Effects of oxidative modifications induced by the glycation of bovine serum albumin on its structure and on cultured adipose cells

Glycosylation editing: an innovative therapeutic opportunity in precision oncology

Cancer is still one of the most arduous challenges in the human society, even though humans have found many ways to try to conquer it. With our incremental understandings on the impact of sugar on human health, the clinical relevance of glycosylation has attracted our attention. The fact that altered glycosylation profiles reflect and define different health statuses provide novel opportunities for cancer diagnosis and therapeutics. By reviewing the mechanisms and critical enzymes involved in protein, lipid and glycosylation, as well as current use of glycosylation for cancer diagnosis and therapeutics, we identify the pivotal connection between glycosylation and cellular redox status and, correspondingly, propose the use of redox modulatory tools such as cold atmospheric plasma (CAP) in cancer control via glycosylation editing. This paper interrogates the clinical relevance of glycosylation on cancer and has the promise to provide new ideas for laboratory practice of cold atmospheric plasma (CAP) and precision oncology therapy.

D-Ribose-Induced Glycation and Its Attenuation by the Aqueous Extract of Nigella sativa Seeds

Background and Objectives: Glycation and oxidative stress are the major contributing factors responsible for diabetes and its secondary complications. Aminoguanidine, a hydrazine derivative, is the only approved drug that reduces glycation with its known side effects. As a result, research into medicinal plants with antioxidant and antiglycation properties is beneficial in treating diabetes and its consequences. This investigation aimed to examine the efficacy of the aqueous extract of Nigella sativa seeds against the D-ribose-induced glycation system. Materials and Methods: The suppression of α-amylase and α-glucosidase enzymes were used to assess the antidiabetic capacity. UV-Visible, fluorescence, and FTIR spectroscopy were used to characterize the Nigella sativa seed extract and its efficacy in preventing glycation. The inhibition of albumin glycation, fluorescent advanced glycation end products (AGEs) formation, thiol oxidation, and amyloid formation were used to evaluate the extracts' antiglycation activity. In addition, the extent of glycoxidative DNA damage was analyzed using agarose gel electrophoresis. Results: The IC₅₀ for the extract in the α-amylase and α-glucosidase enzyme inhibition assays were approximately 1.39 ± 0.016 and 1.01 ± 0.022 mg/mL, respectively. Throughout the investigation, it was found that the aqueous extract of Nigella sativa seeds (NSAE) inhibited the level of ketoamine, exerted a considerable drop in fluorescence intensity, and reduced carbonyl production and thiol modification when added to the D-ribose-induced glycation system. In addition, a reduction in the BSA-cross amyloid formation was seen in the Congo red, thioflavin T assay, and electrophoretic techniques. NSAE also exhibited a strong capability for DNA damage protection. Conclusion: It can be concluded that Nigella sativa could be used as a natural antidiabetic, antiglycation treatment and a cost-effective and environmentally friendly source of powerful bioactive chemicals.

Macromolecules Influence Cellular Competence and Expression Level of IGFs Genes in Bovine Oocytes In Vitro

In vitro maturation (IVM) of mammalian oocytes, which influences subsequent in vitro development of embryos, is affected by the macromolecule content in culture media for the success of oocyte maturation competence, in which the cytoplasmic and nuclear reprogramming events occur. The insulin-like growth factor family (IGFs) promotes the maturation of bovine oocytes and the expansion of cumulus cells and also inhibits apoptosis. This study was, therefore, designed to examine the effects of macromolecules (bovine serum albumin, BSA; fetal calf serum, FCS; and polyvinyl alcohol, PVA) on in vitro nuclear maturation, total cellular protein, glutathione peroxidase (GPx) enzyme activity, and the gene expression level of IGF1, IGF2, and their receptor in bovine oocytes. Oocytes obtained from bovine ovaries were cultured in bicarbonate-buffered medium 199 supplemented with 4 mg/mL BSA, 10% FCS, 1 mg/mL PVA, and without macromolecule supplement (control) during 22 h in the air with a humidified atmosphere and 5% CO2 at 38.5 °C temperature. Supplementation of BSA and FCS increased (χ2 = 9.84; p < 0.05) the percentages of oocytes that reached metaphase II compared to the control and PVA. The amount of protein per ml of cell extracts of oocytes matured in FCS supplemented culture media was higher (p < 0.05) than the oocytes in the PVA and control. The levels of GPx enzyme activity in cell extracts isolated from oocytes in each experimental group did not change over time, but the GPx enzyme activity in oocytes matured in PVA-supplemented culture media was lower (p < 0.05) than in oocytes in the other experimental groups. Transcript for the IGF1 gene was not detected in all experimental groups, but the supplementation of BSA and FCS significantly elevated the transcript level of the IGF2 gene. In addition, the maturation of oocytes with BSA-supplemented media increased the transcript level of the IGF1R gene, whereas the transcript level of the IGF2R gene was similar among macromolecule supplementation groups. The current study concluded that BSA and FCS could improve in vitro bovine oocyte development due to supporting nuclear maturation and increasing the total cellular protein content, GPx enzyme, and transcript activity.

Integrative Role of Albumin: Evolutionary, Biochemical and Pathophysiological Aspects

Being one of the main proteins in the human body and many animal species, albumin plays a crucial role in the transport of various ions, electrically neutral molecules and in maintaining the colloidal osmotic pressure of the blood. Albumin is able to bind almost all known drugs, many nutraceuticals and toxic substances, determining their pharmaco- and toxicokinetics. However, albumin is not only the passive but also the active participant of the pharmacokinetic and toxicokinetic processes possessing a number of enzymatic activities. Due to the thiol group of Cys34, albumin can serve as a trap for reactive oxygen and nitrogen species, thus participating in redox processes. The interaction of the protein with blood cells, blood vessels, and also with tissue cells outside the vascular bed is of great importance. The interaction of albumin with endothelial glycocalyx and vascular endothelial cells largely determines its integrative role. This review provides information of a historical nature, information on evolutionary changes, inflammatory and antioxidant properties of albumin, on its structural and functional modifications and their significance in the pathogenesis of some diseases.

Serum Albumin in Health and Disease: Esterase, Antioxidant, Transporting and Signaling Properties

Being one of the main proteins in the human body and many animal species, albumin plays a decisive role in the transport of various ions-electrically neutral and charged molecules-and in maintaining the colloidal osmotic pressure of the blood. Albumin is able to bind to almost all known drugs, as well as many nutraceuticals and toxic substances, largely determining their pharmaco- and toxicokinetics. Albumin of humans and respective representatives in cattle and rodents have their own structural features that determine species differences in functional properties. However, albumin is not only passive, but also an active participant of pharmacokinetic and toxicokinetic processes, possessing a number of enzymatic activities. Numerous experiments have shown esterase or pseudoesterase activity of albumin towards a number of endogeneous and exogeneous esters. Due to the free thiol group of Cys34, albumin can serve as a trap for reactive oxygen and nitrogen species, thus participating in redox processes. Glycated albumin makes a significant contribution to the pathogenesis of diabetes and other diseases. The interaction of albumin with blood cells, blood vessels and tissue cells outside the vascular bed is of great importance. Interactions with endothelial glycocalyx and vascular endothelial cells largely determine the integrative role of albumin. This review considers the esterase, antioxidant, transporting and signaling properties of albumin, as well as its structural and functional modifications and their significance in the pathogenesis of certain diseases.

Glycation of albumin and its implication in Diabetes: A comprehensive analysis using mass spectrometry

AIM

To understand the mechanism of glycation of albumin and effects on cysteinylation and methionine oxidation.

METHODS

The in vitro glycation of HSA and BSA was studied with varying concentrations of glucose. Clinical blood samples of diabetic subjects with varying HbA1c values, were analyzed to assess in vivo glycation. All samples and their tryptic digests were analyzed using liquid chromatography/mass spectrometry. Glycation sites were mapped on to the three-dimensional structure of the HSA and BSA.

RESULTS

A total thirty-one sites for glycation and eight sites of N^ε-carboxymethyl-lysine (CML) modification were identified on albumin. The site selectivity of glycation was correlated with the environment of the reactive residue in the three-dimensional structure.

CONCLUSIONS

The maximum percentage glycation under extreme conditions was in the range of ~55 to 88% in four weeks. Two major glycation sites K-233 and K-525 were identified, which together accounted for 40-50% of total glycation. A correlation was observed between glycation and oxidation of methionine residues in samples glycated in vitro. The role of spatially proximate residues in facilitating the glycation process is evident. The tri- and tetra-glycated isoforms of albumin can serve as biomarkers for the severe uncontrolled diabetic state.

Generation and Characterization of Anti-Glucosepane Antibodies Enabling Direct Detection of Glucosepane in Retinal Tissue

Although there is ample evidence that the advanced glycation end-product (AGE) glucosepane contributes to age-related morbidities and diabetic complications, the impact of glucosepane modifications on proteins has not been extensively explored due to the lack of sufficient analytical tools. Here, we report the development of the first polyclonal anti-glucosepane antibodies using a synthetic immunogen that contains the core bicyclic ring structure of glucosepane. We investigate the recognition properties of these antibodies through ELISAs involving an array of synthetic AGE derivatives and determine them to be both high-affinity and selective in binding glucosepane. We then employ these antibodies to image glucosepane in aging mouse retinae via immunohistochemistry. Our studies demonstrate for the first time accumulation of glucosepane within the retinal pigment epithelium, Bruch's membrane, and choroid: all regions of the eye impacted by age-related macular degeneration. Co-localization studies further suggest that glucosepane colocalizes with lipofuscin, which has previously been associated with lysosomal dysfunction and has been implicated in the development of age-related macular degeneration, among other diseases. We believe that the anti-glucosepane antibodies described in this study will prove highly useful for examining the role of glycation in human health and disease.

The Universal Soldier: Enzymatic and Non-Enzymatic Antioxidant Functions of Serum Albumin

As a carrier of many biologically active compounds, blood is exposed to oxidants to a greater extent than the intracellular environment. Serum albumin plays a key role in antioxidant defence under both normal and oxidative stress conditions. This review evaluates data published in the literature and from our own research on the mechanisms of the enzymatic and non-enzymatic activities of albumin that determine its participation in redox modulation of plasma and intercellular fluid. For the first time, the results of numerous clinical, biochemical, spectroscopic and computational experiments devoted to the study of allosteric modulation of the functional properties of the protein associated with its participation in antioxidant defence are analysed. It has been concluded that it is fundamentally possible to regulate the antioxidant properties of albumin with various ligands, and the binding and/or enzymatic features of the protein by changing its redox status. The perspectives for using the antioxidant properties of albumin in practice are discussed.

Fewer Exposed Lysine Residues May Explain Relative Resistance of Chicken Serum Albumin to In Vitro Protein Glycation in Comparison to Bovine Serum Albumin

Protein glycation and formation of advanced glycation end products is associated with several diseases resulting from high blood glucose concentrations. Plasma albumin is directly exposed to circulating glucose concentrations and is therefore at greater risk of glycation than hemoglobin. As plasma glucose concentrations in birds are 1.5-2 times higher than mammals of similar mass, avian albumin may be particularly at risk of glycation. Thus, the goal of the present study was to compare the in vitro formation of glycated albumin in chicken serum albumin (CSA) and bovine serum albumin (BSA) exposed to a range of glucose concentrations over a 16-week period. The level of glycation for CSA and BSA was quantified using boronate affinity columns to separate glycated albumin from non-glycated albumin and calculating the difference in protein concentration of each sample. The results indicate that CSA is glycated to a lesser degree than BSA when the albumins are exposed to increasing concentrations of glucose (38.8-500 mM). This was most apparent at week sixteen (500 mM glucose) where BSA expressed a higher degree of glycation (37.8 ± 0.76%) compared to CSA (19.7 ± 1.06%, P < 0.05). Additionally, percent glycation at week sixteen was significantly higher than the glucose-free solutions for both BSA and CSA, indicating that glycation is glucose-dependent. Analyses of the protein structures suggest that the relative resistance of CSA to glycation may be due to fewer lysine residues and variations in protein folding that shield more lysine residues from the plasma. Moreover, comparisons of reconstructed ancestral albumin sequences show that the ancestor of birds had 6-8 fewer lysine residues compared to that of mammals.

Study of glycation process of human carbonic anhydrase II as well as investigation concerning inhibitory influence of 3-beta-hydroxybutyrate on it

Glycation is a non-enzymatic reaction between carbonyl groups in sugar and free amino groups in proteins. This reaction leads to changes in structure and functions of proteins in which the advanced glycation end products (AGEs) are the final outcome and cause many complications in diabetic patients. We herein examined the effect of fasting on the glycation process of human Carbonic anhydrase II under physiological conditions (37 °C and pH 7.4) employing various techniques, including Ultraviolet-visible spectroscopy, fluorescence spectroscopy and CD Spectroscopy. We found an increased 3-beta-hydroxybutyrate upon fasting. We studied various samples of control carbonic anhydrase (without glucose and 3-beta-hydroxybutyrate), carbonic anhydrase with glucose, carbonic anhydrase treated with 3-beta-hydroxybutyrate (BHB) and carbonic anhydrase along with glucose and 3-beta-hydroxybutyrate. The samples were incubated for 35 days under physiological conditions. Our results indicated that 3-beta-hydroxybutyrate inhibited the glycation process, decreased glucose binding to the protein, prevented the formation of AGEs, and modified the enzyme activity. Our findings would open new windows toward the enzymatic procedure which would have profound implication in understanding the diabetes mechanisms.

Glucose-mediated protein glycation: Contribution of methanolic extract of Ceratonia siliqua L. in protection and in vitro potential inhibition of acetylcholinesterase

Chronic hyperglycemia presents the major etiology of diabetes mellitus and related complications mainly Alzheimer's disease, via the protein glycation and toxic products generated. In the current study, we investigated the eventual protective effect of the methanolic extract of Ceratonia siliqua L. (CsME) against glucose-mediated glycation in serum bovine albumin. The multi-stage glycation markers, namely fructosamines and advanced glycation end products (AGEs) levels were monitored along with measurement of thiol groups; moreover, the in vitro acetylcholinesterase (AChE) inhibition potential was carried out. HPLC was also assessed. Rutin was the main phenolic compound found in CsME. CsME showed a good capacity to inhibit AGEs, fructosamines and protected thiol groups against glycation. CsME exhibited a great AChE inhibition activity. In the present study, CsME prevented glucose-induced protein glycation, it also exhibited a good inhibition of AChE, suggesting its DM complications such as memory troubles related to AD. PRACTICAL APPLICATIONS: Neurodegenerative disorders ranging from memory troubles to Alzheimer's disease present the most diabetes mellitus complications and mainly attributed to protein glycation process. Currently, there is a strong trend to search for efficient natural sources of glycation and acetylcholinesterase inhibitors to replace the synthetic ones, whose secondary effects were shown. The present article tries to justify scientifically the wide use of Ceratonia siliqua L. in Moroccan folk medicine, demonstrating that the methanolic extract of leaves from this species presents a promising source of new natural compounds inhibiting acetylcholinesterase and acting in vitro against glycation generated compounds. Furthermore, for the first time, Rutin was the main phenolic compound found in this extract, these encouraging results should be coupled with further studies to integrate it in pharmaceutical formulations. As such, this paper should be of interest to a broad readership, including those interested in Biochemistry, Phytochemistry, pharmacology, and neurosciences.

Advanced Glycation End Products of Bovine Serum Albumin Suppressed Th1/Th2 Cytokine but Enhanced Monocyte IL-6 Gene Expression via MAPK-ERK and MyD88 Transduced NF-κB p50 Signaling Pathways

Advanced glycation end products (AGE), the most known aging biomarker, may cause “inflamm-aging” (i.e., chronic low-grade inflammation that develops with aging) in both aged and diabetes groups. However, the molecular bases of inflamm-aging remain obscure. We prepared AGE by incubating BSA (0.0746 mmol/L) + glucose (0.5 mol/L) at 37 °C in 5% CO₂–95% air for 1–180 days. The lysine glycation in BSA–AGE reached 77% on day 30 and 100% after day 130, whereas the glycation of arginine and cysteine was minimal. The N^ε-(carboxymethyl)-lysine content in BSA–AGE was also increased with increasing number of incubation days. The lectin-binding assay revealed that the glycation of BSA not only altered the conformational structure, but lost binding capacity with various lectins. An immunological functional assay showed that BSA–AGE > 8 μg/mL significantly suppressed normal human Th1 (IL-2 and IFN-γ) and Th2 (IL-10) mRNA expression, whereas AGE > 0.5 μg/mL enhanced monocyte IL-6 production irrelevant to cell apoptosis. The AGE-enhanced monocyte IL-6 production was via MAPK–ERK and MyD88-transduced NF-κBp50 signaling pathways. To elucidate the structure–function relationship of BSA–AGE-enhanced IL-6 production, we pre-preincubated BSA–AGE with different carbohydrate-degrading, protein-degrading, and glycoprotein-degrading enzymes. We found that trypsin and carboxypeptidase Y suppressed whereas β-galactosidase enhanced monocyte IL-6 production. In conclusion, BSA–AGE exerted both immunosuppressive and pro-inflammatory effects that are the molecular basis of inflamm-aging in aged and diabetes groups.

Glycation of hemoglobin leads to the immunogenicity as a result of neo-epitope generation

Non-enzymatic glycation occurs rapidly which ultimately leads to the formation of advanced glycation endproducts (AGEs). These AGEs have shown to associated with the development of many diseases such as diabetes-mellitus. This study is focused on immunological characterization of glycated-Hb induced by d-ribose. Here, we analysed the immunogenicity of glycated-Hb by direct binding and competitive inhibition ELISA. Direct binding ELISA confirmed that glycated-Hb was highly immunogenic and induced high titre antibodies as compared to native-Hb. The antigen binding specificity and cross reactivity of these antibodies were also screened by competitive inhibition ELISA. The IgG from rabbit sera showed enhanced binding of glycated-Hb than native-Hb. Thus, it is possible that alterations in Hb induced by d-ribose could have generated highly immunogenic neoepitopes. Moreover, induced antibodies were also found to cross-react with other modified/native proteins. On the basis of the results of this study, we presume that this type of structural perturbations in Hb in vivo by d-ribose might take place in untreated diabetic condition that could induce such type of immunogenic auto-antibodies. Furthermore, increased level of these auto-antibodies could serve as a biomarker in diabetes and its progression.

Glycation Damage: A Possible Hub for Major Pathophysiological Disorders and Aging

Glycation is both a physiological and pathological process which mainly affects proteins, nucleic acids and lipids. Exogenous and endogenous glycation produces deleterious reactions that take place principally in the extracellular matrix environment or within the cell cytosol and organelles. Advanced glycation end product (AGE) formation begins by the non-enzymatic glycation of free amino groups by sugars and aldehydes which leads to a succession of rearrangements of intermediate compounds and ultimately to irreversibly bound products known as AGEs. Epigenetic factors, oxidative stress, UV and nutrition are important causes of the accumulation of chemically and structurally different AGEs with various biological reactivities. Cross-linked proteins, deriving from the glycation process, present both an altered structure and function. Nucleotides and lipids are particularly vulnerable targets which can in turn favor DNA mutation or a decrease in cell membrane integrity and associated biological pathways respectively. In mitochondria, the consequences of glycation can alter bioenergy production. Under physiological conditions, anti-glycation defenses are sufficient, with proteasomes preventing accumulation of glycated proteins, while lipid turnover clears glycated products and nucleotide excision repair removes glycated nucleotides. If this does not occur, glycation damage accumulates, and pathologies may develop. Glycation-induced biological products are known to be mainly associated with aging, neurodegenerative disorders, diabetes and its complications, atherosclerosis, renal failure, immunological changes, retinopathy, skin photoaging, osteoporosis, and progression of some tumors.

Association between Fluorescent Advanced Glycation End-Products and Vascular Complications in Type 2 Diabetic Patients

Objectives

Diabetes is a major health problem associated with hyperglycemia and chronically increased oxidative stress and enhanced formation of advanced glycation end-products (AGEs). The aim of this study was to determine whether oxidative plasma biomarkers in diabetic patients could be evidenced and associated with vascular complications.

Methods

Oxidative stress biomarkers such as thiols, ischemia-modified albumin (IMA), glycated albumin (GA), fructosamine, and AGEs were measured in 75 patients with poorly controlled type 2 diabetes (HbA1c > 7.5%) with (44) or without (31) vascular disease and in 31 nondiabetic controls.

Results

Most biomarkers of oxidation and glycation were significantly increased in diabetic patients in comparison with nondiabetics. Fructosamines, GA, IMA, and AGEs were positively correlated and levels of fluorescent AGEs were significantly increased in the plasma from patients presenting vascular complication.

Conclusions

These results bring new evidence for the potential interest of glycated albumin, oxidative stress, and glycoxidation parameters in the monitoring of type 2 diabetic patients. Furthermore, it emphasizes fluorescent AGEs as a putative indicator for vascular event prediction in diabetic patients.

Photo-based PDT/PTT dual model killing and imaging of cancer cells using phycocyanin-polypyrrole nanoparticles

Photodynamic therapy (PDT) and photothermal therapy (PTT) using nanoparticles have gained significant attention for its therapeutic effect for cancer treatment. In the present study, we fabricated polypyrrole nanoparticles by employing bovine serum albumin-phycocyanin complex and the formulated particles were stable in various physiological solutions like water, phosphate buffered saline and culture media. The formulated nanoparticles did not cause any noticeable toxicity to MDA-MB-231 and HEK-293 cells. The obtained nanoparticles effectively killed MDA-MB-231 cells in a dual way upon laser illumination, one is through phycocyanin propagated reactive oxygen species (PDT) upon laser illumination and in another way it eradicated the treated cells by converting optical energy into heat energy (PTT). Additionally, the nanoparticles generated good amplitude of ultrasound signals under photoacoustic imaging (PAT) system that facilitates imaging of treated cells. In conclusion, the fabricated particles could be used as a multimodal therapeutic agent for treatment of cancer in the biomedical field.

Aptasensor based optical detection of glycated albumin for diabetes mellitus diagnosis

Glycated albumin (GA) has been reported as an important biomarker for diabetes mellitus. This study investigates an optical sensor comprised of deoxyribonucleic acid (DNA) aptamer, semiconductor quantum dot and gold (Au) nanoparticle for the detection of GA. The system functions as a 'turn on' sensor because an increase in photoluminescence intensity is observed upon the addition of GA to the sensor. This is possibly because of the structure of the DNA aptamer, which folds to form a large hairpin loop before the addition of the analyte and is assumed to open up after the addition of target to the sensor in order to bind to GA. This pushes the quantum dot and the Au nanoparticle away causing an increase in photoluminescence. A linear increase in photoluminescence intensity and quenching efficiency of the sensor is observed as the GA concentration is varied between 0-14 500 nM. Time based photoluminescence studies with the sensor show the decrease in binding rate of the aptamer to the target within a specific time period. The sensor was found to have a higher selectivity towards GA than other control proteins. Further investigation of this simple sensor with greater number of clinical samples can open up avenues for an efficient diagnosis and monitoring of diabetes mellitus when used in conjunction with the traditional method of glucose level monitoring.

Glycated human albumin alters mitochondrial respiration in preadipocyte 3T3-L1 cells

Diabetes and obesity are strongly associated with increased levels of circulating advanced glycation end products (AGEs) and reactive oxygen species (ROS). These two molecular phenomena affect the physiology of adipose tissue, a biological driver of the metabolic syndrome, leading to an inflammatory profile and insulin resistance, which could contribute to obesity/diabetes-associated complications, such as cardiovascular diseases. Herein, we investigated the impact of AGEs on mitochondrial bioenergetics in murine preadipocyte cells (3T3-L1) and cellular redox homeostasis. We show that incubation of preadipocytes with AGEs stimulates mitochondrial activity and respiration while inducing oxidative stress. This AGE-induced intracellular ROS production was blocked by diphenylene iodonium, an NAD(P)H oxidase inhibitor. In parallel, antioxidant enzymes (catalase, superoxide dismutase, and glutathione peroxidase) were found to be activated upon AGE treatment. Our results suggest that AGE-induced oxidative stress is generated by NAD(P)H oxidase and leads to a cellular proliferation arrest associated with enhanced mitochondrial metabolism and biogenesis, and with increased levels of ROS-detoxifying enzymes, as well. These new data show how AGEs may be involved in hyperglycemia-induced oxidative damage in preadipocytes and their potential links to diabetes progression. © 2017 BioFactors, 43(4):577-592, 2017.

Inhibitory Effect of Bunium Persicum Hydroalcoholic Extract on Glucose-Induced Albumin Glycation, Oxidation, and Aggregation In Vitro

BACKGROUND

Glucose-induced protein glycation has been implicated in the progression of diabetic complications and age-related diseases. The anti-glycation potential of polyphenol-rich plant extracts has been shown previously. Bunium Persicum has been demonstrated to possess a high level of polyphenols. The aim of current in vitro study was to determine the possible inhibitory effect of Bunium Persicum hydroalcoholic extract (BPE) on glucose-induced bovine serum albumin (BSA) glycation, oxidation, and aggregation.

METHODS

Folin-Ciocalteu assay was used to measure the content of total phenolic compounds of BPE. To test the in vitro effect of BPE on the formation of glycated BSA, thiol group oxidation, and protein aggregation of BSA, various concentrations of BPE were incubated with BSA and glucose at 37 °C for 72 hr. Glycation, thiol group oxidation, and aggregation of BSA were then measured using thiobarbituric acid, 2, 4-dinitrophenylhydrazine, and Congo red colorimetric methods, respectively. Data were analyzed using the SPSS software (version 16.0). One-way ANOVA followed by Tukey's post hoc test was used to compare group means. P<0.05 was accepted as the statistically significant difference between groups.

RESULTS

The results demonstrated that the content of total phenolics of BPE was 122.41 mg gallic acid equivalents per gram dried extract. BPE (10, 15, and 30 μg/ml) significantly inhibited the formation of GA in a concentration-dependent manner. BPE also significantly decreased the levels of thiol group oxidation and BSA aggregation.

CONCLUSION

The results showed that BPE has anti-glycation and antioxidant properties and might have therapeutic potentials in the prevention of glycation-mediated diabetic complications.

Non-enzymatic glucosylation induced neo-epitopes on human serum albumin: A concentration based study

Hyperglycaemia induced non enzymatic glycation is accelerated in diabetic patients and aggressively involved in diabetes progression. Human serum albumin (HSA) is the most abundant protein in blood circulation. In hyperglycaemia, it undergoes fast glycation and results in the impairment of structure. Our previous study has demonstrated structural alterations in Amadori-albumin modified with different glucose concentrations from physiological to pathophysiological range. Here, we focused on immunological characterization of Amadori-albumin. Immunogenicity of Amadori-albumin was analysed by direct binding and competitive ELISA. Amadori-albumin was found to be highly immunogenic (expect albumin modified with 5mM) and induced high titre antibodies depending upon the extent of modification. Very high titre antibodies were obtained with albumin modified with 75mM glucose as compared to native albumin. Anti-Amadori-albumin-IgG from rabbit sera exhibited increased recognition of Amadori-albumin than native albumin in competitive immunoassay. Alteration induced in albumin after glucosylation has made it highly immunogenic. Induced antibodies were quite specific for respective immunogens but showed cross-reaction with other Amadori/native proteins. It suggests that glucosylation has generated highly immunogenic epitopes on albumin. Formation of high molecular weight immune complex with retarded mobility further supports specificity of anti-Amadori-albumin-IgG towards Amadori-albumin. It may be concluded that due to early glycation, an array of modification occurred in HSA structure. Such gross structural changes might favour polymerization of most of the native epitopes into potent immunogenic neo-epitopes, but some original epitopes were still active and has contributed in the immunogenicity. It could be concluded that induction of anti-Amadori-albumin antibodies may be due to protection of glucose modified albumin from protiolytic breakdown. We assumed that this type of protein modifications might occur in diabetic patients in hyperglycaemic conditions that may be recognised as foreign molecules and can induce autoantibodies. Increased level of anti-Amadori-albumin autoantibodies may be used as a biomarker in disease diagnosis and its progression.

Cellular mechanisms and consequences of glycation in atherosclerosis and obesity

Post-translational modification of proteins imparts diversity to protein functions. The process of glycation represents a complex set of pathways that mediates advanced glycation endproduct (AGE) formation, detoxification, intracellular disposition, extracellular release, and induction of signal transduction. These processes modulate the response to hyperglycemia, obesity, aging, inflammation, and renal failure, in which AGE formation and accumulation is facilitated. It has been shown that endogenous anti-AGE protective mechanisms are thwarted in chronic disease, thereby amplifying accumulation and detrimental cellular actions of these species. Atop these considerations, receptor for advanced glycation endproducts (RAGE)-mediated pathways downregulate expression and activity of the key anti-AGE detoxification enzyme, glyoxalase-1 (GLO1), thereby setting in motion an interminable feed-forward loop in which AGE-mediated cellular perturbation is not readily extinguished. In this review, we consider recent work in the field highlighting roles for glycation in obesity and atherosclerosis and discuss emerging strategies to block the adverse consequences of AGEs. This article is part of a Special Issue entitled: The role of post-translational protein modifications on heart and vascular metabolism edited by Jason R.B. Dyck & Jan F.C. Glatz.

Mechanism of increased clearance of glycated albumin by proximal tubule cells

Serum albumin is the most abundant plasma protein and has a long half-life due to neonatal Fc receptor (FcRn)-mediated transcytosis by many cell types, including proximal tubule cells of the kidney. Albumin also interacts with, and is modified by, many small and large molecules. Therefore, the focus of the present study was to address the impact of specific known biological albumin modifications on albumin-FcRn binding and cellular handling. Binding at pH 6.0 and 7.4 was performed since FcRn binds albumin strongly at acidic pH and releases it after transcytosis at physiological pH. Equilibrium dissociation constants were measured using microscale thermophoresis. Since studies have shown that glycated albumin is excreted in the urine at a higher rate than unmodified albumin, we studied glucose and methylgloxal modified albumins (21 days). All had reduced affinity to FcRn at pH 6.0, suggesting these albumins would not be returned to the circulation via the transcytotic pathway. To address why modified albumin has reduced affinity, we analyzed the structure of the modified albumins using small-angle X-ray scattering. This analysis showed significant structural changes occurring to albumin with glycation, particularly in the FcRn-binding region, which could explain the reduced affinity to FcRn. These results offer an explanation for enhanced proximal tubule-mediated sorting and clearance of abnormal albumins.

Non-enzymatic glycation mediated structure–function changes in proteins: case of serum albumin

Albumin, a major plasma protein with extraordinary ligand binding properties, transports various ligands ranging from drugs, hormones, fatty acids, and toxins to different tissues and organs in the body.

Hyperglycemia induced structural and functional changes in human serum albumin of diabetic patients: a physico-chemical study

Structural and functional changes in glycated-HSA, isolated from diabetic patients, suggests it has a significant role in diabetes progression and kidney dysfunction.

Oxidative stress and adipocyte biology: focus on the role of AGEs

Diabetes is a major health problem that is usually associated with obesity, together with hyperglycemia and increased advanced glycation endproducts (AGEs) formation. Elevated AGEs elicit severe downstream consequences via their binding to receptors of AGEs (RAGE). This includes oxidative stress and oxidative modifications of biological compounds together with heightened inflammation. For example, albumin (major circulating protein) undergoes increased glycoxidation with diabetes and may represent an important biomarker for monitoring diabetic pathophysiology. Despite the central role of adipose tissue in many physiologic/pathologic processes, recognition of the effects of greater AGEs formation in this tissue is quite recent within the obesity/diabetes context. This review provides a brief background of AGEs formation and adipose tissue biology and thereafter discusses the impact of AGEs-adipocyte interactions in pathology progression. Novel data are included showing how AGEs (especially glycated albumin) may be involved in hyperglycemia-induced oxidative damage in adipocytes and its potential links to diabetes progression.

Inhibitory effect of Clitoria ternatea flower petal extract on fructose-induced protein glycation and oxidation-dependent damages to albumin in vitro

BACKGROUND

The accumulation of advanced glycation end products (AGEs) in body tissue has been implicated in the progression of age-related diseases. Inhibition of AGE formation is the imperative approach for alleviating diabetic complications. Clitoria ternatea extract (CTE) has been demonstrated to possess anti-diabetic activity. However, there is no scientific evidence supporting its anti-glycation activity. The objective of this study was to determine the inhibitory effect of CTE on fructose-induced formation of AGEs and protein oxidation. Antioxidant activity of CTE was also assessed by various methods.

METHODS

The aqueous extract of CTE (0.25-1.00 mg/ml) was measured for the content of total phenolic compounds, flavonoid, and anthocyanin by Folin-Ciocalteu assay, AlCl3 colorimetric method, and pH differential method, respectively. The various concentrations of CTE were incubated with BSA and fructose at 37°C for 28 days. The formation of fluorescent AGEs, the level of fructosamine, protein carbonyl content, and thiol group were measured. The in vitro antioxidant activity was measured by the 1,1-diphenyl 2-picrylhydrazyl (DPPH) scavenging activity, trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP), hydroxyl radical scavenging activity (HRSA), superoxide radical scavenging activity (SRSA), and ferrous ion chelating power (FICP).

RESULTS

The results demonstrated that the content of total phenolics, flavonoids and total anthocyanins in CTE was 53 ± 0.34 mg gallic acid equivalents/g dried extract, 11.2 ± 0.33 mg catechin equivalents/g dried extract, and 1.46 ± 0.04 mg cyanidin-3-glucoside equivalents/g dried extract, respectively. Moreover, CTE (0.25-1.00 mg/ml) significantly inhibited the formation of AGEs in a concentration-dependent manner. CTE also markedly reduced the levels of fructosamine and the oxidation of protein by decreasing protein carbonyl content and preventing free thiol depletion. In the DPPH radical scavenging activity and SRSA, CTE had the IC50 values of 0.47 ± 0.01 mg/ml and 0.58 ± 0.04 mg/ml. Furthermore, the FRAP and TEAC values of CTE were 0.38 ± 0.01 mmol FeSO4 equivalents/mg dried extract and 0.17 ± 0.01 mg trolox equivalents/mg dried extract. However, CTE showed weak scavenging activity on hydroxyl radical and a weak antioxidant iron chelator.

CONCLUSIONS

The results showed that CTE has strong antiglycation and antioxidant properties and might have therapeutic potentials in the prevention of AGE-mediated diabetic complications.

Influence of reactive species on the modification of biomolecules generated from the soft plasma

Plasma medicine is an upcoming research area that has attracted the scientists to explore more deeply the utility of plasma. So, apart from the treating biomaterials and tissues with plasma, we have studied the effect of soft plasma with different feeding gases such as Air, N2 and Ar on modification of biomolecules. Hence, in this work we have used the soft plasma on biomolecules such as proteins ((Hemoglobin (Hb) and Myoglobin (Mb)), calf thymus DNA and amino acids. The structural changes or structural modification of proteins and DNA have been studied using circular dichroism (CD), fluorescence spectroscopy, protein oxidation test, gel electrophoresis, UV-vis spectroscopy, dynamic light scattering (DLS) and 1D NMR, while Liquid Chromatograph/Capillary Electrophoresis-Mass Spectrometer (LC/CE-MS) based on qualitative and quantitative bio-analysis have been used to study the modification of amino acids. Further, the thermal analysis of the protein has been studied with differential scanning calorimetry (DSC) and CD. Additionally, we have performed docking studies of H2O2 with Hb and Mb, which reveals that H2O2 molecules preferably attack the amino acids near heme group. We have also shown that N2 gas plasma has strong deformation action on biomolecules and compared to other gases plasma.

Electrocatalytic assay for monitoring methylglyoxal-mediated protein glycation

Protein glycation is a complex process that plays an important role in diabetes mellitus, aging, and the regulation of protein function in general. As a result, current methodological research on proteins is focused on the development of novel approaches for investigating glycation and the possibility of monitoring its modulation and selective inhibition. In this paper, a first sensing strategy for protein glycation is proposed, based on protein electroactivity measurement. Concretely, the label-free method proposed is based on the application of a constant-current chronopotentiometric stripping (CPS) analysis at Hg-containing electrodes. The glycation process was monitored as the decrease in the electrocatalytic protein signal, peak H, observed at highly negative potentials at around -1.8 V (vs Ag/AgCl3 M KCl), which was previously ascribed to a catalytic hydrogen evolution reaction (CHER). Using this method, a model protein bovine serum albumin was investigated over 3 days of incubation with the glycation agent methylglyoxal in the absence or presence of the glycation inhibitor aminoguanidine (pimagedine). The electrochemical methodology presented here could open up new possibilities in research on protein glycation and oxidative modification. The methodology developed also provides a new option for the analysis of protein intermolecular interactions using electrochemical sensors, which was demonstrated by the application of a silver solid amalgam electrode (AgSAE) for monitoring the glycation process in samples of bovine serum albumin, human serum albumin, and lysozyme.

Fabrication of multifunctional SiO2@GN-serum composites for chemo-photothermal synergistic therapy

Recently, the chemo-photothermal synergistic therapy has become a potential method for cancer treatment. Herein, we developed a multifunctional nanomaterial for chemo-photothermal therapeutics based on silica and graphene core/shell structure (SiO2@GN) because of the ability of GN to convert light energy into heat. Serum protein was further modified onto the surface of GN (SiO2@GN-Serum) to improve the solubility and stability of GN-based nanoparticles in physiological conditions. The as-synthesized SiO2@GN-Serum nanoparticles (NPs) have been revealed to have high photothermal conversion efficiency and stability, as well as high storage and release capacity for anticancer drug doxorubicin (SiO2@GN-Serum-Dox). The therapeutic efficacy of SiO2@GN-Serum-Dox has been evaluated in vitro and in vivo for cervical cancer therapy. In vitro cytotoxicity tests demonstrate that SiO2@GN-Serum NPs have excellent biocompatibility. However, SiO2@GN-Serum-Dox NPs show higher cytotoxicity than SiO2@GN-Serum and free Dox under irradiation with NIR laser at 1.0 W/cm(2) for 5 min owing to both SiO2@GN-Serum-mediated photothermal ablation and cytotoxicity of light-triggered Dox release. In mouse models, the tumor growth is significantly inhibited by chem-photothermal effect of SiO2@GN-Serum-Dox. Overall, compared with single chemotherapy or photothermal therapy, the combined treatment demonstrates better therapeutic efficacy. Our results suggest a promising GN-based core/shell nanostructure for biomedical applications.

Effect of nanosecond-pulsed plasma on the structural modification of biomolecules

Nanosecond-pulsed plasma (NPP) action on biomolecules modification.

Emerging trends in optical sensing of glycemic markers for diabetes monitoring

In the past decade, considerable attention has been focused on the measurement of glycemic markers, such as glycated hemoglobin and glycated albumin, that provide retrospective indices of average glucose levels in the bloodstream. While these biomarkers have been regularly used to monitor long-term glucose control in established diabetics, they have also gained traction in diabetic screening. Detection of such glycemic markers is challenging, especially in a point-of-care setting, due to the stringent requirements for sensitivity and robustness. A number of non-separation based measurement strategies were recently proposed, including photonic tools that are well suited to reagent-free marker quantitation. Here, we critically review these methods while focusing on vibrational spectroscopic methods, which offer highly specific molecular fingerprinting capability. We examine the underlying principles and the utility of these approaches as reagentless assays capable of multiplexed detection of glycemic markers and also the challenges in their eventual use in the clinic.

Hemoglobin fructation promotes heme degradation through the generation of endogenous reactive oxygen species

Protein glycation is a cascade of nonenzymatic reactions between reducing sugars and amino groups of proteins. It is referred to as fructation when the reducing monosaccharide is fructose. Some potential mechanisms have been suggested for the generation of reactive oxygen species (ROS) by protein glycation reactions in the presence of glucose. In this state, glucose autoxidation, ketoamine, and oxidative advance glycation end products (AGEs) formation are considered as major sources of ROS and perhaps heme degradation during hemoglobin glycation. However, whether fructose mediated glycation produces ROS and heme degradation is unknown. Here we report that ROS (H2O2) production occurred during hemoglobin fructation in vitro using chemiluminescence methods. The enhanced heme exposure and degradation were determined using UV-Vis and fluorescence spectrophotometry. Following accumulation of ROS, heme degradation products were accumulated reaching a plateau along with the detected ROS. Thus, fructose may make a significant contribution to the production of ROS, glycation of proteins, and heme degradation during diabetes.

Oxidative damage in diabetics: insights from a graduate study in La Reunion University

Due to the growing incidence of diabetes in developed nations, there is a compelling case to be made for teaching graduate students more deeply about mechanisms underlying this disease. Diabetes is associated with enhanced oxidative stress and protein glycation via the covalent binding of glucose molecules. Albumin represents the major plasmatic protein and undergoes enhanced glycoxidative modifications in diabetic condition. La Réunion Island, a French department located in the Indian Ocean exhibit a growing incidence of diabetes. At the University of La Réunion, our research group named GEICO (Groupe d'Etude sur l'Inflammation Chronique et l'Obésité) participated to foster research and training in diabetes context and focuses on the impact of glycated albumin mediated oxidative stress on cell physiopathology. A laboratory course was designed by our group to introduce graduate students to cutting edge techniques in redox biology while providing insights into scientific processes and methods. This two weeks research laboratory training took place at CYROI, a local biotechnology center that provides advanced facilities for research, business, and education. Using histochemistry, molecular biology, biochemical techniques, student investigated oxidative damages in liver from leptin receptor deficient diabetic mice compared to control littermates. In addition, they used an in vitro model by assaying oxidative impact of glycated albumin on hepatoma carcinoma HepG2 cells. This article gives an overview of the organization and protocol used by the students during their two weeks training in the laboratory. Therefore, it may be helpful for teaching graduate students techniques used in research laboratory working on redox biology.

Effect of dietary n - 3 polyunsaturated fatty acids on oxidant/antioxidant status in macrosomic offspring of diabetic rats

The aim of this work was to determine the effect of dietary n − 3 PUFA on oxidant/antioxidant status, in vitro very low and low density lipoprotein (VLDL-LDL), and VLDL-LDL-fatty acid composition in macrosomic pups of diabetic mothers. We hypothesized that n − 3 PUFA would improve oxidative stress in macrosomia. Diabetes was induced in female Wistar rats fed with the ISIO diet (control) or with the EPAX diet (enriched in n − 3 PUFAs), by streptozotocin. The macrosomic pups were killed at birth (day 0) and at adulthood (day 90). Lipid parameters and VLDL-LDL-fatty acid composition were investigated. The oxidant/antioxidant status was determined by measuring plasma oxygen radical absorbance capacity (ORAC), hydroperoxides, carbonyl proteins, and VLDL-LDL oxidation. Macrosomic rats of ISIO fed diabetic mothers showed an increase in plasma and VLDL-LDL-triglycerides and VLDL-LDL-cholesterol levels and altered VLDL-LDL-fatty acid composition. Plasma ORAC was low with high hydroperoxide and carbonyl protein levels. The in vitro oxidizability of VLDL-LDL was enhanced in these macrosomic rats. The EPAX diet corrected lipid parameters and improved oxidant/antioxidant status but increased VLDL-LDL susceptibility to oxidation. Macrosomia is associated with lipid abnormalities and oxidative stress. n − 3 PUFA exerts favorable effects on lipid metabolism and on the oxidant/antioxidant status of macrosomic rats. However, there are no evident effects on VLDL-LDL oxidation.

Fucoidan as an inhibitor of thermally induced collagen glycation examined by acetate electrophoresis

Non-enzymatic glycation (Maillard reaction) in vitro could be a simple method to obtain glycoconjugates for studying their biological properties. Hence, fucoidan was retained by acetate electrophoresis indicating a strong interaction with the protein. A loss of colour in fucoidan bands was found for samples incubated with collagen as compared with samples of free fucoidan. Also under in vitro conditions at 100°C - simulating a sudden burn incident - fucoidan binds with collagen as a result of the Maillard reaction. In contrast, the colour of the fucoidan bands intensified for samples incubated with collagen, with the addition of glucose. Electrophoretic analyses were carried out after heating the samples to a temperature simulating a burn incident. The bands were found to intensify for samples incubated with collagen during a 30-day-long incubation. Thus, spontaneous in vitro glycation - i.e. without the addition of glucose - was confirmed. This process is highly intensified both by the temperature and time of incubation. For a sample incubated in vitro in a fucoidan solution containing glucose, glycation was confirmed in a preliminary FTIR and acetate electrophoresis examinations, occurring in collagen obtained from chicken skins. In particular, a new band emerging around 1746 cm(-1) was observed for above samples, as was its increasing intensity, as compared with samples without the addition of glucose. In the collagen glycation assay, while glucose reacts with collagen and forms cross-linked aggregates, fucoidan decreases the process of aggregation and recovery of native collagen.

Role of oxidative stress in physiological albumin glycation: a neglected interaction

Protein glycation is a key mechanism involved in chronic disease development in both diabetic and nondiabetic individuals. About 12-18% of circulating proteins are glycated in vivo in normoglycemic blood, but in vitro studies have hitherto failed to demonstrate glucose-driven glycation below a concentration of 30mM. Bovine serum albumin (BSA), reduced BSA (mercaptalbumin) (both 40g/L), and human plasma were incubated with glucose concentrations of 0-30mM for 4 weeks at 37°C. All were tested preoxidized for 8h before glycation with 10nM H2O2 or continuously exposed to 10nM H2O2 throughout the incubation period. Fructosamine was measured (nitroblue tetrazolium method) at 2 and 4 weeks. Oxidized BSA (both preoxidized and continuously exposed to H2O2) was more readily glycated than native BSA at all glucose concentrations (p = 0.03). Moreover, only oxidized BSA was glycated at physiological glucose concentration (5mM) compared to glucose-free control (glycation increased by 35% compared to native albumin, p < 0.05). Both 5 and 10mM glucose led to higher glycation when mercaptalbumin was oxidized than when unoxidized (p < 0.05). Fructosamine concentration in human plasma was also significantly higher when oxidized and exposed to 5mM glucose, compared to unoxidized plasma (p = 0.03). The interaction between glucose concentration and oxidation was significant in all protein models (p < 0.05). This study has for the first time demonstrated albumin glycation in vitro, using physiological concentrations of albumin, glucose, and hydrogen peroxide, identifying low-grade oxidative stress as a key element early in the glycation process.

New insights into deleterious impacts of in vivo glycation on albumin antioxidant activities

BACKGROUND

Albumin constitutes the most abundant circulating antioxidant and prevents oxidative damages. However, in diabetes, this plasmatic protein is exposed to several oxidative modifications, which impact on albumin antioxidant properties.

METHODS

Most studies dealing on albumin antioxidant activities were conducted on in vitro modified protein. Here we tried to decipher whether reduced antioxidant properties of albumin could be evidenced in vivo. For this, we compared the antioxidant properties of albumin purified from diabetic patients to in vitro models of glycated albumin.

RESULTS

Both in vivo and in vitro glycated albumins displayed impaired antioxidant activities in the free radical-induced hemolysis test. Surprisingly, the ORAC method (Oxygen Radical Antioxidant Capacity) showed an enhanced antioxidant activity for glycated albumin. Faced with this paradox, we investigated antioxidant and anti-inflammatory activities of our albumin preparations on cultured cells (macrophages and adipocytes). Reduced cellular metabolism and enhanced intracellular oxidative stress were measured in cells treated with albumin from diabetics. NF-kB -mediated gene induction was higher in macrophages treated with both type of glycated albumin compared with cells treated with native albumin. Anti inflammatory activity of native albumin is significantly impaired after in vitro glycation and albumin purified from diabetics significantly enhanced IL6 secretion by adipocytes. Expression of receptor for advanced glycation products is significantly enhanced in glycated albumin-treated cells.

CONCLUSIONS AND GENERAL SIGNIFICANCE

Our results bring new evidences on the deleterious impairments of albumin important functions after glycation and emphasize the importance of in vivo model of glycation in studies relied to diabetes pathology.

Impaired drug-binding capacities of in vitro and in vivo glycated albumin

Albumin, the major circulating protein in blood, can undergo increased glycation in diabetes. One of the main properties of this plasma protein is its strong affinity to bind many therapeutic drugs, including warfarin and ketoprofen. In this study, we investigated whether or not there were any significant changes related to in vitro or in vivo glycation in the structural properties and the binding of human albumin to both therapeutic drugs. Structural parameters, including redox state and ketoamine contents of in vitro and in vivo glycated purified albumins, were investigated in parallel with their affinity for warfarin and ketoprofen. High-performance liquid chromatography was used to determine the free drug concentrations and dissociation constants according to the Scatchard method. An alternative method based on fluorescence spectroscopy was also used to assess drug-binding properties. Oxidation and glycation levels were found to be enhanced in albumin purified from diabetic patients or glycated with glucose or methylglyoxal, after determination of their ketoamine, free thiol, amino group and carbonyl contents. In parallel, significant impairments in the binding affinity of in vitro and in vivo glycated albumin, as indicated by the higher dissociation constant values and confirmed by higher free drug fractions, were observed. To a lesser extent, this alteration also significantly affected diabetic albumin affinity, indicated by a lower static quenching in fluorescence spectroscopy. This work provides useful information supporting in vivo diabetic albumin could be the best model of glycation for monitoring diabetic physiopathology and should be valuable to know if glycation of albumin could contribute to variability in drugs response during diabetes.

Structural and immunological characterization of Amadori-rich human serum albumin: role in diabetes mellitus

Proteins modifications in diabetes may lead to early glycation products (EGPs) as well as advanced glycation end products (AGEs). Whereas no extensive studies have been carried out to assess the role of EGPs in secondary complications of diabetes, numerous investigators have demonstrated the role of AGEs. Early glycation involves attachment of glucose on ε-NH2 of lysine residues of proteins leading to generation of the Amadori product (an early glycation species). This study reports the structural and immunological characterization of EGPs of HSA because we believe that during persistent hyperglycemia the HSA, one of the major blood proteins, can undergo fast glycation. Glucose mediated generation of EGPs of HSA was quantitated as Amadori products by NBT assay and authenticated by boronate affinity chromatography and LC/MS. Compared to native HSA changes in glycated-HSA were characterized by hyperchromicity, loss in fluorescence intensity and a new peak in the FTIR profile. Immunogenicity of native- and glycated-HSA was evaluated by inducing antibodies in rabbits. Results suggest generation of neo-epitopes on glycated-HSA rendering it highly immunogenic compared to native HSA. Quantization of EGPs of HSA by authentic antibodies against HSA-EGPs can be used as marker for early detection of the initiation/progression of secondary complications of diabetes.