Aldehyde toxicity and metabolism: the role of aldehyde dehydrogenases in detoxification, drug resistance and carcinogenesis

Neurotoxic and cardiotoxic effects of pyrogallol on catfish (Clarias gariepinus)

Pyrogallol, a botanical hydrolysable tannin, has diverse medical and industrial applications. Its impact on aquatic ecosystems and fish health has been previously studied, revealing histopathological, immunological, biochemical, and haematological alterations in African catfish (Clarias gariepinus). In this study, the neurotoxic potential of pyrogallol was assessed through a 15-day exposure of catfish to concentrations of 1, 5, or 10 mg/L. Enzyme activities such as acetylcholinesterase (AchE), monoamine oxidase (MAO), aldehyde oxidase (AO), and nitric oxide (NO) were measured in serum and brain, along with histopathological examinations in the brain and heart. Pyrogallol exposure led to decreased AchE activity in the brain and serum, increased serum MAO activity, elevated AO in both brain and serum, and suppressed NO levels. Morphological abnormalities and dose-dependent pathological alterations were observed in the brain and heart, including neuropile deformities, shrunken Purkinje cells, cardiomyocyte degeneration, and increased collagen fibers. This suggests that pyrogallol induces adverse effects in fish.

Functional single-cell analyses of mesenchymal stromal cell proliferation and differentiation using ALDH-activity and mitochondrial ROS content

BASKGROUND

Previous research has unveiled a stem cell-like transcriptome enrichment in the aldehyde dehydrogenase-expressing (ALDHhigh) mesenchymal stromal cell (MStroC) fraction. However, considering the heterogeneity of MStroCs, with only a fraction of them presenting bona fide stem cells (MSCs), the actual potency of ALDH as an MSC-specific selection marker remains an issue.

METHODS

To address this, the proliferative and differentiation potential of individual ALDHhigh and ALDHlow MStroCs incubated at low oxygen concentrations, estimated to mimic stem cell niches (0.1% O2), were assayed using single-cell clonal analysis, compared to standard conditions (20% O2).

RESULTS

We confirm that a high proliferative capacity and multi-potent MSCs are enriched in the ALDHhigh MStroC population, especially when cells are cultured at 0.1% O2. Measurements of reduced/oxidized glutathione and mitochondrial superoxide anions with MitoSoX (MSX) indicate that this advantage induced by low oxygen is related to a decrease in the oxidative and reactive oxygen species (ROS) levels in the stem cell metabolic setup. However, ALDH expression is neither specific nor exclusive to MSCs, as high proliferative capacity and multi-potent cells were also found in the ALDHlow fraction. Furthermore, single-cell assays performed after combined cell sorting based on ALDH and MSX showed that the MSXlow MStroC population is enriched in stem/progenitor cells in all conditions, irrespective of ALDH expression or culture oxygen concentration. Importantly, the ALDHhighMSXlow MStroC fraction exposed to 0.1% O2 was almost exclusively composed of genuine MSCs. In contrast, neither progenitors nor stem cells (with a complete absence of colony-forming ability) were detected in the MSXhigh fraction, which exclusively resides in the ALDHlow MStroC population.

CONCLUSION

Our study reveals that ALDH expression is not exclusively associated with MSCs. However, cell sorting using combined ALDH expression and ROS content can be utilized to exclude MStroCs lacking stem/progenitor cell properties.

Alcohol- and Low-Iron Induced Changes in Antioxidant and Energy Metabolism Associated with Protein Lys Acetylation

Understanding the role of iron in ethanol-derived hepatic stress could help elucidate the efficacy of dietary or clinical interventions designed to minimize liver damage from chronic alcohol consumption. We hypothesized that normal levels of iron are involved in ethanol-derived liver damage and reduced dietary iron intake would lower the damage caused by ethanol. We used a pair-fed mouse model utilizing basal Lieber-DeCarli liquid diets for 22 weeks to test this hypothesis. In our mouse model, chronic ethanol exposure led to mild hepatic stress possibly characteristic of early-stage alcoholic liver disease, seen as increases in liver-to-body weight ratios. Dietary iron restriction caused a slight decrease in non-heme iron and ferritin (FeRL) expression while it increased transferrin receptor 1 (TfR1) expression without changing ferroportin 1 (FPN1) expression. It also elevated protein lysine acetylation to a more significant level than in ethanol-fed mice under normal dietary iron conditions. Interestingly, iron restriction led to an additional reduction in nicotinamide adenine dinucleotide (NAD+) and NADH levels. Consistent with this observation, the major mitochondrial NAD+-dependent deacetylase, NAD-dependent deacetylase sirtuin-3 (SIRT3), expression was significantly reduced causing increased protein lysine acetylation in ethanol-fed mice at normal and low-iron conditions. In addition, the detection of superoxide dismutase 1 and 2 levels (SOD1 and SOD2) and oxidative phosphorylation (OXPHOS) complex activities allowed us to evaluate the changes in antioxidant and energy metabolism regulated by ethanol consumption at normal and low-iron conditions. We observed that the ethanol-fed mice had mild liver damage associated with reduced energy and antioxidant metabolism. On the other hand, iron restriction may exacerbate certain activities of ethanol further, such as increased protein lysine acetylation and reduced antioxidant metabolism. This metabolic change may prove a barrier to the effectiveness of dietary reduction of iron intake as a preventative measure in chronic alcohol consumption.

Rv0687 a Putative Short-Chain Dehydrogenase Is Required for In Vitro and In Vivo Survival of Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb), a successful human pathogen, resides in host sentinel cells and combats the stressful intracellular environment induced by reactive oxygen and nitrogen species during infection. Mtb employs several evasion mechanisms in the face of the host as a survival strategy, including detoxifying enzymes as short-chain dehydrogenases/reductases (SDRs) to withstand host-generated insults. In this study, using specialized transduction, we have generated a Rv0687 deletion mutant and its complemented strain and investigated the functional role of Rv0687, a member of SDRs family genes in Mtb pathogenesis. A wildtype (WT) and a mutant Mtb strain lacking Rv0687 (RvΔ0687) were tested for the in vitro stress response and in vivo survival in macrophages and mice models of infection. The study demonstrates that the deletion of Rv0687 elevated the sensitivity of Mtb to oxidative and nitrosative stress-inducing agents. Furthermore, the lack of Rv0687 compromised the survival of Mtb in primary bone marrow macrophages and led to an increase in the levels of the secreted proinflammatory cytokines TNF-α and MIP-1α. Interestingly, the growth of WT and RvΔ0687 was similar in the lungs of infected immunocompromised mice; however, a significant reduction in RvΔ0687 growth was observed in the spleen of immunocompromised Rag-/- mice at 4 weeks post-infection. Moreover, Rag-/- mice infected with RvΔ0687 survived longer compared to those infected with the WT Mtb strain. Additionally, we observed a significant reduction in the bacterial burden in the spleens and lungs of immunocompetent C57BL/6 mice infected with RvΔ0687 compared to those infected with complemented and WT Mtb strains. Collectively, this study reveals that Rv0687 plays a role in Mtb pathogenesis.

Dual effects of endogenous formaldehyde on the organism and drugs for its removal

Endogenous formaldehyde (FA) is produced in the human body via various mechanisms to preserve healthy energy metabolism and safeguard the organism. However, endogenous FA can have several negative effects on the body through epigenetic alterations, including cancer growth promotion; neuronal, hippocampal and endothelial damages; atherosclerosis acceleration; haemopoietic stem cell destruction and haemopoietic cell production reduction. Certain medications with antioxidant effects, such as glutathione, vitamin E, resveratrol, alpha lipoic acid and polyphenols, lessen the detrimental effects of endogenous FA by reducing oxidative stress, directly scavenging endogenous FA or promoting its degradation. This study offers fresh perspectives for managing illnesses associated with endogenous FA exposure.

Aldo-keto reductase-7A2 protects against atorvastatin-induced hepatotoxicity via Nrf2 activation

Atorvastatin (ATO), as a cholesterol-lowering drug, was the world's best-selling drug in the early 2000s. However, ATO overdose-induced liver or muscle injury is a threat to many patients, which restricts its application. Previous studies suggest that ATO overdose is accompanied with ROS accumulation and increased lipid peroxidation, which are the leading causes of ATO-induced liver damage. This study is, therefore, carried out to investigate the roles of anti-oxidant pathways and enzymes in protection against ATO-induced hepatotoxicity. Here we show that in ATO-challenged HepG2 cells, the expression levels of transcription factor NFE2L2/Nrf2 (nuclear factor erythroid 2 p45-related factor 2) are significantly upregulated. When Nrf2 is pharmacologically inhibited or genetically inactivated, ATO-induced cytotoxicity is significantly aggravated. Aldo-keto reductase-7A (AKR7A) enzymes, transcriptionally regulated by Nrf2, are important for bioactivation and biodetoxification. Here, we reveal that in response to ATO exposure, mRNA levels of human AKR7A2 are significantly upregulated in HepG2 cells. Furthermore, knockdown of AKR7A2 exacerbates ATO-induced hepatotoxicity, suggesting that AKR7A2 is essential for cellular adaptive response to ATO-induced cell damage. In addition, overexpression of AKR7A2 in HepG2 cells can significantly mitigate ATO-induced cytotoxicity and this process is Nrf2-dependent. Taken together, these findings indicate that Nrf2-mediated AKR7A2 is responsive to high concentrations of ATO and contributes to protection against ATO-induced hepatotoxicity, making it a good candidate for mitigating ATO-induced side effects.

Exploiting high-energy hydration sites for the discovery of potent peptide aldehyde inhibitors of the SARS-CoV-2 main protease with cellular antiviral activity

Small-molecule antivirals that prevent the replication of the SARS-CoV-2 virus by blocking the enzymatic activity of its main protease (Mpro) are and will be a tenet of pandemic preparedness. However, the peptidic nature of such compounds often precludes the design of compounds within favorable physical property ranges, limiting cellular activity. Here we describe the discovery of peptide aldehyde Mpro inhibitors with potent enzymatic and cellular antiviral activity. This structure-activity relationship (SAR) exploration was guided by the use of calculated hydration site thermodynamic maps (WaterMap) to drive potency via displacement of waters from high-energy sites. Thousands of diverse compounds were designed to target these high-energy hydration sites and then prioritized for synthesis by physics- and structure-based Free-Energy Perturbation (FEP+) simulations, which accurately predicted biochemical potencies. This approach ultimately led to the rapid discovery of lead compounds with unique SAR that exhibited potent enzymatic and cellular activity with excellent pan-coronavirus coverage.

Reactive Carbonyl Species Scavenger: Epigallocatechin-3-Gallate

Epigallocatechin-3-gallate (EGCG), a prominent polyphenol found abundantly in tea, has garnered significant attention for its potential in preventing and ameliorating a wide range of diseases. Its remarkable antioxidant properties and ability to capture reactive carbonyl species make it a key player among tea's polyphenolic components. This paper delves into the synthesis and origins of both EGCG and reactive carbonyl species (RCS), emphasizing the toxicity of RCS in various food sources and their formation during food processing. Understanding EGCG's capability to capture and metabolize RCS is crucial for harnessing its health benefits. Thus, this paper explores the underlying mechanisms of EGCG for RCS inhibition and its role in capturing these compounds to generate EGCG-RCS adducts. And the absorption and metabolism of EGCG-RCS adducts is also discussed.

Mechanisms of Nitrosamine Mutagenicity and Their Relationship to Rodent Carcinogenic Potency

A thorough literature review was undertaken to understand how the pathways of N-nitrosamine transformation relate to mutagenic potential and carcinogenic potency in rodents. Empirical and computational evidence indicates that a common radical intermediate is created by CYP-mediated hydrogen abstraction at the α-carbon; it is responsible for both activation, leading to the formation of DNA-reactive diazonium species, and deactivation by denitrosation. There are competing sites of CYP metabolism (e.g., β-carbon), and other reactive species can form following initial bioactivation, although these alternative pathways tend to decrease rather than enhance carcinogenic potency. The activation pathway, oxidative dealkylation, is a common reaction in drug metabolism and evidence indicates that the carbonyl byproduct, e.g., formaldehyde, does not contribute to the toxic properties of N-nitrosamines. Nitric oxide (NO), a side product of denitrosation, can similarly be discounted as an enhancer of N-nitrosamine toxicity based on carcinogenicity data for substances that act as NO-donors. However, not all N-nitrosamines are potent rodent carcinogens. In a significant number of cases, there is a potency overlap with non-N-nitrosamine carcinogens that are not in the Cohort of Concern (CoC; high-potency rodent carcinogens comprising aflatoxin-like-, N-nitroso-, and alkyl-azoxy compounds), while other N-nitrosamines are devoid of carcinogenic potential. In this context, mutagenicity is a useful surrogate for carcinogenicity, as proposed in the ICH M7 (R2) (2023) guidance. Thus, in the safety assessment and control of N-nitrosamines in medicines, it is important to understand those complementary attributes of mechanisms of mutagenicity and structure-activity relationships that translate to elevated potency versus those which are associated with a reduction in, or absence of, carcinogenic potency.

Homologous recombination contributes to the repair of acetaldehyde-induced DNA damage

Acetaldehyde, a chemical that can cause DNA damage and contribute to cancer, is prevalently present in our environment, e.g. in alcohol, tobacco, and food. Although aldehyde potentially promotes crosslinking reactions among biological substances including DNA, RNA, and protein, it remains unclear what types of DNA damage are caused by acetaldehyde and how they are repaired. In this study, we explored mechanisms involved in the repair of acetaldehyde-induced DNA damage by examining the cellular sensitivity to acetaldehyde in the collection of human TK6 mutant deficient in each genome maintenance system. Among the mutants, mismatch repair mutants did not show hypersensitivity to acetaldehyde, while mutants deficient in base and nucleotide excision repair pathways or homologous recombination (HR) exhibited higher sensitivity to acetaldehyde than did wild-type cells. We found that acetaldehyde-induced RAD51 foci representing HR intermediates were prolonged in HR-deficient cells. These results indicate a pivotal role of HR in the repair of acetaldehyde-induced DNA damage. These results suggest that acetaldehyde causes complex DNA damages that require various types of repair pathways. Mutants deficient in the removal of protein adducts from DNA ends such as TDP1-/- and TDP2-/- cells exhibited hypersensitivity to acetaldehyde. Strikingly, the double mutant deficient in both TDP1 and RAD54 showed similar sensitivity to each single mutant. This epistatic relationship between TDP1-/- and RAD54-/- suggests that the protein-DNA adducts generated by acetaldehyde need to be removed for efficient repair by HR. Our study would help understand the molecular mechanism of the genotoxic and mutagenic effects of acetaldehyde.

Effects of pejus and pessimum zone salinity stress on gill proteome networks and energy homeostasis in Oreochromis mossambicus

Salinity tolerance in fish involves a suite of physiological changes, but a cohesive theory leading to a mechanistic understanding at the organismal level is lacking. To examine the potential of adapting energy homeostasis theory in the context of salinity stress in teleost fish, Oreochromis mossambicus were acclimated to hypersalinity at multiple rates and durations to determine salinity ranges of tolerance and resistance. Over 3000 proteins were quantified simultaneously to analyze molecular phenotypes associated with hypersalinity. A species- and tissue-specific data-independent acquisition (DIA) assay library of MSMS spectra was created. Protein networks representing complex molecular phenotypes associated with salinity acclimation were generated. O. mossambicus has a wide "zone of resistance" from 75 g/kg salinity to 120 g/kg. Crossing into the zone of resistance resulted in marked phenotypic changes including blood osmolality over 400 mOsm/kg, reduced body condition, and cessation of feeding. Protein networks impacted by hypersalinity consist of electron transport chain (ETC) proteins and specific osmoregulatory proteins. Cytoskeletal, cell adhesion, and extracellular matrix proteins are enriched in networks that are sensitive to the critical salinity threshold. These network analyses identify specific proteome changes that are associated with distinct zones described by energy homeostasis theory and distinguish them from general hypersalinity-induced proteome changes.

Impaired Detoxification of Trans, Trans-2,4-Decadienal, an Oxidation Product from Omega-6 Fatty Acids, Alters Insulin Signaling, Gluconeogenesis and Promotes Microvascular Disease

Omega-6 fatty acids are the primary polyunsaturated fatty acids in most Western diets, while their role in diabetes remains controversial. Exposure of omega-6 fatty acids to an oxidative environment results in the generation of a highly reactive carbonyl species known as trans, trans-2,4-decadienal (tt-DDE). The timely and efficient detoxification of this metabolite, which has actions comparable to other reactive carbonyl species, such as 4-hydroxynonenal, acrolein, acetaldehyde, and methylglyoxal, is essential for disease prevention. However, the detoxification mechanism for tt-DDE remains elusive. In this study, the enzyme Aldh9a1b is identified as having a key role in the detoxification of tt-DDE. Loss of Aldh9a1b increased tt-DDE levels and resulted in an abnormal retinal vasculature and glucose intolerance in aldh9a1b-/- zebrafish. Transcriptomic and metabolomic analyses revealed that tt-DDE and aldh9a1b deficiency in larval and adult zebrafish induced insulin resistance and impaired glucose homeostasis. Moreover, alterations in hyaloid vasculature is induced by aldh9a1b knockout or by tt-DDE treatment can be rescued by the insulin receptor sensitizers metformin and rosiglitazone. Collectively, these results demonstrated that tt-DDE is the substrate of Aldh9a1b which causes microvascular damage and impaired glucose metabolism through insulin resistance.

Rv0687 a Putative Short-Chain Dehydrogenase is indispensable for pathogenesis of Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb), a successful human pathogen, resides in host sentinel cells and combats the stressful intracellular environment induced by reactive oxygen and nitrogen species during infection. Mtb employs several evasion mechanisms in the face of the host as a survival strategy, including detoxifying enzymes as short-chain dehydrogenases/ reductases (SDRs) to withstand host-generated insults. In this study, using specialized transduction we have generated a Rv0687 deletion mutant and its complemented strain and investigated the functional role of Rv0687, a member of SDRs family genes in Mtb pathogenesis. Wildtype (WT) and mutant Mtb strain lacking Rv0687 (RvΔ0687) were tested for in-vitro stress response and in-vivo survival in macrophages and mice models of infection. The study demonstrates that Rv0687 is crucial for sustaining bacterial growth in nutrition-limited conditions. The deletion of Rv0687 elevated the sensitivity of Mtb to oxidative and nitrosative stress-inducing agents. Furthermore, the lack of Rv0687 compromised the survival of Mtb in primary bone marrow macrophages and led to an increase in the levels of the secreted proinflammatory cytokines TNF-α, and MIP-1α. Interestingly, the growth of WT and RvΔ0687 was similar in the lungs of infected immunocompromised mice however, a significant reduction in RvΔ0687 growth was observed in the spleen of immunocompromised Rag -/- mice at 4 weeks post-infection. Moreover Rag -/- mice infected with RvΔ0687 survived longer compared to WT Mtb strain. Additionally, we observed significant reduction in bacterial burden in spleens and lungs of immunocompetent C57BL/6 mice infected with RvΔ0687 compared to complemented and WT Mtb strains. Collectively, this study reveals that Rv0687 plays a role in Mtb pathogenesis.

Binding of flavonoids to yeast aldehyde dehydrogenase: a molecular mechanism and computational approach

The interaction of three flavonoids, apigenin, fisetin and quercetin with yeast aldehyde dehydrogenase, ALDH was studied by spectroscopic and molecular docking methods. A combination of both static and dynamic processes interaction mechanism for the binding of flavonoids with ALDH was found. The interaction takes place with moderate binding and the interaction was driven by hydrophobic contacts. The microenvironments of the fluorescent amino acids changed upon flavonoids binding. The distances between ALDH and flavonoids determined by Förster Resonant Energy Transfer (FRET) confirmed the results obtained by fluorescence. The structure of ALDH against thermal denaturation was stabilized by apigenin and destabilized by fisetin and quercetin. Molecular docking simulation showed that all flavonoids bind to the same site of ALDH and confirmed the moderate binding straight found in fluorescence.Communicated by Ramaswamy H. Sarma.

From clinical variables to multiomics analysis: a margin morphology-based gross classification system for hepatocellular carcinoma stratification

OBJECTIVE

Selecting interventions for patients with solitary hepatocellular carcinoma (HCC) remains a challenge. Despite gross classification being proposed as a potential prognostic predictor, its widespread use has been restricted due to inadequate studies with sufficient patient numbers and the lack of established mechanisms. We sought to investigate the prognostic impacts on patients with HCC of different gross subtypes and assess their corresponding molecular landscapes.

DESIGN

A prospective cohort of 400 patients who underwent hepatic resection for solitary HCC was reviewed and analysed and gross classification was assessed. Multiomics analyses were performed on tumours and non-tumour tissues from 49 patients to investigate the mechanisms underlying gross classification. Inverse probability of treatment weight (IPTW) was used to control for confounding factors.

RESULTS

Overall 3-year survival rates varied significantly among the four gross subtypes (type I: 91%, type II: 80%, type III: 74.6%, type IV: 38.8%). Type IV was found to be independently associated with poor prognosis in both the entire cohort and the IPTW cohort. The four gross subtypes exhibited three distinct transcriptional modules. Particularly, type IV tumours exhibited increased angiogenesis and immune score as well as decreased metabolic pathways, together with highest frequency of TP53 mutations. Patients with type IV HCC may benefit from adjuvant intra-arterial therapy other than the other three subtypes. Accordingly, a modified trichotomous margin morphological gross classification was established.

CONCLUSION

Different gross types of HCC showed significantly different prognosis and molecular characteristics. Gross classification may aid in development of precise individualised diagnosis and treatment strategies for HCC.

Identification of urinary volatile organic compounds as a potential non-invasive biomarker for esophageal cancer

Early diagnosis of esophageal cancer (EC) is extremely challenging. The study presented herein aimed to assess whether urinary volatile organic compounds (VOCs) may be emerging diagnostic biomarkers for EC. Urine samples were collected from EC patients and healthy controls (HCs). Gas chromatography-ion mobility spectrometry (GC-IMS) was next utilised for volatile organic compound detection and predictive models were constructed using machine learning algorithms. ROC curve analysis indicated that an 8-VOCs based machine learning model could aid the diagnosis of EC, with the Random Forests having a maximum AUC of 0.874 and sensitivities and specificities of 84.2% and 90.6%, respectively. Urine VOC analysis aids in the diagnosis of EC.

Aldehyde-functionalized cellulose as reactive sorbents for the capture and retention of polyamine odor molecules associated with chronic wounds

Aldehyde-functionalized cellulose (AFC) was prepared by oxidizing cellulose with sodium metaperiodate. The reaction was characterized by Schiff's test, FT-IR, and UV-vis study. AFC was evaluated as a reactive sorbent for controlling polyamine-based odor from chronic wounds, and its performance was compared with charcoal, one of the most widely utilized odor-control sorbents through physisorption. Cadaverine was used as the model odor molecule. A liquid chromatography/mass spectrometry (LC/MS) method was established to quantify the compound. AFC was found to rapidly react with cadaverine through the Schiff-base reaction, which was confirmed by FT-IR, visual observation, CHN elemental analysis, and the ninhydrin test. The sorption and desorption behaviors of cadaverine onto AFC were quantified. With clinic-relevant cadaverine concentrations, AFC demonstrated much better sorption performance than charcoal. At even higher cadaverine concentrations charcoal showed higher sorption capacity, probably due to its high surface area. On the other hand, in desorption studies, AFC retained much more of the sorbed cadaverine than charcoal. When AFC and charcoal were combined, the pair demonstrated excellent sorption and desorption behaviors. The XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) assay confirmed that AFC has very good in vitro biocompatibility. These results suggest that AFC-based reactive sorption can be a new strategy to control odors associated with chronic wounds for improved healthcare.

Human Aldehyde Dehydrogenases: A Superfamily of Similar Yet Different Proteins Highly Related to Cancer

The superfamily of human aldehyde dehydrogenases (hALDHs) consists of 19 isoenzymes which are critical for several physiological and biosynthetic processes and play a major role in the organism's detoxification via the NAD(P) dependent oxidation of numerous endogenous and exogenous aldehyde substrates to their corresponding carboxylic acids. Over the last decades, ALDHs have been the subject of several studies as it was revealed that their differential expression patterns in various cancer types are associated either with carcinogenesis or promotion of cell survival. Here, we attempt to provide a thorough review of hALDHs' diverse functions and 3D structures with particular emphasis on their role in cancer pathology and resistance to chemotherapy. We are especially interested in findings regarding the association of structural features and their changes with effects on enzymes' functionalities. Moreover, we provide an updated outline of the hALDHs inhibitors utilized in experimental or clinical settings for cancer therapy. Overall, this review aims to provide a better understanding of the impact of ALDHs in cancer pathology and therapy from a structural perspective.

The Overexpression of Peanut (Arachis hypogaea L.) AhALDH2B6 in Soybean Enhances Cold Resistance

Soybeans are the main source of oils and protein for humans and animals; however, cold stress jeopardizes their growth and limits the soybean planting area. Aldehyde dehydrogenases (ALDH) are conserved enzymes that catalyze aldehyde oxidation for detoxification in response to stress. Additionally, transgenic breeding is an efficient method for producing stress-resistant germplasms. In this study, the peanut ALDH gene AhALDH2B6 was heterologously expressed in soybean, and its function was tested. We performed RNA-seq using transgenic and wild-type soybeans with and without cold treatment to investigate the potential mechanism. Transgenic soybeans developed stronger cold tolerance, with longer roots and taller stems than P3 soybeans. Biochemically, the transgenic soybeans exhibited a decrease in malondialdehyde activity and an increase in peroxidase and catalase content, both of which are indicative of stress alleviation. They also possessed higher levels of ALDH enzyme activity. Two phenylpropanoid-related pathways were specifically enriched in up-regulated differentially expressed genes (DEGs), including the phenylpropanoid metabolic process and phenylpropanoid biosynthetic process. Our findings suggest that AhALDH2B6 specifically up-regulates genes involved in oxidoreductase-related functions such as peroxidase, oxidoreductase, monooxygenase, and antioxidant activity, which is partially consistent with our biochemical data. These findings established the function of AhALDH2B6, especially its role in cold stress processes, and provided a foundation for molecular plant breeding, especially plant-stress-resistance breeding.

Serum Concentrations of Benzaldehyde, Isopentanaldehyde and Sex Hormones: Evidence from the National Health and Nutrition Examination Survey

Exposure to environmental chemicals could disturb the balance of sex hormones. However, the studies on Benzaldehyde, Isopentanaldehyde exposure and sex hormones are still limited. Based on the data of 1064 participants in the National Health and Nutrition Examination Survey (NHANES), we used the linear regression model and restricted cubic spline (RCS) model to evaluate the associations of Benzaldehyde/Isopentanaldehyde exposure with testosterone (TT), estradiol (E2), sex hormone binding globulin (SHBG), free androgen index (FAI) and the ratio of TT to E2 (TT/E2). A ln-unit increase in Benzaldehyde was associated with lower TT (β = -0.048, P = 0.030) and E2 (β = -0.094, P = 0.046) in all participants. After further adjustment for menopausal status, Benzaldehyde was negatively associated with E2 (β = -0.174, P = 0.045) in females. The interaction between Benzaldehyde and gender was significant (P_inter = 0.031). However, Isopentanaldehyde showed a positive association with SHBG and TT/E2 in all participants (all P < 0.05). The positive associations of Isopentanaldehyde with TT, SHBG and TT/E2 were found in males but not in females. RCS plots illustrated the linear associations of Benzaldehyde with E2 (P_non-linear = 0.05) in females and Isopentanaldehyde with TT (P_non-linear = 0.07) and TT/E2 (P_non-linear = 0.350) in males. The non-linear relationships were identified between Isopentanaldehyde and SHBG in males (P_non-linear = 0.035). Our findings indicated the effects of Benzaldehyde and Isopentanaldehyde exposure on sex hormones, and the effects had the gender specificity. Cohort studies and high-quality in vitro and in vivo experiments are needed to confirm the specific effects and uncover the underlying mechanisms.

Organoiridium Complexes Enhance Cellular Defense Against Reactive Aldehydes Species

Although reactive aldehyde species (RASP) are associated with the pathogenesis of many major diseases, there are currently no clinically approved treatments for RASP overload. Conventional aldehyde detox agents are stoichiometric reactants that get consumed upon reacting with their biological targets, which limits their therapeutic efficiency. To achieve longer-lasting detoxification effects, small-molecule intracellular metal catalysts (SIMCats) were used to protect cells by converting RASP into non-toxic alcohols. It was shown that SIMCats were significantly more effective in lowering cell death from the treatment with 4-hydroxynon-2-enal than aldehyde scavengers over a 72 h period. Studies revealed that SIMCats reduced the aldehyde accumulation in cells exposed to the known RASP inducer arsenic trioxide. This work demonstrates that SIMCats offer unique benefits over stochiometric agents, potentially providing new ways to combat diseases with greater selectivity and efficiency than existing approaches.

Aldehyde-Associated Mutagenesis─Current State of Knowledge

Aldehydes are widespread in the environment, with multiple sources such as food and beverages, industrial effluents, cigarette smoke, and additives. The toxic effects of exposure to several aldehydes have been observed in numerous studies. At the molecular level, aldehydes damage DNA, cross-link DNA and proteins, lead to lipid peroxidation, and are associated with increased disease risk including cancer. People genetically predisposed to aldehyde sensitivity exhibit severe health outcomes. In various diseases such as Fanconi's anemia and Cockayne syndrome, loss of aldehyde-metabolizing pathways in conjunction with defects in DNA repair leads to widespread DNA damage. Importantly, aldehyde-associated mutagenicity is being explored in a growing number of studies, which could offer key insights into how they potentially contribute to tumorigenesis. Here, we review the genotoxic effects of various aldehydes, focusing particularly on the DNA adducts underlying the mutagenicity of environmentally derived aldehydes. We summarize the chemical structures of the aldehydes and their predominant DNA adducts, discuss various methodologies, in vitro and in vivo, commonly used in measuring aldehyde-associated mutagenesis, and highlight some recent studies looking at aldehyde-associated mutation signatures and spectra. We conclude the Review with a discussion on the challenges and future perspectives of investigating aldehyde-associated mutagenesis.

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.

The stereoselective toxicity of dinotefuran to Daphnia magna: A systematic assessment from reproduction, behavior, oxidative stress and digestive function

Dinotefuran is a promising neonicotinoid insecticide with chiral structure. In the present study, the stereoselective toxicity of dinotefuran to Daphnia magna (D. magna) was studied. The present result showed that S-dinotefuran inhibited the reproduction of D. magna at 5.0 mg/L. However, both R-dinotefuran and S-dinotefuran had no genotoxicity to D. magna. Additionally, neither R-dinotefuran nor S-dinotefuran had negative influences on the motor behavior of D. magna. However, S-dinotefuran inhibited the feeding behavior of D. magna at 5.0 mg/L. Both R-dinotefuran and S-dinotefuran induced oxidative stress effect in D. magna after exposure. R-dinotefuran significantly activated the activities of superoxide dismutase (SOD) and glutathione S-transferase (GST), while S-dinotefuran showed the opposite effect. S-dinotefuran had more obvious activation effect on the acetylcholinesterase (AchE) activity and trypsin activity compared to R-dinotefuran. The transcriptome sequencing results showed that S-dinotefuran induced more DEGs in D. magna, and affected the normal function of ribosome. The DEGs were mainly related to the synthesis and metabolism of biomacromolecules, indicating the binding mode between dinotefuran enantiomer and biomacromolecules were different. Additionally, the present result indicated that the digestive enzyme activity and digestive gene expression levels in D. magna were greatly enhanced to cope with the inhibition of S-dinotefuran on the feeding.

Volatile organic compounds for early detection of prostate cancer from urine

Prostate cancer (PCa) is one of the most common cancers in men worldwide. Early diagnosis of PCa is extremely challenging due to the lack of effective diagnostic methods. The study presented here aims to evaluate whether urine volatile organic compounds (VOCs) can be used as an emerging diagnostic biomarker for PCa. Gas chromatography-ion mobility spectrometry (GC-IMS) was used to detect VOCs in urine samples from 66 patients with PCa and to comparatively analyze samples from 87 patients with non-cancerous controls (NCs). A total of 86 substance peak heights were detected in urine samples from all patients. Analysis using four machine learning algorithms suggested that the diagnosis of PCa could be effectively facilitated. Ultimately, diagnostic models were constructed based on the four VOCs selected. The AUC for the RF and SVM model were 0.955 and 0.981, respectively. Both the NN and DT diagnostic models also achieved an AUC of 0.8 or more, but their sensitivity or specificity was poor compared to the RF and SVM models.

Cytosolic Enzymes Generate Cannabinoid Metabolites 7-Carboxycannabidiol and 11-Nor-9-carboxytetrahydrocannabinol

The cannabinoids cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) undergo extensive oxidative metabolism in the liver. Although cytochromes P450 form the primary, pharmacologically active, hydroxylated metabolites of CBD and THC, less is known about the enzymes that generate the major in vivo circulating metabolites of CBD and THC, 7-carboxy-CBD and 11-carboxy-THC, respectively. The purpose of this study was to elucidate the enzymes involved in forming these metabolites. Cofactor dependence experiments with human liver subcellular fractions revealed that 7-carboxy-CBD and 11-carboxy-THC formation is largely dependent on cytosolic NAD+-dependent enzymes, with lesser contributions from NADPH-dependent microsomal enzymes. Experiments with chemical inhibitors provided evidence that 7-carboxy-CBD formation is mainly dependent on aldehyde dehydrogenases and 11-carboxy-THC formation is mediated also in part by aldehyde oxidase. This study is the first to demonstrate the involvement of cytosolic drug-metabolizing enzymes in generating major in vivo metabolites of CBD and THC and addresses a knowledge gap in cannabinoid metabolism.

Haldol Targets IQGAP1 Pathway and Promotes Novel Partner Interactions in Glioblastoma Cell Lines

Glioblastoma multiform (GBM) is an incurable heterogenous brain cancer with few clinical target options. IQGAP1 is a scaffold oncoprotein involved in GBM with unclear mechanism. Here we report that the antipsychotic drug Haldol differentially alters IQGAP1 signaling and inhibits GBM cell proliferation, thus providing novel molecular signatures for GBM classification and potential targeted therapy in personalized medicine.

Toxicological Effects of Secondary Air Pollutants

Secondary air pollutants, originating from gaseous pollutants and primary particulate matter emitted by natural sources and human activities, undergo complex atmospheric chemical reactions and multiphase processes. Secondary gaseous pollutants represented by ozone and secondary particulate matter, including sulfates, nitrates, ammonium salts, and secondary organic aerosols, are formed in the atmosphere, affecting air quality and human health. This paper summarizes the formation pathways and mechanisms of important atmospheric secondary pollutants. Meanwhile, different secondary pollutants' toxicological effects and corresponding health risks are evaluated. Studies have shown that secondary pollutants are generally more toxic than primary ones. However, due to their diverse source and complex generation mechanism, the study of the toxicological effects of secondary pollutants is still in its early stages. Therefore, this paper first introduces the formation mechanism of secondary gaseous pollutants and focuses mainly on ozone's toxicological effects. In terms of particulate matter, secondary inorganic and organic particulate matters are summarized separately, then the contribution and toxicological effects of secondary components formed from primary carbonaceous aerosols are discussed. Finally, secondary pollutants generated in the indoor environment are briefly introduced. Overall, a comprehensive review of secondary air pollutants may shed light on the future toxicological and health effects research of secondary air pollutants.

Enlightening the Path to Protein Engineering: Chemoselective Turn-On Probes for High-Throughput Screening of Enzymatic Activity

Many successful stories in enzyme engineering are based on the creation of randomized diversity in large mutant libraries, containing millions to billions of enzyme variants. Methods that enabled their evaluation with high throughput are dominated by spectroscopic techniques due to their high speed and sensitivity. A large proportion of studies relies on fluorogenic substrates that mimic the chemical properties of the target or coupled enzymatic assays with an optical read-out that assesses the desired catalytic efficiency indirectly. The most reliable hits, however, are achieved by screening for conversions of the starting material to the desired product. For this purpose, functional group assays offer a general approach to achieve a fast, optical read-out. They use the chemoselectivity, differences in electronic and steric properties of various functional groups, to reduce the number of false-positive results and the analytical noise stemming from enzymatic background activities. This review summarizes the developments and use of functional group probes for chemoselective derivatizations, with a clear focus on screening for enzymatic activity in protein engineering.

Targeting aldehyde dehydrogenase enzymes in combination with chemotherapy and immunotherapy: An approach to tackle resistance in cancer cells

Modern cancer chemotherapy originated in the 1940s, and since then, many chemotherapeutic agents have been developed. However, most of these agents show limited response in patients due to innate and acquired resistance to therapy, which leads to the development of multi-drug resistance to different treatment modalities, leading to cancer recurrence and, eventually, patient death. One of the crucial players in inducing chemotherapy resistance is the aldehyde dehydrogenase (ALDH) enzyme. ALDH is overexpressed in chemotherapy-resistant cancer cells, which detoxifies the generated toxic aldehydes from chemotherapy, preventing the formation of reactive oxygen species and, thus, inhibiting the induction of oxidative stress and the stimulation of DNA damage and cell death. This review discusses the mechanisms of chemotherapy resistance in cancer cells promoted by ALDH. In addition, we provide detailed insight into the role of ALDH in cancer stemness, metastasis, metabolism, and cell death. Several studies investigated targeting ALDH in combination with other treatments as a potential therapeutic regimen to overcome resistance. We also highlight novel approaches in ALDH inhibition, including the potential synergistic employment of ALDH inhibitors in combination with chemotherapy or immunotherapy against different cancers, including head and neck, colorectal, breast, lung, and liver.

Identification of a novel ALDH1A3-selective inhibitor by a chemical probe with unrelated bioactivity: An approach to affinity-based drug target discovery

The identification of biologically active target compounds and their binding proteins is important in mechanism-of-action studies for drug development. Additionally, the newly discovered binding proteins provide unforeseen ideas for novel drug discovery and for subsequent structural transformation to improve target specificity. Based on the lead and final candidate compounds related to the type 5 phosphodiesterase (PDE5) inhibitor E4021, we designed chemical probes and identified their target proteins by the affinity chromatography approach. Aldehyde dehydrogenase family 1 member A3 (ALDH1A3), currently reported as a cancer stem cell target, was clearly isolated as a binding protein of the lead 'immature' inhibitor probe against PDE5. In the early derivatization to the closely related structure, Compound 5 (ER-001135935) was found to significantly inhibit ALDH1A3 activity. The discovery process of a novel ALDH1A3-selective inhibitor with affinity-based binder identification is described, and the impact of this identification method on novel drug discovery is discussed.

Scavenging neurotoxic aldehydes using lysine carbon dots

Reactive aldehydes generated in cells and tissues are associated with adverse physiological effects. Dihydroxyphenylacetaldehyde (DOPAL), the biogenic aldehyde enzymatically produced from dopamine, is cytotoxic, generates reactive oxygen species, and triggers aggregation of proteins such as α-synuclein implicated in Parkinson's disease. Here, we demonstrate that carbon dots (C-dots) prepared from lysine as the carbonaceous precursor bind DOPAL molecules through interactions between the aldehyde units and amine residues on the C-dot surface. A set of biophysical and in vitro experiments attests to attenuation of the adverse biological activity of DOPAL. In particular, we show that the lysine-C-dots inhibit DOPAL-induced α-synuclein oligomerization and cytotoxicity. This work underlines the potential of lysine-C-dots as an effective therapeutic vehicle for aldehyde scavenging.

Breath VOC analysis and machine learning approaches for disease screening: a review

Early disease detection is often correlated with a reduction in mortality rate and improved prognosis. Currently, techniques like biopsy and imaging that are used to screen chronic diseases are invasive, costly or inaccessible to a large population. Thus, a non-invasive disease screening technology is the need of the hour. Existing non-invasive methods like gas chromatography-mass spectrometry, selected-ion flow-tube mass spectrometry, and proton transfer reaction-mass-spectrometry are expensive. These techniques necessitate experienced operators, making them unsuitable for a large population. Various non-invasive sources are available for disease detection, of which exhaled breath is preferred as it contains different volatile organic compounds (VOCs) that reflect the biochemical reactions in the human body. Disease screening by exhaled breath VOC analysis can revolutionize the healthcare industry. This review focuses on exhaled breath VOC biomarkers for screening various diseases with a particular emphasis on liver diseases and head and neck cancer as examples of diseases related to metabolic disorders and diseases unrelated to metabolic disorders, respectively. Single sensor and sensor array-based (Electronic Nose) approaches for exhaled breath VOC detection are briefly described, along with the machine learning techniques used for pattern recognition.

Anti-Candida, docking studies, and in vitro metabolism-mediated cytotoxicity evaluation of Eugenol derivatives

The high morbidity and mortality rates of Candida infections, especially among immunocompromised patients, are related to the increased resistance rate of these species and the limited therapeutic arsenal. In this context, we evaluated the anti-Candida potential and the cytotoxic profile of eugenol derivatives. Anti-Candida activity was evaluated on C. albicans and C. parapsilosis strains by minimum inhibitory concentration (MIC), scanning electron microscopy (SEM), and molecular docking calculations at the site of the enzyme lanosterol-14-α-demethylase active site, responsible for ergosterol formation. The cytotoxic profile was evaluated in HepG2 cells, in the presence and absence of the metabolizing system (S9 system). The results indicated compounds 1b and 1d as the most active ones. The compounds have anti-Candida activity against both strains with MIC ranging from 50 to 100 μg ml^-1 . SEM analyses of 1b and 1d indicated changes in the envelope architecture of both C. albicans and C. parapsilosis like the ones of eugenol and fluconazole, respectively. Docking results of the evaluated compounds indicated a similar binding pattern of fluconazole and posaconazole at the lanosterol-14-α-demethylase binding site. In the presence of the S9 system, compound 1b showed the same cytotoxicity profile as fluconazole (1.08 times) and compound 1d had 1.23 times increase in cytotoxicity. Eugenol and other evaluated compounds showed a significant increase in cytotoxicity. Our results suggest compound 1b as a promising starting point candidate to be used in the design of new anti-Candida agent prototypes.

Nicotinaldehyde, a Novel Precursor of NAD Biosynthesis, Abrogates the Anti-Cancer Activity of an NAD-Lowering Agent in Leukemia

Targeting NAD depletion in cancer cells has emerged as an attractive therapeutic strategy for cancer treatment, based on the higher reliance of malignant vs. healthy cells on NAD to sustain their aberrant proliferation and altered metabolism. NAD depletion is exquisitely observed when NAMPT, a key enzyme for the biosynthesis of NAD, is inhibited. Growing evidence suggests that alternative NAD sources present in a tumor environment can bypass NAMPT and render its inhibition ineffective. Here, we report the identification of nicotinaldehyde as a novel precursor that can be used for NAD biosynthesis by human leukemia cells. Nicotinaldehyde supplementation replenishes the intracellular NAD level in leukemia cells treated with NAMPT inhibitor APO866 and prevents APO866-induced oxidative stress, mitochondrial dysfunction and ATP depletion. We show here that NAD biosynthesis from nicotinaldehyde depends on NAPRT and occurs via the Preiss-Handler pathway. The availability of nicotinaldehyde in a tumor environment fully blunts the antitumor activity of APO866 in vitro and in vivo. This is the first study to report the role of nicotinaldehyde in the NAD-targeted anti-cancer treatment, highlighting the importance of the tumor metabolic environment in modulating the efficacy of NAD-lowering cancer therapy.

Association of Different Combinations of ALDH2 rs671, APOE rs429358, rs7412 Polymorphisms with Hypertension in Middle-Aged and Elderly People: A Case-Control Study

Background

Hypertensive patients have a younger trend, and studies on the role of genetic factors in hypertension susceptibility have been inconsistent. Aldehyde dehydrogenases 2 (ALDH2) and apolipoprotein E (APOE) are involved in the pathophysiological processes of hypertension. To investigate the relationship of ALDH2 and APOE polymorphisms with hypertension in middle-aged (30-59 years old) and elderly (≥60 years old) persons.

Methods

Two thousand six hundred and ten hypertensive patients and 1921 controls were included (between 30 and 100 years old). The genotypes of common polymorphisms in APOE and ALDH2 genes (APOE rs429358, rs7412, and ALDH2 rs671) of the subjects were analyzed by polymerase-chain reaction (PCR)-microarray. Statistical analyses (Student's t-test, Mann-Whitney U-test, χ ² test, and logistic regression analysis) were performed with SPSS v21.0.

Results

There were 4531 participants (66.60 ± 12.10 years old) in this study, including 3057 (67.5%) males and 1474 (32.5%) females. There were no significant differences in distributions of ALDH2 rs671, APOE rs429358/rs7412 genotypes and alleles between hypertensive patients and controls. Persons with ALDH2 rs671 G/A or A/A genotype were less likely to have hypertension (G/A+A/A vs G/G: gender-, age-, smoking-, and drinking-adjusted OR 0.885, 95% CI 0.785-0.997, P=0.045), while ALDH2 rs671 A/A+APOE rs429358 or rs7412 wild-type genotype may decrease the risk of hypertension. In middle-aged group, ALDH2 rs671 G/A+APOE rs429358 T/C carriers (adjusted OR 0.547, 95% CI 0.350-0.856, P=0.008), and ALDH2 rs671 A/A+APOE rs7412 C/C genotypes (adjusted OR 0.567, 95% CI 0.361-0.891, P=0.014) were less likely to have hypertension. In elderly group, APOE rs7412 T/T carriers were more likely to have hypertension (rs671 T/T vs C/C: adjusted OR 4.755, 95% CI 1.075-21.027, P=0.040; rs671 T/T vs C/C or C/T: adjusted OR 4.734, 95% CI 1.071-20.928, P=0.040).

Conclusion

Polymorphism-polymorphism interactions of ALDH2 rs671 and APOE rs429358/rs7412 may effect on hypertension susceptibility. Different genotypes comparison shows different roles in middle-aged and elderly people, respectively.

ALDH2 rs671 Polymorphism Likely a Risk Factor for Hemorrhagic Stroke: A Hospital-Based Study

Background

Hypertension is the main risk factor for hemorrhagic stroke. Aldehyde dehydrogenase 2 (ALDH2) may inhibit the occurrence of hypertension by anti-oxidative stress and vascular dilation. The purpose was to investigate the relationship of ALDH2 polymorphisms with hemorrhagic stroke in Hakka Chinese.

Methods

A total of 329 patients with hemorrhagic stroke and 515 controls were enrolled, and medical records (smoking and drinking history, hypertension, and diabetes) were collected. The genotypes of ALDH2 rs671 of the two groups were detected and analyzed.

Results

The proportion of the ALDH2 rs671 G/G, G/A, and A/A genotype in patients with hemorrhagic stroke was 55.9%, 37.4%, and 6.7%, respectively, while those were 65.0%, 30.7%, and 4.3% in controls, respectively. There was statistically significant difference in ALDH2 rs671 genotypes distribution (P=0.021) and alleles distribution (P=0.005) between patients and controls. Among hemorrhagic stroke patients, no statistically significant differences were observed between patients with ALDH2 different genotypes. Logistic regression analysis showed that there was significantly high risk of hemorrhagic stroke in men (male vs female: adjusted OR 1.711, 95% CI 1.154-2.538, P=0.008), the presence of hypertension (with vs without hypertension: adjusted OR 16.095, 95% CI 10.958-23.641, P<0.001), and the presence of ALDH2 rs671 G/A genotype (G/A vs G/G: adjusted OR 1.679, 95% CI 1.151-2.450, P=0.007) or A/A genotype (A/A vs G/G: adjusted OR 2.516, 95% CI 1.132-5.591, P=0.024).

Conclusion

ALDH2 rs671 polymorphism likely a risk factor for hemorrhagic stroke.

From linoleic acid to hexanal and hexanol by whole cell catalysis with a lipoxygenase, hydroperoxide lyase and reductase cascade in Komagataella phaffii

Green leaf volatiles (GLVs) cover a group of mainly C6-and C9-aldehydes, -alcohols and -esters. Their name refers to their characteristic herbal and fruity scent, which is similar to that of freshly cut grass or vegetables. Lipoxygenases (LOXs) catalyze the peroxidation of unsaturated fatty acids. The resulting hydroperoxy fatty acids are then cleaved into aldehydes and oxo acids by fatty acid hydroperoxide lyases (HPLs). Herein, we equipped the yeast Komagataella phaffii with recombinant genes coding for LOX and HPL, to serve as a biocatalyst for GLV production. We expressed the well-known 13S-specific LOX gene from Pleurotus sapidus and a compatible HPL gene from Medicago truncatula. In bioconversions, glycerol induced strains formed 12.9 mM hexanal using whole cells, and 8 mM hexanol was produced with whole cells induced by methanol. We applied various inducible and constitutive promoters in bidirectional systems to influence the final ratio of LOX and HPL proteins. By implementing these recombinant enzymes in Komagataella phaffii, challenges such as biocatalyst supply and lack of product specificity can finally be overcome.

Virtual Screening of FDA-Approved Drugs for Enhanced Binding with Mitochondrial Aldehyde Dehydrogenase

Mitochondrial aldehyde dehydrogenase (ALDH2) is a potential target for the treatment of substance use disorders such as alcohol addiction. Here, we adopted computational methods of molecular dynamics (MD) simulation, docking, and molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) analysis to perform a virtual screening of FDA-approved drugs, hitting potent inhibitors against ALDH2. Using MD-derived conformations as receptors, butenafine (net charge q = +1 e) and olaparib (q = 0) were selected as promising compounds with a low toxicity and a binding strength equal to or stronger than previously reported potent inhibitors of daidzin and CVT-10216. A few negatively charged compounds were also hit from the docking with the Autodock Vina software, while the MM-PBSA analysis yielded positive binding energies (unfavorable binding) for these compounds, mainly owing to electrostatic repulsion in association with a negatively charged receptor (q = -6 e for ALDH2 plus the cofactor NAD⁺). This revealed a deficiency of the Vina scoring in dealing with strong charge-charge interactions between binding partners, due to its built-in protocol of not using atomic charges for electrostatic interactions. These observations indicated a requirement of further verification using MD and/or MM-PBSA after docking prediction. The identification of key residues for the binding implied that the receptor residues at the bottom and entrance of the substrate-binding hydrophobic tunnel were able to offer additional interactions with different inhibitors such as π-π, π-alkyl, van der Waals contacts, and polar interactions, and that the rational use of these interactions is beneficial to the design of potent inhibitors against ALDH2.

Metabolite profiling of human-originated Lachnospiraceae at the strain level

The human gastrointestinal (GI) tract harbors diverse microbes, and the family Lachnospiraceae is one of the most abundant and widely occurring bacterial groups in the human GI tract. Beneficial and adverse effects of the Lachnospiraceae on host health were reported, but the diversities at species/strain levels as well as their metabolites of Lachnospiraceae have been, so far, not well documented. In the present study, we report on the collection of 77 human-originated Lachnospiraceae species (please refer hLchsp, https://hgmb.nmdc.cn/subject/lachnospiraceae) and the in vitro metabolite profiles of 110 Lachnospiraceae strains (https://hgmb.nmdc.cn/subject/lachnospiraceae/metabolites). The Lachnospiraceae strains in hLchsp produced 242 metabolites of 17 categories. The larger categories were alcohols (89), ketones (35), pyrazines (29), short (C2-C5), and long (C > 5) chain acids (31), phenols (14), aldehydes (14), and other 30 compounds. Among them, 22 metabolites were aromatic compounds. The well-known beneficial gut microbial metabolite, butyric acid, was generally produced by many Lachnospiraceae strains, and Agathobacter rectalis strain Lach-101 and Coprococcus comes strain NSJ-173 were the top 2 butyric acid producers, as 331.5 and 310.9 mg/L of butyric acids were produced in vitro, respectively. Further analysis of the publicly available cohort-based volatile-metabolomic data sets of human feces revealed that over 30% of the prevailing volatile metabolites were covered by Lachnospiraceae metabolites identified in this study. This study provides Lachnospiraceae strain resources together with their metabolic profiles for future studies on host-microbe interactions and developments of novel probiotics or biotherapies.

An insecticide target in mechanoreceptor neurons

Hundreds of neurotoxic insecticides are currently in use. However, only a few direct targets have been identified. Here, using Drosophila and the insecticide flonicamid, we identified nicotinamidase (Naam) as a previous unidentified molecular target for an insecticide. Naam is expressed in chordotonal stretch-receptor neurons, and inhibition of Naam by a metabolite of flonicamid, TFNA-AM (4-trifluoromethylnicotinamide), induces accumulation of substrate nicotinamide and greatly inhibits negative geotaxis. Engineered flies harboring a point mutation in the active site show insecticide resistance and defects in gravity sensing. Bees are resistant to flonicamid because of a gene duplication, resulting in the generation of a TFNA-AM-insensitive Naam. Our results, in combination with the absence of genes encoding Naam in vertebrate genomes, suggest that TFNA-AM and potential species-specific Naam inhibitors could be developed as novel insecticides, anthelmintics, and antimicrobials for agriculture and human health.

Five new secondary metabolites from an endophytic fungus Phomopsis sp. SZSJ-7B

Two previously undescribed lactones, phomolides A and B (1 and 2), and three new sesquiterpenoids, phomenes A-C (3-5), together with one known compound, colletotricholide A (6), were isolated from the endophytic fungus Phomopsis sp. SZSJ-7B. Their chemical structures, including the absolute configurations, were comprehensively established by extensive analyses of NMR, high-resolution electrospray ionization mass spectrometry, electronic circular dichroism powered by theoretical calculations, and X-ray diffractions. Moreover, the cytotoxic and antibacterial activities of compounds 1-6 were also evaluated, and the results demonstrated that compound 2 showed significant antibacterial effects towards methicillin-resistant Staphylococcus aureus and S. aureus strains with minimum inhibitory concentration as low as 6.25 μg/ml, which was comparable to that of the clinical drug vancomycin. Moreover, all compounds showed no cytotoxic activity.

Comparative Metabolomic Profiling of the Metabolic Differences of Δ9-Tetrahydrocannabinol and Cannabidiol

More than one hundred cannabinoids have been found in cannabis. Δ9-Tetrahydrocannabinol (THC) is the recognized addictive constituent in cannabis; however, the mechanisms underlying THC-induced toxicity remain elusive. To better understand cannabis-induced toxicity, the present study compared the metabolic pathways of THC and its isomer cannabidiol (CBD) in human and mouse liver microsomes using the metabolomic approach. Thirty-two metabolites of THC were identified, including nine undescribed metabolites. Of note, two glutathione (GSH) and two cysteine (Cys) adducts were found in THC’s metabolism. Molecular docking revealed that THC conjugates have a higher affinity with GSH and Cys than with the parent compound, THC. Human recombinant cytochrome P450 enzymes, and their corresponding chemical inhibitors, demonstrated that CYP3A4 and CYP1B1 were the primary enzymes responsible for the formation of THC-GSH and THC-Cys, thus enabling conjugation to occur. Collectively, this study systematically compared the metabolism of THC with the metabolism of CBD using the metabolomic approach, which thus highlights the critical role of metabolomics in identifying novel drug metabolites. Moreover, this study also facilitates mechanistic speculation in order to expand the knowledge of drug metabolism and safety.

Association of aldehyde exposure with bone mineral density in the national health and nutrition examination survey (NHANES 2013-2014)

PURPOSE

The association between aldehyde exposure and bone health in humans remains unclear. This study was to evaluate the association of serum aldehydes with bone mineral density (BMD) and osteopenia/osteoporosis.

METHODS

We analyzed the US National Health and Nutrition Examination Survey cross-sectional data from 2013 to 2014. Weighted multivariate-adjusted linear regression and logistic regression models were used to assess the association between specific aldehydes and osteopenia/osteoporosis. Associations between aldehyde combinations and BMD were also evaluated using the restricted cubic spline (RCS) method.

RESULTS

Compared with men in the first tertile, those in the third tertile of propanaldehyde concentration were negatively associated with proximal femur and lumbar spine BMD. Significant inverse associations were observed between benzaldehyde exposure and trochanter BMD in women. Benzaldehyde increased the risk of osteopenia/osteoporosis 2.75-fold [95% confidence interval (CI) = 1.06, 7.11] in the highest tertile in women compared to the lowest tertile concentration. In males, the prevalence of total femur, femur neck, and trochanter osteopenia/osteoporosis was significantly higher in the highest versus the lowest tertile of propanaldehyde exposure, with odds ratios (ORs) of 6.84 (95% CI = 2.33, 20.04), 2.72 (95% CI = 1.18, 6.27), and 3.26 (95% CI = 1.25, 8.56), respectively. RCS regression also showed decreased BMD continuously with increasing serum mixed aldehyde levels.

CONCLUSIONS

Serum aldehyde concentrations were associated with low BMD and high osteopenia/osteoporosis risk in adults, with propanaldehyde and benzaldehyde being the most critical. Co-exposure to aldehyde combinations was negatively correlated with BMD.

A novel approach for the bioanalysis of short-lived aldehydes

Background: The instability of aldehydes in biological matrices is associated with their reactions with thiol and amino moieties in proteins. This chemical reaction is reversible by nature and highly pH dependent. Method: A novel approach that includes protein precipitation with an acidic solution of acetonitrile/water/formic acid (85/14/1; v/v/v) was developed to efficiently recover Aldehyde-1 from plasma by shifting the equilibrium toward the formation of the free form. Results: This enabled the support of two GLP studies where Aldehyde-1 was administered to mice. The recovery of Aldehyde-1 from plasma exceeded 88% at three concentration levels. Plasma stability was confirmed at ambient conditions for 24 h and in the freezer for at least 43 (-20°C) and 64 (-70°C) days.

Preliminary study on the effect of using heat-not-burn tobacco products on indoor air quality

In this study, the effect of the use of heat-not-burn (HnB) products on indoor air quality (IAQ) was evaluated. To do this, the concentrations of nicotine, propylene glycol (PG), and vegetable glycerin (VG) directly emitted when using HnB products were analyzed and compared to those from conventional cigarettes. Furthermore, the levels of VOCs, aldehydes, nanoparticle, and particulate matter (PM) detected when subjects used HnB products in the exposure chamber were evaluated the effect on IAQ. As a result, the range of nicotine levels transferred by HnB products (0.8-1.2 mg cigarette^-1) is lower than that by conventional cigarettes (2.4-3.6 mg cigarette^-1). On the other hand, the range of VG levels emitted from HnB products (3.1-5.9 mg cigarette^-1) were higher than that emitted from conventional cigarettes (0.6-3.0 mg cigarette^-1). In addition, although the amount generated from HnB products was small compared to those from conventional cigarettes, various kinds of VOCs, aldehydes, nanoparticle and PM were produced, and these were confirmed to affect IAQ.

Evaluation of air quality in indoor and outdoor environments: Impact of anti-COVID-19 measures

This study monitors the presence of 88 volatile organic compounds (VOCs) and semi-volatile organic compounds (semi-VOCs) at the gas phase of seven indoor settings in a school in the city of Tarragona, Spain, and five outdoor locations around the city. The VOCs and semi-VOCs monitored were solvents (∑Solvents), aldehydes (∑Aldehydes), emerging organic compounds (∑EOCs), and other VOCs and semi-VOCs (∑Others). Passive sampling campaigns were performed using Carbopack X tubes followed by thermal desorption coupled to gas chromatography with mass spectrometry (TD-GC-MS). Overall, 70 of the target compounds included in the method were determined in the indoor air samples analysed, and 42 VOCs and semi-VOCs in the outdoor air samples. Our results showed that solvents were ubiquitous throughout the school at concentrations ranging from 272 μg m^-3 to 423 μg m^-3 and representing 68%-83% of total target compounds (∑Total). The values of ∑Total in 2021 were three times as high as those observed at the same indoor settings in 2019, with solvents experiencing the greatest increase. A plausible explanation for these observations is the implementation of anti-COVID-19 measures in the indoor settings, such as the intensification of cleaning activities and the use of hydroalcoholic gels as personal hygiene. The ∑Total values observed in the indoor settings evaluated were twenty times higher than those found outdoors. ∑Solvents were the most representative compounds found indoors (74% of the ∑Total). The concentrations of VOCs and semi-VOCs observed in the outdoors were strictly related to combustion processes from automobile traffic and industrial activities, with ∑Others contributing 58%, ∑Solvents 31%, and ∑Aldehydes 11% of the ∑Total. EOCs, on the other hand, were not detected in any outdoor sample.

Chitin Nanocrystals Provide Antioxidant Activity to Polylactic Acid Films

About 1/3rd of produced food goes to waste, and amongst others, advanced packaging concepts need to be developed to prevent this from happening. Here, we target the antioxidative functionality of food packaging to thus address food oxidation without the need for the addition of antioxidants to the food product, which is not desirable from a consumer point of view. Chitin nanocrystals (ChNC) have been shown to be promising bio-fillers for improving the mechanical strength of biodegradable plastics, but their potential as active components in plastic films is rather unexplored. In the current study, we investigate the antioxidant activity of chitin nanocrystals as such and as part of polylactic acid (PLA) films. This investigation was conducted using DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity. Chitin nanocrystals produced via acid hydrolysis showed five times higher activity compared to crude chitin powder. When using these crystals as part of a polylactic acid film (either inside or on top), in both scenarios, antioxidant activity was found, but the effect was considerably greater when the particles were at the surface of the film. This is an important proof of the principle that it is possible to create biodegradable plastics with additional functionality through the addition of ChNC.