Aldehydes: occurrence, carcinogenic potential, mechanism of action and risk assessment

Aldehyde dehydrogenases as drug targets for cancer: SAR and structural biology aspects for inhibitor design

Aldehydes are organic compounds containing a carbonyl group found exogenously or produced by normal metabolic processes and their accumulation can lead to toxicity if not cleared. Aldehyde dehydrogenases (ALDHs) are NAD(P)+-dependent enzymes that catalyze the oxidation of such aldehydes and prevent their accumulation. Along with this primary detoxification function, the known 19 human isoforms of ALDHs, which act on different substrates, are also involved in various physiological and developmental processes. Functional alterations of ALDHs via mutations or expression levels cause various disease conditions, including many different cancer types like lung, ovarian, etc. These properties make this family of enzymes an ideal therapeutic and prognostic target for drug development. However, sequence similarities between the ALDH isoforms force the need to design inhibitors for a specific isoform using the differences in the substrate-binding sites of each protein. This has resulted in developing isoform-specific inhibitors, especially for ALDH1A1, ALDH2, and ALDH3A1, which are implicated in various cancers. In this review, we briefly outline the functional roles of the different isoforms of the ALDH family members, their role in cancer and discuss the various selective inhibitors that have been developed for the ALDH1A1 and ALDH3A1 enzymes, along with a detailed examination of the respective structure-activity relationship (SAR) studies available. From the available SAR and structural biology data, insights into the functional groups and interactions necessary to develop selective inhibitors for ALDH1A1 and ALDH3A1 are highlighted, which can act as a guide for developing more potent and selective inhibitors of ALDH isoforms.

The biochemistry of the carcinogenic alcohol metabolite acetaldehyde

Acetaldehyde (AcH) is the first metabolite of ethanol and is proposed to be responsible for the genotoxic effects of alcohol consumption. As an electrophilic aldehyde, AcH can form multiple adducts with DNA and other biomolecules, leading to function-altering and potentially toxic and carcinogenic effects. In this review, we describe sources of AcH in humans, including AcH biosynthesis mechanisms, and outline the structures, properties and functions of AcH-derived adducts with biomolecules. We also describe human AcH detoxification mechanisms and discuss ongoing challenges in the field.

Evaluating the therapeutic potential of genetically engineered probiotic Zbiotics (ZB183) for non-alcoholic steatohepatitis (NASH) management via modulation of the cGAS-STING pathway

NAFLD/NASH has emerged as a global health concern with no FDA-approved treatment, necessitating the exploration of novel therapeutic elements for NASH. Probiotics are known as an important adjunct therapy in NASH. Zbiotics (ZB183) is the first commercially available genetically engineered probiotic. Herein, we aimed to evaluate the potential therapeutic effects of Zbiotics administration on NASH management by modulating the cGAS-STING-signaling pathway-related RNA network. In silico data analysis was performed and three DEGs (MAPK3/EDN1/TNF) were selected with their epigenetic modulators (miR-6888-5p miRNA, and lncRNA RABGAP1L-DT-206). The experimental design included NASH induction with an HSHF diet in Wistar rats and Zbiotics administration in NASH rats in comparison to statin treatment. Liver functions and lipid profile were assessed. Additionally, the expression levels of the constructed molecular network were assessed using RT-PCR. Moreover, the Zbiotics effects in NASH were further validated with histopathological examination of liver and colon samples. Also, immunohistochemistry staining of hepatic TNF-α and colonic occludin was assessed. Oral administration of Zbiotics for four weeks downregulated the expression of the cGAS-STING-related network (MAPK3/EDN1/TNF/miR-6888-5p miRNA/lncRNA RABGAP1L-DT-206) in NASH models. Zbiotics also ameliorated hepatic inflammation and steatosis, as evidenced by a notable improvement in NAS score and decreased hepatic TNF-α levels. Furthermore, Zbiotics exhibited favorable effects on colon health, including increased crypt length, reduced inflammatory cell infiltration, and restoration of colonic mucosa occludin expression. In conclusion, our findings suggest that Zbiotics has potential therapeutic effects on NASH via modulating the gut-liver axis and the cGAS-STING signaling pathway.

A Comparison Analysis of Four Different Drying Treatments on the Volatile Organic Compounds of Gardenia Flowers

The gardenia flower not only has extremely high ornamental value but also is an important source of natural food and spices, with a wide range of uses. To support the development of gardenia flower products, this study used headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) technology to compare and analyze the volatile organic compounds (VOCs) of fresh gardenia flower and those after using four different drying methods (vacuum freeze-drying (VFD), microwave drying (MD), hot-air drying (HAD), and vacuum drying (VD)). The results show that, in terms of shape, the VFD sample is almost identical to fresh gardenia flower, while the HAD, MD, and VD samples show significant changes in appearance with clear wrinkling; a total of 59 volatile organic compounds were detected in the gardenia flower, including 13 terpenes, 18 aldehydes, 4 esters, 8 ketones, 15 alcohols, and 1 sulfide. Principal component analysis (PCA), cluster analysis (CA), and partial least-squares regression analysis (PLS-DA) were performed on the obtained data, and the research found that different drying methods impact the VOCs of the gardenia flower. VFD or MD may be the most effective alternative to traditional sun-drying methods. Considering its drying efficiency and production cost, MD has the widest market prospects.

Dual role of Nrf2 signaling in hepatocellular carcinoma: promoting development, immune evasion, and therapeutic challenges

Hepatocellular carcinoma (HCC) is the predominant form of liver cancer and ranks as the third leading cause of cancer-related mortality globally. The liver performs a wide range of tasks and is the primary organ responsible for metabolizing harmful substances and foreign compounds. Oxidative stress has a crucial role in growth and improvement of hepatocellular carcinoma (HCC). Nuclear factor erythroid 2 (1)-related factor 2 (Nrf2) is an element that regulates transcription located in the cytoplasm. It controls the balance of redox reactions by stimulating the expression of many genes that depend on antioxidant response elements. Nrf2 has contrasting functions in the normal, healthy liver and HCC. In the normal liver, Nrf2 provides advantageous benefits, while in HCC it promotes harmful effects that support the growth and survival of HCC. Continuous activation of Nrf2 has been detected in HCC and promotes its advancement and aggressiveness. In addition, Activation of Nrf2 may lead to immune evasion, weakening the immune cells' ability to attack tumors and thereby promoting tumor development. Furthermore, chemoresistance in HCC, which is considered a form of stress response to chemotherapy medications, significantly impedes the effectiveness of HCC treatment. Stress management is typically accomplished by activating specific signal pathways and chemical variables. One important element in the creation of chemoresistance in HCC is nuclear factor-E2-related factor 2 (Nrf2). Nrf2 is a transcription factor that regulates the activation and production of a group of genes that encode proteins responsible for protecting cells from damage. This occurs through the Nrf2/ARE pathway, which is a crucial mechanism for combating oxidative stress within cells.

[Harmful health effects of flavors in e-cigarettes]

BACKGROUND

Almost all e-cigarettes contain flavorings that make the product more attractive. In the evaluation of e-cigarettes on health, flavors have so far played a subordinate role.

METHOD

Selective literature search in PubMed, supplemented by legal regulations on the use of flavors in e-cigarettes.

RESULTS

Flavors make it easier to start using e-cigarettes and have a consumption-promoting effect. Deeper inhalation increases nicotine uptake and the absorption of toxic substances from the e-cigarette liquid. For some flavors, pathological effects have been demonstrated in addition to other toxic components of the e-cigarette. To date, no toxicological analyses are available for the vast majority of flavors contained in e-cigarettes.

CONCLUSIONS

The proven consumption-promoting effect and the health risks that can be extrapolated from preclinical data are significant for the political discussion of a ban on flavors for e-cigarettes, analogous to the ban on flavors in tobacco products already in force.

Occurrence and Synthesis Pathways of (Suspected) Genotoxic α,β-Unsaturated Carbonyls in Chocolate and Other Commercial Sweet Snacks

α,β-Unsaturated carbonyls are highly reactive and described as structural alerts for genotoxicity. Ten of them (either commercially available or synthesized here by combinatorial chemistry) were first investigated throughout the chocolate-making process by solvent-assisted flavor evaporation (SAFE) coupled to GC-MS/SIM. Monitored α,β-unsaturated aldehydes were formed during chocolate production, primarily through aldol condensation of Strecker aldehydes triggered by bean roasting. Notably, levels of 2-phenylbut-2-enal (up to 399 μg·kg-1) and 5-methyl-2-phenylhex-2-enal (up to 216 μg·kg-1) increased up to 40-fold. Dry conching caused evaporation of α,β-unsaturated carbonyls, while wet conching partially restored or increased their levels due to cocoa butter addition. Further analyses showed that α,β-unsaturated aldehydes also occurred in most commercial sweet snacks (up to 16 μg·kg-1), although often at lower concentrations than in roasted cocoa or derived chocolates. In the end, none of the monitored α,β-unsaturated aldehydes did raise a health concern compared to current maximum use levels (2-5 mg·kg-1). On the other hand, much higher levels of genotoxic furan-2(5H)-one were found in crepe and cake samples (up to 4.3 mg·kg-1).

Prioritizing of potential environmental exposure carcinogens beyond IARC group 1-2B based on weight of evidence (WoE) approach

Environmental exposures are the main cause of cancer, and their carcinogenicity has not been fully evaluated, identifying potential carcinogens that have not been evaluated is critical for safety. This study is the first to propose a weight of evidence (WoE) approach based on computational methods to prioritize potential carcinogens. Computational methods such as read across, structural alert, (Quantitative) structure-activity relationship and chemical-disease association were evaluated and integrated. Four different WoE approach was evaluated, compared to the best single method, the WoE-1 approach gained 0.21 and 0.39 improvement in the area under the receiver operating characteristic curve (AUC) and Matthew's correlation coefficient (MCC) value, respectively. The evaluation of 681 environmental exposures beyond IARC list 1-2B prioritized 52 chemicals of high carcinogenic concern, of which 21 compounds were known carcinogens or suspected carcinogens, and eight compounds were identified as potential carcinogens for the first time. This study illustrated that the WoE approach can effectively complement different computational methods, and can be used to prioritize chemicals of carcinogenic concern.

[Harmful health effects of flavors in e-cigarettes]

BACKGROUND

 Almost all e-cigarettes contain flavorings that make the product more attractive. In the evaluation of e-cigarettes on health, flavors have so far played a subordinate role.

METHOD

 Selective literature search in PubMed, supplemented by legal regulations on the use of flavors in e-cigarettes.

RESULTS

 Flavors make it easier to start using e-cigarettes and have a consumption-promoting effect. Deeper inhalation increases nicotine uptake and the absorption of toxic substances from the e-cigarette liquid. For some flavors, pathological effects have been demonstrated in addition to other toxic components of the e-cigarette. To date, no toxicological analyses are available for the vast majority of flavors contained in e-cigarettes.

CONCLUSIONS

 The proven consumption-promoting effect and the health risks that can be extrapolated from preclinical data are significant for the political discussion of a ban on flavors for e-cigarettes, analogous to the ban on flavors in tobacco products already in force.

Degradation Mechanism Study for Secondary Degradants in Rosuvastatin Calcium and Determination of Degradant Acetaldehyde Using Static Headspace Gas Chromatography Coupled with Matrix Precipitation

During the development of headspace gas chromatography (HSGC) method for assessing residual solvents in rosuvastatin calcium (RSV) drug substance, acetaldehyde (AA) was detected in obtained chromatograms, with a calculated concentration of up to 226 ppm. After a series of experiments, it was established that acetaldehyde originates from matrix interference due to direct degradation of Imp-C, which is accompanied by the formation of impurity at relative retention time (RRT) 2.18, without the involvement of impurity at RRT 2.31. The thermal instability of Imp-C also results in the formation of impurity at RRT 2.31 through dehydration and decarboxylation. In addition, cyclization reaction of degradant at RRT 2.18 further resulted in the generation of impurity at RRT 2.22. The structure of these three degradants, were confirmed by liquid chromatography-mass spectrometry (LC-MS), 1D and 2D nuclear magnetic resonance (NMR) measurement. In order to minimize the said matrix interference, a simple precipitation procedure was proposed as a pretreatment to mitigate the impact of Imp-C. Subsequently, an HSGC method was developed for the simultaneous determination of the degradant AA and the other five residual solvents used in RSV synthetic process. The final method was validated concerning precision, limit of detection (LOD) and limit of quantitation (LOQ), linearity, and accuracy.

Relevance of Carcinogen-Induced Preclinical Cancer Models

Chemical agents can cause cancer in animals by damaging their DNA, mutating their genes, and modifying their epigenetic signatures. Carcinogen-induced preclinical cancer models are useful for understanding carcinogen-induced human cancers, as they can reproduce the diversity and complexity of tumor types, as well as the interactions with the host environment. However, these models also have some drawbacks that limit their applicability and validity. For instance, some chemicals may be more effective or toxic in animals than in humans, and the tumors may differ in their genetics and phenotypes. Some chemicals may also affect normal cells and tissues, such as by causing oxidative stress, inflammation, and cell death, which may alter the tumor behavior and response to therapy. Furthermore, some chemicals may have variable effects depending on the exposure conditions, such as dose, route, and duration, as well as the animal characteristics, such as genetics and hormones. Therefore, these models should be carefully chosen, validated, and standardized, and the results should be cautiously interpreted and compared with other models. This review covers the main features of chemically induced cancer models, such as genetic and epigenetic changes, tumor environment, angiogenesis, invasion and metastasis, and immune response. We also address the pros and cons of these models and the current and future challenges for their improvement. This review offers a comprehensive overview of the state of the art of carcinogen-induced cancer models and provides new perspectives for cancer research.

Acetaldehyde as a Food Flavoring Substance: Aspects of Risk Assessment

The Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) has reviewed the currently available data in order to assess the health risks associated with the use of acetaldehyde as a flavoring substance in foods. Acetaldehyde is genotoxic in vitro. Following oral intake of ethanol or inhalation exposure to acetaldehyde, systemic genotoxic effects of acetaldehyde in vivo cannot be ruled out (induction of DNA adducts and micronuclei). At present, the key question of whether acetaldehyde is genotoxic and mutagenic in vivo after oral exposure cannot be answered conclusively. There is also insufficient data on human exposure. Consequently, it is currently not possible to reliably assess the health risk associated with the use of acetaldehyde as a flavoring substance. However, considering the genotoxic potential of acetaldehyde as well as numerous data gaps that need to be filled to allow a comprehensive risk assessment, the SKLM considers that the use of acetaldehyde as a flavoring may pose a safety concern. For reasons of precautionary consumer protection, the SKLM recommends that the scientific base for approval of the intentional addition of acetaldehyde to foods as a flavoring substance should be reassessed.

Cryo-EM structure of bifunctional malonyl-CoA reductase from Chloroflexus aurantiacus reveals a dynamic domain movement for high enzymatic activity

The platform chemical 3-hydroxypropionic acid is used to synthesize various valuable materials, including bioplastics. Bifunctional malonyl-CoA reductase is a key enzyme in 3-hydroxypropionic acid biosynthesis as it catalyzes the two-step reduction of malonyl-CoA to malonate semialdehyde to 3-hydroxypropionic acid. Here, we report the cryo-EM structure of a full-length malonyl-CoA reductase protein from Chloroflexus aurantiacus (CaMCR^Full). The EM model of CaMCR^Full reveals a tandem helix architecture comprising an N-terminal (CaMCR^ND) and a C-terminal (CaMCR^CD) domain. The CaMCR^Full model also revealed that the enzyme undergoes a dynamic domain movement between CaMCR^ND and CaMCR^CD due to the presence of a flexible linker between these two domains. Increasing the flexibility and extension of the linker resulted in a twofold increase in enzyme activity, indicating that for CaMCR, domain movement is crucial for high enzyme activity. We also describe the structural features of CaMCR^ND and CaMCR^CD. This study reveals the protein structures underlying the molecular mechanism of CaMCR^Full and thereby provides valuable information for future enzyme engineering to improve the productivity of 3-hydroxypropionic acid.

Improving Saccharomyces cerevisiae acid and oxidative stress resistance using a prokaryotic gene identified by functional metagenomics

Innovations in obtaining products from lignocellulosic biomass have been largely based on the improvement of microorganisms and enzymes capable of degrading these materials. To complete the whole process, microorganisms must be able to ferment the resulting sugars and tolerate high concentrations of product, osmotic pressure, ion toxicity, temperature, toxic compounds from lignocellulose pretreatment, low pH, and oxidative stress. In this work, we engineered laboratory and industrial Saccharomyces cerevisiae strains by combining a gene (hu) recovered from a metagenomic approach with different native and synthetic promoters to obtain improved acid and oxidative stress resistance. Laboratorial strains harboring hu gene under the control of the synthetic stress responsive PCCW14v5 showed increased survival rates after 2 h exposure to pH 1.5. The hu gene was also able to significantly enhance the tolerance of the industrial strain to high concentrations of H₂O₂ when combined with PTEF1, PYGP1 or PYGP1v7 after 3 h exposure.

Characterization of human oxidoreductases involved in aldehyde odorant metabolism

Oxidoreductases are major enzymes of xenobiotic metabolism. Consequently, they are essential in the chemoprotection of the human body. Many xenobiotic metabolism enzymes have been shown to be involved in chemosensory tissue protection. Among them, some were additionally shown to be involved in chemosensory perception, acting in signal termination as well as in the generation of metabolites that change the activation pattern of chemosensory receptors. Oxidoreductases, especially aldehyde dehydrogenases and aldo-keto reductases, are the first barrier against aldehyde compounds, which include numerous odorants. Using a mass spectrometry approach, we characterized the most highly expressed members of these families in the human nasal mucus sampled in the olfactory vicinity. Their expression was also demonstrated using immunohistochemistry in human epitheliums sampled in the olfactory vicinity. Recombinant enzymes corresponding to three highly expressed human oxidoreductases (ALDH1A1, ALDH3A1, AKR1B10) were used to demonstrate the high enzymatic activity of these enzymes toward aldehyde odorants. The structure‒function relationship set based on the enzymatic parameters characterization of a series of aldehyde odorant compounds was supported by the X-ray structure resolution of human ALDH3A1 in complex with octanal.

Ozone based inactivation and disinfection in the pandemic time and beyond: Taking forward what has been learned and best practice

The large-scale global COVID-19 has a profound impact on human society. Timely and effectively blocking the virus spread is the key to controlling the pandemic growth. Ozone-based inactivation and disinfection techniques have been shown to effectively kill SARS-CoV-2 in water, aerosols and on solid surface. However, the lack of an unified information and discussion on ozone-based inactivation and disinfection in current and previous pandemics and the absence of consensus on the main mechanisms by which ozone-based inactivation of pandemic causing viruses have hindered the possibility of establishing a common basis for identifying best practices in the utilization of ozone technology. This article reviews the research status of ozone (O3) disinfection on pandemic viruses (especially SARS-CoV-2). Taking sterilization kinetics as the starting point while followed by distinguishing the pandemic viruses by enveloped and non-enveloped viruses, this review focuses on analyzing the scope of application of the sterilization model and the influencing factors from the experimental studies and data induction. It is expected that the review could provide an useful reference for the safe and effective O3 utilization of SARS-CoV-2 inactivation in the post-pandemic era.

Aldehyde Accumulation in Aged Alcoholic Beer: Addressing Acetaldehyde Impacts on Upper Aerodigestive Tract Cancer Risks

Aldehydes, particularly acetaldehyde, are carcinogenic molecules and their concentrations in foodstuffs should be controlled to avoid upper aerodigestive tract (UADT) and liver cancers. Highly reactive, acetaldehyde forms DNA and protein adducts, impairing physiological functions and leading to the development of pathological conditions. The consumption of aged beer, outside of the ethanol metabolism, exposes habitual drinkers to this carcinogen, whose concentrations can be over-increased due to post-brewing chemical and biochemical reactions. Storage-related changes are a challenge faced by the brewing industry, impacting volatile compound formation and triggering flavor instability. Aldehydes are among the volatile compounds formed during beer aging, recognized as off-flavor compounds. To track and understand aldehyde formation through multiple pathways during beer storage, consequent changes in flavor but particularly quality losses and harmful compound formation, this systematic review reunited data on volatile compound profiles through gas chromatography analyses from 2011 to 2021. Conditions to avoid flavor instability and successful methods for reducing beer staling, and consequent acetaldehyde accumulation, were raised by exploring the dynamic conversion between free and bound-state aldehydes. Future research should focus on implementing sensory analyses to investigate whether adding aldehyde-binding agents, e.g., cysteine and bisulfite, would contribute to consumer acceptance, restore beer flavor, and minimize acetaldehyde-related health damage.

The Synthesis, Fungicidal Activity, and in Silico Study of Alkoxy Analogues of Natural Precocenes I, II, and III

This study aimed to synthesize, characterize, and explore the eco-friendly and antifungal potential of precocenes and their derivatives. The organic synthesis of the mono-O-alkyl-2,2-dimethyl 2H-1-chromene series, including the natural product precocene I, and the di-O-alkyl 2,2-dimethyl-2H-1-chromene series, including the natural 2H-1-chromenes precocenes II and III, was achieved. The synthetic compounds were subjected to spectroscopic analysis, 1HNMR,13CNMR, and mass characterization. The antifungal activity of synthesized precocenes I, II, and III, as well as their synthetic intermediates, was evaluated by the poison food technique. Precocene II (EC50 106.8 µg × mL−1 and 4.94 µg mL−1), and its regioisomers 7a (EC50 97.18 µg × mL−1 and 35.30 µg × mL−1) and 7d (EC50 170.58 × µg mL−1), exhibited strong fungitoxic activity against Aspergillus niger and Rhizoctonia solani. Some of the novel chromenes, 11a and 11b, which had never been evaluated before, yielded stronger fungitoxic effects. Finally, docking simulations for compounds with promising fungitoxic activity were subjected to structure–activity relationship analyses against the polygalactouronases and voltage-dependent anion channels. Conclusively, precocenes and their regioisomers demonstrated promising fungitoxic activity; such compounds can be subjected to minor structural modifications to yield promising and novel fungicides.

Pulmonary effects of e-liquid flavors: a systematic review

Electronic cigarettes (ECs) are purported to be tobacco harm-reduction products whose degree of harm has been highly debated. EC use is considered less hazardous than smoking but is not expected to be harmless. Following the banning of e-liquid flavors in countries such as the US, Finland, Ukraine, and Hungary, there are growing concerns regarding the safety profile of e-liquid flavors used in ECs. While these are employed extensively in the food industry and are generally regarded as safe (GRAS) when ingested, GRAS status after inhalation is unclear. The aim of this review was to assess evidence from 38 reports on the adverse effects of flavored e-liquids on the respiratory system in both in vitro and in vivo studies published between 2006 and 2021. Data collected demonstrated greater detrimental effects in vitro with cinnamon (9 articles), strawberry (5 articles), and menthol (10 articles), flavors than other flavors. The most reported effects among these investigations were perturbations of pro-inflammatory biomarkers and enhanced cytotoxicity. There is sufficient evidence to support the toxicological impacts of diacetyl- and cinnamaldehyde-containing e-liquids following human inhalation; however, safety profiles on other flavors are elusive. The latter may result from inconsistencies between experimental approaches and uncertainties due to the contributions from other e-liquid constituents. Further, the relevance of the concentration ranges to human exposure levels is uncertain. Evidence indicates that an adequately controlled and consistent, systematic toxicological investigation of a broad spectrum of e-liquid flavors may be required at biologically relevant concentrations to better inform public health authorities on the risk assessment following exposure to EC flavor ingredients.

Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk

Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.

Hofmeister effect-enhanced gelatin/oxidized dextran hydrogels with improved mechanical properties and biocompatibility for wound healing

Compared with other types of hydrogels, natural derived hydrogels possess intrinsic advantages of degradability and biocompatibility. However, due to the low mechanical strength, their potential applications in biomedical areas are limited. In this study, Hofmeister effect-enhanced gelatin/oxidized dextran (Gel/O-Dex) hydrogels were designed with improved mechanical properties and biocompatibility to accelerate wound healing. Gel and O-Dex were chemically crosslinked through Schiff base reaction of aldehyde and amino groups. After soaking in kosmotrope solutions physical crosslinking domains were induced by Hofmeister effect including α-helix structures, hydrophobic interaction regions and helical junction zones among Gel molecular chains. The type of anions played different influence on the properties of hydrogels, which was consistent with the order of Hofmeister series. Particularly, H₂PO₄^- treated hydrogels showed enhanced mechanical strength and fatigue resistance superior to that of Gel/O-Dex hydrogels. The underlying mechanism was that the physical crosslinking domains sustained additional mechanical stress and dissipated energy through cyclic association and dissociation process. Furthermore, Hofmeister effect only induced polymer chain entanglements without triggering any chemical reaction. Due to Hofmeister effect of H₂PO₄^- ions, aldehyde groups were embedded in the center of entangled polymer chains that resulted in better biocompatibility. In the full-thickness skin defects of SD rats, Hofmeister effect-enhanced Gel/O-Dex hydrogels by H₂PO₄^- ions accelerated wound healing and exhibited better histological morphology than ordinary hydrogels. Therefore, Hofmeister effect by essential inorganic anions is a promising method of improving mechanical properties and biocompatibility of natural hydrogels to promote medical translation in the field of wound healing from bench to clinic. STATEMENT OF SIGNIFICANCE: Hofmeister effect enhanced hydrogel mechanical properties in accordance with the order of Hofmeister series through physical crosslinking that induced α-helix structures, hydrophobic interaction regions and helical junction zones among Gel molecular chains. Due to the Hofmeister effect of H₂PO₄^- ions, aldehyde groups were embedded in the center of entangled polymer chains that resulted in better biocompatibility. Hofmeister effect-enhanced Gel/O-Dex hydrogels through H₂PO₄^- ions accelerated wound healing and exhibited better histological morphology than ordinary hydrogels. Therefore, Hofmeister effect by essential inorganic anions is a promising method to improve mechanical properties and biocompatibility of natural hydrogels for their medical applications..

Quantitative measurement of harmful and potentially harmful constituents, pH, and moisture content in 16 commercial smokeless tobacco products

Smokeless tobacco products expose adult and youth tobacco users to various addictive and carcinogenic constituents that can cause long-term nicotine dependence and oral cancers. In this study, nicotine, benzo[a]pyrene (B[a]P), N'-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), acetaldehyde, crotonaldehyde, formaldehyde, moisture, and pH levels in 16 smokeless tobacco products were measured on a wet-weight basis (wwb). In addition, change in analytical variability with increasing replicate measurements was assessed. Total nicotine in the products varied from 6.2 to 35.5 mg/g. The percentage of total nicotine in the unprotonated form ranged from 0.1 to 62%; whereas, product moisture varied from 7.4 to 57%. The quantities of harmful and potentially harmful constituents (HPHCs) range from 0.46 to 179.9 ng/g for B [a]P, 270-12206 and 81-20716 ng/g for NNN and NNK, respectively, and 0.33-6.85 and 0.13-5.67 μg/g for acetaldehyde and formaldehyde, respectively. This study shows wide variation in smokeless tobacco product HPHC quantities. The results also show that analytical variability stabilizes after seven replicate measurements.

Origin and Fate of Acrolein in Foods

Acrolein is a highly toxic agent that may promote the occurrence and development of various diseases. Acrolein is pervasive in all kinds of foods, and dietary intake is one of the main routes of human exposure to acrolein. Considering that acrolein is substantially eliminated after its formation during food processing and re-exposed in the human body after ingestion and metabolism, the origin and fate of acrolein must be traced in food. Focusing on molecular mechanisms, this review introduces the formation of acrolein in food and summarises both in vitro and in vivo fates of acrolein based on its interactions with small molecules and biomacromolecules. Future investigation of acrolein from different perspectives is also discussed.

The role of endogenous versus exogenous sources in the exposome of putative genotoxins and consequences for risk assessment

The "totality" of the human exposure is conceived to encompass life-associated endogenous and exogenous aggregate exposures. Process-related contaminants (PRCs) are not only formed in foods by heat processing, but also occur endogenously in the organism as physiological components of energy metabolism, potentially also generated by the human microbiome. To arrive at a comprehensive risk assessment, it is necessary to understand the contribution of in vivo background occurrence as compared to the ingestion from exogenous sources. Hence, this review provides an overview of the knowledge on the contribution of endogenous exposure to the overall exposure to putative genotoxic food contaminants, namely ethanol, acetaldehyde, formaldehyde, acrylamide, acrolein, α,β-unsaturated alkenals, glycation compounds, N-nitroso compounds, ethylene oxide, furans, 2- and 3-MCPD, and glycidyl esters. The evidence discussed herein allows to conclude that endogenous formation of some contaminants appears to contribute substantially to the exposome. This is of critical importance for risk assessment in the cases where endogenous exposure is suspected to outweigh the exogenous one (e.g. formaldehyde and acrolein).

Evidence-Based Challenges to the Continued Recommendation and Use of Peroxidatively-Susceptible Polyunsaturated Fatty Acid-Rich Culinary Oils for High-Temperature Frying Practises: Experimental Revelations Focused on Toxic Aldehydic Lipid Oxidation Products

In this manuscript, a series of research reports focused on dietary lipid oxidation products (LOPs), their toxicities and adverse health effects are critically reviewed in order to present a challenge to the mindset supporting, or strongly supporting, the notion that polyunsaturated fatty acid-laden frying oils are "safe" to use for high-temperature frying practises. The generation, physiological fates, and toxicities of less commonly known or documented LOPs, such as epoxy-fatty acids, are also considered. Primarily, an introduction to the sequential autocatalytic peroxidative degradation of unsaturated fatty acids (UFAs) occurring during frying episodes is described, as are the potential adverse health effects posed by the dietary consumption of aldehydic and other LOP toxins formed. In continuance, statistics on the dietary consumption of fried foods by humans are reviewed, with a special consideration of French fries. Subsequently, estimates of human dietary aldehyde intake are critically explored, which unfortunately are limited to acrolein and other lower homologues such as acetaldehyde and formaldehyde. However, a full update on estimates of quantities derived from fried food sources is provided here. Further items reviewed include the biochemical reactivities, metabolism and volatilities of aldehydic LOPs (the latter of which is of critical importance regarding the adverse health effects mediated by the inhalation of cooking/frying oil fumes); their toxicological actions, including sections focussed on governmental health authority tolerable daily intakes, delivery methods and routes employed for assessing such effects in animal model systems, along with problems encountered with the Cramer classification of such toxins. The mutagenicities, genotoxicities, and carcinogenic potential of aldehydes are then reviewed in some detail, and following this the physiological concentrations of aldehydes and their likely dietary sources are considered. Finally, conclusions from this study are drawn, with special reference to requirements for (1) the establishment of tolerable daily intake (TDI) values for a much wider range of aldehydic LOPs, and (2) the performance of future nutritional and epidemiological trials to explore associations between their dietary intake and the incidence and severity of non-communicable chronic diseases (NCDs).

Development of wheat bran hydrolysate as Komagataella phaffii medium for heterologous protein production

Developing a Komagataella phaffii (K. phaffii, named as Pichia pastoris formerly) medium using wheat bran hydrolysate (WBH) is a potential approach for wheat bran utilization and heterologous protein by K. phaffii because K. phaffii is used as protein producer by researchers and engineers widely. In this research, the detoxification process of WBH was optimized to obtain the final procedure as pH adjusting to 10 by calcium hydroxide addition, then, 2.0 g/L active carbon absorption followed by 1 h shaking and 3,600 × g centrifugation for 10 min, finally, 3.75 mmol/L sodium thiosulfate addition for 10 min shaking followed by 3,600 × g centrifugation for 10 min. Recombinant K. phaffii-xynB harboring xylanase B gene from Aspergillus niger ATCC 1015 under alcohol oxidase 1 promoter (P_AOX1) was cultivated in detoxified WBH expressing 1059.8 U/mL xylanase B which was 90.9% of that in complex medium from Pichia protocols. These researches built a solid base for detoxified WBH as a low-cost medium of K. phaffii to express heterologous protein, also provided a bright outlet for wheat bran utilization.

Backhousia citriodora F. Muell. (Lemon Myrtle), an Unrivalled Source of Citral

Lemon oils are amongst the highest volume and most frequently traded of the flavor and fragrance essential oils. Citronellal and citral are considered the key components responsible for the lemon note with citral (neral + geranial) preferred. Of the myriad of sources of citral, the Australian myrtaceous tree, Lemon Myrtle, Backhousia citriodora F. Muell. (Myrtaceae), is considered superior. This review examines the history, the natural occurrence, the cultivation, the taxonomy, the chemistry, the biological activity, the toxicology, the standardisation and the commercialisation of Backhousia citriodora especially in relation to its essential oil.

Assessment of the potential vaping-related exposure to carbonyls and epoxides using stable isotope-labeled precursors in the e-liquid

The formation of carbonyls and epoxides in e-cigarette (EC) aerosol is possible due to heating of the liquid constituents. However, high background levels of these compounds have inhibited a clear assessment of exposure during use of ECs. An EC containing an e-liquid replaced with 10% of ¹³C-labeled propylene glycol and glycerol was used in a controlled use clinical study with 20 EC users. In addition, five smokers smoked cigarettes spiked with the described e-liquid. Seven carbonyls (formaldehyde, acetaldehyde, acrolein, acetone, crotonaldehyde, methacrolein, propionaldehyde) were measured in the aerosol and the mainstream smoke. Corresponding biomarkers of exposure were determined in the user’s urine samples. ¹³C-labeled formaldehyde, acetaldehyde and acrolein were found in EC aerosol, while all seven labeled carbonyls were detected in smoke. The labeled biomarkers of exposure to formaldehyde (¹³C-thiazolidine carboxylic acid and ¹³C-N-(1,3-thiazolidine-4-carbonyl)glycine), acrolein (¹³C₃-3-hydroxypropylmercapturic acid) and glycidol (¹³C₃-dihydroxypropylmercapturic acid) were present in the urine of vapers indicating an EC use-specific exposure to these toxicants. However, other sources than vaping contribute to a much higher extent by several orders of magnitude to the overall exposure of these toxicants. Comparing data for the native (unlabeled) and the labeled (exposure-specific) biomarkers revealed vaping as a minor source of user’s exposure to these toxicants while other carbonyls and epoxides were not detectable in the EC aerosol.

One-pot synthesis of 6-aminohexanoic acid from cyclohexane using mixed-species cultures

6-Aminohexanoic acid (6AHA) is a vital polymer building block for Nylon 6 production and an FDA-approved orphan drug. However, its production from cyclohexane is associated with several challenges, including low conversion and yield, and severe environmental issues. We aimed at overcoming these challenges by developing a bioprocess for 6AHA synthesis. A mixed-species approach turned out to be most promising. Thereby, Pseudomonas taiwanensis VLB120 strains harbouring an upstream cascade converting cyclohexane to either є-caprolactone (є-CL) or 6-hydroxyhexanoic acid (6HA) were combined with Escherichia coli JM101 strains containing the corresponding downstream cascade for the further conversion to 6AHA. ε-CL was found to be a better 'shuttle molecule' than 6HA enabling higher 6AHA formation rates and yields. Mixed-species reaction performance with 4 g l-1 biomass, 10 mM cyclohexane, and an air-to-aqueous phase ratio of 23 combined with a repetitive oxygen feeding strategy led to complete substrate conversion with 86% 6AHA yield and an initial specific 6AHA formation rate of 7.7 ± 0.1 U gCDW -1 . The same cascade enabled 49% 7-aminoheptanoic acid yield from cycloheptane. This combination of rationally engineered strains allowed direct 6AHA production from cyclohexane in one pot with high conversion and yield under environmentally benign conditions.

A comprehensive insight into aldehyde deformylation: mechanistic implications from biology and chemistry

Aldehyde deformylation is an important reaction in biology, organic chemistry and inorganic chemistry and the process has been widely applied and utilized. For instance, in biology, the aldehyde deformylation reaction has wide differences in biological function, whereby cyanobacteria convert aldehydes into alkanes or alkenes, which are used as natural products for, e.g., defense mechanisms. By contrast, the cytochromes P450 catalyse the biosynthesis of hormones, such as estrogen, through an aldehyde deformylation reaction step. In organic chemistry, the aldehyde deformylation reaction is a common process for replacing functional groups on a molecule, and as such, many different synthetic methods and procedures have been reported that involve an aldehyde deformylation step. In bioinorganic chemistry, a variety of metal(iii)-peroxo complexes have been synthesized as biomimetic models and shown to react efficiently with aldehydes through deformylation reactions. This review paper provides an overview of the various aldehyde deformylation reactions in organic chemistry, biology and biomimetic model systems, and shows a broad range of different chemical reaction mechanisms for this process. Although a nucleophilic attack at the carbonyl centre is the consensus reaction mechanism, several examples of an alternative electrophilic reaction mechanism starting with hydrogen atom abstraction have been reported as well. There is still much to learn and to discover on aldehyde deformylation reactions, as deciphered in this review paper.

Maternal Reproductive Toxicity of Some Essential Oils and Their Constituents

Even though several plants can improve the female reproductive function, the use of herbs, herbal preparations, or essential oils during pregnancy is questionable. This review is focused on the effects of some essential oils and their constituents on the female reproductive system during pregnancy and on the development of the fetus. The major concerns include causing abortion, reproductive hormone modulation, maternal toxicity, teratogenicity, and embryo-fetotoxicity. This work summarizes the important studies on the reproductive effects of essential oil constituents anethole, apiole, citral, camphor, thymoquinone, trans-sabinyl acetate, methyl salicylate, thujone, pulegone, β-elemene, β-eudesmol, and costus lactone, among others.

Alcohol Oxidase from the Methylotrophic Yeast Ogataea polymorpha: Isolation, Purification, and Bioanalytical Application

Alcohol oxidase (EC 1.1.3.13; AOX) is a flavoprotein that catalyzes the oxidation of primary short-chain alcohols to corresponding carbonyl compounds with a concomitant release of hydrogen peroxide. It is a key enzyme of methanol metabolism in methylotrophic yeasts, catalyzing the first step of methanol oxidation to formaldehyde.Here we describe the isolation and purification of AOX from the thermotolerant methylotrophic yeast Ogataea (Hansenula) polymorpha, and using this enzyme in enzymatic assay of ethanol, simultaneous analysis of methanol and formaldehyde, and in construction of amperometric biosensors selective to primary alcohols and formaldehyde.

trans,trans-2,4-Decadienal induces endothelial cell injury by impairing mitochondrial function and autophagic flux

This study investigated the toxic effects of trans,trans-2,4-decadienal (tt-DDE) on vascular endothelial cells as well as the underlying mechanisms involved. Human umbilical vascular endothelial cells (HUVECs) were treated with different concentrations of tt-DDE for 24 h, and cell viability, colony formation ability, apoptosis, mitochondrial function and autophagy pathway were determined. The results showed that tt-DDE dose-dependently inhibited cell viability and colony formation, and increased lactate dehydrogenase (LDH) release and apoptosis in HUVECs. Besides, tt-DDE exposure induced extensive mitochondrial damage, as evidenced by the decreased mitochondrial DNA copy number, ATP synthesis, and mitochondrial membrane potential, and increased mitochondrial reactive oxygen species (ROS) production and cytochrome c release from mitochondria. tt-DDE also induced mitochondrial fragmentation and fission by increasing DNM1L protein expression and DNM1L mitochondrial translocation. Additionally, tt-DDE treatment resulted in the blockage of autophagic flux and accumulation of autophagosomes in endothelial cells. Further investigation revealed that the inhibition of autophagy by 3-methyladenine aggravated tt-DDE-induced mitochondrial dysfunction and cell injury. However, scavenging of ROS by N-acetyl-l-cysteine (NAC) significantly prevented tt-DDE-induced mitochondrial damage, autophagy dysfunction, and cell injury. These data indicated that tt-DDE induced endothelial cell injury through impairing mitochondrial function and autophagic flux.

Optical detection of formaldehyde in air in the 3.6 µm range

The optical detector of formaldehyde designed for sensing cancer biomarkers in air exhaled from human lungs with possible application in free atmosphere is described. The measurements were performed at wavelengths ranging from 3595.77-3596.20 nm. It was stated that at the pressure of 0.01 atm this absorption band exhibits the best immunity to typical interferents that might occur at high concentration in human breath. Multipass absorption spectroscopy was also applied. The method of optical fringes quenching by wavelength modulation and signal averaging over the interferences period was presented. The application of such approaches enabled the detection limit of about single ppb to be achieved.

Disease-associated acrolein: A possible diagnostic and therapeutic substrate for in vivo synthetic chemistry

Acrolein, a highly reactive α,β-unsaturated aldehyde, is a compound to which humans are exposed in many different situations and often causes various human diseases. This paper summarizes the reports over the past twenty-five years regarding disease-associated acrolein detected in clinical patients and the role acrolein plays in various diseases. In several diseases, it was found that the increased acrolein acts as a pathogenetic factor. Thus, we propose the utility of over-produced acrolein as a substrate for a promising therapeutic or diagnostic method applicable to a wide range of diseases based on an in vivo synthetic chemistry strategy.

Carbon Dot Cross-Linked Gelatin Nanocomposite Hydrogel for pH-Sensing and pH-Responsive Drug Delivery

Delivery of therapeutics to the intestinal region bypassing the harsh acidic environment of the stomach has long been a research focus. On the other hand, monitoring a system's pH during drug delivery is a crucial diagnosis factor as the activity and release rate of many therapeutics depend on it. This study answered both of these issues by fabricating a novel nanocomposite hydrogel for intestinal drug delivery and near-neutral pH sensing at the same time. Gelatin nanocomposites (GNCs) with varying concentrations of carbon dots (CDs) were fabricated through simple solvent casting methods. Here, CDs served a dual role and simultaneously acted as a cross-linker and chromophore, which reduced the usage of toxic cross-linkers. The proposed GNC hydrogel sample acted as an excellent pH sensor in the near-neutral pH range and could be useful for quantitative pH measurement. A model antibacterial drug (cefadroxil) was used for the in vitro drug release study at gastric pH (1.2) and intestinal pH (7.4) conditions. A moderate and sustained drug release profile was noticed at pH 7.4 in comparison to the acidic medium over a 24 h study. The drug release profile revealed that the pH of the release medium and the percentage of CDs cross-linking influenced the drug release rate. Release data were compared with different empirical equations for the evaluation of drug release kinetics and found good agreement with the Higuchi model. The antibacterial activity of cefadroxil was assessed by the broth microdilution method and found to be retained and not hindered by the drug entrapment procedure. The cell viability assay showed that all of the hydrogel samples, including the drug-loaded GNC hydrogel, offered acceptable cytocompatibility and nontoxicity. All of these observations illustrated that GNC hydrogel could act as an ideal pH-monitoring and oral drug delivery system in near-neutral pH at the same time.

Acrolein-Trapping Mechanism of Theophylline in Green Tea, Coffee, and Cocoa: Speedy and Successful

Increasing evidence has identified the unsaturated aldehyde acrolein (ACR) as the potential factor that causes deoxyribonucleic acid cross-linking and the development of chronic diseases. The objective of this study was to investigate the mechanism by which theophylline (TP) scavenges ACR for the first time. TP efficiently scavenged ACR through forming adducts, which was demonstrated in a system in which TP was incubated with ACR at different ratios for different times for liquid chromatography with tandem mass spectrometry. Then, the mono- and di-ACR-TP adducts were purified, and their structures were elucidated by high-resolution mass spectrometry and nuclear magnetic resonance analysis. We found that the ACR residue on mono-ACR-TP further trapped one more ACR and formed di-ACR-TP adducts. Furthermore, mono- and di-ACR-TP had similar time-dependent ACR-scavenging activity to TP. Finally, we demonstrated that green tea, coffee, and cocoa inhibited ACR by trapping ACR to form mono- and di-ACR-TP adducts during the incubation of green tea, coffee, and cocoa with ACR.

Formation and Fate of Carbonyls in Potable Water Reuse Systems

Low molecular weight, uncharged compounds have been the subject of considerable study at advanced treatment plants employed for potable water reuse. However, previously identified compounds only account for a small fraction of the total dissolved organic carbon remaining after reverse osmosis treatment. Uncharged carbonyl compounds (e.g., aldehydes and ketones) formed during oxidation have rarely been monitored in potable water reuse systems. To determine the relative importance of these compounds to final product water quality, samples were collected from six potable water reuse facilities and one conventional drinking water treatment plant. Saturated carbonyl compounds (e.g., formaldehyde, acetone) and α,β-unsaturated aldehydes (e.g., acrolein, crotonaldehyde) were quantified with a sensitive new analytical method. Relatively high concentrations of carbonyls (i.e., above 7 μM) were observed after ozonation of wastewater effluent. Biological filtration reduced concentrations of carbonyls by over 90%. Rejection of the carbonyls during reverse osmosis was correlated with molecular weight, with concentrations decreasing by 33% to 58%. Transformation of carbonyls resulted in decreases in concentration of 10% to 90% during advanced oxidation, with observed decreases consistent with rate constants for reactions of the compounds with hydroxyl radicals. Overall, carbonyl compounds accounted for 19% to 38% of the dissolved organic carbon in reverse osmosis-treated water.

Chemical and Toxicological Characterization of Vaping Emission Products from Commonly Used Vape Juice Diluents

Recent reports have linked severe lung injuries and deaths to the use of e-cigarettes and vaping products. Nevertheless, the causal relationship between exposure to vaping emissions and the observed health outcomes remains to be elucidated. Through chemical and toxicological characterization of vaping emission products, this study demonstrates that during vaping processes, changes in chemical composition of several commonly used vape juice diluents (also known as cutting agents) lead to the formation of toxic byproducts, including quinones, carbonyls, esters, and alkyl alcohols. The resulting vaping emission condensates cause inhibited cell proliferation and enhanced cytotoxicity in human airway epithelial cells. Notably, substantial formation of the duroquinone and durohydroquinone redox couple was observed in the vaping emissions from vitamin E acetate, which may be linked to acute oxidative stress and lung injuries reported by previous studies. These findings provide an improved molecular understanding and highlight the significant role of toxic byproducts in vaping-associated health effects.

In vitro and in silico genetic toxicity screening of flavor compounds and other ingredients in tobacco products with emphasis on ENDS

Electronic nicotine delivery systems (ENDS) are regulated tobacco products and often contain flavor compounds. Given the concern of increased use and the appeal of ENDS by young people, evaluating the potential of flavors to induce DNA damage is important for health hazard identification. In this study, alternative methods were used as prioritization tools to study the genotoxic mode of action (MoA) of 150 flavor compounds. In particular, clastogen-sensitive (γH2AX and p53) and aneugen-sensitive (p-H3 and polyploidy) biomarkers of DNA damage in human TK6 cells were aggregated through a supervised three-pronged ensemble machine learning prediction model to prioritize chemicals based on genotoxicity. In addition, in silico quantitative structure-activity relationship (QSAR) models were used to predict genotoxicity and carcinogenic potential. The in vitro assay identified 25 flavors as positive for genotoxicity: 15 clastogenic, eight aneugenic and two with a mixed MoA (clastogenic and aneugenic). Twenty-three of these 25 flavors predicted to induce DNA damage in vitro are documented in public literature to be in e-liquid or in the aerosols produced by ENDS products with youth-appealing flavors and names. QSAR models predicted 46 (31%) of 150 compounds having at least one positive call for mutagenicity, clastogenicity or rodent carcinogenicity, 49 (33%) compounds were predicted negative for all three endpoints, and remaining compounds had no prediction call. The parallel use of these predictive technologies to elucidate MoAs for potential genetic damage, hold utility as a screening strategy. This study is the first high-content and high-throughput genotoxicity screening study with an emphasis on flavors in ENDS products.

Identification of C9-C11 unsaturated aldehydes as prediction markers of growth and feed intake for non-ruminant animals fed oxidized soybean oil

Background

The benefits of using the oxidized oils from rendering and recycling as an economic source of lipids and energy in animal feed always coexist with the concerns that diverse degradation products in these oxidized oils can negatively affect animal health and performance. Therefore, the quality markers that predict growth performance could be useful when feeding oxidized oils to non-ruminants. However, the correlations between growth performance and chemical profiles of oxidized oils have not been well examined. In this study, six thermally oxidized soybean oils (OSOs) with a wide range of quality measures were prepared under different processing temperatures and processing durations, including 45 °C-336 h; 67.5 °C-168 h; 90 °C-84 h; 135 °C-42 h; 180 °C-21 h; and 225 °C-10.5 h. Broilers and nursery pigs were randomly assigned to diets containing either unheated control soybean oil or one of six OSOs. Animal performance was determined by measuring body weight gain, feed intake, and gain to feed ratio. The chemical profiles of OSOs were first evaluated by common indicative tests, including peroxide value, thiobarbituric acid reactive substances, p-anisidine value, free fatty acids, oxidized fatty acids, unsaponifiable matter, insoluble impurities, and moisture, and then analyzed by the liquid chromatography-mass spectrometry-based chemometric analysis.

Results

Among common quality indicators, p-anisidine value (AnV), which reflects the level of carbonyl compounds, had the greatest inverse correlation with the growth performance of both broilers and pigs, followed by free fatty acids and oxidized fatty acids. Among the 17 aldehydes identified in OSOs, C9-C11 alkenals, especially 2-decenal and 2-undecenal, had stronger inverse correlations (r < − 0.8) with animal performance compared to C5-C8 saturated alkanals, suggesting that chain length and unsaturation level affect the toxicity of aldehydes.

Conclusions

As the major lipid oxidation products contributing to the AnV, individual C9-C11 unsaturated aldehydes in heavily-oxidized oils could function as effective prediction markers of growth and feed intake in feeding non-ruminants.

Formation of resonances and anionic fragments upon electron attachment to benzaldehyde

Benzaldehyde is a simple aromatic aldehyde and has a wide range of applications in the food, pharmaceutical, and chemical industries. The positive electron affinity of this compound suggests that low-energy electrons can be easily trapped by neutral benzaldehyde. In the present study, we investigated the formation of negative ions following electron attachment to benzaldehyde in the gas-phase. Calculations on elastic electron scattering from benzaldehyde indicate a π* valence bound state of the anion at -0.48 eV and three π* shape resonances (0.78, 2.48 and 5.51 eV). The excited state spectrum of the neutral benzaldehyde is also reported to complement our findings. Using mass spectrometry, we observed the formation of the intact anionic benzaldehyde at ∼0 eV. We ascribe the detection of the benzaldehyde anion to stabilization of the π* valence bound state upon dissociative electron attachment to a benzaldehyde dimer. In addition, we report the cross sections for nine fragment anions formed through electron attachment to benzaldehyde. Investigations carried out with partially deuterated benzaldehyde show that the hydrogen loss is site-selective with respect to the incident electron energy. In addition, we propose several dissociation pathways, backed up by quantum chemical calculations on their thermodynamic thresholds. The threshold calculations also support that the resonances formed at higher energies lead to fragment anions observable by mass spectrometry, whereas the resonances at low electron energies decay only by electron autodetachment.

Potential Adverse Public Health Effects Afforded by the Ingestion of Dietary Lipid Oxidation Product Toxins: Significance of Fried Food Sources

Exposure of polyunsaturated fatty acid (PUFA)-rich culinary oils (COs) to high temperature frying practices generates high concentrations of cytotoxic and genotoxic lipid oxidation products (LOPs) via oxygen-fueled, recycling peroxidative bursts. These toxins, including aldehydes and epoxy-fatty acids, readily penetrate into fried foods and hence are available for human consumption; therefore, they may pose substantial health hazards. Although previous reports have claimed health benefits offered by the use of PUFA-laden COs for frying purposes, these may be erroneous in view of their failure to consider the negating adverse public health threats presented by food-transferable LOPs therein. When absorbed from the gastrointestinal (GI) system into the systemic circulation, such LOPs may significantly contribute to enhanced risks of chronic non-communicable diseases (NCDs), e.g. cancer, along with cardiovascular and neurological diseases. Herein, we provide a comprehensive rationale relating to the public health threats posed by the dietary ingestion of LOPs in fried foods. We begin with an introduction to sequential lipid peroxidation processes, describing the noxious effects of LOP toxins generated therefrom. We continue to discuss GI system interactions, the metabolism and biotransformation of primary lipid hydroperoxide LOPs and their secondary products, and the toxicological properties of these agents, prior to providing a narrative on chemically-reactive, secondary aldehydic LOPs available for human ingestion. In view of a range of previous studies focused on their deleterious health effects in animal and cellular model systems, some emphasis is placed on the physiological fate of the more prevalent and toxic α,β-unsaturated aldehydes. We conclude with a description of targeted nutritional and interventional strategies, whilst highlighting the urgent and unmet clinical need for nutritional and epidemiological trials probing relationships between the incidence of NCDs, and the frequency and estimated quantities of dietary LOP intake.

Arsenic inhibits human salivary aldehyde dehydrogenase: Mechanism and a population-based study

Human salivary aldehyde dehydrogenase (hsALDH) is an important detoxifying enzyme and maintains oral health. Subjects with low hsALDH activity are at a risk of developing oral cancers. Arsenic (As) toxicity causes many health problems in humans. The objective of this population-based study was to correlate As contamination and hence low hsALDH activity with high incidence of cancer cases in Bareilly district of India. Here, it was observed that As inhibited hsALDH (IC₅₀ value: 33.5 ± 2.5 μM), and the mechanism of inhibition was mixed type (in between competitive and non-competitive). Binding of As to hsALDH changed the conformation of the enzyme. A static quenching mechanism was observed between the enzyme and As with a binding constant (K_b) of 9.77 × 10⁴ M^-1. There is one binding site for As on hsALDH molecule. Further, the activity of hsALDH in volunteers living in regions of higher As levels in drinking water (Bahroli and Mirganj village of Bareilly district, India), and those living in region having safe levels of As (Aligarh city, India) was determined. The As level in the saliva samples of the volunteers was determined by inductively coupled plasma mass spectroscopy (ICP-MS). Low hsALDH activity was found in volunteers living in the region of higher As levels. The activity of hsALDH and As concentration in the saliva was found to be negatively correlated (r = - 0.427, p < 0.0001). Therefore, we speculate that the high incidence of cancer cases reported in Bareilly district may be due to higher As contamination.

Acetylresveratrol as a Potential Substitute for Resveratrol Dragged the Toxic Aldehyde to Inhibit the Mutation of Mitochondrial DNA

The aim of this study was to explore whether or not acetylresveratrol as a potential substitute for resveratrol dragged the toxic aldehyde to inhibit the mutation of mitochondrial DNA. The results revealed that the acetylresveratrol shifted ultraviolet peak of trans-crotonaldehyde from 316 to 311 nm. In mitochondria, the acetylresveratrol split the ultraviolet peak at 311 nm of trans-crotonaldehyde into 311 nm and 309 nm; the aldehyde Raman band of trans-crotonaldehyde was red shifted by the acetylresveratrol from 1689 to 1686 cm^-1 with obvious band decline; Raman bands at 1149 cm^-1, 1168 cm^-1, and 1325 cm^-1 of acetylresveratrol disappeared. In aldehyde dehydrogenase, the aldehyde Raman band of trans-crotonaldehyde was red shifted by the acetylresveratrol from 1689 to 1684 cm^-1 with band decline; Raman bands at 1150 cm^-1, 1168 cm^-1, and 1324 cm^-1 of acetylresveratrol declined. The weak acidic microenvironment was the best, for the acetylresveratrol dragged the toxic aldehyde of trans-crotonaldehyde. Compared with the resveratrol, the effect of the acetylresveratrol on the toxic aldehyde of trans-crotonaldehyde was very similar to that of the resveratrol. The acetylresveratrol is very suitable as a potential substitute for resveratrol dragged the toxic aldehyde to inhibit the mutation of mitochondrial DNA. Graphical Abstract In mitochondria, the Raman band of the toxic -CH=O of trans-crotonaldehyde (TCA) dragged by the Acetyl-Res from 1689 to 1686 cm^-1 with obvious band decline, while the Raman bands at 1149 cm^-1, 1168 cm^-1, and 1325 cm^-1 of the Acetyl-Res disappeared, respectively. The Acetyl-Res is very suitable as a potential substitute, for the Res dragged the toxic -CH=O of TCA to inhibit the mutation of mitochondrial DNA for anticancer.

Xanthohumol protects against Azoxymethane-induced colorectal cancer in Sprague-Dawley rats

Colorectal cancer (CRC) is a major health problem and third most common deaths in western world. Dietary interventions together with modified dietary style can prevent the CRC in humans. Xanthohumol (XHA), a polyphenol isolated from Humulus lupulus L. contains many beneficial effects. The aim of the study is to analyze the effect of XHA on Azoxymethane (AOM)-induced experimental CRC in rats. Levels of MDA were increased and enzymic antioxidants levels were decreased in AOM-induced rats. However, these levels were reversed upon XHA treatment. Further, the mRNA expressions of iNOS and COX-2 were also downregulated in XHA treated rats compared to AOM-induced rats. Further, we found that administration of XHA suppressed the wnt/β-catenin signaling together with modulation of apoptotic proteins Bax, Bcl-2, and caspase 3. We conclude that XHA can able to quench the free radicals, inhibits cell proliferation and induces apoptosis, thus it can be a chemopreventive/therapeutic agent against CRC.

trans, trans-2,4-Decadienal, a lipid peroxidation product, induces inflammatory responses via Hsp90- or 14-3-3ζ-dependent mechanisms

Peroxidation of polyunsaturated fatty acids leads to the formation of a large array of lipid-derived electrophiles (LDEs), many of which are important signaling molecules involved in the pathogenesis of human diseases. Previous research has shown that one of such LDEs, trans, trans-2,4-decadienal (tt-DDE), increases inflammation, however, the underlying mechanisms are not well understood. Here we used click chemistry-based proteomics to identify the cellular targets which are required for the pro-inflammatory effects of tt-DDE. We found that treatment with tt-DDE increased cytokine production, JNK phosphorylation, and activation of NF-κB signaling in macrophage cells, and increased severity of dextran sulfate sodium (DSS)-induced colonic inflammation in mice, demonstrating its pro-inflammatory effects in vitro and in vivo. Using click chemistry-based proteomics, we found that tt-DDE directly interacts with Hsp90 and 14-3-3ζ, which are two important proteins involved in inflammation and tumorigenesis. Furthermore, siRNA knockdown of Hsp90 or 14-3-3ζ abolished the pro-inflammatory effects of tt-DDE in macrophage cells. Together, our results support that tt-DDE increases inflammatory responses via Hsp90- and 14-3-3ζ-dependent mechanisms.