A new method for quantifying glyoxalase II activity in biological samples.

Glyoxalase II (Glo II) is a crucial enzyme in the glyoxalase system, and plays a vital role in detoxifying harmful metabolites and maintaining cellular redox balance. Dysregulation of Glo II has been linked to various health conditions, including cancer and diabetes. This study introduces a novel method using 2,4-dinitrophenylhydrazine (2,4-DNPH) to measure Glo II activity. The principle behind this approach is the formation of a colored hydrazone complex between 2,4-DNPH and pyruvate produced by the Glo II-catalyzed reaction. Glo II catalyzes the hydrolysis of S-D-lactoylglutathione (SLG), generating D-lactate and reduced glutathione (GSH). The D-lactate is then converted to pyruvate by lactate dehydrogenase, then reacting with 2,4-DNPH to form a brown-colored hydrazone product. The absorbance of this complex, measured at 430 nm, allows for the quantification of Glo II activity. The study rigorously validates the 2,4-DNPH method, demonstrating its stability, sensitivity, linearity, and resistance to interference from various biochemical substances. Compared to the existing UV method, this 2,4-DNPH-Glo II assay shows a strong correlation. The new protocol for measuring Glo II activity using 2,4-DNPH is simple, cost-effective, and accurate, making it a valuable tool for researchers and medical professionals. Its potential for widespread use in various laboratory settings, from academic research to clinical diagnostics, offers significant opportunities for future research and medical applications.

Crosstalk of methylglyoxal and calcium signaling in maize (Zea mays L.) thermotolerance through methylglyoxal-scavenging system.

Methylglyoxal (MG) and calcium ion (Ca2+) can increase multiple-stress tolerance including plant thermotolerance. However, whether crosstalk of MG and Ca2+ exists in the formation of maize thermotolerance and underlying mechanism still remain elusive. In this paper, maize seedlings were irrigated with MG and calcium chloride alone or in combination, and then exposed to heat stress (HS). The results manifested that, compared with the survival percentage (SP, 45.3%) of the control seedlings, the SP of MG and Ca2+ alone or in combination was increased to 72.4%, 74.2%, and 83.4% under HS conditions, indicating that Ca2+ and MG alone or in combination could upraise seedling thermotolerance. Also, the MG-upraised SP was separately weakened to 42.2%, 40.3%, 52.1%, and 39.4% by Ca2+ chelator (ethylene glycol tetraacetic acid, EGTA), plasma membrane Ca2+ channel blocker (lanthanum chloride, LaCl3), intracellular Ca2+ channel blocker (neomycin, NEC), and calmodulin (CaM) antagonist (trifluoperazine, TFP). However, significant effect of MG scavengers N-acetylcysteine (NAC) and aminoguanidine (AG) on Ca2+-induced thermotolerance was not observed. Similarly, an endogenous Ca2+ level in seedlings was increased by exogenous MG under non-HS and HS conditions, while exogenous Ca2+ had no significant effect on endogenous MG. These data implied that Ca2+ signaling, at least partly, mediated MG-upraised thermotolerance in maize seedlings. Moreover, the activity and gene expression of glyoxalase system (glyoxalase I, glyoxalase II, and glyoxalase III) and non-glyoxalase system (MG reductase, aldehyde reductase, aldo-keto reductase, and lactate dehydrogenase) were up-regulated to a certain extent by Ca2+ and MG alone in seedlings under non-HS and HS conditions. The up-regulated MG-scavenging system by MG was enhanced by Ca2+, while impaired by EGTA, LaCl3, NEC, or TFP. These data suggest that the crosstalk of MG and Ca2+ signaling in maize thermotolerance through MG-scavenging system. These findings provided a theoretical basis for breeding climate-resilient maize crop and developing smart agriculture.

Quantitative NMR Analysis of Marine Macroalgae for AGE Inhibition by Methylglyoxal Scavenging.

Reactive carbonyl species (RCS) induce a fundamental form of biological stress that has driven the evolution of diverse mechanisms for minimizing its impact on organismal health. The complications that accompany uncontrolled hyperglycemia exemplify the health implications when RCS stress exceeds the body's capacity to prevent the excessive formation of advanced glycation end-products. Presented here is a novel quantitative NMR (qNMR) technique for evaluating scavengers of the prominent sugar-derived carbonyl methylglyoxal (MGO). This tool was employed to screen the chemical diversity of marine macroalgae extracts, with a focus on species that have a history of consumption by the World's healthiest populations and are subject to global scale aquacultural production. Fucus vesiculosus demonstrated the highest capacity for inhibiting glycation and scavenging MGO. Additionally, the Chondrus cripsus, Gracilaria vermiculophyla, and Gracilaria tikvahiae extracts had a high capacity for scavenging MGO, representing the first report of this activity. This new qNMR methodology presented is highly applicable for screening extracts and compounds from diverse sources, and the results highlight the potential of macroalgae extracts to be employed as RCS and AGE targeting therapeutics and food additives.

Theoretical investigation on the oxidation mechanism of methylglyoxal in the aqueous phase.

The oxidation mechanism of methylglyoxal (CH3COCHO) in the aqueous phase plays a crucial role in the formation of secondary organic aerosols (SOA). To date, the investigations of reaction mechanisms of MG in the aqueous phase still needs to be refined, and the oxidation mechanisms of MG in the existence of various oxidants (e.g., H2O2, O3, ∙NO3, etc.) are in controversy. In this paper, we investigated the hypothesis that small-molecule organic acids are the primary products in cloud water and fog droplets, while large-molecule organic acids and oligomers play crucial roles in wet aerosols. Specifically, the hydration reaction, oxidation mechanism and oligomerization reaction of MG in aqueous phase were investigated on a theoretical basis. It has been indicated that the hydration reaction is a significant initiating reaction of MG in the atmospheric aqueous phase, whose generated hydrated compounds played a critical part in the process of forming oligomers. The aqueous oxidation reaction of MG could form a variety of organic acids, including pyruvic acid, formic acid, acetic acid, and oxalic acid. In the presence of OH radicals, pyruvic acid was the main first-generation production, which undergoes further reactions to form acetic acid, oxalic acid, and mesoxalic acid. Acetic acid was mainly derived from the reaction of OH radicals with pyruvic acid, whereas oxalic and mesoxalic acids were mainly generated by the OH radical reaction for MG and pyruvic acid. Of these, the formation of acetic acid was thermodynamically most favorable. Additionally, the reactions of MG with other oxidants also provided the possible pathways for pyruvic acid production. At 298 K, we calculated the rate constants for the reaction of MGHY with NO3, OH, HO2 radicals, and O3 to be 4.48 × 108, 2.54 × 107, 1.26 × 10-2, and 4.38 × 10-4 M-1 s-1, with atmospheric aqueous phase lifetimes (τ) of 4.43, 3.12 × 103, 2.21 × 1011, and 3.17 × 108 h, respectively. The theoretical results from this work will facilitate the explanation for the MG reaction process in the aqueous phase so as to further correctly estimate the relationship between the aqueous phase chemistry of MG and the formation of SOA.

Monascus pigments suppress fructose-mediated BSA glycation by trapping methylglyoxal and covalent binding to proteins.

In this study, four Monascus pigments (ankaflavin, AK; monascin MS; rubropunctatin, O1; monascorubrin, O2) were proved to exhibit considerable anti-glycation properties in bovine serum albumin (BSA)-fructose model. AK (40.62 %) and MS (48.38 %) were found to exert lower inhibitory effects on the formation of fluorescent advanced glycation end products (AGEs) than aminoguanidine (59.4 %), while O1 (90.64 %) and O2 (93.82 %) displayed much stronger abilities. AK and MS could trap methylglyoxal (MGO) with maximum capture rates of 85.67 % and 84.90 %, respectively, and only mono-MGO adducts of them were detected. LC-Orbitrap MS/MS analysis revealed that four pigments significantly altered the type and reduced the number of the glycated sites and they all covalently bound to BSA, with O1 and O2 possessing high reactivity. Altogether, AK and MS suppressed fluorescent AGEs formation mainly via trapping MGO and covalently interacting with BSA, and blocking free amino groups was the dominant mechanism for O1 and O2. These findings presented new insights into Monascus pigments as dietary supplement for inhibiting protein glycation.

Methylglyoxal alters collagen fibril nanostiffness and surface potential.

Collagen fibrils are fundamental to the mechanical strength and function of biological tissues. However, they are susceptible to changes from non-enzymatic glycation, resulting in the formation of advanced glycation end-products (AGEs) that are not reversible. AGEs accumulate with aging and disease and can adversely impact tissue mechanics and cell-ECM interactions. AGE-crosslinks have been related, on the one hand, to dysregulation of collagen fibril stiffness and damage and, on the other hand, to altered collagen net surface charge as well as impaired cell recognition sites. While prior studies using Kelvin probe force microscopy (KPFM) have shown the effect glycation has on collagen fibril surface potential (i.e., net charge), the combined effect on individual and isolated collagen fibril mechanics, hydration, and surface potential has not been documented. Here, we explore how methylglyoxal (MGO) treatment affects the mechanics and surface potential of individual and isolated collagen fibrils by utilizing atomic force microscopy (AFM) nanoindentation and KPFM. Our results reveal that MGO treatment significantly increases nanostiffness, alters surface potential, and modifies hydration characteristics at the collagen fibril level. These findings underscore the critical impact of AGEs on collagen fibril physicochemical properties, offering insights into pathophysiological mechanical and biochemical alterations with implications for cell mechanotransduction during aging and in diabetes. STATEMENT OF SIGNIFICANCE: Collagen fibrils are susceptible to glycation, the irreversible reaction of amino acids with sugars. Glycation affects the mechanical properties and surface chemistry of collagen fibrils with adverse alterations in biological tissue mechanics and cell-ECM interactions. Current research on glycation, at the level of individual collagen fibrils, is sparse and has focused either on collagen fibril mechanics, with contradicting evidence, or surface potential. Here, we utilized a multimodal approach combining Kelvin probe force (KPFM) and atomic force microscopy (AFM) to examine how methylglyoxal glycation induces structural, mechanical, and surface potential changes on the same individual and isolated collagen fibrils. This approach helps inform structure-function relationships at the level of individual collagen fibrils.

Recent advances in the potential of Phyllanthus emblica L. and its related foods for combating metabolic diseases through methylglyoxal trapping.

Methylglyoxal (MG) serves as the primary precursor for the nonenzymatic glycation of proteins and DNA, leading to advanced glycation end products (AGEs). Regular intake of dietary MG is strongly correlated with low-grade inflammation, potentially accelerating the pathogenesis of metabolic diseases, including obesity, diabetes, cancers, liver diseases, Alzheimer's disease, cardiovascular diseases, aging, and bone loss. Although pharmaceutical agents (pimagedine and candesartan) have been developed to inhibit MG formation, they often come with serious side effects (nausea, diarrhea, headache, gastrointestinal disturbance, symptomatic hypotension, abnormal renal and liver function tests, development of antinuclear antibody, pernicious-like anemia, and hyperkalemia), highlighting the need for an efficient and safe approach to scavenging MG. Phyllanthus emblica Linn fruit, a nutritious edible fruit, and medicinal plant contains over 300 bioactive compounds. Among twenty-three herbals, 100 µg/mL of the aqueous extract of Phyllanthus emblica fruit (APF) exhibits the highest potency in trapping MG, achieving an 87.3 % reduction under d-fructose induced BSA-AGEs formation. However, there are few reports detailing APF and its related foods' specific impact on disease prevention through MG trapping. This review summarizes the mechanisms through which MG is linked to the development of metabolic diseases and provides several strategies for reducing MG levels using APF and its bioactive compounds. The potential antiglycation properties of APF may offer new applications in the food industry and pharmacological research.

The Role of Natural Low Molecular Weight Dicarbonyls in Atherogenesis and Diabetogenesis.

This review summarises the data from long-term experimental studies and literature data on the role of oxidatively modified low-density lipoproteins (LDL) in atherogenesis and diabetogenesis. It was shown that not "oxidized" (lipoperoxide-containing) LDL, but dicarbonyl-modified LDL are atherogenic (actively captured by cultured macrophages with the help of scavenger receptors), and also cause expression of lectin like oxidized low density lipoprotein receptor 1 (LOX-1) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 1 (NOX-1) genes in endotheliocytes, which stimulate apoptosis and endothelial dysfunction. The obtained data allowed us to justify new approaches to pharmacotherapy of atherosclerosis and diabetes mellitus.

Transcriptomic characterization of recombinant Clostridium beijerinckii NCIMB 8052 expressing methylglyoxal synthase and glyoxal reductase from Clostridium pasteurianum ATCC 6013.

Bioconversion of abundant lactose-replete whey permeate to value-added chemicals holds promise for valorization of this expanding food processing waste. Efficient conversion of whey permeate-borne lactose requires adroit microbial engineering to direct carbon to the desired chemical. An engineered strain of Clostridium beijerinckii NCIMB 8052 (C. beijerinckii_mgsA+mgR) that produces 87% more butanol on lactose than the control strain was assessed for global transcriptomic changes. The results revealed broadly contrasting gene expression patterns in C. beijerinckii_mgsA+mgR relative to the control strain. These were characterized by widespread decreases in the abundance of mRNAs of Fe-S proteins in C. beijerinckii_mgsA+mgR, coupled with increased differential expression of lactose uptake and catabolic genes, iron uptake genes, two-component signal transduction and motility genes, and genes involved in the biosynthesis of vitamins B5 and B12, aromatic amino acids (particularly tryptophan), arginine, and pyrimidines. Conversely, the mRNA patterns suggest that the L-aspartate-dependent de novo biosynthesis of NAD as well as biosynthesis of lysine and asparagine and metabolism of glycine and threonine were likely down-regulated. Furthermore, genes involved in cysteine and methionine biosynthesis and metabolism, including cysteine desulfurase-a central player in Fe-S cluster biosynthesis-equally showed reductions in mRNA abundance. Genes involved in biosynthesis of capsular polysaccharides and stress response also showed reduced mRNA abundance in C. beijerinckii_mgsA+mgR. The results suggest that remodeling of cellular and metabolic networks in C. beijerinckii_mgsA+mgR to counter anticipated effects of methylglyoxal production from heterologous expression of methylglyoxal synthase led to enhanced growth and butanol production in C. beijerinckii_mgsA+mgR. IMPORTANCE: Biological production of commodity chemicals from abundant waste streams such as whey permeate represents an opportunity for decarbonizing chemical production. Whey permeate remains a vastly underutilized feedstock for bioproduction purposes. Thus, enhanced understanding of the cellular and metabolic repertoires of lactose-mediated production of chemicals such as butanol promises to identify new targets that can be fine tuned in recombinant and native microbial strains to engender stronger coupling of whey permeate-borne lactose to value-added chemicals. Our results highlight new genetic targets for future engineering of C. beijerinckii for improved butanol production on lactose and ultimately in whey permeate.

An innovative, sustainable, and environmentally friendly approach for wheat drought tolerance using vermicompost and effective microorganisms: upregulating the antioxidant defense machinery, glyoxalase system, and osmotic regulatory substances.

BACKGROUND: Vermicompost contains humic acids, nutrients, earthworm excretions, beneficial microbes, growth hormones, and enzymes, which help plants to tolerate a variety of abiotic stresses. Effective microorganisms (EM) include a wide range of microorganisms' e.g. photosynthetic bacteria, lactic acid bacteria, yeasts, actinomycetes, and fermenting fungi that can stimulate plant growth and improve soil fertility. To our knowledge, no study has yet investigated the possible role of vermicompost and EM dual application in enhancing plant tolerance to water scarcity. METHODS: Consequently, the current study investigated the effectiveness of vermicompost and EM in mitigating drought-induced changes in wheat. The experiment followed a completely randomized design with twelve treatments. The treatments included control, as well as individual and combined applications of vermicompost and EM at three different irrigation levels (100%, 70%, and 30% of field capacity). RESULTS: The findings demonstrated that the application of vermicompost and/or EM significantly improved wheat growth and productivity, as well as alleviated drought-induced oxidative damage with decreased the generation of superoxide anion radical and hydrogen peroxide. This was achieved by upregulating the activities of several antioxidant enzymes, including superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, glutathione peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase. Vermicompost and/or EM treatments also enhanced the antioxidant defense system by increasing the content of antioxidant molecules such as ascorbate, glutathione, phenolic compounds, and flavonoids. Additionally, the overproduction of methylglyoxal in water-stressed treated plants was controlled by the enhanced activity of the glyoxalase system enzymes; glyoxalase I and glyoxalase II. The treated plants maintained higher water content related to the higher content of osmotic regulatory substances like soluble sugars, free amino acids, glycinebetaine, and proline. CONCLUSIONS: Collectively, we offer the first report that identifies the underlying mechanism by which the dual application of vermicompost and EM confers drought tolerance in wheat by improving osmolyte accumulation and modulating antioxidant defense and glyoxalase systems.

Scavenging of Methylglyoxal by the Total Flavonoids of Apocyni Veneti Folium in Mice.

Scavenging MGO has been considered as an effective strategy for preventing atherosclerosis. A previous study showed that the total flavonoids of Apocyni Veneti Folium (TFAVF) had a significant antiatherosclerotic effect. However, there are no studies that have investigated the MGO scavenging capacities of TFAVF in mice. We found that TFAVF consisted mainly of quercetin glycosides and kaempferol glycosides using ultrahigh performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS/MS). TFAVF was first demonstrated to effectively scavenge MGO in mice based on the formation of mono-MGO-quercetin, mono-MGO-dehydroquercetin, mono-MGO-isorhamnetin, mono-MGO-dehydroisorhamnetin, mono-MGO-kaempferol, and mono-MGO-dehydrokaempferol. In addition, one mono-MGO-quercetin was separated and purified, and its structure was elucidated as 8-MGO-quercetin based on UHPLC-QTOF-MS/MS and NMR data. Quantification studies have demonstrated that kaempferol, dehydrokaempferol, quercetin, dehydroquercetin, isorhamnetin, and dehydroisorhamnetin can dose dependently scavenge MGO in mice. Taken together, these results indicated that TFAVF showed a significant antiatherosclerotic effect, which might be based on MGO detoxification.

Multi-response kinetic study of Maillard reaction hazards in the glucose-lysine model system.

BACKGROUND: Nε-carboxymethyllysine (CML), Nε-carboxyethyllysine (CEL) and α-aminoadipic acid (AAA) are important foodborne hazards and their intake can cause a variety of diseases in humans. It is extremely important to investigate the formation mechanism of CML, CEL and AAA, as well as their association with each other when aiming to control their production. RESULTS: A multi-response kinetic model was developed within the glucose-lysine Maillard reaction model system. The concentrations of glucose, lysine, glyoxal (GO), methylglyoxal (MGO), CML, CEL and AAA were quantified at different temperature (100-160 °C) and at different intervals (0-60 min). The experimental data were fitted to the proposed model to calculate kinetic parameters for the corresponding steps. The results indicated that the production of CML was primarily relied on the direct oxidative cleavage of the Amadori product, rather than the reaction between GO and Lys, whereas CEL and AAA were generated through the reaction of MGO with Lys. Significantly, the reaction between α-dicarbonyl compounds and Lys preferentially generated CML and CEL, resulting in the lower concentrations of AAA compared to CML and CEL. CONCLUSION: The multi-response kinetic model developed in the present study can be applied well to the Maillard reaction. The relationship between the formation mechanisms of CML, CEL and AAA is also explained. © 2024 Society of Chemical Industry.

Methylglyoxal mediates the association between 2-hour plasma glucose and HbA1c with inflammation: The Maastricht Study.

CONTEXT: Glucose excursions in persons with diabetes may drive chronic inflammation. Methylglyoxal (MGO) is formed from glucose, is elevated in persons with diabetes, and is a potent glycating agent linked with inflammation. OBJECTIVE: We investigated whether glucose excursions are associated with low-grade inflammation and whether MGO mediates this association. DESIGN: We used data from The Maastricht Study, an extensive phenotyping study into the etiology of type 2 diabetes and its complications. PARTICIPANTS: Data of 3017 participants, who underwent an oral glucose tolerance test and where data on MGO levels and inflammation were available, were used. MAIN OUTCOME MEASURES: Linear regression analyses, adjusted for potential confounders, evaluated associations between fasting plasma glucose (FPG), 2-hours plasma glucose (2h-PG) and HbA1c and low-grade inflammation (stdß, [95% confidence interval]), calculated from plasma concentrations of C-reactive protein, serum amyloid A, interleukin-6, interleukin-8, tumor necrosis factor and soluble intercellular adhesion molecule-1. Mediation analyses investigated whether MGO mediated these associations. RESULTS: 2h-PG (0.172 [0.110; 0.234]) and HbA1c (0.148 [0.101; 0.196]), but not FPG (0.049 [-0.002; 0.100]), were associated with low-grade inflammation. 2h-PG and HbA1c were also associated with 2h-MGO (0.471 [0.407; 0.534], and 0.244 [0.195; 0.294], respectively). Furthermore, 2h-MGO was independently and positively associated with low-grade inflammation (0.078 [0.037, 0.120]). 2h-MGO mediated 23% of the association between 2h-PG and inflammation, and 16% of the association between HbA1c and inflammation. CONCLUSIONS: MGO mediates the association between post-load glucose excursions and HbA1c with inflammation, providing evidence for a role of postprandial MGO formation to hyperglycemia-induced low-grade inflammation.

Loss of NAMPT and SIRT2 but not SIRT1 attenuate GLO1 expression and activity in human skeletal muscle.

Glyoxalase I (GLO1) is the primary enzyme for detoxification of the reactive dicarbonyl methylglyoxal (MG). Loss of GLO1 promotes accumulation of MG resulting in a recapitulation of diabetic phenotypes. We previously demonstrated attenuated GLO1 protein in skeletal muscle from individuals with type 2 diabetes (T2D). However, whether GLO1 attenuation occurs prior to T2D and the mechanisms regulating GLO1 abundance in skeletal muscle are unknown. GLO1 expression and activity were determined in skeletal muscle tissue biopsies from 15 lean healthy individuals (LH, BMI: 22.4 ± 0.7) and 5 individuals with obesity (OB, BMI: 32.4 ± 1.3). GLO1 protein was attenuated by 26 ± 0.3 % in OB compared to LH skeletal muscle (p = 0.019). Similar reductions for GLO1 activity were observed (p = 0.102). NRF2 and Keap1 expression were equivocal between groups despite a 2-fold elevation in GLO1 transcripts in OB skeletal muscle (p = 0.008). GLO1 knock-down (KD) in human immortalized myotubes promoted downregulation of muscle contraction and organization proteins indicating the importance of GLO1 expression for skeletal muscle function. SIRT1 KD had no effect on GLO1 protein or activity whereas, SIRT2 KD attenuated GLO1 protein by 28 ± 0.29 % (p < 0.0001) and GLO1 activity by 42 ± 0.12 % (p = 0.0150). KD of NAMPT also resulted in attenuation of GLO1 protein (28 ± 0.069 %, p = 0.003), activity (67 ± 0.09 %, p = 0.011) and transcripts (50 ± 0.13 %, p = 0.049). Neither the provision of the NAD+ precursors NR nor NMN were able to prevent this attenuation in GLO1 protein. However, NR did augment GLO1 specific activity (p = 0.022 vs NAMPT KD). These perturbations did not alter GLO1 acetylation status. SIRT1, SIRT2 and NAMPT protein levels were all equivocal in skeletal muscle tissue biopsies from individuals with obesity and lean individuals. These data implicate NAD+-dependent regulation of GLO1 in skeletal muscle independent of altered GLO1 acetylation and provide rationale for exploring NR supplementation to rescue attenuated GLO1 abundance and activity in conditions such as obesity.

Methylglyoxal Affects the Expression of miR-125b, miR-107, and Oxidative Stress Pathway-associated Genes in the SH-SY5Y Cell Line.

Purpose: Alzhеimеr's disеasе (AD) is thе most prеvalеnt form of dеmеntia globally. Rеsеarch links thе incrеasе of rеactivе oxidativе spеciеs (ROS) to thе pathogеnеsis of AD; thus, this study invеstigatеd thе impact of mеthylglyoxal (MGO) on thе еxprеssion of miR-125b, miR-107, and gеnеs involvеd in oxidativе strеss signaling in SH-SY5Y cеlls. Methods: Thе MTT assay assеssеd MGO's еffеcts on SH-SY5Y viability. miR-125b and miR-107 еxprеssion was analyzеd via rеal-timе PCR. Additionally, thе Human Oxidativе Strеss Pathway Plus RT2 Profilеr PCR array quantifiеd oxidativе pathway gеnе еxprеssion. Results: MGO concеntrations undеr 700µM did not significantly rеducе SH-SY5Y viability. MiR-125b and miR-107 еxprеssion in SH-SY5Y cеlls incrеasеd and dеcrеasеd rеspеctivеly (P<0.05). Cеlls trеatеd with 700µM MGO еxhibitеd incrеasеd CCS, CYBB, PRDX3, SPINK1, CYGB, DHCR24 and BAG2 еxprеssion (P<0.05). Thosе trеatеd with 1400µM MGO showеd incrеasеd CCS, CYBB, PRDX3, SPINK1, DUSP1, EPHX2, EPX, FOXM1, and GPX3 еxprеssion (P<0.05). Conclusion: MGO altеrs oxidativе strеss pathway gеnе, miR-125b, and miR-107 еxprеssion in SH-SY5Y cеlls. Targеting MGO or miR-125b and miR-107 may providе novеl AD thеrapеutic stratеgiеs or improvе sеvеrе symptoms. Furthеr rеsеarch should еlucidatе thе prеcisе mеchanisms.

Capture of single or multiple reactive carbonyl species by mangiferin under high temperatures.

Reactive carbonyl species (RCS), including acrolein (ACR), methylglyoxal (MGO), and glyoxal (GO), are typically generated in food processing and accumulate in the body for ages, triggering various chronic diseases. Here, we investigated the capture capability and reaction pathways of mangiferin one-to-one and one-to-many on RCS in high temperatures using UPLC-MS/MS. We found that mangiferin can capture ACR/MGO/GO to form their adducts, yet, the ability to capture RCS is arranged in different orders, with ACR > MGO > GO for a single RCS and MGO > ACR > GO for multiple RCS. After synthesizing and identifying the structures of the ACR- and MGO-adducts of MGF, our results indicated that MGF-ACR-MGO produced in the multiple-RCS-MGF system was formed by capturing MGO through MGF-ACR rather than through MGF-MGO capturing ACR, which resulting in higher inhibitory activity of MGF against MGO than against ACR. Then, the capture ability and path of MGF on RCS were verified in the coffee-leaves tea and cake.

Catalytic elevation effect of methylglyoxal on invertase and characterization of MGO modification products.

Reactive carbonyl species can modify digestive enzymes upon intake due to their electrophilic nature. This study evaluated the effects of methylglyoxal (MGO), glyoxal, acrolein, and formaldehyde on invertase, an enzyme presents in digestive tract. Unexpectedly, MGO enhanced, rather than inhibited, invertase activity. Moreover, MGO counteracted the inhibitory effects of the other three carbonyls on invertase activity. Kinetic analyses revealed that 150 mmolLexp.-1 MGO resulted in a 2-fold increase in the Km and a 3.3-fold increase in Vmax, indicating that MGO increased the turnover rate of sucrose while reducing the substrate binding affinity of invertase. Additionally, MGO induced dynamic quenching of fluorescence, reduced free amino groups, increased hydrophobicity, the content of Amadori products, fluorescent and nonfluorescent AGEs, and amyloid fibrils of invertase. The specific modifications responsible for the elevated activity of MGO on invertase require further investigation.

Methylglyoxal induces death in human brain neuronal cells (SH-SY5Y), prevented by metformin and dapagliflozin.

Diabetes mellitus is a metabolic disorder caused by a dysfunction in insulin action or secretion, leading to an elevation in blood glucose levels. It is a highly prevalent condition and as a result, the NHS spends 10 % of its entire budget on diabetes mellitus care, that is equivalent to £10 billion a year. Diabetes mellitus has been linked with vascular and neurological complications which may be associated with the progression of neurodegeneration and Alzheimer's disease. Chronic hyperglycaemia increases the production of the reactive oxidant species (ROS) such as methylglyoxal (MGO). MGO has been linked with vascular complications, neuropathy and cytotoxicity. The main aim of this study was to investigate the potential beneficial effect of antidiabetic agents such as metformin and dapagliflozin on human brain neuronal cells (SH-SY5Y) treated with MGO. SH-SY5Y cells were cultured in DMEM/F12 media and subjected overnight incubation with one of the following treatment conditions: Control (untreated); MGO (1 µM); MGO (100 µM); metformin (100 µM) + MGO (100 µM); and dapagliflozin (10 µM) + MGO (100 µM). Several assays were conducted to explore the effect of the treatment groups on the SH-SY5Y cells. These included: MTT assay; LDH assay, peroxynitrite fluorescence assay, and laser scanning confocal microscopy. MGO (100 µM) led to significant cell injury and damage and significantly reduced the survival of the cells by approximately 50-75 %, associated with significant increase in peroxynitrite. The addition of metformin (100 µM) or dapagliflozin (10 µM) represented significant protective effects on the cells and prevented the cell damage caused by the high MGO concentration. As a result, the findings of this research reveal that MGO-induced cell damage may partly be mediated by the generation of peroxynitrite, while the antidiabetic agents such as metformin and dapagliflozin prevent brain cell death, which potentially may play prophylactic roles against the risk of dementia in diabetic patients.

Taurine, alpha lipoic acid and vitamin B6 ameliorate the reduced developmental competence of immature mouse oocytes exposed to methylglyoxal.

Advanced glycation end products (AGEs) are the final products of the Maillard reaction, formed through the interaction of carbohydrates and proteins. Reactive dicarbonyl compounds such as methylglyoxal (MGO) serve as precursors for AGEs formation. Elevated levels of MGO/AGEs are observed in conditions like obesity, polycystic ovarian syndrome (PCOS), and diabetes, negatively impacting oocyte development. Previous studies have shown that hydrogen sulfide, a gasotransmitter with anti-AGEs effects, is produced in a process influenced by vitamin B6. R-α-lipoic acid (ALA) inhibits protein glycation and AGEs formation while stimulating glutathione (GSH) production. Taurine mitigates oxidative stress and acts as an anti-glycation compound, preventing in vitro glycation and AGEs accumulation. This study aimed to explore the ameliorative effects of a micronutrient support (Taurine, ALA and B6: TAB) on mouse oocytes challenged with MGO. Our results indicate that MGO reduces oocyte developmental competence, while TAB supplementation improves maturation, fertilization, and blastocyst formation rates. TAB also restores cell lineage allocation, redox balance and mitigates mitochondrial dysfunction in MGO-challenged oocytes. Furthermore, cumulus cells express key enzymes in the transsulfuration pathway, and TAB enhances their mRNA expression. However, TAB does not rescue MGO-induced damage in denuded oocytes, emphasizing the supportive role of cumulus cells. Overall, these findings suggest that TAB interventions may have significant implications for addressing reproductive dysfunctions associated with elevated MGO/AGEs levels. This study highlights the potential of TAB supplementation in preserving the developmental competence of COCs exposed to MGO stress, providing insights into mitigating the impact of dicarbonyl stress on oocyte quality and reproductive outcomes.