognitive impairment and late-stage Alzheimer disease (LAD). Recently preclinical AD (PCAD) subjects, who demonstrate normal antemortem neuropsychological test scores but abundant AD pathology at autopsy, have become the focus of increased study. Levels of extractable HNE and acrolein were quantified by gas chromatography-mass spectrometry with negative chemical ionization, and protein-bound HNE and acrolein were quantified by dot-blot immunohistochemistry in the hippocampus/parahippocampal gyrus (HPG), superior and middle temporal gyri (SMTG), and cerebellum (CER) of 10 PCAD and 10 age-matched normal control (NC) subjects. Results of the analyses show a significant (P<0.05) increase in levels of extractable acrolein in the HPG of PCAD subjects compared to age-matched NC subjects and a significant decrease in extractable acrolein in PCAD CER. Significant increases in protein-bound HNE in HPG and a significant decrease in CER of PCAD subjects compared to NC subjects were observed. No significant alterations were observed in either extractable or protein-bound HNE or acrolein in the SMTG of PCAD subjects. Additionally, no significant differences in levels of protein carbonyls were observed in the HPG, SMTG, or CER of PCAD subjects compared to NC subjects.

Formation of a vitamin C conjugate of acrolein and its paraoxonase-mediated conversion into 5,6,7,8-tetrahydroxy-4-oxooctanal

Vitamin C (ascorbic acid) has been reported to participate in Michael addition reactions in vitro to form vitamin C conjugates with alpha,beta-unsaturated aldehydes, such as acrolein. This study shows evidence for the formation and metabolism of the vitamin C conjugate of acrolein (AscACR) in cultured human monocytic THP-1 cells exposed to acrolein diacetate. By using (18)O and (13)C labeling in combination with liquid chromatography-tandem mass spectrometry, AscACR was shown to undergo hydrolytic conversion of the ascorbyl lactone into an intermediate carboxylic acid. Subsequent decarboxylation of the carboxylic acid yielded 5,6,7,8-tetrahydroxy-4-oxooctanal (THO). When THP-1 cells were pretreated with ascorbic acid (1 mM, 18 h) and then exposed to acrolein diacetate, THO was detected as its pentafluorobenzyl oxime derivative in the cell lysates and medium. Treatment of THP-1 cells with both ascorbic acid and acrolein diacetate was required for THO formation. The formation of THO from AscACR was facilitated by the lactonase enzymes, human recombinant paraoxonases 1 and 2. THP-1 cells exhibited PON activity, which explains the catalytic conversion of AscACR into THO in these cells. THO was formed in addition to metabolites of the glutathione conjugate of acrolein, indicating that THO formation contributes to the elimination of acrolein in a cellular environment.

[Analysis of cardiac toxicity caused by cyclophosphamide in the H9c2 cell line and isolated and perfused rat hearts]

Cyclophosphamide is used for liver cancer, breast cancer and multiple myeloma, and the pretreatment of hematopoietic stem cell transplantation. A medium to high dose of cyclophosphamide is known to cause irreversible heart failure in some cases, and recently cardiac tamponade and pericarditis have been reported to occur when cyclophosphamide is administered for the pretreatment of hematopoietic stem cell transplantation. To test whether cyclophosphamide itself induces cellular toxicity, we investigated a toxic effect of cyclophosphamide, acrolein, a metabolite of cyclophosphamide, and doxorubicin, which is known to have cardiac toxicity, in the H9c2 cell line and the isolated Langendorff-perfused rat hearts. Cyclophosphamide itself did not have a toxic effect, whereas the toxicity of acrolein is 1, 000 times higher than that of doxorubicin in the H9c2 cell line. Acrolein, but not cyclophosphamide, reduced the left ventricular developed pressure and heart rate, and increased the left ventricular end diastolic pressure. These results suggest that the cardiac toxicity of cyclophosphamide may be caused by acrolein, one of its metabolites. Cyclophosphamide is known to cause hemorrhagic cystitis, and uromitexan was shown not to protect against the cardiac toxicity of cyclophosphamide. Development of new cardioprotective compounds is needed to administer CPA more safely.

Redox mechanism of neurotoxicity by a serotonin-acrolein polymeric melanoid

Postoperative cognitive dysfunction may be associated with the toxic products of lipid peroxidation, such as the α,β-unsaturated aldehyde acrolein, which accumulates in aging. We previously identified an acrolein-mediated, serotonin-derived melanoid product, or SDM. This study further characterizes this putative novel neuromelanin, which is not made from catecholamines. In addition to its strong protein-binding properties, we observed that SDM binds Fe(2+) readily and exhibits complex redox characteristics. SDM may exist as a two-dimensional network of polymers that coalesce into larger entities exhibiting electroactive properties. These observations suggest that SDM may contribute to the decline in cognition due to focal degeneration from SDM-mediated free-radical production. We know that inhalational anesthetics sequester acrolein, which is toxic to neurons, and we propose that the local increase in acrolein depletes serotonin levels and enhances neuronal vulnerability through the production of neuromelanin-like structures, such as SDM.

Acrolein in wine: importance of 3-hydroxypropionaldehyde and derivatives in production and detection

Certain lactic acid bacteria strains belonging to the genus Lactobacillus have been implicated in the accumulation of 3-hydroxypropionaldehyde (3-HPA) during anaerobic glycerol fermentation. In aqueous solution 3-HPA undergoes reversible dimerization and hydration, resulting in an equilibrium state between different derivatives. Wine quality may be compromised by the presence of 3-HPA due to the potential for spontaneous conversion into acrolein under winemaking conditions. Acrolein is highly toxic and has been implicated in the development of bitterness in wine. Interconversion between 3-HPA derivatives and acrolein is a complex and highly dynamic process driven by hydration and dehydration reactions. Acrolein is furthermore highly reactive and its steady-state concentration in complex systems very low. As a result, analytical detection and quantification in solution is problematic. This paper reviews the biochemical and environmental conditions leading to accumulation of its precursor, 3-HPA. Recent advances in analytical detection are summarized, and the roles played by natural chemical derivatives are highlighted.