Reduction of anthranilic acid to 2-aminobenzaldehyde by the white-rot fungus Bjerkandera adusta DSMZ 4708

The biocatalytic aerobic "in-water" reduction of anthranilic acid to 2-aminobenzaldehyde by growing cultures of the basidiomycetous white-rot fungus Bjerkandera adusta has been studied. The high specific activity of Bjerkandera adusta towards the carboxylic group of anthranilic acid that allows avoiding the formation of the corresponding alcohol has been demonstrated using different substrate concentrations. The presence of ethanol as co-solvent allows increasing the yield of target product. In contrast to chemical reducing agents that usually yield 2-aminobenzyl alcohol, an overreduction of anthranilic acid is completely suppressed by the fungus and gives the target flavor compound in satisfactory preparative yields. It was shown that the activity of Bjerkandera adusta towards anthranilic acid does not apply to its m- and p-isomers.

Metallosalen modified carbon nitride a versatile and reusable catalyst for environmentally friendly aldehyde oxidation

The development of environmentally friendly catalysts for organic transformations is of great importance in the field of green chemistry. Aldehyde oxidation reactions play a crucial role in various industrial processes, including the synthesis of pharmaceuticals, agrochemicals, and fine chemicals. This paper presents the synthesis and evaluation of a new metallosalen carbon nitride catalyst named Co(salen)@g-C3N4. The catalyst was prepared by doping salicylaldehyde onto carbon nitride, and subsequently, incorporating cobalt through Schiff base chemistry. The Co(salen)@g-C3N4 catalyst was characterized using various spectroscopic techniques including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Infrared Spectroscopy (IR), and Thermogravimetric Analysis (TGA). Furthermore, after modification with salicylaldehyde, the carbon nitride component of the catalyst exhibited remarkable yields (74-98%) in oxidizing various aldehyde derivatives (20 examples) to benzoic acid. This oxidation reaction was carried out under mild conditions and resulted in short reaction times (120-300 min). Importantly, the catalyst demonstrated recyclability, as it could be reused for five consecutive runs without any loss of activity. The reusable nature of the catalyst, coupled with its excellent yields in oxidation reactions, makes it a promising and sustainable option for future applications.

Interactions between phosvitin and aldehydes affect the release of flavor from Russian sturgeon caviar

The release mechanism of flavor during caviar storage was studied by the interaction between phosvitin and four aldehydes. Gas chromatography-mass spectrometry showed that the binding rate of phosvitin with 3-methylbutanal, nonanal, (E,Z)-2,6-nonadienal, and (E)-2-octenal decreased with an increase in the aldehyde concentrations. Among them, (E,Z)-2,6-Nonadienal (0.5 mM) had the highest binding rate (84.47%). The main quenching mechanism of (E,Z)-2,6-nonadienal with phosvitin was static quenching and the binding force comprised spontaneous hydrophobic interactions. An increase in the aldehyde concentrations reduced the α-helix content of phosvitin and led to aggregation of the microstructure of phosvitin. The results of molecular docking showed that tyr residue contributed the most to the binding of phosvitin to aldehydes. This study has elucidated the mechanism of the effect of caviar protein on changes in the caviar flavor during storage and provides effective strategies for regulation of caviar flavor during storage.

Monitoring stability indicating impurities and aldehyde content in lipid nanoparticle raw material and formulated drugs

Lipid nanoparticles (LNPs) are designed to protect and transport sensitive payloads or active pharmaceutical ingredients as part of new therapeutic modalities. As a multi-component particle, a high degree of quality control is necessary to ensure raw materials are free of critical impurities that could adversely impact the drug product. In this study, we demonstrate a reversed phase liquid chromatography method hyphenated with a single quadrupole mass spectrometer (RPLC-MS) as an alternative platform to methods that incorporate evaporative light scattering or charged aerosol detectors in the detection and quantitation of critical impurities associated with LNPs. The proposed RPLC-MS method offers an increase of up to 2 orders of magnitude in dynamic range and 3 orders of magnitude in sensitivity in the analysis of impurities associated with LNPs compared to conventional detectors. Access to complementary mass data enabled the detection and identification of stability indicating impurities as part of stress studies carried out on an ionizable lipid. In addition to confirmation of peak identity, complementary mass data was also used to assess residual aldehydes in raw material and formulated LNPs in accordance with regulatory guidance. Following derivatization using 2,4-dinitrophenylhydrazine, aldehyde content in the ionizable lipid raw material was determined to exceed the reporting threshold of 0.05% in 30% of the test cases. The experimental findings observed in this study demonstrate the utility of the proposed RPLC-MS method in the identification and monitoring of stability-indicating attributes associated with LNPs as part of current Good Manufacturing Practices for improved consumer safety in drug products.

Formation of free acetaldehydes derived from lipid peroxidation in U937 monocyte-like cells

Acetaldehyde can be found in human cells as a byproduct of various metabolic pathways, including oxidative processes such as lipid peroxidation. This secondary product of lipid peroxidation plays a role in various pathological processes, leading to various types of civilization diseases. In this study, the formation of free acetaldehyde induced by oxygen-centred radicals was studied in monocyte-like cell line U937. Exposure of U937 cells to peroxyl/alkoxyl radicals induced by azocompound resulted in the formation of free acetaldehyde. Acetaldehyde is formed by the cleavage of fatty acids, which represents the breakdown of fatty acids into smaller fragments initiated by the cyclization of lipid peroxyl radical and β-scission of lipid alkoxyl radical. The cleavage of fatty acids alters the integrity of the plasma and nuclear membrane, leading to the loss of cell viability. Understanding the pathological processes of acetaldehyde formation is an active area of research with potential implications for preventing and treating various diseases associated with oxidative stress.

Rapid and Practical Synthesis of gem-Dibromoalkanes from Aldehydes by Tribromide Reagent

gem-Dibromoalkanes are important synthetic building block in organic chemistry, but their preparation is still troublesome. Herein, we have developed a simple and practical protocol for the synthesis of gem-dibromoalkanes from aldehydes using tetrabutylammonium tribromide and triphenyl phosphite. A variety of alkyl and aromatic aldehydes can be transformed into the corresponding products within 10 minutes. This protocol is also applicable to alcohols, and the configuration of chiral alcohol is inverted during the process with excellent enantiopurity.

Investigation on formaldehyde generation characteristics and influencing factors of PODE/methanol dual-fuel combustion mode

Polyoxymethylene dimethyl ether (PODE) and methanol are important low-carbon substitutable fuels for reducing carbon emissions in internal combustion engines. In the research, the impacts of methanol ratio, injection timing, and intake temperature on HCHO generation and emission were investigated using both engine tests and numerical simulations. Results suggest that an increase in methanol ratio suppresses auto-ignition tendency of PODE, leading to the increase of ignition delay period, pressure peak, and heat release rate peak inside the cylinder. The decrease in in-cylinder combustion temperature contributes to an increase in HCHO emission due to partial oxidation of methanol in the cylinder and exhaust pipe. While the injection timing is gradually postponed from -10 °CA ATDC to 2 °CA ATDC, in-cylinder high-temperature area decreases, the quantity of unburned methanol increases, but part of HCHO is converted to HCO due to H radical influence, resulting in 72% increased HCHO emission. With the increment of intake temperature, the oxidation and decomposition of in-cylinder methanol accelerate, leading to an improvement in combustion stability, more uniform temperature distribution, and a decrease in unburned methanol, which results in lower HCHO emission. When the intake temperature is rose from 30 to 60 °C, HCHO emission decreases by 11.2%.

Unexpected synthesis of 4-(4,5-dihydro-1H-imidazol-2-ylsulfanyl)butyl-H-sulfite as a catalyst for the synthesis of pyrazolophthalazines

Several attempts for preparation of 4,4'-(2-thioxoimidazolidine-1,3-diyl)bis(butane-1-sulfonic acid) were not successful despite taking 2 mmol of 1,4-butane sultone in reaction with 1 mmol of imidazolidine-2-thione. Instead, 4-(4,5-dihydro-1H-imidazol-2-ylsulfanyl)butyl hydrogen sulfite (DISBHS) was prepared unexpectedly, characterized and used for the synthesis of diverse pyrazolophthalazines from the one-pot three component condensation reaction of phthalhydrazide, malononitrile and aldehydes under mild conditions.

4-Hydroxynonenal impairs miRNA maturation in heart failure via Dicer post-translational modification

BACKGROUND AND AIMS

Developing novel therapies to battle the global public health burden of heart failure remains challenging. This study investigates the underlying mechanisms and potential treatment for 4-hydroxynonenal (4-HNE) deleterious effects in heart failure.

METHODS

Biochemical, functional, and histochemical measurements were applied to identify 4-HNE adducts in rat and human failing hearts. In vitro studies were performed to validate 4-HNE targets.

RESULTS

4-HNE, a reactive aldehyde by-product of mitochondrial dysfunction in heart failure, covalently inhibits Dicer, an RNase III endonuclease essential for microRNA (miRNA) biogenesis. 4-HNE inhibition of Dicer impairs miRNA processing. Mechanistically, 4-HNE binds to recombinant human Dicer through an intermolecular interaction that disrupts both activity and stability of Dicer in a concentration- and time-dependent manner. Dithiothreitol neutralization of 4-HNE or replacing 4-HNE-targeted residues in Dicer prevents 4-HNE inhibition of Dicer in vitro. Interestingly, end-stage human failing hearts from three different heart failure aetiologies display defective 4-HNE clearance, decreased Dicer activity, and miRNA biogenesis impairment. Notably, boosting 4-HNE clearance through pharmacological re-activation of mitochondrial aldehyde dehydrogenase 2 (ALDH2) using Alda-1 or its improved orally bioavailable derivative AD-9308 restores Dicer activity. ALDH2 is a major enzyme responsible for 4-HNE removal. Importantly, this response is accompanied by improved miRNA maturation and cardiac function/remodelling in a pre-clinical model of heart failure.

CONCLUSIONS

4-HNE inhibition of Dicer directly impairs miRNA biogenesis in heart failure. Strikingly, decreasing cardiac 4-HNE levels through pharmacological ALDH2 activation is sufficient to re-establish Dicer activity and miRNA biogenesis; thereby representing potential treatment for patients with heart failure.

Liver enzymes mediate the association between aldehydes co-exposure and hypertriglyceridemia

Aldehydes are recognized environmental toxicants that may affect lipid metabolism. For instance, acrolein has been found to increase serum triglyceride (TG) levels exclusively. However, it remains unclear whether other aldehydes are also associated with hypertriglyceridemia (HTG), and what mechanisms may be involved. This cross-sectional study analyzed data from the National Health and Nutrition Examination Survey (NHANES, 2013-2014) to identify associations between serum aldehydes, liver enzymes, and HTG. Serum aldehydes included crotonaldehyde (CRAL), propanaldehyde (3AL), butyraldehyde (4AL), pentanaldehyde (5AL), isopentanaldehyde (I5AL), and heptanaldehyde (7AL). Liver enzymes included alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and gamma-glutamyltransferase (GGT). HTG was defined as fasting TG levels ≥ 1.7 mmol/L. Aldehyde co-exposure was quantified using weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR), while mediation analysis was performed to investigate the role of liver enzymes. Among 1474 participants (mean age 38.6 years, male 50.0%), 426 were diagnosed with HTG. 4AL, 5AL, I5AL, and 7AL were shown to be positively associated with HTG (all P values <0.05). Aldehydes co-exposure was also positively associated with HTG (OR 1.706, 95%CI 1.299-2.240), with 5AL contributing the highest weight (35.3%). Furthermore, aldehydes co-exposure showed positive associations with ALT, AST, and GGT (all P values <0.05), and all four liver enzymes were positively associated with HTG (all P values <0.05). Mediation analysis revealed that liver enzymes (ALT, AST, and GGT) may mediate the associations of 5AL and 7AL with HTG (all P values <0.05). This study identified a positive association between aldehyde co-exposure and HTG, which may be partially mediated by liver enzymes.

Intermolecular Metal-Catalyzed C‒C Coupling of Unactivated Alcohols or Aldehydes for Convergent Ketone Construction beyond Premetalated Reagents

Intermolecular metal-catalyzed C‒C couplings of unactivated primary alcohols or aldehydes to form ketones are catalogued. Reactions are classified on the basis of pronucleophile. Protocols involving premetalated reagents or reactants that incorporate directing groups are not covered. These methods represent an emerging alternative to classical multi-step protocols for ketone construction that exploit premetalated reagents, and/or steps devoted to redox manipulations and carboxylic acid derivatization.

Reliable Cerebrospinal Fluid Cytology and Immunocytochemistry Reporting over an Extended Period by the Addition of Aldehyde and Osmolyte-Based Preservative Solution

INTRODUCTION

The cytological examination of cerebrospinal fluid (CSF) is an important investigation in the workup of various inflammatory, malignant, or traumatic disorders of the central nervous system. The cells in the CSF lyse and degenerate at a very fast rate owing to its low tonicity, buffering capacity, redox potential, and pH, making it crucial to examine it within 2 h of sampling. We have hereby designed an aliphatic aldehyde, osmolyte, metal halide, and a buffer-based solution which will preserve the cellular components of CSF for 48 h.

METHODS

Thirty-nine CSF specimens were examined within 2 h of collection, and this reading was recorded as time zero reading. The CSF specimens were then divided into two tubes with (i) pre-servative:CSF ratio of 1:5; and (ii) no preservative. Total and differential leukocyte counts and immunocytochemistry were performed on the paired specimens at 24 h and 48 h and were compared with the readings at zero hours.

RESULTS

The preservative-containing CSF showed significantly higher cellularity than the undiluted samples at 24 h and 48 h (p < 0.001). Median cell counts observed in the preservative-containing CSF were 5 times and 12 times higher than in the undiluted CSF. Neutrophils, lymphocytes, and RBCs showed immunopositivity for MPO, CD45, and GLUT-1 at both time intervals.

CONCLUSION

Adding the prepared preservative solution to CSF in the ratio of 1:5 can optimally preserve the CSF cells for absolute and differential quantitation, morphological assessment, and immunological testing at a later date.

Using three statistical methods to analyze the association between aldehyde exposure and markers of inflammation and oxidative stress

BACKGROUND

Exposure to aldehydes has been linked to adverse health outcomes such as inflammation and oxidative stress, but research on the effects of these compounds is limited. This study is aimed at assessing the association between aldehyde exposure and markers of inflammation and oxidative stress.

METHODS

The study used data from the NHANES 2013-2014 survey (n = 766) and employed multivariate linear models to investigate the relationship between aldehyde compounds and various markers of inflammation (alkaline phosphatase (ALP) level, absolute neutrophil count (ANC), and lymphocyte count) and oxidative stress (bilirubin, albumin, and iron levels) while controlling for other relevant factors. In addition to generalized linear regression, weighted quantile sum (WQS) and Bayesian kernel machine regression (BKMR) analyses were applied to examine the single or overall effect of aldehyde compounds on the outcomes.

RESULTS

In the multivariate linear regression model, each 1 standard deviation (SD) change in propanaldehyde and butyraldehyde was significantly associated with increases in serum iron levels (beta and 95% confidence interval, 3.25 (0.24, 6.27) and 8.40 (0.97, 15.83), respectively) and the lymphocyte count (0.10 (0.04, 0.16) and 0.18 (0.03, 0.34), respectively). In the WQS regression model, a significant association was discovered between the WQS index and both the albumin and iron levels. Furthermore, the results of the BKMR analysis showed that the overall impact of aldehyde compounds was significantly and positively correlated with the lymphocyte count, as well as the levels of albumin and iron, suggesting that these compounds may contribute to increased oxidative stress.

CONCLUSIONS

This study reveals the close association between single or overall aldehyde compounds and markers of chronic inflammation and oxidative stress, which has essential guiding value for exploring the impact of environmental pollutants on population health.

Synthesis, characterization, antibacterial activity of thiosemicarbazones derivatives and their computational approaches: Quantum calculation, molecular docking, molecular dynamic, ADMET, QSAR

The thiosemicarbazones and their derivatives have been recognized as antimicrobial agents against human pathogenic bacteria and fungi. Regarding these prospective, this study was designed to address the new antimicrobial agents from thiosemicarbazones and their derivatives. These derivatives were synthesized by multi-step synthesis methods, such as alkylation, acidification, esterification, and formed the 4-(4'-alkoxybenzoyloxy) thiosemicarbazones and its derivatives (THS1, THS2, THS3, THS4, and THS5). Afterward the synthesis, compounds were characterized by ¹H NMR, FTIR spectra, and melting point. Later, the computational tools were applied to evaluate the drug likeness properties, bioavailability score, Lipinski rule, absorption, distribution, metabolism, excretion, and toxicity (ADMET). Secondly, the quantum calculations, for instance HOMO, LUMO and chemical descriptors, were calculated by the density functional theory (DFT). Finally, the molecular docking was performed against seven human pathogenic bacteria, black fungus (Rhizomucor mieh, Mucor lusitanicus, Mycolicibacterium smegmatis) and white fungus strains (Candida Auris, Aspergillus luchuensis, Candida albicans). To check and validate of molecular docking procedure and stability of docked complex for ligand and protein, the molecular dynamic was performed of docked complex. From the docking score with calculating the binding affinity, these derivatives could show a higher affinity than standard drug against all pathogens. From the computational details, it could be decided to do in-vitro test as antimicrobial activity against Staphylococcus aurious, Staphylococcus homonis, Salmonella typhi, and Shigella flexneria. The obtained result of antibacterial activity compared to standard drugs, and it was found that the synthesized compounds were almost same value of standard drug. Finally, it could be said from the in-vitro and in-silico study that the thiosemicarbazones derivatives are good antimicrobial agents.

coli resting cells

Aldehydes are attractive chemical targets both as end products in the flavors and fragrances industry and as intermediates due to their propensity for C-C bond formation. Here, we identify and address unexpected oxidation of a model collection of aromatic aldehydes, including many that originate from biomass degradation. When diverse aldehydes are supplemented to E. coli cells grown under aerobic conditions, as expected they are either reduced by the wild-type MG1655 strain or stabilized by a strain engineered for reduced aromatic aldehyde reduction (the E. coli RARE strain). Surprisingly, when these same aldehydes are supplemented to resting cell preparations of either E. coli strain, under many conditions we observe substantial oxidation. By performing combinatorial inactivation of six candidate aldehyde dehydrogenase genes in the E. coli genome using multiplexed automatable genome engineering (MAGE), we demonstrate that this oxidation can be substantially slowed, with greater than 50% retention of 6 out of 8 aldehydes when assayed 4 h after their addition. Given that our newly engineered strain exhibits reduced oxidation and reduction of aromatic aldehydes, we dubbed it the E. coli ROAR strain. We applied the new strain to resting cell biocatalysis for two kinds of reactions - the reduction of 2-furoic acid to furfural and the condensation of 3-hydroxy-benzaldehyde and glycine to form a beta hydroxylated non-standard amino acid. In each case, we observed substantial improvements in product titer 20 h after reaction initiation (9-fold and 10-fold, respectively). Moving forward, the use of this strain to generate resting cells should allow aldehyde product isolation, further enzymatic conversion, or chemical reactivity under cellular contexts that better accommodate aldehyde toxicity.

Carboxylic acid reductases: Structure, catalytic requirements, and applications in biotechnology

Biocatalysts have been gaining extra attention in recent decades due to their industrial-relevance properties, which may hasten the transition to a cleaner environment. Carboxylic acid reductases (CARs) are large, multi-domain proteins that can catalyze the reduction of carboxylic acids to corresponding aldehydes, with the presence of adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH). This biocatalytic reaction is of great interest due to the abundance of carboxylic acids in nature and the ability of CAR to convert carboxylic acids to a wide range of aldehydes essentially needed as end products such as vanillin or reaction intermediates for several compounds production such as alcohols, alkanes, and amines. This modular enzyme, found in bacteria and fungi, demands an activation via post-translational modification by the phosphopantetheinyl transferase (PPTase). Recent advances in the characterization and structural studies of CARs revealed valuable information about the enzymes' dynamics, mechanisms, and unique features. In this comprehensive review, we summarize the previous findings on the phylogeny, structural and mechanistic insight of the domains, post-translational modification requirement, strategies for the cofactors regeneration, the extensively broad aldehyde-related industrial application properties of CARs, as well as their recent immobilization approaches.

Association between mixed aldehydes and bone mineral density based on four statistical models

Aldehydes as an environmental pollutant may lead to oxidative stress, which is an important mechanism in the development of osteoporosis. This suggests a possible link between aldehyde exposure and osteoporosis. Considering the mixed nature of aldehyde exposure and the interactions between different aldehydes, we explored for the first time the associations between mixed six aldehydes (benzaldehyde, butyraldehyde, heptanal, hexanal, isovaleraldehyde, and propionaldehyde) and BMD in three populations (men, premenopausal women, and postmenopausal women) by applying four statistical models: quantile g-computation (qgcomp) model, Bayesian kernel machine regression (BKMR) model, generalized linear regression model (GLM), and generalized additive model (GAM), based on the National Health and Nutrition Examination Survey (NHANES) 2013-2014. We found that mixed aldehydes could significantly reduce BMD in men, with hexanaldehyde and propanaldehyde having the greatest negative qgcomp model and BKMR model weights, also confirmed by GLM. The associations between isopentanaldehyde and propanaldehyde and femoral BMD in men were non-linear and had threshold effects as derived from the BKMR model and GAM. The associations turned positive when the concentrations of isopentanaldehyde and propanaldehyde exceeded their respective inflection points. To conclude, our study might provide new ideas for the prevention and treatment of osteoporosis, and hexanaldehyde and propanaldehyde should be more regulated to prevent osteoporosis.

Association between aldehyde exposure and sex steroid hormones among adults

Exogenous and endogenous exposure to aldehydes is seen worldwide. Aldehydes are closely associated with human diseases, especially reproductive toxicity. However, the effect of aldehyde exposure on sex steroid hormones among adults remains uninvestigated. A total of 851 participants aged over 18 years were included in this cross-sectional analysis based on data from National Health and Nutrition Examination Survey (NHANES) 2013-2014. Serum aldehyde concentrations were quantified following an automated analytical method. Sex steroid hormones including total testosterone, estradiol, and sex hormone binding globulin (SHBG) were detected. Multivariate linear regression models, forest plots, generalized additive model (GAM), and smooth curve fitting analysis were used to assess the associations between quartiles of aldehydes and sex steroid hormones levels after adjusting for potential confounders. Butyraldehyde and propanaldehyde were found to be negatively associated with estradiol and SHBG in females and males, respectively. β values with 95% confidence intervals (95% CIs) were - 20.59 (- 38.30 to - 2.88) for Q2 vs. Q1 of butyraldehyde and - 8.13 (- 14.92 to - 1.33) and - 7.79 (- 14.91 to - 0.67) for Q2 vs. Q1 and Q4 vs. Q1 of propanaldehyde. No significant associations were observed between other aldehydes and sex hormones. In premenopausal women, isopentanaldehyde was inversely associated with serum total testosterone levels (Q4 vs. Q1: OR =  - 7.95, 95% CI: - 15.62 to - 0.27), whereas propanaldehyde was positively associated with serum estradiol concentration (Q3 vs. Q1: β = 28.88, 95% CI: 0.83 to 56.94). Compared with Q1, Q3 of isopentanaldehyde was associated with 3.53 pg/mL higher concentration of estradiol in postmenopausal women (β = 3.53, 95% CI: 0.08 to 6.97). Moreover, in males under 40 years, butyraldehyde and heptanaldehyde were inversely proportional to total testosterone levels and heptanaldehyde and butyraldehyde were negatively associated with estradiol and SHBG. Decreased total testosterone, elevated estradiol, and decreased SHBG levels were found in higher quartiles of benzaldehyde, hexanaldehyde and isopentanaldehyde, and propanaldehyde, respectively, in males aged over 60 years. In male participants aged 40-60 years, only hexanaldehyde was observed to be correlated with higher serum estradiol levels. In conclusion, our current research presented the association between six serum aldehydes and sex hormones. Of note, stratification analyses were conducted in participants with different menopausal statuses and age among males and females. Sex- and age-specific effect of aldehyde exposure on alterations in sex hormone levels were observed. Further studies are warranted to confirm the causal relationship and explore the underlying mechanisms.

Bioconjugation via Hetero-Selective Clamping of Two Different Amines with ortho-Phthalaldehyde

Amino groups are common in both natural and synthetic compounds and offer a very attractive class of endogenous handles for bioconjugation. However, the ability to differentiate two types of amino groups and join them with high hetero-selectivity and efficiency in a complex setting remains elusive. Herein, we report a new method for bioconjugation via one-pot chemoselective clamping of two different amine nucleophiles using a simple ortho-phthalaldehyde (OPA) reagent. Various α-amino acids, aryl amines, and secondary amines can be crosslinked to the ϵ-amino side chain of lysine on peptides or proteins with high efficiency and hetero-selectivity. This method offers a simple and powerful means to crosslink small molecule drugs, imaging probes, peptides, proteins, carbohydrates, and even virus particles without any pre-functionalization.

Optimization of Testicular Fixation-Embedding Techniques for Improved Evaluation of Mammalian Spermatogonial Morphology and Function

Numerous methods have been successfully used to evaluate mammalian spermatogonial biology However, the conventional light microscopy assays present a challenge in precisely identifying spermatogonial phenotypes, which can result in discrepancies between molecular and morphological findings. Such precise association could lead to a more robust interpretation of spermatogonial activity in steady-state spermatogenesis, which may facilitate the translation from basic research to clinical applications. In this chapter, we present two histological processing methods that enable a comprehensive analysis of spermatogonial morphology and function, involving fixation of mammalian testicular tissue in glutaraldehyde and embedding in plastic resin. These techniques have proven to be effective in light microscopy studies.

VUV/UV oxidation performance for the elimination of recalcitrant aldehydes in water and its variation along the light-path

Vacuum ultraviolet/ultraviolet (VUV/UV) oxidation using a low-pressure mercury lamp emitting dual wavelengths (185 nm (VUV) and 254 nm (UV)) significantly varies in performance along the light-path (l_P), which has not been fully characterized. Therefore, VUV/UV oxidation in solution was investigated at various l_P in terms of the degradation kinetics and mineralization pathway of representative aldehydes with various alkyl-chain lengths. Oxidative degradation of parent aldehydes with shorter alkyl chains was less efficient, specifically the pseudo-zero-order rate constant (k_obs) of formaldehyde was only 51% of that of propionaldehyde (k_obs = 0.078 μM s^-1). In contrast, the mineralization of aldehydes with longer alkyl chains was less efficient because these aldehydes underwent mineralization into more refractory carboxylic byproducts, e.g., oxalic acid. VUV was mainly absorbed by superficial water (l_P < 0.55 cm), which resulted in highly heterogeneous oxidation in homogeneous water. Thus, k_obs of acetaldehyde dramatically decreased from 0.13 to 0.033 μM s^-1 as the total l_P of solution increased from 1.0 to 3.0 cm. On the basis of mineralization pathways proposed above, an iterative kinetic model was developed to characterize the degradation of parent aldehydes and the formation of carboxylic acids along l_P. This model predicted the VUV/UV oxidaton for the first time by considering the fast diffusion of pollutants by limited diffusion of transient radical species. Thus, it realized the prediction of ^•OH concentration at specific water solution and byproduct evolution within specific water solution in turbulent flow regime, wherein ^•OH was predominantly formed in superficial water-layers wherein ^•OH in water-layers of l_P <0.16 cm and <0.81 cm contributed to 50% and 90% of the total oxidation performance, respectively. This result would help to improve the VUV-UV-reactor design in terms of optimizing the thickness of water-layer and turbulence of water-flow.

A Flexible Hydrogen-Bonded Organic Framework Constructed from a Tetrabenzaldehyde with a Carbazole N-H Binding Site for the Highly Selective Recognition and Separation of Acetone

Rational design of hydrogen-bonded organic frameworks (HOFs) with multiple functionalities is highly sought after but challenging. Herein, we report a multifunctional HOF (HOF-FJU-2) built from 4,4',4'',4'''-(9H-carbazole-1,3,6,8-tetrayl)tetrabenzaldehyde molecule with tetrabenzaldeyde for their H bonding interactions and carbazole N-H site for its specific recognition of small molecules. The Lewis acid N-H sites allow HOF-FJU-2 facilely separate acetone from its mixture with another solvent like methanol with smaller pK_a value. The donor (D)-π-acceptor (A) aromatic nature of the organic building molecule endows this HOF with solvent dependent luminescent/chromic properties, so the column acetone/methanol separation on HOF-FJU-2 can be readily visualized.

A Neglected Challenge in the Analysis of Active Pharmaceutical Substances with Aldehyde Functional Group in Aqueous Matrices

Aldehydes are compounds that are widely used and popular in organic synthesis due to their high reactivity. This advantage is a disadvantage in medicinal chemistry. Due to the ability of aldehydes to participate in nucleophilic reactions (especially in aqueous biological media) and access to nucleophiles such as amino acids and nucleic acids, drugs with aldehyde functional groups are always used with caution and carefully quantified in biological fluids. Our experience in working on biologically active aldehydes indicates the transformation of these groups of compounds in aqueous or alcoholic solution and thus the failure of analytical methods for their accurate monitoring in such media. Both mass spectrometry and Proton nuclear magnetic resonance spectroscopic findings indicate the reaction of spiramycin with water molecules in an aqueous solution, resulting in the conversion of spiramycin to a new molecule with 18 mass unit difference and thus, the residue amount which is measured and reported based on a mass spectrometries method does not show the correct amount of spiramycin in these samples.

Electronic cigarette vaping with aged coils causes acute lung injury in mice

Electronic cigarettes (e-cigarettes) have been used widely as an alternative to conventional cigarettes and have become particularly popular among young adults. A growing body of evidence has shown that e-cigarettes are associated with acute lung injury and adverse effects in multiple other organs. Previous studies showed that high emissions of aldehydes (formaldehyde and acetaldehyde) in aerosols were associated with increased usage of the same e-cigarette coils. However, the impact on lung function of using aged coils has not been reported. We investigated the relationship between coil age and acute lung injury in mice exposed to experimental vaping for 1 h (2 puffs/min, 100 ml/puff). The e-liquid contains propylene glycol and vegetable glycerin (50:50, vol) only. The concentrations of formaldehyde and acetaldehyde in the vaping aerosols increased with age of the nichrome coils starting at 1200 puffs. Mice exposed to e-cigarette aerosols produced from 1800, but not 0 or 900, puff-aged coils caused acute lung injury, increased lung wet/dry weight ratio, and induced lung inflammation (IL-6, TNF-α, IL-1β, MIP-2). Exposure to vaping aerosols from 1800 puff-aged coils decreased heart rate, respiratory rate, and oxygen saturation in mice compared to mice exposed to air or aerosols from new coils. In conclusion, we observed that the concentration of aldehydes (formaldehyde and acetaldehyde) increased with repeated and prolonged usage of e-cigarette coils. Exposure to high levels of aldehyde in vaping aerosol was associated with acute lung injury in mice. These findings show significant risk of lung injury associated with prolonged use of e-cigarette devices.

Fatty alcohol oxidase 3 (FAO3) and FAO4b connect the alcohol- and alkane-forming pathways in Arabidopsis stem wax biosynthesis

The alcohol- and alkane-forming pathways in cuticular wax biosynthesis are well characterized in Arabidopsis. However, potential interactions between the two pathways remain unclear. Here, we reveal that mutation of CER4, the key gene in the alcohol-forming pathway, also led to a deficiency in the alkane-forming pathway in distal stems. To trace the connection between the two pathways, we characterized two homologs of fatty alcohol oxidase (FAO), FAO3 and FAO4b, which were highly expressed in distal stems and localized to the endoplasmic reticulum. The amounts of waxes from the alkane-forming pathway were significantly decreased in stems of fao4b and much lower in fao3 fao4b plants, indicative of an overlapping function for the two proteins in wax synthesis. Additionally, overexpression of FAO3 and FAO4b in Arabidopsis resulted in a dramatic reduction of primary alcohols and significant increases of aldehydes and related waxes. Moreover, expressing FAO3 or FAO4b led to significantly decreased amounts of C18-C26 alcohols in yeast co-expressing CER4 and FAR1. Collectively, these findings demonstrate that FAO3 and FAO4b are functionally redundant in suppressing accumulation of primary alcohols and contributing to aldehyde production, which provides a missing and long-sought-after link between these two pathways in wax biosynthesis.

Neutron encoded derivatization of endothelial cell lysates for quantitation of aldehyde metabolites using nESI-LC-HRMS

Biological aldehydes are difficult to analyze by electrospray ionization mass spectrometry due to their poor proton affinity and low biological concentrations. Chemical derivatization with stable isotope tags is used here for sample multiplexing, increased throughput, improved signal intensity, and quantitation. Nine quaternary amine tags with mass differences as low as 0.0058 Da had no observable chromatographic shifts, small amounts of ion suppression, and minimal matrix effects. Low concentration perfluoropentanoic acid was used as an ion pairing reagent to improve the retention of derivatized aldehydes. Perfluoropentanoic acid addition showed an average of three-fold improvement in limits of detection, 50% reduction in peak width, and 2.5 fold increase in analyte retention. Analysis of fifteen tagged aldehydes yielded an average of 13 nM limit of detection, 9 %RSD, R² of 0.995, and linear dynamic range of 40-1000 nM. In a single 20 min separation, absolute quantitative data was obtained for 11 reactive aldehydes across 8 aortic endothelial cell samples. High glucose treatment produced significant changes to malondialdehyde, decanal, and (2E)-hexadecenal. These changes are consistent with glucose-induced oxidative stress. This method demonstrates that neutron encoded tagging of aldehydes is suitable for the analysis of complex samples.

Catalytic Hydroboration and Reductive Amination of Carbonyl Compounds by HBpin using a Zinc Promoter

In this paper, the chemoselective hydroboration of aldehydes and ketones, catalyzed by Zinc(II) complexes [ k 2 -(PyCH=NR)ZnX 2 ] [R = CPh 3 , X = Cl ( 1 ) and R = Dipp (2,6-diisoropylphenyl) and X = I ( 2 )], in the presence of pinacolborane (HBpin) in ambient temperature and solvent-free conditions, which produced corresponding boronate esters in high yield, is reported. Zinc metal complexes 1 and 2 were derived in 80-90% yield from the reaction of iminopyridine [PyCH=NR] with anhydrous zinc dichloride in dichloromethane at room temperature. The solid-state structures of both zinc complexes were confirmed using X-ray crystallography. Zinc complex 1 was also used as a competent pre-catalyst in the reductive amination of carbonyl compounds with HBpin under mild and solvent-free conditions to afford a high yield (up to 97%) of the corresponding secondary amines. The wider substrate scope of both reactions was explored. Catalytic protocols using zinc as a pre-catalyst demonstrated an atom-economic and green method with diverse substrates bearing excellent functional group tolerance. Computational studies established a plausible mechanism for catalytic hydroboration.

Bombyx mori-derived aldo-keto reductase AKR2E8 detoxifies aldehydes present in mulberry leaves

Lepidopterans are agricultural pests. Since the silkworm is a model for lepidopterans, analysis of the enzymes produced by silkworms is of great interest for developing methods of pest control. The aldo-keto reductase (AKR) superfamily catalyzes the reduction of aldehydes by converting a carbonyl group to an alcohol group. Here, we characterized a new AKR present in the silkworm Bombyx mori, which has been designated as AKR2E8. Amino acid sequence and phylogenetic analyses showed that AKR2E8 is similar to human AKR1B1 and AKR1B10. Three amino acid residues in the active site were identical among AKR2E8, AKR1B1, and AKR1B10. Recombinant AKR2E8 overexpressed in Escherichia coli used nicotinamide adenine dinucleotide phosphate as a coenzyme to reduce the aldehydes present in mulberry (Morus alba) leaves. AKR2E8 was found to reduce benzaldehyde, hexanal, heptanal, nonanal, trans-2-nonenal, and citral. No nicotinamide adenine dinucleotide-dependent activity was detected. Akr2e8 mRNA was detected in the testes, ovaries, and fat body; the highest expression was found in the midgut. The substrate specificity and highest observed expression of AKR2E8 in the midgut suggests that AKR2E8 may play a major role in aldehyde detoxification in silkworms. The findings of this study may assist in the development of pest control methods for controlling the population of lepidopterans, such as silkworms, that damage crops.

Distribution of aldehydes compared to other oxidation parameters in oil matrices during autoxidation

Distribution of aldehydes between headspace (HS) and inner matrix (IM) of bulk oil or oil-in-water (O/W) emulsion was determined and contents of aldehydes were compared with other oxidation parameters in soybean oil or O/W emulsion during 50 °C autoxidation. Bulk oil matrix had higher portion of IM aldehydes than O/W emulsion. HS aldehydes in O/W emulsion reflected aldehyde content better than in bulk oil. Moisture content in soybean oil increased distinctively before the generation of oxidation products including hydroperoxides and volatiles. HS aldehydes and other oxidation parameters were simultaneously increased in soybean oil. In case of O/W emulsion, HS aldehydes had a sudden increase point while lipid hydroperoxides and conjugated did not show such increase during autoxidation. HS aldehydes reflected oxidation stage better in O/W emulsion than in bulk oil based on partition distribution and linear changes during autoxidation.

Development and characterization of aldehyde-sensitive cellulose/chitosan/beeswax colorimetric papers for monitoring kiwifruit maturity

In this study, we developed an in-package colorimetric paper to monitor the ripeness of kiwifruit by detecting the release of aldehydes. Strongly hydrophobic composite films were prepared using chitosan as the matrix and beeswax as an additive. A piece of cellulose paper containing methyl red and bromocresol violet as color indicators was heat-sealed between two hydrophobic films to protect the indicators from the effects of fruit respiration and transpiration. The nucleophilic addition reaction between aldehydes and OH^- (Cannizzaro reaction) changes the pH in the paper and triggers a color change in the indicators. As the kiwifruit ripens, the colorimetric paper changes from bluish-purple to dark red and then gradually to red. A mobile phone application was further used to measure the RGB values and link them to kiwifruit ripeness. This intelligent paper can be used for the accurate and convenient monitoring of produce in real time.

Catalytic Reductive Cross-Coupling between Aromatic Aldehydes and Arylnitriles

A reductive cross-coupling reaction between aromatic aldehydes and arylnitriles using a copper catalyst and a silylboronate as a reductant is reported. This protocol represents an unprecedented approach to the chemoselective synthesis of α-hydroxy ketones by electrophile-electrophile cross-coupling.

Reduction of aldehyde emission and attribution of environment burden in cooking fumes from food stalls using a novel fume collector

Uncontrolled cooking emissions from commercial kitchens are problematic due to their corresponding health effects and malodors. To reduce cooking emissions, medium and large commercial kitchens install air pollution control devices, such as electrostatic precipitators and wet scrubbers, while small-scale commercial cooking workplaces, such as street-food stalls, use smaller, simpler, and less costly filtration and absorption devices. However, these smaller devices may be poorly designed and recirculate cooking emissions in the workplace. The objectives of this study were to design and implement a novel fume collector and evaluate its effectiveness in reducing aldehydes and the corresponding environmental burden emitted by food stalls. Two stalls, which had malodor problems despite the use of fume collectors, volunteered to participate in the study. To increase the efficiency of the existing fume collectors, a new collector was designed comprising two buckets connected in series, each with pollutant absorption (NaClO-surfactant mixed solution) and particulate filtration (activated-carbon filters) components. Total aldehyde concentrations measured at the exhaust outlets of the original and new collectors were 342.2 and 80.8 μg/m³ for stall A, and 622.7 and 283.1 μg/m³ for stall B, respectively. The corresponding concentration reductions for stall A and B were 76% and 55%, and the emission rate reductions were 91% (from 749 to 71 g/yr) and 76% (from 1040 g/yr to 248 g/h), respectively. These results demonstrate that the effectiveness of the novel collector at removing cooking fumes was significantly improved. The high efficiency and low-cost nature of the collector make it highly applicable in small-scale commercial kitchens and street-food stalls.

DNA methylome signatures as epigenetic biomarkers of hexanal associated with lung toxicity

Background

Numerous studies have investigated the relationship of environmental exposure, epigenetic effects, and human diseases. These linkages may contribute to the potential toxicity mechanisms of environmental chemicals. Here, we investigated the epigenetic pulmonary response of hexanal, a major indoor irritant, following inhalation exposure in F-344 rats.

Methods

Based on DNA methylation profiling in gene promoter regions, we identified hexanal-characterized methylated sites and target genes using an unpaired t-test with a fold-change cutoff of ≥ 3.0 and a p-value < 0.05. We also conducted an integrated analysis of DNA methylation and mRNA expression data to identify core anti-correlated target genes of hexanal exposure. To further investigate the potential key biological processes and pathways of core DNA methylated target genes, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis were performed.

Results

Thirty-six dose-dependent methylated genes and anti-correlated target genes of DNA methylation and mRNA in lung tissue of hexanal exposed F-344 rats were identified. These genes were involved in diverse biological processes such as neuroactive ligand-receptor interaction, protein kinase cascade, and intracellular signaling cascade associated with pulmonary toxicity. These results suggest that novel DNA methylation-based epigenetic biomarkers of exposure to hexanal and elucidate the potential pulmonary toxicological mechanisms of action of hexanal.

Electronic cigarette aerosols induce oxidative stress-dependent cell death and NF-κB mediated acute lung inflammation in mice

Electronic cigarette (e-cigarette) use has been linked to recent acute lung injury case clusters in over 2000 patients and dozens of deaths in the United States, however, the mechanism leading to lung injury is not certain although ultrafine particles, heavy metals, volatile organic compounds, and other harmful ingredients have been implicated. To systematically evaluate e-cigarette toxicity, we generated e-cigarette aerosols by varying the puff numbers (20-480), nicotine contents (0-24 mg/mL), and collected e-cigarette samples through an impinger system for biological assays. The calculated samples' concentration ranged from 1.96 to 47.06 mg/mL. THP-1 monocyte-differentiated macrophages, BEAS-2B bronchial epithelial cells, wild-type C57BL/6 mice, and NF-κB-luc transgenic mice were used to test the effects of these samples. E-cigarette samples showed cytotoxicity to THP-1 cells and BEAS-2B in vitro, leading to increased oxidative stress, inflammatory cytokine production with or without nicotine, and cell death. Furthermore, aerosol generated from PG is more toxic than VG. The toxicity of e-cigarette samples is at least partially due to the reactive oxygen species and aldehydes, which are generated during the aerosolization processes by the e-cigarette device. After NF-κB-luc mice exposed with e-cigarette samples by oropharyngeal aspiration, NF-κB expressions were observed in a dose-response fashion with or without nicotine. In addition, the e-cigarette samples induced neutrophil infiltration, IL-1β production, oxidative stress marker heme oxygenase-1 expression in wild-type C57BL/6 mice. These results suggested that oxidative stress, pro-inflammatory NF-κB pathway activation, and cell death are involved in e-cigarette aerosol-induced acute lung inflammation.

A novel LC-MS/MS method for quantification of unstable endogenous 3,4-dihydroxyphenylacetaldehyde in rat brain after chemical derivatization

3,4-dihydroxyphenylacetaldehyde (DOPAL), a toxic intermediary metabolite of dopamine (DA), causes catecholaminergic neurodegeneration via covalent binding with functional proteins or other biomolecules. Accurate quantification of DOPAL is essential to investigate the etiological factors associated with DOPAL and the pathogenetic role of DOPAL in Parkinson's disease (PD). However, no validated quantitative methods are available. Quantification of DOPAL in biosample is challenging since it is a reactive endogenous aldehyde with poor ionization efficiency and chromatographic behavior in the LC-MS system. Here, a sensitive, simple, and robust UPLC-MS/MS method has been established and validated for the determination of DOPAL in rat brain tissue specimens. DOPAL was found to be unstable in biosample due to reactive aldehyde whereas it was stable in acidic condition. The analyte was stabilized by pH and temperature control during the sample preparation and derivatization. Then, a chemical derivatization method that can be readily performed in acidic conditions and at low temperature was employed using 2-hydrazino-4-(trifluoromethyl)-pyrimidine (HTP) to block the reactive aldehyde and improve the detection sensitivity (about 100-fold increase) and chromatographic retention. Bovine serum albumin was used as a surrogate matrix, which was validated by the parallelism assay and post-column infusion experiment. This method was fully validated and the lower limit of quantification (LLOQ) was 0.5 ng/mL. With the method, a significant increase of DOPAL level was found in striatum region of rats received 6-hydroxydopamine (6-OHDA) injection for 12 h, indicating DOPAL may play a pathogenic role in 6-OHDA-induced PD model.

Modified hyaluronic acid hydrogels with chemical groups that facilitate adhesion to host tissues enhance cartilage regeneration

Stable integration of hydrogel implants with host tissues is of critical importance to cartilage tissue engineering. Designing and fabricating hydrogels with high adhesive strength, stability and regeneration potential are major challenges to be overcome. This study fabricated injectable adhesive hyaluronic acid (HA) hydrogel modified by aldehyde groups and methacrylate (AHAMA) on the polysaccharide backbone with multiple anchoring mechanisms (amide bond through the dynamic Schiff base reaction, hydrogen bond and physical interpenetration). AHAMA hydrogel exhibited significantly improved durability and stability within a humid environment (at least 7 days), together with higher adhesive strength (43 KPa to skin and 52 KPa to glass), as compared to commercial fibrin glue (nearly 10 KPa) and HAMA hydrogel (nearly 20 KPa). The results showed that AHAMA hydrogel was biocompatible and could be easily and rapidly prepared in situ. In vitro cell culture experiments showed that AHAMA hydrogel could enhance proliferation (1.2-folds after 3 days) and migration (1.5-folds after 12 h) of bone marrow stem cells (BMSCs), as compared to cells cultured in a culture dish. Furthermore, in a rat osteochondral defect model, implanted AHAMA hydrogel significantly promoted integration between neo-cartilage and host tissues, and significantly improved cartilage regeneration (modified O'Driscoll histological scores of 16.0 ± 4.1 and 18.3 ± 4.6 after 4 and 12-weeks of post-implantation in AHAMA groups respectively, 12.0 ± 2.7 and 12.2 ± 2.8 respectively in HAMA groups, 9.8 ± 2.4 and 11.5 ± 2.1 respectively in untreated groups). Hence, AHAMA hydrogel is a promising adhesive biomaterial for clinical cartilage regeneration and other biomedical applications.

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Adhesive hydrogel composed of single natural polymer component.

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The single component enhance stable and easy to use in surgical operation of hydrogel.

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Adhesive hydrogel exhibited strong adhesive strength through multiple anchoring mechanisms.

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Adhesive hydrogel promoted integration between neo-cartilage and host tissues, drastically improved cartilage regeneration.

Highly Efficient Reusable Carboxy Group Functionalized Imidazolium Salts for a Simple and Cost-effective Preparation of pyrano[2,3-d]pyrimidinone Derivatives

AIMS AND OBJECTIVE

In the current study, environmentally benign and cost-effective procedures were suggested for the preparation of carboxy group functionalized imidazolium salts, including [Cmmim]BF4 - or [Cmmim]Br- as a new, reusable Brønsted acidic ionic liquid (BAIL) catalyst. Then, the catalytic performance of [Cmmim]BF4 - or [Cmmim]Br- were successfully inspected towards the three---components one---pot preparation of pyrano[2,3-d]pyrimidinone derivatives 4a-4q. The mentioned procedures show short reaction times, easy work-up procedure, green conditions, high yields of the products, high potent of recovering, and reusing capability. The current study is useful and adequate for the application and development of imidazolium salts on the basis of green chemistry principles.

MATERIALS AND METHODS

An aromatic aldehyde (1 mmol), barbituric acid (1 mmol), and malononitrile (1 mmol) were placed in a round---bottomed flask containing ethanol (5 mL). BAILs A and B (0.1 mmol, 10 mol%) were added to the mixture. The suspension was magnetically stirred at room temperature for an appropriate time (Table 2). After completion of the reaction, which was monitored by TLC (n---hexane:ethyl acetate = 3:1), the pure product was filtered off to separate the catalyst, washed with water, and recrystallized from ethanol to afford the pure compound. After separation of the product, the catalyst was recovered by evaporation of water, washed with Et2O, dried under vacuum for 2 h, and reused for the same reaction.

RESULTS

The mentioned procedure shows short reaction times, easy work-up procedure, green conditions, high yields of the products, and high potent of recovering and reusing capability.

CONCLUSION

In this study, we unveiled the synthesis of a new acetic acid functionalized ionic liquids [Cmmim]BF4 - BAIL A or [Cmmim]Br- BAIL B and their application for the preparation of pyrano[2,3-d]pyrimidinone derivatives via a three-component reaction among various aromatic aldehydes, barbituric acid, and malononitrile under mild and metal-free conditions. A wide range of pyrano[2,3-d]pyrimidinone derivatives bearing diverse functional groups was obtained in short reaction and excellent yields. Operational simplicity, recoverability, and reusability of catalysts, cheap and chemically stable reagents, high catalytic activity, easy work-up, and the eco-friendly procedure, make this method environmentally benign and cost-effective.

Aldehyde Production as a Calibrant of Ultrasonic Power Delivery During Protein Misfolding Cyclic Amplification

The protein misfolding cyclic amplification (PMCA) technique employs repeated cycles of incubation and sonication to amplify minute amounts of misfolded protein conformers. Spontaneous (de novo) prion formation and ultrasonic power level represent two potentially interrelated sources of variation that frustrate attempts to replicate results from different laboratories. We previously established that water splitting during PMCA provides a radical-rich environment leading to oxidative damage to substrate molecules as well as the polypropylene PCR tubes used for sample containment. Here it is shown that the cross-linking agent formaldehyde is generated from buffer ions that are attacked by hydroxyl radicals. In addition, free radical damage to protein, nucleic acid, lipid, and detergent molecules produces a substantial concentration of aldehydes (hundreds of micromolar). The measurement of aldehydes using the Hantzsch reaction provides a reliable and inexpensive method for measuring the power delivered to individual PMCA samples, and for calibrating the power output characteristics of an individual sonicator. The proposed method may also be used to better account for inter-assay and inter-laboratory variation in prion replication and de novo prion generation, the latter of which may correlate with aldehyde-induced cross-linking of substrate molecules.

Formation of disinfection by-products from coexisting organic matter during vacuum ultraviolet (VUV) or ultraviolet (UV) treatment following pre-chlorination and their fates after post-chlorination

Vacuum ultraviolet (VUV) treatment is a promising advanced oxidation process for the removal of organic contaminants during water treatment. Here, we investigated the formation of disinfection by-products from coexisting organic matter during VUV or ultraviolet (UV) treatment following pre-chlorination, and their fates after post-chlorination, in a standard Suwannee River humic acid water and a natural lake water. VUV treatment after pre-chlorination decreased the total trihalomethane (THM) concentration but increased total aldehyde and chloral hydrate concentrations; total haloacetic acid (HAA) and haloacetonitrile (HAN) concentrations did not change. UV treatment after pre-chlorination produced similar changes in the by-products as those observed for VUV treatment, with the exception that the total THM concentration was not changed, and the total HAN concentration was increased. The final concentrations of by-products after post-chlorination were increased by VUV or UV treatment, except for the total HAA concentration, which remained unchanged after UV treatment. The increases were greater after VUV treatment than after UV treatment, probably because the larger amount of hydroxyl radicals generated during VUV treatment compared with during UV treatment transformed coexisting organic matter into precursors of by-products that were then converted to by-products during post-chlorination.

The structures of cyclic aminals from aldehydes and "roofed" mono-N-sulfonyl cis-diamines

Racemic Aldehydes were converted into aminals by using "roofed" mono-N-sulfonyl cis-diamines. Diastereomeric aminals could be separated by silica-gel TLC. The whole configuration of each aminal could be determined by NMR analyses. The chiral reagents were prepared from aminals of racemic reagents and a chiral aldehyde. The reverse may be also true. Epimerization of some aminal remains to be solved. Abbreviations: RDA-Ms: N-(12-amino-9,10-dihydro-9,10-ethanoanthracen-11-yl)-methylsulfonamide; RDA-Ts: N-(12-amino-9,10-dihydro-9,10-ethanoanthracen-11-yl)-4-methylbenzenesulfonamide; RDA-1Nps: N-(12-amino-9,10-dihydro-9,10-ethanoanthracen-11-yl)-1-　naphthylsulfonamide; RDA-2Nps: N-(12-amino-9,10-dihydro-9,10-ethanoanthracen-11-yl)-2-naphthylsulfonamide.

Evaluation of the effects of aldehydes on association colloid properties and oxidative stability in bulk oils

The effects of amphiphilic aldehydes, including propanal, hexanal, and nonanal, on the critical micelle concentration (CMC) of phospholipids, moisture content, and oxidative stability in soybean oil were evaluated. The selected aldehydes are typical secondary oxidation products from unsaturated fatty acids. Moisture content increased as aldehydes were added to soybean oil during thermal oxidation at a storage temperature of 50 or 100 °C. The CMC of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) increased as propanal and hexanal were added, whereas nonanal decreased the CMC of DOPC, which implies that aldehydes participate in forming association colloids in bulk oils. The addition of aldehydes increased the rates of lipid oxidation significantly in both 50 and 100 °C treatments (p < 0.05), with the effect being more evident in oils treated at 50 °C than at 100 °C. Therefore, aldehydes formed from lipid oxidation affected the association colloidal structures and oxidative stability in a bulk oil matrix.

Metabolic profiling of norepinephrine reuptake inhibitor atomoxetine

Atomoxetine (ATX), a selective and potent inhibitor of the presynaptic norepinephrine transporter, is used mainly to treat attention-deficit hyperactivity disorder. Although multiple adverse effects associated with ATX have been reported including severe liver injuries, the mechanisms of ATX-related toxicity remain largely unknown. Metabolism frequently contributes to adverse effects of a drug through reactive metabolites, and the bioactivation status of ATX is still not investigated yet. Here, we systematically investigated ATX metabolism, bioactivation, species difference in human, mouse, and rat liver microsomes (HLM, MLM, and RLM) and in mice using metabolomic approaches as mice and rats are commonly used animal models for the studies of drug toxicity. We identified thirty one ATX metabolites and adducts in LMs and mice, 16 of which are novel. In LMs, we uncovered two methoxyamine-trapped aldehydes, two cyclization metabolites, detoluene-ATX, and ATX-N-hydroxylation for the first time. Detoluene-ATX and one cyclization metabolite were also observed in mice. Using chemical inhibitors and recombinant CYP enzymes, we demonstrated that CYP2C8 and CYP2B6 mainly contribute to the formation of aldehyde; CYP2D6 is the dominant enzyme for the formation of ATX cyclization and detoluene-ATX; CYP3A4 is major enzyme responsible for the hydroxylamine formation. The findings concerning aldehydes should be very useful to further elucidate the mechanistic aspects of adverse effects associated with ATX from metabolic angles. Additionally, the species differences for each metabolite should be helpful to investigate the contribution of specific metabolites to ATX toxicity and possible drug-drug interactions in suitable models.

Data on synthesis and characterization of new p-nitro stilbene Schiff bases derivatives as an electrochemical DNA potential spacer

The structural investigation of synthesized compounds can be carried out by various spectroscopic techniques. It is an important prospect in order to elucidate the structure of the desired products before being further utilized. The preparation of new p-nitro stilbene Schiff base derivatives as an electrochemical DNA potential spacer was synthesized using (E)-4-(4-nitrostyryl)aniline from Heck reaction with aldehydes in ethanolic solution. The data presented here in this article contains FTIR, UV-Vis and ¹H and ¹³C NMR of (E)-4-(4-nitrostyryl)aniline and nitrostyryl aniline derivatives.

A Remote 'Imidazole'-Based Ruthenium(II) Para-Cymene Pre-catalyst for the Selective Oxidation Reaction of Alkyl Arenes and Alcohols

Herein we disclosed the use of a remote 'imidazole'-based precatalyst [(para-cymene)Ru^II (L)Cl]⁺ , C-1 where L=2-(4-substituted-phenyl)-1H-imidazo[4,5-f]^[1,10] phenanthroline) for the selective oxidation of a variety of alkyl arenes/heteroarenes and alcohols to their corresponding aldehydes or ketones in presence of tert-butyl hydroperoxide (TBHP). The remote 'imidazole' moiety present in the complex facilitates the activation of oxidant and subsequent generation of active species via the release of para-cymene from C-1, which in-turn was less effective without the 'imidazole' moiety. The mechanistic features of C-1 promoted oxidation of alkyl arenes were also assessed from spectroscopic, kinetic, and few control experiments. The substrate scope for C-1 promoted oxidation reaction was assessed based on the selective oxidation of 27-different alkyl arenes/heteroarenes and 25 different alcohols to their corresponding aldehydes/ketones in moderate to good yields.

Is there enough evidence to classify cycloalkyl amine substituents as structural alerts?

Basic amine substituents provide several pharmacokinetic benefits relative to acidic and neutral functional groups, and have been extensively utilized as substituents of choice in drug design. On occasions, basic amines have been associated with off-target pharmacology via interactions with aminergic G-protein coupled receptors, ion-channels, kinases, etc. Structural features associated with the promiscuous nature of basic amines have been well-studied, and can be mitigated in a preclinical drug discovery environment. In addition to the undesirable secondary pharmacology, α-carbon oxidation of certain secondary or tertiary cycloalkyl amines can generate electrophilic iminium and aldehyde metabolites, potentially capable of covalent adduction to proteins or DNA. Consequently, cycloalkyl amines have been viewed as structural alerts (SAs), analogous to functional groups such as anilines, furans, thiophenes, etc., which are oxidized to reactive metabolites that generate immunogenic haptens by covalently binding to host proteins. Detailed survey of the literature, however, suggests that cases where preclinical or clinical toxicity has been explicitly linked to the metabolic activation of a cycloalkyl amine group are extremely rare. Moreover, there is a distinct possibility for the formation of electrophilic iminium/amino-aldehyde metabolites with numerous cycloalkyl amine-containing marketed drugs, since stable ring cleavage products have been characterized as metabolites in human mass balance studies. In the present work, a critical analysis of the evidence for and against the role of iminium ions/aldehydes as mediators of toxicity is discussed with a special emphasis on often time overlooked detoxication pathways of these reactive species to innocuous metabolites.

Click Chemistry Conjugations

Click chemistry has found wide application in bioconjugation, enabling control over the site of modification in biomolecules. Demonstrations of this chemistry to construct chemically defined antibody-drug conjugates (ADCs) have increased in recent years, following studies that support benefits of homogeneity and site-specificity of drug placement on the antibody. In this chapter, a brief history of early applications of this chemistry in ADCs is presented. Examples of click chemistries that are utilized for ADC synthesis, including those currently undergoing clinical investigations, are enumerated. Protocols for two common conjugation methods based on carbonyl-aminooxy coupling and strain-promoted azide-alkyne cycloaddition are described.

Thin poly(vinyl alcohol) cryogels: reactive groups, macropores and translucency in microtiter plate assays

Thin macroporous poly(vinyl alcohol) (PVA) hydrogels were produced by cross-linking of PVA in a semi-frozen state with glutaraldehyde (GA) on glass slides or in the wells of microtiter plates. The 100-130 μm-thick gels were mechanically transferable, squamous translucent films with a high porosity of 7.2 ± 0.3 mL/g dry PVA i.e. similar to larger cylindrical PVA monoliths of the same composition. Additional treatment of the gels with 1% GA increased the aldehyde group content from 0.7 to 2.4 μmol/mL as estimated using dinitrophenylhydrazine (DNPH) reagent. Translucency of the gels allowed registration of UV-visible spectra of the DNPH-stained films. The catalytic activity of trypsin covalently immobilized on thin gels in the microtiter plates was estimated with chromogenic substrate directly in the wells, and indicated that the amount of protein immobilized was at least 0.34 mg/mL gel. Human immunoglobulin G (IgG) immobilized on thin gels at 0.1-10 mg/mL starting concentrations could be detected in a concentration-dependent manner due to recognition by anti-human rabbit IgG conjugated with peroxidase and photometric registration of the enzymatic activity. The results indicate good permeability of the hydrogel pores for macromolecular biospecific reagents and suggest applications of thin reactive PVA hydrogels in photometric analytical techniques.

Carboxylic acid reductase: Structure and mechanism

Carboxylic acid reductase (CAR) enzymes are large multi-domain proteins that catalyse the ATP- and NADPH-dependent reduction of wide range of acids to the corresponding aldehydes. This particular reaction is of considerable biotechnological interest. Recent advances in the structural and solution studies of isolated domain, di-domain and full-length CAR enzymes revealed valuable insights into the mechanism of carboxylic acid reduction activity. This review features the phylogenetic, sequence and structural insight into the CAR and implications of these observations in order to improve carboxylic acid reduction activity to develop CAR as robust biocatalyst.

Co-factor demand and regeneration in the enzymatic one-step reduction of carboxylates to aldehydes in cell-free systems

Addressing the challenges associated with the development of in vitro biocatalytic carboxylate reductions for potential applications, important aspects of the co-factor regeneration systems and strategies for minimizing over-reduction were investigated. The ATP recycling can be performed with similarly high efficiency exploiting the polyphosphate source by combining Meiothermus ruber polyphosphate kinase and adenylate kinase or with Sinorhizobium meliloti polyphosphate kinase instead of the latter. Carboxylate reductions with the enzyme candidates used in this work allow operating at co-factor concentrations of adenosine 5'-triphosphate and β-nicotinamide adenine dinucleotide 2'-phosphate of 100 μM and, thereby, reducing the amounts of alcohols formed by side activities in the enzyme preparations. This study confirmed the expected benefits of carboxylic acid reductases in chemoselectively reducing the carboxylates to the corresponding aldehydes while leaving reductively-sensitive nitro, ester and cyano groups intact.

Catalytic Synthesis of 2,5-Furandicarboxylic Acid from Concentrated 2,5-Diformylfuran Mediated by N-hydroxyimides under Mild Conditions

Producing polyester monomer 2,5-furandicarboxylic acid (FDCA) from biomass as an alternative to fossil-derived terephthalic acid has drawn much attention from both academy and industry. In this work, an efficient FDCA synthesis was proposed from 10.6 wt % 2,5-diformylfuran (DFF) in acetic acid using a combined catalytic system of Co/Mn acetate and N-hydroxyimides. The intermediate product of 5-formyl-2-furandicarboxylic acid (FFCA) possesses the least reactive formyl group. N-hydroxysuccinimide was found to be superior to N-hydroxyphthalimide in catalyzing the oxidation of the formyl group in FFCA intermediate, affording a near 95 % yield of FDCA under mild conditions of 100 °C. Trace maleic anhydride was detected as by-product, which mainly came from the oxidative cleavage of DFF via furfural, furoic acid and 5-acetoxyl-2(5H)-furanone as intermediates.