Nutritional load in post-prandial oxidative stress and the pathogeneses of diabetes mellitus

Diabetes mellitus affected more than 500 million of people globally, with an annual mortality of 1.5 million directly attributable to diabetic complications. Oxidative stress, in particularly in post-prandial state, plays a vital role in the pathogenesis of the diabetic complications. However, oxidative status marker is generally poorly characterized and their mechanisms of action are not well understood. In this work, we proposed a new framework for deep characterization of oxidative stress in erythrocytes (and in urine) using home-built micro-scale NMR system. The dynamic of post-prandial oxidative status (against a wide variety of nutritional load) in individual was assessed based on the proposed oxidative status of the red blood cells, with respect to the traditional risk-factors such as urinary isoprostane, reveals new insights into our understanding of diabetes. This new method can be potentially important in drafting guidelines for sub-stratification of diabetes mellitus for clinical care and management.

Dityrosine Aggravates Hepatic Insulin Resistance in Obese Mice by Altering Gut Microbiota and the LPS/TLR4/NF-κB Inflammatory Pathway

SCOPE

Dityrosine is the main product of protein oxidation, which has been proved to be a threat to human health. This study aims to investigate whether dityrosine exacerbates insulin resistance by inducing gut flora disturbance and associated inflammatory responses.

METHODS AND RESULTS

Mice fed with normal diet or high-fat diet (HFD) received daily gavage of dityrosine (320 µg kg-1 BW) or saline for consecutive 13 weeks. The effects of dityrosine on gut microbiota are verified by in vitro fermentation using fecal microbiota from db/m mice and db/db mice. As a result, dityrosine causes the insulin resistance in mice fed normal diet, and aggravates the effects of HFD on insulin sensitivity. Dityrosine increases the levels of lipopolysaccharide (LPS), lipopolysaccharide-binding protein (LBP), toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8) but decreases levels of interleukin-10 (IL-10) in the plasma of CON and HFD-fed mice. The changes of gut flora composition caused by dityrosine are significantly correlated with the changes of inflammatory biomarkers.

CONCLUSION

The effects of dityrosine on insulin resistance may be attributed to the reshaping of the gut microbiota composition and promoting the activity of the LPS/TLR4/NF-κB inflammatory pathway in HFD-induced obese individuals.

Potential implications of oxidative modification on dietary protein nutritional value: A review

During food processing and storage, proteins are sensitive to oxidative modification, changing the structural characteristics and functional properties. Recently, the impact of dietary protein oxidation on body health has drawn increasing attention. However, few reviews summarized and highlighted the impact of oxidative modification on the nutritional value of dietary proteins and related mechanisms. Therefore, this review seeks to give an updated discussion of the effects of oxidative modification on the structural characteristics and nutritional value of dietary proteins, and elucidate the interaction with gut microbiota, intestinal tissues, and organs. Additionally, the specific mechanisms related to pathological conditions are also characterized. Dietary protein oxidation during food processing and storage change protein structure, which further influences the in vitro digestion properties of proteins. In vivo research demonstrates that oxidized dietary proteins threaten body health via complicated pathways and affect the intestinal microenvironment via gut microbiota, metabolites, and intestinal morphology. This review highlights the influence of oxidative modification on the nutritional value of dietary proteins based on organs and the intestinal tract, and illustrates the necessity of appropriate experimental design for comprehensively exploring the health consequences of oxidized dietary proteins.

Dityrosine in food: A review of its occurrence, health effects, detection methods, and mitigation strategies

Protein and amino acid oxidation in food products produce many new compounds, of which the reactive and toxic compound dityrosine, derived from oxidized tyrosine, is the most widely studied. The high reactivity of dityrosine enables this compound to induce oxidative stress and disrupt thyroid hormone function, contributing to the pathological processes of several diseases, such as obesity, diabetes, cognitive dysfunction, aging, and age-related diseases. From the perspective of food safety and human health, protein-oxidation products in food are the main concern of consumers, health management departments, and the food industry. This review highlights the latest research on the formation pathways, toxicity, detection methods, occurrence in food, and mitigation strategies for dityrosine. Furthermore, the control of dityrosine in family cooking and food-processing industry has been discussed. Food-derived dityrosine primarily originates from high-protein foods, such as meat and dairy products. Considering its toxicity, combining rapid high sensitivity dityrosine detection techniques with feasible control methods could be an effective strategy to ensure food safety and maintain human health. However, the current dityrosine detection and mitigation strategies exhibit some inherent characteristics and limitations. Therefore, developing technologies for rapid and effective dityrosine detection and control at the industrial level is necessary.

Metabolic Regulation Effect and Potential Metabolic Biomarkers of Pre-Treated Delphinidin on Oxidative Damage Induced by Paraquat in A549 Cells

Delphinidin (Del) is an anthocyanin component with high in vitro antioxidant capacity. In this study, based on the screening of a cell model, gas chromatography-time of flight mass spectrometry (GC-TOF/MS) was used to evaluate the effect of Del pre-protection on the metabolite levels of intracellular oxidative stress induced by paraquat (PQ). According to the cytotoxicity and reactive oxygen species (ROS) responses of four lung cell lines to PQ induction, A549 cell was selected and treated with 100 μM PQ for 12 h to develop a cellular oxidative stress model. Compared with the PQ-induced group, the principal components of the Del pretreatment group had significant differences, but not significant with the control group, indicating that the antioxidant activity of Del can be correlated to the maintenance of metabolite levels. Del preconditioning protects lipid-related metabolic pathways from the disturbance induced by PQ. In addition, the levels of amino acid- and energy-related metabolites were significantly recovered. Del may also exert an antioxidant effect by regulating glucose metabolism. The optimal combinations of biomarkers in the PQ-treatment group and Del-pretreatment group were alanine-valine-urea and alanine-galactose-glucose. Cell metabolome data provided characteristic fingerprints associated with the antioxidant activity of Del.

Adverse Effects of Thermal Food Processing on the Structural, Nutritional, and Biological Properties of Proteins

Thermal processing is one of the most important processing methods in the food industry. However, many studies have revealed that thermal processing can have detrimental effects on the nutritional and functional properties of foods because of the complex interactions among food components. Proteins are essential nutrients for humans, and changes in the structure and nutritional properties of proteins can substantially impact the biological effects of foods. This review focuses on the interactions among proteins, sugars, and lipids during thermal food processing and the effects of these interactions on the structure, nutritional value, and biological effects of proteins. In particular, the negative effects of modified proteins on human health and strategies for mitigating these detrimental effects from two perspectives, namely, reducing the formation of modified proteins during thermal processing and dietary intervention in vivo, are discussed.

Dityrosine suppresses the cytoprotective action of thyroid hormone T3 via inhibiting thyroid hormone receptor-mediated transcriptional activation

Dityrosine (Dityr) is the most common oxidized form of tyrosine. In the previous studies of mice treated with dityrosine, cell death in the pancreas, kidneys, and liver was detected in the presence of enhanced plasma triiodothyronine (T3) content. Due to its structural similarity with the thyroid hormone T3, we hypothesized that dityrosine might disrupt T3-dependent endocrine signaling. The cytotoxic effect of dityrosine was studied in C57BL/6 mice by gavage with a dityrosine dose of 320 μg per kg per day for 10 weeks. Cell death in the liver was detected in the presence of enhanced plasma thyroid hormone content in mice treated with dityrosine. The antagonistic effect of dityrosine on T3 biofunction was studied using HepG2 cells. Dityrosine incubation reduced T3 transport ability and attenuated the T3-mediated cell survival via regulation of the PI3k/Akt/MAPK pathway. Furthermore, dityrosine inhibited T3 binding to thyroid hormone receptors (TRs) and suppressed the TR-mediated transcription. Dityrosine also downregulated the expressions of T3 action-related factors. Taken together, this study demonstrates that dityrosine inhibits T3-dependent cytoprotection by competitive inhibition, resulting in downstream gene suppression. Our findings offer insights into how dityrosine acts as an antagonist of T3. These findings shed new light on cellular processes underlying the energy metabolism disorder caused by dietary oxidized protein, thus contributing to a better understanding of the diet-health axis at a cellular level.

Oxidized Pork Induces Oxidative Stress and Inflammation by Altering Gut Microbiota in Mice

SCOPE

Reduced digestibility of foods containing oxidized proteins and the subsequent excessive accumulation of undigested components in the colon may cause changes in the intestinal flora composition. This study evaluates the characteristics of this change and the potential adverse effects on organisms.

METHODS AND RESULTS

Pork is cooked using sous-vide or at high temperature and pressure (HTP), then freeze-dried, resulting in different levels of oxidized damage. Mice are fed diets containing low- (LOP), medium- (MOP), or high-oxidative damage pork (HOP) for 12 weeks. HOP intake increases mice body weight, induces inflammatory response, and causes oxidative stress, as indicated by the accumulation of oxidative products. Increased serum LPS levels and downregulation of tight junction-related genes in the mucosa suggest mucosal barrier damage. Alterations in the cecal microbiota include reduced relative abundance of the mucin-degrading bacteria Akkermansia, beneficial bacteria Lactobacillus and Bifidobacterium, and H₂ S-producing bacteria Desulfovibrio and increased relative abundance of the pro-inflammatory bacteria Escherichia-Shigella and pathobiont Mucispirillum.

CONCLUSION

HOP intake causes the accumulation of oxidative products, increases body weight, damages the intestinal barrier, and induces oxidative stress and inflammatory response, likely by altering gut microbiota through protein oxidation (POX).

Untargeted UPLC-MS metabolomics reveals multiple changes of urine composition in healthy adult volunteers after consumption of curcuma longa L. extract

Curcuma longa L. is used as food supplement to prevent diseases, although limited studies have been performed on healthy subjects up to now. In the present work, an untargeted UPLC-MS metabolomics approach was applied to study the changes of 24-hours urinary composition on healthy volunteers due to a 28-days daily consumption of a dried C. longa extract containing a standardized amount of curcuminoids. Changes in the excretion of different metabolites were observed after supplementation. Curcumin and two metabolic derivatives (hexahydrocurcumin and dihydrocurcumin) were detected in urine, indicating the absorption of the main curcuminoid from the extract and its further metabolism by liver and gut microbiota. For the first time ar-turmerone, the main apolar constituent of curcuma, was detected in urine in intact form, and its presence was confirmed by a targeted GC-MS analysis. The increase of tetranor-PGJM and tetranor-PGDM, two prostaglandin-D2 metabolites, was observed, being related to the anti-inflammatory effect exerted by curcuma. The variation of the amounts of HPAG, PAG, proline-betaine and hydroxyphenyllactic acid indicate that the supplementation induced changes to the activity of gut microbiota. Finally, the reduced excretion of niacin metabolites (nicotinuric acid, trigonelline and 2PY) and medium- and short-chain acylcarnitines suggests that curcuma could induce the mitochondrial β-oxidation of fatty acids for energy production in healthy subjects. Overall, the results indicate that a prolonged daily consumption of a dried curcuma extract exerts multiple effects on healthy subjects, furthermore they show the opportunity offered by untargeted metabolomics for the study of the bioactivity of natural extracts in healthy human volunteers.

Spatial Learning and Memory Impairment in Growing Mice Induced by Major Oxidized Tyrosine Product Dityrosine

This study focused on the effects of oxidized tyrosine products (OTPs) and major component dityrosine (DT) on the brain and behavior of growing mice. Male and female mice were treated with daily intragastric administration of either tyrosine (Tyr; 420 μg/kg body weight), DT (420 μg/kg body weight), or OTPs (1909 μg/kg body weight) for 35 days. We found that pure DT and OTPs caused redox state imbalance, elevated levels of inflammatory factors, hippocampal oxidative damage, and neurotransmitter disorders while activating the mitochondrial apoptosis pathway in the hippocampus and downregulating the genes associated with learning and memory. These events eventually led to growing mice learning and memory impairment, lagging responses, and anxiety-like behaviors. Furthermore, the male mice exhibited slightly more oxidative damage than the females. These findings imply that contemporary diets and food-processing strategies of the modern world should be modified to reduce oxidized protein intake.

Dietary methionine restriction reduces hepatic steatosis and oxidative stress in high-fat-fed mice by promoting H2S production

Dietary methionine restriction reduces hepatic steatosis and oxidative stress in high-fat-fed mice by promoting H₂S production.

Untargeted NMR-based metabolomics for field-scale monitoring: Temporal reproducibility and biomarker discovery in mosquitofish (Gambusia holbrooki) from a metal(loid)-contaminated wetland

There is considerable interest in applying omics techniques, which have proven extremely valuable for laboratory-based toxicology studies, towards field-scale ecotoxicology and environmental monitoring. Concerns that confounding factors in natural ecosystems may exacerbate variability in omics datasets must be addressed to validate the transition from laboratory to field. This study explores how temporal variability related to seasonal and climatic trends influence qualitative and quantitative metabolomics outcomes, in fish from reference and metal(loid)-polluted wetlands in Australia. Female mosquitofish (Gambusia holbrooki) were sampled on two separate occasions, from a rehabilitated tailings wetland at the site of historic antimony (Sb) processing and a reference wetland with comparable water quality. The first sampling coincided with greater monthly rainfall and colder water temperature, whereas the second sampling was drier and water was warmer. Despite temporal changes and associated differences in metal(loid) concentrations, site differences in metabolite profiles were qualitatively very similar between sampling events. However, quantitative differences were observed, with a greater number of significantly altered metabolites identified during the second sampling event, which coincided with greater metal(loid) concentrations in both water and fish. The majority of identified metabolites were elevated in fish from the contaminated wetland, but with notable decreases in several metabolites that are known to play a role in various aspects of metal(loid) binding, detoxification and excretion. Specifically, decreased aspartate, histidine, myo-inositol, taurine and choline were observed in fish from the contaminated wetland, and may therefore represent a metabolite suite that is broadly indicative of metal toxicity. Quantitative differences between sampling events are suggestive of a dose-response relationship observable at the cellular level which, if harnessed, may be useful for assigning levels of concern based on the degree of change in a multi-parameter set of metabolite biomarkers.

Visible Light-Induced Aerobic Epoxidation of α,β-Unsaturated Ketones Mediated by Amidines

An aerobic photoepoxidation of α,β-unsaturated ketones driven by visible light in the presence of tetramethylguanidine (3b), tetraphenylporphine (H₂TPP), and molecular oxygen under mild conditions was revealed. The corresponding α,β-epoxy ketones were obtained in yields of up to 94% in 96 h. The reaction time was shortened to 4.6 h by flow synthesis. The mechanism related to singlet oxygen was supported by experiments and density functional theory (DFT) calculations.

Health Effects of Dietary Oxidized Tyrosine and Dityrosine Administration in Mice with Nutrimetabolomic Strategies

This study aims to investigate the health effects of long-term dietary oxidized tyrosine (O-Tyr) and its main product (dityrosine) administration on mice metabolism. Mice received daily intragastric administration of either O-Tyr (320 μg/kg body weight), dityrosine (Dityr, 320 μg/kg body weight), or saline for consecutive 6 weeks. Urine and plasma samples were analyzed by NMR-based metabolomics strategies. Body weight, clinical chemistry, oxidative damage indexes, and histopathological data were obtained as complementary information. O-Tyr and Dityr exposure changed many systemic metabolic processes, including reduced choline bioavailability, led to fat accumulation in liver, induced hepatic injury, and renal dysfunction, resulted in changes in gut microbiota functions, elevated risk factor for cardiovascular disease, altered amino acid metabolism, induced oxidative stress responses, and inhibited energy metabolism. These findings implied that it is absolutely essential to reduce the generation of oxidation protein products in food system through improving modern food processing methods.