Glyoxalase Research Articles

A D-lactate dehydrogenase from rice is involved in conferring tolerance to multiple abiotic stresses by maintaining cellular homeostasis

D-lactate dehydrogenase (D-LDH) converts D-lactate (the end product of glyoxalase system) to pyruvate and thereby completes the detoxification process of methylglyoxal. D-LDH detoxifies and diverts the stress induced toxic metabolites, MG and D-lactate, towards energy production and thus, protects the cell from their deteriorating effects. In this study, a D-LDH enzyme from rice (OsD-LDH2, encoded by Os07g08950.1) was characterized for its role in abiotic stress tolerance. For this, a combination of in silico, molecular, genetic and biochemical approaches was used. The kinetic analysis revealed OsD-LDH2 to be the most efficient D-LDH enzyme in comparison to D-LDHs from other plant species. Heterologous overexpression of OsD-LDH2 provides tolerance against multiple abiotic stresses in E. coli, yeast and plant system. The analysis of D-LDH mutant and OsD-LDH2 overexpressing transgenic plants uncovered the crucial role of D-LDH in mitigation of abiotic stresses. OsD-LDH2 overexpressing plants maintained lower level of ROS and other toxic metabolites along with better functioning of antioxidant system. This is the first report on correlation of D-LDH with multiple abiotic stress tolerance. Overall, OsD-LDH2 emerged as a promising candidate which can open a new direction for engineering stress tolerant crop varieties by maintaining their growth and yield in unfavorable conditions.

Resveratrol, Curcumin and Piperine Alter Human Glyoxalase 1 in MCF-7 Breast Cancer Cells.

Breast cancer is the leading cause of cancer mortality in women worldwide. Conventional cancer treatment is costly and results in many side effects. Dietary bioactive compounds may be a potential source for breast cancer prevention and treatment. In this scenario, the aim of this study was to investigate the effects of the bioactive compounds resveratrol, curcumin and piperine (R-C-P) on MCF-7 breast cancer cells and to associate them to Glyoxalase 1 (GLO1) activity. The findings indicate that R-C-P exhibits cytotoxicity towards MCF-7 cells. R-C-P decreased mitochondrial membrane potential (ΔΨm) by 1.93-, 2.04- and 1.17-fold, respectively. Glutathione and N-acetylcysteine were able to reverse the cytotoxicity of the assessed bioactive compounds in MCF-7 cells. R-C-P reduced GLO1 activity by 1.36-, 1.92- and 1.31-fold, respectively. R-C-P in the presence of antimycin A led to 1.98-, 1.65- and 2.16-fold decreases in D-lactate levels after 2 h of treatment, respectively. Glyoxal and methylglyoxal presented cytotoxic effects on MCF-7 cells, with IC50 values of 2.8 and 2.7 mM and of 1.5 and 1.4 mM after 24 and 48 h of treatment, respectively. In conclusion, this study demonstrated that R-C-P results in cytotoxic effects in MCF-7 cells and that this outcome is associated with decreasing GLO1 activity and mitochondrial dysfunction.

Ellagic acid: A potent glyoxalase-I inhibitor with a unique scaffold.

The glyoxalase system, particularly glyoxalase-I (GLO-I), has been approved as a potential target for cancer treatment. In this study, a set of structurally diverse polyphenolic natural compounds were investigated as potential GLO-I inhibitors. Ellagic acid was found, computationally and experimentally, to be the most potent GLO-I inhibitor among the tested compounds which showed an IC50 of 0.71 mmol L-1. Its binding to the GLO-I active site seemed to be mainly driven by ionic interaction via its ionized hydroxyl groups with the central Zn ion and Lys156, along with other numerous hydrogen bonding and hydrophobic interactions. Due to its unique and rigid skeleton, it can be utilized to search for other novel and potent GLO-I inhibitors via computational approaches such as pharmacophore modeling and similarity search methods. Moreover, an inspection of the docked poses of the tested compounds showed that chlorogenic acid and dihydrocaffeic acid could be considered as lead compounds worthy of further optimization.

Involvement of L-Cysteine Desulfhydrase and Hydrogen Sulfide in Glutathione-Induced Tolerance to Salinity by Accelerating Ascorbate-Glutathione Cycle and Glyoxalase System in Capsicum.

The aim of this study is to assess the role of l-cysteine desulfhydrase (l-DES) and endogenous hydrogen sulfide (H2S) in glutathione (GSH)-induced tolerance to salinity stress (SS) in sweet pepper (Capsicum annuum L.). Two weeks after germination, before initiating SS, half of the pepper seedlings were retained for 12 h in a liquid solution containing H2S scavenger, hypotaurine (HT), or the l-DES inhibitor dl-propargylglycine (PAG). The seedlings were then exposed for three weeks to control or SS (100 mmol L−1 NaCl) and supplemented with or without GSH or GSH+NaHS (sodium hydrosulfide, H2S donor). Salinity suppressed dry biomass, leaf water potential, chlorophyll contents, maximum quantum efficiency, ascorbate, and the activities of dehydroascorbate reductase, monodehydroascorbate reductase, and glyoxalase II in plants. Contrarily, it enhanced the accumulation of hydrogen peroxide, malondialdehyde, methylglyoxal, electrolyte leakage, proline, GSH, the activities of glutathione reductase, peroxidase, catalase, superoxide dismutase, ascorbate peroxidase, glyoxalase I, and l-DES, as well as endogenous H2S content. Salinity enhanced leaf Na+ but reduced K+; however, the reverse was true with GSH application. Overall, the treatments, GSH and GSH+NaHS, effectively reversed the oxidative stress and upregulated salt tolerance in pepper plants by controlling the activities of the AsA-GSH and glyoxalase-system-related enzymes as well as the levels of osmolytes.

Nitrate reductase is required for salicylic acid-induced water stress tolerance of pepper by upraising the AsA-GSH pathway and glyoxalase system.

A trial was conducted to evaluate whether nitrate reductase (NR) participates in salicylic acid (SA)-improved water stress (WS) tolerance in pepper (Capsicum annuum L.) plants. Before starting WS treatment, 0.5 mM SA was applied to half of the well-watered (WW) plants as well as to WS-plants as a foliar spray once a day for a week. The soil water holding capacity was maintained at 40 and 80% of the full water storing capacity for WS and and well-watered (WW) plants, respectively. Water stress caused substantial decreases in total plant dry weight, Fv /Fm , chlorophyll a and b, relative water content, leaf water potential (ΨI) by 53, 37, 49, 21, 36 and 33%, respectively relative to control, but significant increases in malondialdehyde (MDA), hydrogen peroxide (H2 O2 ), electrolyte leakage (EL), methylglyoxal (MG), proline, key antioxidant enzymes' activities, NO and NR activity. The SA reduced oxidative stress, but improved antioxidant defence system, ascorbate-glutathione (AsA-GSH) cycle enzymes, glyoxalase system-related enzymes, glyoxalase I (Gly I) and glyoxalase II (Gly II), plant growth, photosynthetic traits, NO, NR and proline. SA-induced WS tolerance was further improved by supplementation of sodium nitroprusside (SNP), a donor of NO. NR inhibitor, sodium tungstate (ST) was applied in conjunction with SA and SA + SNP to the WW and WS-plants to assess whether NR contributes to SA-improved WS tolerance. ST abolished the beneficial effects of SA by reducing NO and NR activity in WS-pepper, but the application of SNP along with SA + ST reversed negative effects of ST, showing that NO and NR are jointly needed for SA-induced WS tolerance of pepper plants.

Zinc Oxide Nanoparticles Application Alleviates Arsenic (As) Toxicity in Soybean Plants by Restricting the Uptake of as and Modulating Key Biochemical Attributes, Antioxidant Enzymes, Ascorbate-Glutathione Cycle and Glyoxalase System

Accumulation of arsenic (As) in soils is increasing consistently day-by-day, which has resulted in increased toxicity of this element in various crop plants. Arsenic interferes with several plant metabolic processes at molecular, biochemical and physiological levels, which result in reduced plant productivity. Hence, the introduction of novel ameliorating agents to combat this situation is the need of the hour. The present study was designed to examine the effect of zinc oxide nanoparticles (ZnO–NPs) in As-stressed soybean plants. Various plant growth factors and enzymes were studied at varying concentrations of As and ZnO–NPs. Our results showed that with the application of ZnO–NPs, As concentration declined in both root and shoot of soybean plants. The lengths of shoot and root, net photosynthetic rate, transpiration, stomatal conductance, photochemical yield and other factors declined with an increase in external As level. However, the application of ZnO–NPs to the As-stressed soybean plants resulted in a considerable increase in these factors. Moreover, the enzymes involved in the ascorbate–glutathione cycle including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) showed a significant increase in their activity with the application of ZnO–NPs to the As-stressed plants. Hence, our study confirms the significance of ZnO–NPs in alleviating the toxicity of As in soybean plants.

Effects of exogenous melatonin and glutathione on zinc toxicity in safflower (Carthamus tinctorius L.) seedlings.

The phytotoxicity caused by 500μM ZnSO4.7H2O and its detoxifying by co-application of 100μM of MT melatonin (MT) and glutathione (GSH) in 6-week-old safflower plants have been investigated. Reduced biomass production and total chlorophyll content on the one hand and increased content of hydrogen peroxide (H2O2), malondialdehyde (MDA) with increase in lipoxygenase activity, on the other hand, showed Zn- induced oxidative damage in safflower seedlings. When MT, GSH and especially MT+GSH exogenously were applied to Zn-stressed seedlings, the content of H2O2, MDA and the activity of lipoxygenase considerably decreased. In Zn- treated seedlings, the application of these signaling molecules led to a considerable increment in ascorbate (ASC), GSH and phytochelatin (PC) contents along with the induction of activity of antioxidant enzymes including ascorbate-glutathione cycle enzymes when compared with the plants stressed with Zn only. In Zn-stressed safflower seedlings treated with MT, GSH and MT+GSH, decreased activity of enzymes involved in glyoxalase system may be associated with the role of MT and GSH in reducing Zn uptake and reducing Zn-induced toxicity and subsequently, lower plant's defense responses. The data showed that the effects of MT and GSH, in particular, the combination of these two molecules in reducing Zn uptake and diminishing its accumulation in the shoots of safflower seedlings, and also the participation of MT and GSH on increasing plant ability to tolerate high amount of Zn through stimulation of various antioxidant defense systems suggest them as suitable candidates to better the survival of safflower in soils contaminated with Zn excess.

609 The topical tanning agent dihydroxyacetone induces stress response gene expression and signaling in human reconstructed epidermis and SKH1 hairless mouse skin

Chemical tanning is widely regarded as a safe alternative to solar UV-induced skin tanning, but the cutaneous biology impacted by chemical tanning remains largely unexplored. Chemical tanning is based on the formation of melanin-mimetic cutaneous pigments (‘melanoidins’) from spontaneous glycation reactions between epidermal amino acid/protein components and reactive sugars including the glycolytic ketose dihydroxyacetone (DHA). Here, we have examined cutaneous effects of acute DHA exposure on cultured human keratinocytes, epidermal reconstructs, and mouse skin employing gene epression array analysis and immunodetection. In human HaCaT keratinocytes, DHA (1-20 mM; 6 h) did not impair viability while causing a stress response with activation of phospho-protein signal transduction [p-p38, p-Hsp27, p-eIF2α] and gene expression (HSPA6, HMOX1, CRYAB, CCL3), not observed in response to the tanning-inactive DHA-control glycerol. Formation of DHA-specific advanced glycation endproducts resulting from posttranslational protein adduction was confirmed by mass spectrometric detection of N-ε-(carboxyethyl)-L-lysine and N7-carboxyethyl-L-arginine. Skin cells with CRISPR-Cas9 elimination of the carbonyl stress response gene GLO1 (glyoxalase 1) displayed hypersensitivity to DHA cytotoxicity. A topical DHA regimen elicited a similar stress response in human epidermal reconstructs [EpidermTM; 1-10% DHA in carrier; 6-24 h] as revealed by expression array (HSPA1A, HSPA6, HSPD1, IL6, DDIT3, EGR1) and IHC analysis (CEL, HO-1, p-Hsp27). In SKH1 mouse skin, gene expression analysis confirmed a topical DHA-induced stress response substantiated by IHC-detection of CEL and p-Hsp27. Given the worldwide use of chemical tanners including DHA in consumer products these prototype data deserve further molecular exploration in living human skin.

RES transformation for biosynthesis and detoxification.

The reactive electrophilic species (RES), typically the molecules bearing α,β-unsaturated carbonyl group, are widespread in living organisms and notoriously known for their damaging effects. Many of the mycotoxins released from phytopathogenic fungi are RES and their contamination to cereals threatens food safety worldwide. However, due to their high reactivity, RES are also used by host organisms to synthesize specific metabolites. The evolutionary conserved glyoxalase (GLX) system scavenges the cytotoxic α-oxoaldehydes that bear RES groups, which cause host disorders and diseases. In cotton, a specialized enzyme derived from glyoxalase I (GLXI) through gene duplications and named as specialized GLXI (SPG), acts as a distinct type of aromatase in the gossypol pathway to transform the RES intermediates into the phenolic products. In this review, we briefly introduce the research progress in understanding the RES, especially the RES-type mycotoxins, the GLX system and SPG, and discuss their application potential in detoxification and synthetic biology.

Construction of 6x myc tagged plant expression vector pBA 002 carrying Rhizophora mucronata Lam. specific glyoxalase I via homologous recombination

Plants are subjected to internal damage during stress conditions due to enhanced levels of methyl glyoxal (MG). Glyoxalase enzymes play the key role in MG detoxification and help the plant to survive. The glyoxalase system of Rhizophora mucronata Lam. was decoded; characterized and salt dependant increase in gene expression was analyzed in our previous studies ( GenBank Accessions GGEC01061405, GGEC01044968, and GGEC01022591) . In order to utilize these stress responsive genes in crop improvement, it is needed to monitor their methylglyoxal detoxification efficiency in vivo . For this, over expression of the glyoxalase enzyme(s) in a model/cop plant system can be done. Construction of a binary vector carrying coding region of glyoxalase gene(s) which can replicate both in E coli and Agrobacterium tumefaciens is the prime step in plant transformation research. In the present study in silico cloning of glyoxalase I, II and III specific to R. mucronata (Rm GLY I, Rm GLY II and Rm GLY III) were performed into pBA 002 plant expression vector carrying 6x myc insert. The binary vector is linearized with BSrG1 restriction enzyme. Cloning primers for all the three glyoxalase coding regions with 5’ end terminal homology to the linear myc pBA were synthesized and validated in vitro . To account for in silico cloning, the Rm GLY I insert was successfully cloned via homologous recombination into myc pBA. The presence of Rm GLYI insert in the final construct was confirmed by colony PCR and sequence analysis.

Silicon is dependent on hydrogen sulphide to improve boron toxicity tolerance in pepper plants by regulating the AsA-GSH cycle and glyoxalase system

The role of endogenous hydrogen sulphide (H2S) in silicon-induced improvement in boron toxicity (BT) tolerance in pepper plants was studied. Two-week old seedlings were subjected to control (0.05 mM B) or 2.0 mM BT in a nutrient solution. These two treatments were combined with 2.0 mM Si. BT caused considerable reduction in biomass, chlorophyll a &b, photosystem II maximum quantum efficiency (Fv/Fm), glutathione and ascorbate in the pepper seedlings. However, it enhanced malondialdehyde (MDA) and hydrogen peroxide, electrolyte leakage, proline, H2S, and activities of catalase, superoxide dismutase, peroxidase, and L-DES. Silicon stimulated growth, proline content and activities of various antioxidant biomolecules and enzymes, leaf Ca2+, K+ and N, endogenous H2S and L-DES activity, but reduced H2O2 and MDA contents, membrane leakage and leaf B. Silicon-induced B tolerance was further enhanced by 0.2 mM NaHS, a H2S donor. A scavenger of H2S, hypotaurine (0.1 mM HT), was supplied together with Si and Si + NaHS to assess the involvement of H2S in Si-induced BT tolerance of pepper plants. Hypotaurine inverted the positive role of Si on the antioxidant defence system by reducing endogenous H2S, but NaHS supply along with Si + HT reversed the negative effects of HT, showing that H2S participated in Si-induced BT tolerance of pepper plants.

434-P: Possible Mechanisms of Cardioprotective Effects of Metformin in Patients with Type 2 Diabetes and Chronic Heart Failure

Background and Aims: Metformin (MET) treatment in patients with type 2 diabetes (T2D) and chronic heart failure (HF) is associated with better cardiovascular outcomes. Possible mechanism of cardioprotective effect of metformin may be a reduction of dicarbonyl and oxidative stress. In particular, a reduction of methylglyoxal levels (MG). The aim of our study was to evaluate the effect of MET on cardiac structure, cardiac function and exercise capacity in patients with T2D and HF. Materials and Methods: A randomized, double-blind, placebo-controlled, crossover study in a total time of six months testing the effect of 3- month usage of MET (2 g/day) vs. placebo. A group of 44 treatment naive patients with T2D and HF were included. At the beginning and at the end of each intervention period various metabolic tests were done including echocardiography, spiroergometry, and parameters of dicarbonyl stress like MG, Glutathione (GSH), glutathione disulfide (GSSG), and the activity of Glyoxalase1 (GLO-1). Results: MET treatment led to a decrease in HbA1c levels (∆ MET vs. placebo: -3.39 ± 5.33mmol/mol, p = 0.00007), and fasting plasma glucose levels (∆MET vs. placebo: -0.381 ± 1.1mmol/l; p = 0.00145). MET had no effect on oxygen consumption at the maximum tolerated load during spiroergometry (VOmax) (∆MET vs. placebo: -0.142 ± 1.18ml/kg/min; p = 0.64). MET did not affect left ventricular ejection fraction (∆MET vs. placebo: -0.789 ± 6.32%; p = 0.53). The levels of MG didn’t change after MET (∆ MET vs. placebo: 0.0306 ± 0.13nmol/ml; p = 0.19). The activity of GLO-1 was not affected too (∆ MET vs. placebo: 0.0073 ± 0.017 mmol/min/mg Hb; p = 0.22). Conclusion: MET treatment is safe in patients with severe heart failure. Our results do not support the evidence that one of the cardioprotective pathways of metformin is through reducing dicarbonyl stress. Disclosure E. Hošková: None. J. Kopecky: None. J. Veleba: None. H. Malinska: None. K. Velebova: None. V. Melenovsky: None. T. Pelikanova: None. Funding Institute for Clinical and Experimental Medicine 00023001)

The sunless tanning agent dihydroxyacetone induces stress response gene expression and signaling in cultured human keratinocytes and reconstructed epidermis

Sunless (chemical) tanning is widely regarded as a safe alternative to solar UV-induced skin tanning known to be associated with epidermal genotoxic stress, but the cutaneous biology impacted by chemical tanning remains largely unexplored. Chemical tanning is based on the formation of melanin-mimetic cutaneous pigments (‘melanoidins’) from spontaneous amino-carbonyl (‘glycation’) reactions between epidermal amino acid/protein components and reactive sugars including the glycolytic ketose dihydroxyacetone (DHA). Here, we have examined the cutaneous effects of acute DHA-exposure on cultured human HaCaT keratinocytes and epidermal reconstructs, profiled by gene expression array analysis and immunodetection. In keratinocytes, DHA-exposure performed at low millimolar concentrations did not impair viability while causing a pronounced cellular stress response as obvious from rapid activation of phospho-protein signal transduction [p-p38, p-Hsp27(S15/S78), p-eIF2α] and gene expression changes (HSPA6, HMOX1, CRYAB, CCL3), not observable upon exposure to the non-ketose, tanning-inactive DHA-control glycerol. Formation of advanced glycation end products (AGEs) from posttranslational protein-adduction was confirmed by quantitative mass spectrometric detection of N-ε-(carboxyethyl)-l-lysine (CEL) and N7-carboxyethyl-l-arginine, and skin cells with CRISPR-Cas9-based elimination of the carbonyl stress response gene GLO1 (encoding glyoxalase 1) displayed hypersensitivity to DHA-cytotoxicity. In human epidermal reconstructs a topical use-relevant DHA-dose regimen elicited a comparable stress response as revealed by gene expression array (HSPA1A, HSPA6, HSPD1, IL6, DDIT3, EGR1) and immunohistochemical analysis (CEL, HO-1, p-Hsp27-S78). In DHA-treated SKH-1 hairless mouse skin IHC-detection revealed epidermal occurrence of CEL- and p-Hsp27-epitopes. For comparison, stress response gene expression array analysis was performed in epidermis exposed to a supra-erythemal dose of solar simulated UV (2 MEDs), identifying genes equally or differentially sensitive to either one of these cutaneous stimuli [DHA (‘sunless tanning’) versus solar UV (‘sun-induced tanning’)]. Given the worldwide use of chemical tanners in consumer products, these prototype data documenting a DHA-induced specific cutaneous stress response deserve further molecular exploration in living human skin.

Salicylic acid-induced nitric oxide enhances arsenic toxicity tolerance in maize plants by upregulating the ascorbate-glutathione cycle and glyoxalase system

The role of nitric oxide (NO) in salicylic acid (SA)-induced tolerance to arsenic (As) stress in maize plants is not reported in the literature. Before starting As stress (AsS) treatments, SA (0.5 mM) was sprayed to the foliage of maize plants. Thereafter, AsV (0.1 mM as sodium hydrogen arsenate heptahydrate) stress (AsS) was initiated and during the stress period, sodium nitroprusside (SNP 0.1 mM), a NO donor, was sprayed individually or in combination with SA. Furthermore, cPTIO (0.1 mM) was also applied as a NO scavenger during the stress period. Arsenic stress led to significant reductions in plant growth, photosynthesis, water relation parameters and endogenous NO content, but it increased hydrogen peroxide, malondialdehyde, electrolyte leakage, methylglyoxal, proline, the activities of major antioxidant enzymes, and leaf and root As content. The combined treatment of SA+SNP was more effective to reverse oxidative stress related parameters and reduce the As content in both leaves and roots, with a concomitant increase in antioxidant defense system, the ascorbate-glutathione (AsA-GSH) cycle-related enzymes, glyoxalase system enzymes, plant growth, and photosynthetic traits. The beneficial effects of SA were completely abolished with cPTIO supply by blocking the NO synthesis in AsS-maize plants, indicating that NO effectively participated in SA-improved tolerance to AsS in maize plants.

Discovery of GLO1 New Related Genes and Pathways by RNA-Seq on A2E-Stressed Retinal Epithelial Cells Could Improve Knowledge on Retinitis Pigmentosa.

Endogenous antioxidants protect cells from reactive oxygen species (ROS)-related deleterious effects, and an imbalance in the oxidant/antioxidant systems generates oxidative stress. Glyoxalase 1 (GLO1) is a ubiquitous cellular enzyme involved in detoxification of methylglyoxal (MG), a cytotoxic byproduct of glycolysis whose excess can produce oxidative stress. In retinitis pigmentosa, one of the most diffuse cause of blindness, oxidative damage leads to photoreceptor death. To clarify the role of GLO1 in retinitis pigmentosa onset and progression, we treated human retinal pigment epithelium cells by the oxidant agent A2E. Transcriptome profiles between treated and untreated cells were performed by RNA-Seq, considering two time points (3 and 6 h), after the basal one. The exposure to A2E highlighted significant expression differences and splicing events in 370 GLO1 first-neighbor genes, and 23 of them emerged from pathway clustered analysis as main candidates to be associated with retinitis pigmentosa. Such a hypothesis was corroborated by the involvement of previously analyzed genes in specific cellular activities related to oxidative stress, such as glyoxylate and dicarboxylate metabolism, glycolysis, axo-dendritic transport, lipoprotein activity and metabolism, SUMOylation and retrograde transport at the trans-Golgi network. Our findings could be the starting point to explore unclear molecular mechanisms involved in retinitis pigmentosa etiopathogenesis.

Thiamine pyrophosphate improved vascular complications of diabetes in rats with type 2 diabetes by reducing glycation, oxidative stress, and inflammation markers.

Background: Thiamine deficiency contributes to hyperglycemia and diabetes complications. Thus, in this study, the effect of thiamine pyrophosphate (TPP) on the in vivo and in vitro formation of glycation, oxidative stress, and inflammatory markers (the main contributors of vascular diabetes complications) was examined in type 2 diabetes rat model. Methods: Type 2 diabetes was induced in rats with a combination of streptozotocin and nicotinamide (55+200 mg/kg). Two groups of rats, healthy and diabetic, were treated with 0.1% TPP in drinking water daily for 3 months and the 2 others received water only. The glucose, insulin, early to end glycation products, the activity of glyoxalase system, lipid profile, LDL oxidation markers, inflammatory markers, creatinine in the serum, and proteinuria in the urine of all rats were determined. Moreover, albumin and LDL were incubated with glucose in the presence and absence of TPP, and the samples were investigated for glycation and oxidation products. Different variables in all 4 groups were compared with multiple analysis of variance (MANOVA-Tukey) test using SPSS version 16. Significance level was set at p<0.05. Results: TPP decreased the formation of diverse glycation and oxidation products in both in vivo (glycated LDL= 144.50±3.48 and oxidized LDL= 54.08±2.67 μmol/l) and in vitro (glycated LDL= 107.00±2.82 and oxidized LDL= 50.83±1.22 μmol/l). In addition, the vitamin reduced fasting blood sugar (9.23±0.29), insulin resistance (9.10±0.50), tumor necrosis factor-α (285.43±15.97), interleukin-6 (257.65±13.06), and improved the lipid profile, the activity of Glo system (Glo-I= 31.65±1.06 and Glo-II= 27.01±0.90 U/mL) and renal function in the diabetic rat (p<0.001). Conclusion: TPP decreased the major risk factors for diabetic complications and corrected the alternations of glucose and lipid metabolism in type 2 diabetic rats; thus, it is recommended for diabetes treatment.

The Role of Glyoxalase in Glycation and Carbonyl Stress Induced Metabolic Disorders.

Glycation refers to the covalent binding of sugar molecules to macromolecules, such as DNA, proteins, and lipids in a non-enzymatic reaction, resulting in the formation of irreversibly bound products known as advanced glycation end products (AGEs). AGEs are synthesized in high amounts both in pathological conditions, such as diabetes and under physiological conditions resulting in aging. The body's anti-glycation defense mechanisms play a critical role in removing glycated products. However, if this defense system fails, AGEs start accumulating, which results in pathological conditions. Studies have been shown that increased accumulation of AGEs acts as key mediators in multiple diseases, such as diabetes, obesity, arthritis, cancer, atherosclerosis, decreased skin elasticity, male erectile dysfunction, pulmonary fibrosis, aging, and Alzheimer's disease. Furthermore, glycation of nucleotides, proteins, and phospholipids by α-oxoaldehyde metabolites, such as glyoxal (GO) and methylglyoxal (MGO), causes potential damage to the genome, proteome, and lipidome. Glyoxalase-1 (GLO-1) acts as a part of the anti-glycation defense system by carrying out detoxification of GO and MGO. It has been demonstrated that GLO-1 protects dicarbonyl modifications of the proteome and lipidome, thereby impeding the cell signaling and affecting age-related diseases. Its relationship with detoxification and anti-glycation defense is well established. Glycation of proteins by MGO and GO results in protein misfolding, thereby affecting their structure and function. These findings provide evidence for the rationale that the functional modulation of the GLO pathway could be used as a potential therapeutic target. In the present review, we summarized the newly emerged literature on the GLO pathway, including enzymes regulating the process. In addition, we described small bioactive molecules with the potential to modulate the GLO pathway, thereby providing a basis for the development of new treatment strategies against age-related complications.

Pretreatment of wheat (Triticum aestivum L.) seedlings with 2,4-D improves tolerance to salinity-induced oxidative stress and methylglyoxal toxicity by modulating ion homeostasis, antioxidant defenses, and glyoxalase systems

The commonly used herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) has an as yet undetermined protective role in mitigating salinity-induced damage in crop plants. The aim of this study was to explore the possible roles of antioxidant defense and methylglyoxal (MG) detoxification systems in enhancing salt tolerance in wheat (Triticum aestivum L. cv. Norin 61) seedlings following pretreatment with 2,4-D. Wheat seedlings were grown hydroponically, pretreated with 10 μM 2,4-D for 48 h, and then exposed to salt stress (150 and 250 mM NaCl) for the next five days. The protective effect of 2,4-D was associated with increased antioxidant enzyme activity and ascorbate and glutathione content, and with decreased malondialdehyde and hydrogen peroxide content and reduced electrolytic leakage. Application of 2,4-D increased glyoxalase enzyme activity, resulting in greater MG detoxification. Seedlings pretreated with 2,4-D showed improved growth, biomass, and leaf water content due to reductions in Na+ accumulation and increases in K+, Ca2+, and Mg2+ uptake. Overall, these results highlight the potential use of this common herbicide as a phytoprotectant against salinity stress.

Ethephon mitigates nickel stress by modulating antioxidant system, glyoxalase system and proline metabolism in Indian mustard.

The role of ethylene (through application of ethephon) in the regulation of nickel (Ni) stress tolerance was investigated in this study. Ethephon at concentration of 200µll-1 was applied to mustard (Brassica juncea) plants grown without and with 200mgkg-1 soil Ni to study the increased growthtraits, biochemical attributes, photosynthetic efficiency, nutrients content, activities of antioxidants such as superoxide dismutase, ascorbate peroxidase, glutathione reductase, and glutathione peroxidase, glyoxalase systems and enhanced the proline metabolism. In the absence of ethephon, Ni increased oxidative stress with a concomitant decrease in photosynthesis, growth and nutrients content. However, application of ethephon positively increased growth traits, photosynthetic parameters, nutrients content and also elevated the generation of antioxidants enzymes and glyoxalase systems, proline production to combat oxidative stress. Plants water relations and cellular homeostasis were maintained through increased photosynthetic efficiency and proline production. This signifiesthe role of ethylene in mediating Ni tolerance via regulating proline production and photosynthetic capacity. Ethephon can be used as an exogenous supplement on plants to confer Ni tolerance. The results can be exploited to develop tolerance in plants via gene editing technology encoding enzymes responsible for proline synthesis, antioxidant defence, glyoxalase systems and photosynthetic effectiveness.

Exogenous vanillic acid enhances salt tolerance of tomato: Insight into plant antioxidant defense and glyoxalase systems

We investigated vanillic acid-induced salt tolerance in tomato by exploring the plant defense systems. Ten-d-old tomato (Solanum lycopersicum L. cv. Pusa Ruby) seedlings were treated with salt (NaCl; 150 mM) and vanillic acid (VA; 40 and 50 μM) separately and in combination with salt. Salinity restricted seedlings growth, biomass accumulation, chlorophyll and carotenoid contents. Salt-induced osmotic stress was indicated by lower leaf relative water content (RWC) and elevated proline (Pro) content, where higher Na+/K+ ratio indicated the ionic toxicity. Tomato seedlings went through oxidative damage due to acute reactive oxygen species (ROS) production and lipoxygenase (LOX) activity and confirmed by higher lipid peroxidation and membrane damage under salinity. Conversely, exogenous VA reduced osmotic and ionic toxicity in stressed-seedlings by enhancing the RWC and Pro level, and lowering Na+/K+ ratio, respectively. Exogenous VA up-regulated the components of antioxidant defense system in salt-treated seedlings resulted in the reduction of ROS production, LOX activity and membrane damage in stressed-seedlings. Additionally, VA application caused the reduction of toxic methylglyoxal accumulation under salt stress through the enhancement of glyoxalase system. Thus, VA-induced alleviation of osmotic, ionic and oxidative stresses leading to improve plant growth and chlorophyll synthesis in stressed-seedlings. So, VA significantly improves salinity tolerance and plant growth performance by involving the actions of plant antioxidant defense and glyoxalase systems.