Inhibit Protein Glycation Research Articles

Characterization of polysaccharide fractions from fruit of Actinidia arguta and assessment of their antioxidant and antiglycated activities

A novel cell-wall polysaccharides (AAPs) were extracted from the fruits of Actinidia arguta and separated into four parts which were named water-eluted polysaccharide (WPS), salt-eluted polysaccharide (SPS)-1, SPS-2 and SPS-3. The monosaccharide composition and structural analysis showed that SPS-3 and SPS-2 were homogalacturonan (HG)-rich pectin, SPS-1 was rhamnogalacturonan (RG)-rich pectin and WPS was starch-like polysaccharides. All four kinds of polysaccharides displayed the ability to scavenge free radicals, chelate iron ion, inhibit lipid peroxidation and inhibit protein glycation, but SPS was obviously stronger than WPS. Especially SPS-3 displayed the strongest antioxidant and anti-glycated activities. In addition, the inhibitory effect of AAPs on AGEs formation is attributed to the inhibitory activity on the production of protein carbonyl group and the protective effects on the protein thiol group but not the scavenging capacity of dicarbonyl compounds, suggesting that its mechanisms of antiglycated effects may be of concern to their antioxidant activities.

In vitro antiglycation and hypoglycaemic effects of Syzygium cumini leaf extracts

Glycation is a prime mechanism responsible for chronic diabetic complications, a process which is enhanced under hyperglycaemia. Natural inhibitors of protein glycation and those which can lower postprandial blood glucose elevation are of utmost importance in minimising the damage caused by diabetes. One objective of this study was to assess the in vitro inhibitory effects of Syzygium cumini (SC) leaf extracts on protein glycation and α-glucosidase activity. The other objective was to identify the type of inhibition on α-amylase activity. SC leaf powder was sequentially extracted with hexane (H), ethyl acetate (E), methanol (M) and water (W). In vitro inhibitory effects of extracts on protein glycation, α-amylase and α-glucosidase enzymes were measured. M and W were the major fractions recovered [50.74 and 27.94 % (w/w), respectively] while H was the smallest fraction [7.35 % (w/w)] out of total yield. All extracts inhibited fructosamine formation, protein glycation and protein crosslinking at 2 mgmL-1. At 0.05 mgmL-1, fructosamine formation was inhibited in the presence of E, M and W while there was no significant inhibition with H. At 0.1 mgmL-1, antiglycation effect of the H extract was negligible while other extracts retained their effects. IC50 values of H, E, M and W extracts against α-glucosidase were 7.89, 3.11, 0.86 and 0.69 μgmL-1, respectively. A mixed type inhibitory effect was observed on α-amylase with E, M and W extracts. H extract did not inhibit α-amylase. In conclusion, the results provide evidence for antiglycation and hypoglycaemic effects of SC leaf extracts demonstrating better activities in E, M and W extracts.

Shikimic acid from Artemisia absinthium inhibits protein glycation in diabetic rats

This study investigated the impact of Shikimic Acid (SA) obtained from leaves of Artemisia absinthium on protein glycation in the retina of diabetic rats. The GC/MS analysis of A. absinthium showed that the most abundant bioactive compound was SA (C7H10O5) with a measured retention Index (RI) of 1960 compared to that of the reference sample (1712). Male albino rats were divided into two main groups, Group I (control) and Group II (diabetic); Group II was further divided into four subgroups: Group IIa (diabetic control), Group IIb (diabetic rats were given SA orally [50 mg/kg, body weight (bw)/day], Group IIc diabetic rats were given SA orally [100 mg/kg, bw/day], and Group IId (diabetic rats were given metformin orally [100 mg/kg, bw/day] as positive control). The data obtained suggested that SA reduced glucose and glycated hemoglobin levels. In addition, SA also decreased the formation of glucose-derived advanced glycation end products. Interestingly, SA showed interference with the release of inflammatory mediators in retina and possess antioxidant potential. In conclusion, SA protected the tissues from detrimental effects of hyperglycemia and enhanced antioxidant activity. SA could be a potential lead in the process of drug development in the future to prevent retinopathy in diabetic subjects.

Improved Methods for the Rapid Formation and Prevention of Advanced Glycation End Products (AGEs) In Vitro by Coupling to the Hypoxanthine/Xanthine Oxidase Assay System.

Advanced glycation end products (AGEs) represent a set of molecules that contribute directly to the initiation and aggravation of diseases associated with ageing. AGEs are produced by the reaction between reducing sugars (or α-dicarbonyl compounds), proteins, and amino acid residues. Previous in vitro methods using non-enzymatic procedures described in the literature require an incubation period of 1–3 weeks to generate AGEs. In this study, the reaction time for the formation of AGEs (48 and 3 h) was significantly reduced by adaptation of methods previously described in the literature and coupling them to the free radical generation system termed hypoxanthine/xanthine oxidase assay. The incorporation of this assay into the experimental system accelerated the production of AGEs as a result of the formation of reactive oxygen species (ROS), as shown by increased fluorescence. The capacity of different classes of chemical compounds (aminoguanidine, chlorogenic acid, rutin, and methanol extracts of Hancornia speciosa Gomes) to inhibit protein glycation by acting as scavenging agents of α-dicarbonyl species was evaluated. Aminoguanidine and, especially, rutin identified in the leaf extracts of H. speciosa Gomes showed a high capacity to act as scavengers of reactive carbonyl species RCS-trapping, resulting in the inhibition of AGEs formation.

Anthranilic Acid Derivatives: Novel Inhibitors of Protein Glycation and the Associated Oxidative Stress in the Hepatocytes.

Anthranilic acid derivatives are important pharmacophores in drug discovery. Several of them are currently being used, such as mefenamic acid and meclofenamates, possess analgesic, anti-inflammatory and antipyretic activities. Some anthranilic acid-based scaffolds have also been reported for the management of metabolic disorders. The aim of the current study was to investigate the antiglycation potential of 2-anilino benzoic acid derivatives against (N-phenylanthranilic acid) fructose- human serum albumin (HSA) glycation. The study also analyzed the effects of newly identified antiglycation inhibitors on AGEs-mediated intracellular reactive oxygen species production, and associated impaired proliferation of the hepatocytes. The present study focuses on the antiglycation activity of 2- anilinobenzoic acid derivatives 1-18 in in-vitro human serum albumin (HSA)- fructose model. These derivatives were also identified as non-toxic to 3T3 mouse fibroblast cell-line using metabolic assay. The effect of the most promising derivative 1, 2- (2, 4- dinitroanilino)benzoic acid, was studied in a dose dependent manner, co-incubated with fructose-derived AGEs (0- 200 μg/mL), on rat hepatocytes proliferation and associated intracellular generation of ROS via MTT assay and DCFH-DA technique, respectively. We found that derivative 1 ameliorates the elevated intracellular oxidative stress and associated diminished proliferation of the hepatocytes in response to AGEs. In conclusion, we identify novel 2- anilino benzoic acid derivatives as antiglycation agents through in-vitro and cellular-based models.

GLYCATION INHIBITORS AND PROBIOTICS CAN AMELIORATE THE CHANGES CAUSED BY HIGH FRUCTOSE FEED

Objective: To evaluate the use of protein glycation inhibitors and probiotics to ameliorate secondary complications in diabetes and to improve gut microbiota respectively in high fructose fed Wistar rat.Methods: The study was conducted on male Wistar rats for 7 d. Blood glucose levels in oral glucose tolerance test (OGTT) were measured using glucometer, serum parameters were analyzed using commercial kits, antioxidant status was evaluated by measuring superoxide dismutase (SOD) and catalase (CAT) levels, total reactive oxygen species were estimated using a fluorescent 2’, 7’-dichlorofluorescin diacetate (DCF-DA) dye, and tissue fluorescence of liver, kidney and intestine were measured using a spectrofluorimeter.Results: OGTT pattern shows significant increase in blood glucose of fructose fed rats i.e. 154 mg/dl while, in aminoguanidine (AMG) treated and gut microbiota modulated animals it is 137 and 119 mg/dl resp. after 30 min on glucose administration. Marked reduction was found in SOD 6.37 and 11.25 mg/dl and catalase 186 and 65.5 mg/dl in liver and kidney of fructose fed animals when compared to fructose+AMG and fructose+EUGI. There is 5-6 fold significant increase in general and specific tissue fluorescence of liver and kidney, and 2.2 fold increase in liver reactive oxygen species was observed in fructose fed group as compare to control animals. Significantly higher glycation was found in intestine of fructose fed animals (general fluorescence 2.1 and specific fluorescence 3.1 AU/mg), more than that of diabetic control rats (general fluorescence 0.9 and specific fluorescence 1.6 AU/mg), represented an evidence for adverse impact of excess fructose on healthy gut.Conclusion: The use of protein glycation inhibitor and use of pre and probiotics significantly improved the serum parameters and would prevent progression to secondary complications.

Phytate Decreases Formation of Advanced Glycation End-Products in Patients with Type II Diabetes: Randomized Crossover Trial

Myo-inositol hexaphosphate (phytate; IP6) is a natural compound that is abundant in cereals, legumes, and nuts and it has the ability to chelate metal cations. The binding of IP6 to transition metals suggests that it could be used for the treatment of metal-catalyzed protein glycation, which appears to trigger diabetes-related diseases. Our in vitro studies showed that IP6 reduced the formation of Fe3+-catalyzed advanced glycation end-products (AGEs). This led us to perform a randomized cross-over trial to investigate the impact of the daily consumption IP6 on protein glycation in patients with type 2 diabetes mellitus (T2DM; n = 33). Thus, we measured AGEs, glycated hemoglobin (HbA1c), several vascular risk factors, and urinary IP6 at baseline and at the end of the intervention period. Patients who consumed IP6 supplements for 3 months had lower levels of circulating AGEs and HbA1c than those who did not consume IP6. This is the first report to show that consumption of IP6 inhibits protein glycation in patients with T2DM. Considering that AGEs contribute to microvascular and macrovascular complications in T2DM, our data indicates that dietary supplementation with IP6 should be considered as a therapy to prevent the formation of AGEs and therefore, the development of diabetes-related diseases in patients with T2DM.

Antiglycation and antioxidant activities of mogroside extract from Siraitia grosvenorii (Swingle) fruits.

Siraitia grosvenorii (Swingle) is one kind of medical and edible plants with various health-promoting properties. Recently, its hypoglycemic and antidiabetic activities have been reported, but the underlying mechanism remains to be explored. The current study was aimed to investigate the antioxidant and antiglycation activities of mogroside extract (MGE) from Siraitia grosvenorii (Swingle). The results showed that compared to glycated BSA, MGE at middle (125μg/mL) and high dose (500μg/mL) significantly inhibited BSA glycation evidenced by decreased fluorescent AGEs formation, protein carbonyls and Nε-(carboxymethyl) lysine (CML) level at 500μg/mL by 58.5, 26.7 and 71.2%, respectively. Additionally, the antiglycative activity of MGE (500μg/mL) was comparable to aminoguanidine (AG) at the equal concentration. However, the inhibitory effect of MGE on glycation-induced increase of fructosamine level and decrease of thiol level was not remarkable. MGE was a potent peroxide radicals scavenger (851.8μmol TE/g), moderate DPPH and ABTS radicals scavenger with IC50 1118.1 and 1473.2μg/mL, respectively, corresponding to positive controls ascorbic acid of IC50 9.6μg/mL, and trolox of IC50 47.9μg/mL, respectively, and mild reducing power. These findings suggest that MGE may serve as a new promising antiglycative agent against diabetic complications by inhibiting protein glycation and glycoxidation.

Evaluation of the Antioxidant and Antiglycation Effects of Lactarius deterrimus and Castanea sativa Extracts on Hepatorenal Injury in Streptozotocin-Induced Diabetic Rats.

The present study aimed to investigate the beneficial effects of the treatment with extracts from the edible mushroom Lactarius deterrimus (Ld) and the chestnut Castanea sativa (Cs), separately and in combination (MIX Ld/Cs), on oxidative stress and advanced glycation end-product (AGE)-mediated hepatorenal injury in a rat model of streptozotocin (STZ)-induced diabetes by examining pathways responsible for maintenance of redox homeostasis. An experimental model of diabetes was induced in rats by the administration of 40 mg/kg STZ intraperitoneally (i.p.) for 5 consecutive days. The examined extracts were applied separately at a dose of 60 mg/kg i.p. and in combination (60 mg/kg each extract; i.p.) for 4 weeks, starting from the last day of STZ administration. The improvement of hepatorenal function in diabetic rats treated with the extracts was associated with an improved glycemic and lipid status and suppression of oxidative stress and thereby oxidative damage of lipids and DNA. Besides the fact that both extracts inhibited protein glycation and AGE formation in vitro, they also reduced non-enzymatic glycosylation in diabetic rats in vivo. The observed antiglycation activity of the examined extracts (separately and in combination) was accompanied with the inhibition of CML-mediated RAGE/NF-κB activation and reduction of enzymatic O-GlcNAcylation in liver and kidney tissues of diabetic rats. Taken together, these results reveal that the administration of chestnut and mushroom extracts, either individually or together, activates a coordinated cytoprotective response against diabetes-induced hepatorenal injury not only through recovery of the antioxidant defense system of the cell, but also through a marked antiglycation activity.

Effective inhibition of protein glycation by combinatorial usage of limonene and aminoguanidine through differential and synergistic mechanisms

Protein glycation is a major mechanism for establishing secondary complication in diabetes mellitus. Effective inhibition of this process can prevent progression of the disorder into secondary complications. Aminoguanidine (AMG) and limonene (LM) are known protein glycation inhibitors. The aim of the present study was to demonstrate their differential mechanisms of action and to study whether combinatorial therapy can act synergistically and lower dosage, and thereby lower toxicity in treatment of secondary complications in diabetes. Glycation in the presence of 2M urea was inhibited by 23% with AMG and by 66% with LM. AMG is more effective than LM in reducing protein carbonyl formation. SPR studies revealed binding of LM reduces affinity of BSA for glucose. LM demonstrated an increase by 2°C in thermal transition in DSC studies as against reduction by 0.4°C by AMG proving that LM can effectively stabilize the protein structure. Combinatorial treatment of AMG and LM prevented α-helix to β-sheet transitions in BSA at 100μM and inhibited AGE related fluorescence and pentosidine formation by 80 and 90% respectively. The combination can reduce dosage of AMG by almost twenty times, paving the way for effective protein glycation inhibition without toxicity.

Identification of natural products and their derivatives as promising inhibitors of protein glycation with non-toxic nature against mouse fibroblast 3T3 cells

<p>This study was performed to identify new inhibitors of protein glycation <em>in vitro</em>. Protein glycation is one of the major causes of late diabetic complications. In this study, terpenoids and alkaloids, isolated from different medicinal plants, along with their derivatives, were evaluated for their antiglycation activity <em>in vitro,</em> while MTT assay on mouse fibroblast 3T3 cells was used to assess their potential cytotoxicity. Among the tested compounds, gossypol (2,2′-<em>bis</em>-(formyl-1,6,7-trihydroxy-5-isopropyl-3-methylnaphthalene) (<strong>1</strong>), isolated from<em> Gossypium herbaceum, </em>and its derivatives,<em> </em>gossypol acetic acid (<strong>2</strong>), gossypolidene- 4-aminoantipyrine (<strong>4</strong>), and gazolidone (<strong>6</strong>), showed a potent antiglycation activity (IC<sub>50</sub> < 16 <em>µ</em>M), while gossypolidene-4-aminoantipyrine (<strong>5</strong>) showed a significant antiglycation activity with IC<sub>50 </sub>value 82.934±2.924<em> µ</em>M, in BSA-fluorescence assay. Alkaloid, noscapine (3S)-6,7-Dimethoxy-3-[(5R)-4-methoxy-6-methyl-5,6,7,8-tetrahy-dro-1,3-dioxolo[4,5-g]isoquinolin-5-yl] isobenzofuran-1(3<em>H</em>)-one (<strong>7</strong>), isolated from <em>Papaver somniferum, N</em>-nitrosoaphyllinic acid (<strong>9</strong>), a derivative of alkaloid aphylline<em>, </em>and 2<em>H</em>-quinolizine, octahydro salt (<strong>11</strong>), a salt of alkaloid lupinine, exhibited significant inhibition activity with<em> </em>IC<sub>50 </sub>values 152.662±5.432, 393.758 ±4.001 µM and 110.203±4.816µM, respectively. Similarly, compounds<strong> </strong>gossypolidene thiocarbamide (<strong>3</strong>), deoxypeganine hydrochloride (<strong>8</strong>)<strong>, </strong>lupinine (<strong>10</strong>) and cytisine (<strong>12</strong>) showed moderate inhibition with IC<sub>50</sub> values of 401.865 ±18.450, 863.322 ±6.415, 712.176±7.745, and 728.462±2.331<em> </em>µM, respectively. The results were compared with the standard antiglycation agent, rutin (<strong>13</strong>) (IC<sub>50 </sub>=98.012±2.030 µM).</p>Cellular cytotoxicity assay showed only gossypol acetic acid (<strong>2</strong>) and gossypolidene thiocarbamide (<strong>3</strong>) as somewhat toxic to 3T3 (mouse fibroblast) cells with IC<sub>50 </sub>values<em> </em>2.07 ±0.61 and 5.00 ±1.89 µM, respectively. Cycloheximide was used as a standard in this assay with IC<sub>50</sub> value 0.3 ± 0.089 μM

High Phenolic Beer Inhibits Protein Glycation in Vitro

Protein glycation is a nonenzymatic process in which amino residues of proteins react with sugar groups, causing protein cross-linking. This contributes to many complications associated with diabetes. Phenolic compounds from fruits and vegetables have been found to inhibit protein glycation. Because of the high volume in which beer is consumed, it has the potential to be an excellent phenolic delivery system. We studied five beer styles (American pale ale, porter, stout, India pale ale, and Imperial India pale ale) for their phenolic and antioxidant contents and their effects on protein glycation. All beers were subjected to the Folin–Ciocalteu and ferric-reducing antioxidant power assays to assess the phenolic and antioxidant contents, respectively. All styles significantly inhibited protein glycation on a volumetric (4 μL/mL) basis, and all but one inhibited glycation based on phenolics (4 μg of phenols/mL). All beers significantly inhibited protein glycation based on antioxidant content (60 nmol of FeSO4 equivalents/mL), showing significant inhibition compared with both a control and a noncraft (i.e., mass production) beer. This demonstrates that certain beers can inhibit protein glycation at low concentrations and may, in certain individuals, significantly contribute to daily consumption of phenolic compounds.

Xanthium strumarium as an inhibitor of protein glycation, protein tyrosine phosphatase 1β, and α-glucosidase

Xanthium strumarium as an inhibitor of protein glycation, protein tyrosine phosphatase 1β, and α-glucosidase

Glutathione is the main endogenous inhibitor of protein glycation.

Glycation is the cause of diabetic complications and contributes to the development of other diseases and aging. Numerous exogenous compounds have been tested for their anti-glycating activity. The aim of this study was to answer the question, which endogenous compounds at physiological concentrations can effectively prevent glycation. A set of endogenous compounds has been tested for the ability to protect albumin from glucose-induced glycation in vitro at a concentration of 1 mM and in a physiological concentration range. Only glutathione was found to protect significantly against glycation at physiological concentrations. Glutathione depletion increased the rate of hemoglobin glycation in erythrocytes incubated with high glucose concentrations. These results indicate that the level of glutathione is the main determinant of glycation of intracellular proteins.

Inhibition of Glycation-induced Cytotoxicity, Protein Glycation, and Activity of Proteolytic Enzymes by Extract from Perovskia atriplicifolia Roots.

Background:Protein glycation and glycotoxicity belong to the main oxidative-stress related complications in diabetes. Perovskia species are used in Asian folk medicine as antidiabetic herbs.Objective:The aim of this study was to verify the ability of the methanolic extract from Perovskia atriplicifolia Benth. roots to diminish glycation of albumin and to prevent cell damage in vitro. Furthermore, we tested the extract for in vitro antioxidant activity and inhibition of elastase and collagenase.Material and Methods:The aqueous methanol extract was analyzed by UHPLC-MS for the content of polyphenols and terpenoids. The prevention of glycated albumin-induced cell damage was tested in four mammalian cell lines (peripheral blood mononuclear cells, human embryonic kidney cells – HEK293, normal human fibroblasts, and Chinese hamster ovary cells) with the 5-(3-carboxymethoxyphenyl)-2-(4,5-dimethylthiazoly)-3-(4-sulfophenyl) tetrazolium assay.Results:Glycated albumin is significantly more toxic than native human serum albumin (LC50 from 35.00 to 48.34 μg/mL vs. 5.47–9.10 μg/mL, respectively). The extract, rich in rosmarinic acid (344.27 mg/g dry mass), mitigated the glycated albumin toxicity, and increased glycated albumin-treated cell survival by more than 50%. The inhibition of advanced glycation endproduct formation was confirmed by monitoring conformational changes. The free radical scavenging activity was higher than Trolox and metal reducing power was one-third to half that of ascorbic acid. The activity of elastase and collagenase was inhibited by 54.75% ± 6.87% and 60.03% ± 7.22%, respectively.Conclusions:The results confirm antiglycative and antiglycotoxic potential of Perovskia root and its traditional antidiabetic use. The high activity can be attributed to rosmarinic acid abundance.SUMMARY Perovskia is a small genus of aromatic shrubby plants growing in arid regions of Central and South Asia. Different parts are used in folk medicine as antiparasitic, anti-infectious and antidiabetic remedy. Here, we have studied the extract from roots for inhibition of: glycation-induced cytotoxicity, human serum albumin glycation, inflammation-related enzymes, as well as for antioxidant activity. Result: the extract from P. atriplicifolia roots inhibited protein glycation and AGE-induced toxicity in cell cultures. The mechanism is likely to rely on the antioxidant activity of high content of rosmarinic acid. Abbreviations used: AGE: advanced glycation end-products; DPPH: 2,2-diphenyl-1-picrylhydrazyl; HSA: human serum albumin.

Protective effect of cyanidin against glucose- and methylglyoxal-induced protein glycation and oxidative DNA damage

Cyanidin, a natural anthocyanin abundant in fruits and vegetables, has shown the health benefits due to its pharmacological properties. However, there was no evidence regarding anti-glycation activity of cyanidin. The aim of the study was to investigate the inhibitory effect of cyanidin on methylglyoxal (MG)- and glucose-induced protein glycation in bovine serum albumin (BSA) as well as oxidative DNA damage. Free radical scavenging activity and the MG-trapping ability of cyanidin were also investigated. The results demonstrated that cyanidin (0.125–1mM) significantly inhibited the formation of fluorescent and non-fluorescent AGEs in BSA/MG and BSA/glucose systems. There was a significantly improved protein thiol in BSA/MG and BSA/glucose when incubated with cyanidin. Correspondingly, cyanidin decreased the level of protein carbonyl content in BSA/glucose system. Moreover, cyanidin (0.5–1mM) prevented lysine/MG-mediated oxidative DNA damage in the absence or presence of copper ion. The results demonstrated that cyanidin showed the MG-trapping ability in a concentration-dependent manner. Cyanidin also reduced superoxide anion and hydroxyl radical generation in lysine/MG system. The mechanism by which cyanidin inhibited protein glycation was the MG-trapping ability and the free radical scavenging activity. The present study suggests that cyanidin might be a promising antiglycation agent for preventing or ameliorating AGEs-mediated diabetic complications.

Polyamines regulate cell growth and cellular methylglyoxal in high-glucose medium independently of intracellular glutathione.

Polyamines can presumably inhibit protein glycation, when associated with the methylglyoxal inevitably produced during glycolysis. Herein, we hypothesized a nonenzymatic interaction between putrescine and methylglyoxal in putrescine-deficient or -overexpressing Dictyostelium cells in high-glucose medium, which can control methylglyoxal production. Putrescine was essentially required for growth rescue accompanying methylglyoxal detoxification when cells underwent growth defect and cell cycle G1-arrest when supplemented with high glucose. Furthermore, methylglyoxal regulation by putrescine seemed to be a parallel pathway independent of the changes in cellular glutathione content in high-glucose medium. Consequently, we suggest that Dictyostelium cells need polyamines for normal growth and cellular methylglyoxal regulation.

Aminoguanidine treatment increased NOX2 response in diabetic rats: Improved phagocytosis and killing of Candida albicans by neutrophils

In this study, we show that aminoguanidine (AMG), an inhibitor of protein glycation, increases the NOX2 (phagocyte NADPH oxidase) response and microbicidal activity by neutrophils, regardless of diabetic status. The non-enzymatic glycation of proteins, yielding irreversible advanced glycation end products (AGEs), is involved in the development of diabetes complications, including alterations of signaling pathways and the generation of reactive oxygen species by phagocytes. The phagocytes produce ROS (reactive oxygen species) through activation of the NOX2 complex, which generates superoxide. The purpose of this study was to evaluate the effect of hyperglycemia and the glycation of proteins on the NOX2 activity of neutrophils and its implications for cellular physiology, with a focus on the microbicidal activity of these cells. We treated diabetic rats with AMG and evaluated neutrophil ROS generation and Candida albicans killing ability. We observed a large increase in the microbicidal activity of peritoneal neutrophils from AMG-treated rats. The increase was independent of diabetic status and myeloperoxidase activity. Collectively, our results suggest that AMG has an immunomodulator role that triggers an increase in the microbicidal response of neutrophils mainly related to reactive oxygen species production by NOX2.

The synergistic effect of antiglycating agents (MB-92) on inhibition of protein glycation, misfolding and diabetic complications in diabetic-atherosclerotic rat

Protein glycation due to hyperglycemia resulting in misfolding and aggregation, which is known as one of the most important reasons of diabetes complications. We previously showed the beneficial effects of some antiglycating agents in diabetic rats. Here, the effect of MB-92, a combination of some amino acids and crocetin (Crt, a saffron carotenoid), was studied in the prevention of diabetic complications in diabetic-atherosclerotic rats. In addition, the inhibitory effect of these treatments on glycation intermediates, aggregation and misfolding of proteins was investigated both in vivo and in vitro. Thus, the streptozotocin-induced diabetic rats that underwent an atherogenic diet were treated with Crt, N-acetylcyctein and MB-92. Then, glycated products and markers of oxidation and inflammation, in addition to other markers of diabetes complications were studied. The results of the in vivo study indicated that the mentioned treatments prevented the atheromatos formation, reduced the increased blood glucose; inhibited the formation of various glycation products, induced glyoxalase system (I and II), diminished oxidation and inflammatory markers, and improved lipid profile and atherosclerotic index in the diabetic-atherosclerotic rats; but MB-92 was the most effective treatment. In vitro results also confirmed that MB-92 was the most effective treatment to inhibit protein glycation and misfolding in comparison with the other treatments. In conclusion, MB-92 showed the greatest potential for inhibition of glycation and oxidation products, atheromatose plaque formation and inflammation in diabetic-atherosclerotic rats, and to control protein glycation, misfolding and aggregation in high glucose concentration; thus, it can be suggested as a new drug to prevent diabetic complications.

Ethanolic extract of Passiflora edulis Sims leaves inhibits protein glycation and restores the oxidative burst in diabetic rat macrophages after Candida albicans exposure

abstract This study was conducted to evaluate the effects of the ethanolic extract of Passiflora edulis leaves on blood glucose, protein glycation, NADPH oxidase activity and macrophage phagocytic capacity after Candida albicans exposure in diabetic rats. The Passiflora edulis Sims leaves were dried to 40°C, powdered, extracted by maceration in 70% ethanol, evaporated under reduced pressure and lyophilised. The biochemical tests performed were total phenolic content (TP) as determined by the Folin-Ciocalteu assay, trapping potential DPPH assay and total iron-reducing potential. Diabetes was induced by alloxan injection. Protein glycation was determined by AGE and fructosamine serum concentrations. Extract-treated diabetic animals demonstrated lower fructosamine concentrations compared with the diabetic group. Our results suggest that ethanolic Passiflora edulis Sims leaf extraction may have beneficial effects on diabetes and may improve glycaemic control in diabetic rats.