Use of capillary electrophoresis to evaluate protective effects of methylglyoxal scavengers on the activity of creatine kinase

Methylglyoxal (MGO) is a highly reactive alpha-oxoaldehyde formed endogenously in numerous enzymatic and nonenzymatic reactions. The reactions between MGO and various amino residues in proteins not only result in inactivation of enzymes, but also lead to the formation of different detrimental advanced glycation endproducts (AGEs). Recently, it was reported that creatine kinase (CK, EC 2.7.3.2) activity could be reduced or even lost under incubation with MGO in vitro. In this study, an efficient CE analytical method was developed for the evaluation of CK activity. Based on this CE method, the inhibitory effect of MGO on CK activity was confirmed. Several MGO scavengers such as aminoguanidine (AG) and some thiols showed obvious protective effects on CK activity against MGO. Furthermore, tiopronin (TP), a hepatoprotective drug, was found for the first time to counteract MGO-induced inhibition of CK activity in CK reaction. Meanwhile, TP also retained adenosine diphosphate (ADP) generation level in plasma treated with MGO, which implies that this drug may have potential protective effect on other enzymes which are associated with adenine nucleotide metabolism. Besides, the established CE approach can be utilized as a model for screening effective MGO scavengers by monitoring CK-catalyzed conversion between adenosine triphosphate and ADP.     

Flavour chemistry of methylglyoxal and glyoxal

Methylglyoxal (MGO) and glyoxal (GO), known as reactive carbonyl species, can be generated endogenously and exogenously (human body and food system). They are attracting increased attention because of their relationship with diabetes and flavour generation. In this review, their characteristics relating to flavour chemistry are discussed. MGO and GO can be detected in food systems by GC and HPLC after derivatization. MGO and GO formed in the Maillard reaction play important roles as precursors of aroma and colour compounds, especially in Strecker degradation, a major flavour generation reaction. When combined with amino acids they undergo Schiff base formation, decarboxylation and α-aminoketone condensation leading to heterocyclic aroma compounds such as pyrazines, pyrroles and pyridines. They attack amine groups in amino acids, peptides and proteins to form advanced glycation end products (AGEs) and cause carbonyl stress followed by oxidative stress and tissue damage. Therefore, many studies about scavengers of MGO and GO are seen. The influence of these scavengers on flavour generation is also discussed.     

Inhibition of resveratrol glucosides (REs) on advanced glycation endproducts (AGEs) formation: inhibitory mechanism and structure-activity relationship

Abstract

The study on inhibitory effects of resveratrol glucosides (REs) on advanced glycation endproducts (AGEs) formation is still unmet. Herein, for the first time, the antiglycation activities of five REs in the fetal bovine serum proteins (FBS)/fructose system were evaluated, and its structure-activity relationship and antiglycation mechanism were further explored. These REs showed remarkable inhibition toward AGEs formation. Among them, Piceatannol-3'-O-glucoside (PG) exhibited highest antiglycation activity as reflected in approximately 80% inhibition of fluorescent AGEs at the concentration of 1.0?mM. The structure-activity relationship analysis indicated that glucoside attached to the B ring of resveratrol displays a superior antiglycation activity. Moreover, the results of antiglycation mechanism showed that the antiglycation activity of REs was proportional to their antioxidant capacity and methylglyoxal (MGO) trapping capacity. Therefore, the REs are promising candidates worthy of further exploration for preventing AGEs accumulation in vivo, thereby treating AGEs-associated diseases.     

Methylglyoxal in the Brain: From Glycolytic Metabolite to Signalling Molecule

Highlights

• ●MGO may be essential for glycometabolism and bioenergetics in homeostasis and neural development;
• ●MGO may be an essential molecule in the regulation of neural homeostasis (redox homeostasis, lipid metabolism homeostasis, energy homeostasis, protein steady-state, epigenetic mechanisms, and neurotransmitters);
• ●Glycolysis is a source of protein homeostasis destruction. MGO formation as a by-product of glycolysis drives damage to the proteome.

AbstractAdvances in molecular biology technology have piqued tremendous interest in glycometabolism and bioenergetics in homeostasis and neural development linked to ageing and age-related diseases. Methylglyoxal (MGO) is a by-product of glycolysis, and it can covalently modify proteins, nucleic acids, and lipids, leading to cell growth inhibition and, eventually, cell death. MGO can alter intracellular calcium homeostasis, which is a major cell-permeant precursor to advanced glycation end-products (AGEs). As side-products or signalling molecules, MGO is involved in several pathologies, including neurodevelopmental disorders, ageing, and neurodegenerative diseases. In this review, we demonstrate that MGO (the metabolic side-product of glycolysis), the GLO system, and their analogous relationship with behavioural phenotypes, epigenetics, ageing, pain, and CNS degeneration. Furthermore, we summarise several therapeutic approaches that target MGO and the glyoxalase (GLO) system in neurodegenerative diseases.     

Towards the control and inhibition of glycation-the role of the guanidine reaction center with aldehydic and diketonic dicarbonyls. A mass spectrometry study

Glycation of proteins by glucose and formation of end-stage adducts (AGEs, advanced glycation end products) has been implicated in pathological mechanisms associated with diabetic complications, macrovascular disease, chronic and renal insufficiency, Alzheimer's disease, and aging. Of the carbonyl containing compounds involved in this process, alpha-dicarbonyls have particular importance, being established as direct intermediates in the formation of well-known AGEs. The guanidino group, present in arginine residues, suffers direct modifications by sugars and its derivatives, and is considered to be an important chemical basis, targeting the control and inhibition of glycation.Seven dicarbonyl compounds, aldehydic and diketonic, were reacted with guanidine, in an attempt to establish structure/activity relationships. Electrospray mass spectrometry, together with tandem mass spectrometry, was used to identify and characterize the reaction products. The reactivity of guanidine was found to vary with the dicarbonyls used. For glyoxal, a high amount of dihydroxyimidazolidine was formed, whereas for methylglyoxal, dihydroxyimidazolidine was slowly converted into hydroimidazolone. Interestingly, aqueous guanidine was found to prevent argpyrimidine formation. The formation of several amine-dicarbonyl moieties was observed for the larger alkyl-diketonic dicarbonyls reaction systems, in particular. Molecular structures, bearing a polar chain, of an imidazole ring, and a nonpolar one, of alkyl groups, located at both sides of the imidazole rings, were attributed to these moieties. Gas-phase experiments suggested that the larger alkyl groups have a preference for being located at one of the sides of the imidazole rings. Moreover, the referred amine-dicarbonyl moieties are formed via (dihydroxyimidazolidine - 2H2O) moieties. The latter (dihydroxyimidazolidine - 2H2O) moieties are formed in high amounts in the larger alkyl-diketonic dicarbonyl reactions. Since these moieties react with dicarbonyl molecules, and react even faster with already modified amine functions, we can foresee that these species may be useful for controlling and inhibiting glycation of larger biomolecules, such as proteins.     

Inhibitory effect of eleven herbal extracts on advanced glycation end-products formation and aldose reductase activity

The formation of advanced glycation end-products(AGEs) and aldose reductase(AR) activity have been implicated in the development of diabetic complications. Our study sought to characterize the capacities of eleven herbal extracts against the formation of AGEs and the AR activity. An ultrahigh performance liquid chromatography and tandem mass spectrometry(UPLC–MS/MS) method was used for the detection of AR activity and the screening of AR inhibitors in this research. The amount of sorbitol from each analyte was directly detected using the multiple reaction monitoring mode and the sorbitol level could be reduced via the addition of an inhibitor. Moreover, the BSA/glucose(fructose) system was applied to investigate their inhibitory activities of AGEs formation in glycation model reactions.Compared with other screened herbs used in our study, Flos Sophorae Immaturus and Radix Scutellariae seemed to be more effective on inhibiting the formation of AGEs and AR activity. The inhibiting capacities of herbal extracts against AR activity and AGEs formation may be correlated with the bioactive components of the herbal extracts. The differences were correlated with the amount of polyphenol and flavonoid components. In the study, we have investigated the potential anti-hyperglycemic bioactivity of eleven herbal extracts in vitro, which could provide a reference for further in vivo research in the prevention and treatment of diabetic complications.     

In vitro nonenzymatic glycation of guanosine 5′-triphosphate by dihydroxyacetone phosphate

Dihydroxyacetone phosphate (DHAP) is a glycolytic intermediate that has been found to be significantly elevated in the erythrocytes of diabetic patients and patients with triosephosphate isomerase deficiency. DHAP spontaneously breaks down to methylglyoxal, a potent glycating agent that reacts with proteins and nucleic acids in vivo to form advanced glycation endproducts (AGEs). Like methylglyoxal, DHAP itself is also a glycating metabolite, capable of condensing with proteins and altering their structure or function. The objective of this investigation was to evaluate the susceptibility of nucleotides to nonenzymatic attack by DHAP, and to determine the factors influencing the rate and extent of nucleotide glycation by this sugar. Of the four nucleotide triphosphates (ATP, CTP, GTP and UTP) that were studied, only GTP was reactive, forming a wide range of UV and fluorescent products with DHAP. Increases in temperature and nucleotide concentration enhanced the rate and extent of GTP glycation by DHAP and promoted the heterogeneity of AGEs. Capillary electrophoresis, HPLC, and mass spectrometry allowed for a thorough analysis of the glycated products and demonstrated that the reaction of DHAP with GTP occurred via the classical Amadori pathway.     

Effect of Cirsium japonicum Flower Extract on Skin Aging Induced by Glycation

Advanced glycation end products (AGEs) have recently been increasingly discussed as one factor of skin aging. In this study, we investigated the effects of Cirsium japonicum flower (CFE) extract on glycation in relation to skin aging and skin elasticity. Moreover, we learned the main active constituent of CFE that has effects against glycation. To demonstrate the effects of CFE on glycation, we carried out an in vitro glycation study, 3-dimensional culture, and clinical study. As a result, CFE inhibited formation of AGEs in both bovine serum albumin (BSA)/glucose glycation system and aldehyde-derived glycation system. Moreover, CFE reduced Nε-(carboxymethyl), lysine (CML), and carbonylated proteins that increased by glycation. Furthermore, CFE broke crosslinks of collagen–AGEs and inhibited the increase of matrix metalloproteinase-1 (MMP-1) gene expression by AGEs. In the 3D culture condition, CFE restored the reduction of collagen gel contraction by glycation. Moreover, apigenin was detected as the main active constituent in CFE that has anti-glycation effects. In the clinical study, we confirmed that CFE has effects on skin wrinkles and skin elasticity. Our findings suggest that CFE can be used as a cosmetic or cosmeceutical ingredient for improving skin elasticity and wrinkles. Regulation of AGEs can be an interesting target for anti-aging.     

The structural modification of DNA nucleosides by nonenzymatic glycation: an <Emphasis Type="Italic">in vitro</Emphasis> study based on the reactions of glyoxal and methylglyoxal with 2′-deoxyguanosine

Methylglyoxal and glyoxal are generated from the oxidation of carbohydrates and lipids, and like d-glucose have been shown to nonenzymatically react with proteins to form advanced glycation end products (AGEs). AGEs can occur both in vitro and in vivo, and these compounds have been shown to exacerbate many of the long-term complications of diabetes. Earlier studies in our laboratory reported d-glucose, d-galactose, and d/l-glyceraldehyde formed AGEs with nucleosides. The objective of this study was to focus on purines and pyrimidines and to analyze these DNA nucleoside derived AGE adducts with glyoxal or methylglyoxal using a combination of analytical techniques. Studies using UV and fluorescence spectroscopy along with mass spectrometry provided for a thorough analysis of the nucleoside AGEs and demonstrated that methylglyoxal and glyoxal reacted with 2′-deoxyguanosine via the classic Amadori pathway, and did not react appreciably with 2′-deoxyadenosine, 2′-deoxythymidine, and 2′-deoxycytidine. Additional findings revealed that methylglyoxal was more reactive than glyoxal. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Inhibitory Effects of Myriocin on Non-Enzymatic Glycation of Bovine Serum Albumin

Advanced glycation end products (AGEs) are the compounds produced by non-enzymatic glycation of proteins, which are involved in diabetic-related complications. To investigate the potential anti-glycation activity of Myriocin (Myr), a fungal metabolite of Cordyceps, the effect of Myr on the formation of AGEs resulted from the glycation of bovine serum albumin (BSA) and the interaction between Myr and BSA were studied by multiple spectroscopic techniques and computational simulations. We found that Myr inhibited the formation of AGEs at the end stage of glycation reaction and exhibited strong anti-fibrillation activity. Spectroscopic analysis revealed that Myr quenched the fluorescence of BSA in a static process, with the possible formation of a complex (approximate molar ratio of 1:1). The binding between BSA and Myr mainly depended on van der Waals interaction, hydrophobic interactions and hydrogen bond. The synchronous fluorescence and UV-visible (UV-vis) spectra results indicated that the conformation of BSA altered in the presence of Myr. The fluorescent probe displacement experiments and molecular docking suggested that Myr primarily bound to binding site 1 (subdomain IIA) of BSA. These findings demonstrate that Myr is a potential anti-glycation agent and provide a theoretical basis for the further functional research of Myr in the prevention and treatment of AGEs-related diseases.     

Antiglycation Effects of Adlay Seed and Its Active Polyphenol Compounds: An In Vitro Study

This study aimed to evaluate the antiglycation effects of adlay on protein glycation using in vitro glycation assays. Adlay seed was divided into the following four parts: the hull (AH), testa (AT), bran (AB), and polished adlay (PA). A solvent extraction technique and column chromatography were utilized to investigate the active fractions and components of adlay. Based on a BSA-glucose assay, the ethanolic extracts of AT (ATE) and AB (ABE) revealed a greater capacity to inhibit protein glycation. ATE was further consecutively partitioned into four solvent fractions with n-hexane, ethyl acetate (ATE-Ea), 1-butanol (ATE-BuOH), and water. ATE-BuOH and -Ea show marked inhibition of glucose-mediated glycation. Medium–high polarity subfractions eluted from ATE-BuOH below 50% methanol with Diaion HP-20, ATE-BuOH-c to -f, exhibited superior antiglycation activity, with a maximum inhibitory percentage of 88%. Two phenolic compounds, chlorogenic acid and ferulic acid, identified in ATE-BuOH with HPLC, exhibited potent inhibition of the individual stage of protein glycation and its subsequent crosslinking, as evaluated by the BSA-glucose assay, BS-methylglyoxal (MGO) assay, and G.K. peptide-ribose assay. In conclusion, this study demonstrated the antiglycation properties of ATE in vitro that suggest a beneficial effect in targeting hyperglycemia-mediated protein modification.     

Automating a 96-well microtiter plate assay for identification of AGEs inhibitors or inducers: application to the screening of a small natural compounds library

Advanced glycation end-products (AGEs) are involved in the pathogenesis of numerous affections such as diabetes and neurological diseases. AGEs are also implied in various changes in tissues and organs. Therefore, compounds able to break them or inhibit their formation may be considered as potential drugs, dietary supplements, or bioactive additives. In this study, we have developed a rapid and reliable (Z′ factor calculation) anti-AGEs activity screening based on the overall fluorescence of AGEs. This method was successfully evaluated on known AGEs inhibitors and on a small library of natural compounds, yielding coherent results when compared with literature data.     

Pathobiological role of advanced glycation endproducts via mitogen-activated protein kinase dependent pathway in the diabetic vasculopathy

Advanced glycation endproducts (AGEs) have been reported to play a role in neointimal formation and increase the rate of in-stent restenosis (ISR) in the diabetic coronary artery disease patients treated with stents, but the potential pathogenic mechanisms of AGEs in vascular smooth muscle cell proliferation remain unclear. We sought to determine the AGEs related pathobiological mechanism of diabetic vasculopathy. Rat aortic smooth muscle cell (RAoSMC) culture was done with different concentrations of AGEs and proliferation was assessed. Immunohistochemistry for receptor of AGEs (RAGE) was performed with human carotid atheroma. Western blotting was performed to assess the activation of MAP kinase system in the cultured RAoSMC. AGEs increased RAoSMC proliferation and were associated with increased phosphorylation of ERK and p38 kinase by time and dose dependent manner. The MAP kinase activity was decreased by RNA interference for RAGE. AGEs stimulation increased reactive oxygen species (ROS) generation in cultured RAoSMC. From this study it is concluded that AGEs played a key role in RAoSMC proliferation via MAP kinase dependent pathways. Activation of vascular smooth muscle cell (VSMC) proliferation by MAP kinase system and increased formation of ROS may be the possible mechanisms of AGEs induced diabetic vasculopathy.     

Photosensitizing activity of advanced glycation endproducts on tryptophan, glucose 6-phosphate dehydrogenase, human serum albumin and ascorbic acid evaluated at low oxygen pressure

A comparative study of the photosensitizing activity of advanced glycation endproducts (AGEs) prepared by incubating glucose (Glc), threose (Threo) and ascorbate (AH-) in the presence of lysine (Lys) was performed. Photochemical activity was evaluated under low oxygen pressure with the aim to simulate the conditions of the eye lens. AGE-sensitized tryptophan and AH- photodecomposition and glucose 6-phosphate dehydrogenase inactivation were studied. In all systems, glucose-derived AGEs showed the highest photosensitizing efficiency, followed by ascorbate and threose. The presence of different sensitizers in glycation products mixtures was investigated. For this purpose, Trp decomposition quantum yields were determined at 344 and 367 nm. The values obtained at 344 nm are between three and six times higher than those observed at 367 nm, confirming the presence of at least two compounds with different photosensitizing activities in the mixtures. The chemiluminescence associated with the AGE-mediated oxidation of free Trp and Trp residues in human serum albumin was also studied, and a good correlation between the emission of light and the extent of Trp decomposition was found. In conclusion, it is demonstrated that glucose derived AGEs, which can be formed in vivo in the eye lens of diabetic patients and are accumulated in elderly lenses, have a higher photosensitizing efficiency, at low oxygen pressure, than those arising from ascorbate and threose. This high efficiency is especially significant when proteins are employed as photochemical targets, indicating that protein-sensitizer interaction and the local environment around the sensitizers play an important role.     

In vitro nonenzymatic glycation of DNA nucleobases: an evaluation of advanced glycation end products under alkaline pH

The advanced glycation end products (AGEs) of DNA nucleobases have received little attention, perhaps due to the fact that adenine, guanine, cytosine and thymine do not dissolve under mild pH conditions. To maintain nucleobases in solution, alkaline pH conditions are typically required. The objectives of this investigation were twofold: to study the susceptibility of DNA nucleobases to nonenzymatic attack by different sugars, and to evaluate the factors that influence the formation of nucleobase AGEs at pH 12, i.e., in an alkaline environment that promotes the aldo–keto isomerization and epimerization of sugars. Varying concentrations of adenine, guanine, thymine and cytosine were incubated over time with constant concentrations of D-glucose, D-galactose or D/L-glyceraldehyde under different conditions of temperature and ionic strength. Incubation of the nucleobases with the sugars resulted in a heterogeneous assembly of AGEs whose formation was monitored by UV/fluorescence spectroscopy. Capillary electrophoresis and HPLC were used to resolve the AGEs of the DNA adducts and provided a powerful tool for following the extent of glycation in each of the DNA nucleobases. Mass spectrometry studies of DNA adducts of guanine established that glycation at pH 12 proceeded through an Amadori intermediate.     

Short and long-term effects of Baccharis articulata on glucose homeostasis

In this study, the in vivo effect of the crude extract and n-butanol and aqueous residual fractions of Baccharis articulata (Lam.) Pers. on serum glucose levels, insulin secretion and liver and muscle glycogen content, as well as in vitro action on serum intestinal disaccharidase activity and albumin glycation were investigated. Oral administration of the extract and fractions reduced glycemia in hyperglycemic rats. Additionally, the n-butanol fraction, which has high flavonoids content, stimulated insulin secretion, exhibiting an insulinogenic index similar to that of glipizide. Also, the n-butanol fraction treatment significantly increased glycogen content in both liver and muscle tissue. In vitro incubation with the crude extract and n-butanol and aqueous residual fractions inhibited maltase activity and the formation of advanced glycation end-products (AGEs). Thus, the results demonstrated that B. articulata exhibits a significant antihyperglycemic and insulin-secretagogue role. These effects on the regulation of glucose homeostasis observed for B. articulata indicate potential anti-diabetic properties.     

1,8-Cineole Ameliorates Advanced Glycation End Products-Induced Alzheimer’s Disease-like Pathology In Vitro and In Vivo

Advanced glycation end products (AGEs) are stable products produced by the reaction of macromolecules such as proteins, lipids or nucleic acids with glucose or other reducing monosaccharides, which can be identified by immunohistochemistry in the senile plaques and neurofibrillary tangles of Alzheimer’s disease (AD) patients. Growing evidence suggests that AGEs are important risk factors for the development and progression of AD. 1,8-cineole (CIN) is a monoterpenoid compound which exists in many plant essential oils and has been proven to have neuroprotective activity, but its specific effect and molecular mechanisms are not clear. In this study, AGEs-induced neuronal injury and intracerebroventricular-AGE animals as the possible models for AD were employed to investigate the effects of CIN on AD pathology as well as the molecular mechanisms involved both in vivo and in vitro. Our study demonstrated that CIN could ameliorate tau phosphorylation by down-regulating the activity of GSK-3β and reducing Aβ production by inhibiting the activity of BACE-1 both in vivo and in vitro. It is suggested that CIN has certain therapeutic value in the treatment of AD.     

Open tubular capillary electrochromatography: A useful microreactor for collagen I glycation and interaction studies with low-density lipoprotein particles

Diabetes, a multifunctional disease and a major cause of morbidity and mortality in the industrialized countries, strongly associates with the development and progression of atherosclerosis. One of the consequences of high level of glucose in the blood circulation is glycation of long-lived proteins, such as collagen I, the most abundant component of the extracellular matrix (ECM) in the arterial wall. Glycation is a long-lasting process that involves the reaction between a carbonyl group of the sugar and an amino group of the protein, usually a lysine residue. This reaction generates an Amadori product that may evolve in advanced glycation end products (AGEs). AGEs, as reactive molecules, can provoke cross-linking of collagen I fibrils. Since binding of low-density lipoproteins (LDLs) to the ECM of the inner layer of the arterial wall, the intima, has been implicated to be involved in the onset of the development of an atherosclerotic plaque, collagen modifications, which can affect the affinity of native and oxidized LDL for collagen I, can promote the entrapment of LDLs in the intima and accelerate the progression of atherosclerosis.In this study, open tubular capillary electrochromatography is proposed as a new microreactor to study in situ glycation of collagen I. The kinetics of glycation was first investigated in a fused silica collagen I-coated capillary. Dimethyl sulphoxide, injected as an electroosmotic flow marker, gave information about the charge of coating. Native and oxidized LDL, and selected peptide fragments from apolipoprotein B-100, the protein covering LDL particles, were injected as marker compounds to clarify the interactions between LDLs and the glycated collagen I coating. The method proposed is simple and inexpensive, since only small amounts of collagen and LDL are required. Atomic force microscopy images complemented our studies, highlighting the difference between unmodified and glycated collagen I surfaces.     

Binding Studies of Caffeic and p-Coumaric Acid with α-Amylase: Multispectroscopic and Computational Approaches Deciphering the Effect on Advanced Glycation End Products (AGEs)

Alpha-amylase (α-amylase) is a key player in the management of diabetes and its related complications. This study was intended to have an insight into the binding of caffeic acid and coumaric acid with α-amylase and analyze the effect of these compounds on the formation of advanced glycation end-products (AGEs). Fluorescence quenching studies suggested that both the compounds showed an appreciable binding affinity towards α-amylase. The evaluation of thermodynamic parameters (ΔH and ΔS) suggested that the α-amylase-caffeic/coumaric acid complex formation is driven by van der Waals force and hydrogen bonding, and thus complexation process is seemingly specific. Moreover, glycation and oxidation studies were also performed to explore the multitarget to manage diabetes complications. Caffeic and coumaric acid both inhibited fructosamine content and AGE fluorescence, suggesting their role in the inhibition of early and advanced glycation end-products (AGEs). However, the glycation inhibitory potential of caffeic acid was more in comparison to p-coumaric acid. This high antiglycative potential can be attributed to its additional –OH group and high antioxidant activity. There was a significant recovery of 84.5% in free thiol groups in the presence of caffeic acid, while coumaric attenuated the slow recovery of 29.4% of thiol groups. In vitro studies were further entrenched by in silico studies. Molecular docking studies revealed that caffeic acid formed six hydrogen bonds (Trp 59, Gln 63, Arg 195, Arg 195, Asp 197 and Asp 197) while coumaric acid formed four H-bonds with Trp 59, Gln 63, Arg 195 and Asp 300. Our studies highlighted the role of hydrogen bonding, and the ligands such as caffeic or coumaric acid could be exploited to design antidiabetic drugs.     

Biophysical,Biochemical, and Molecular Docking Investigations of Anti-Glycating,Antioxidant, and Protein Structural Stability Potential of Garlic

Garlic has been reported to inhibit protein glycation, a process that underlies several disease processes, including chronic complications of diabetes mellitus. Biophysical, biochemical, and molecular docking investigations were conducted to assess anti-glycating, antioxidant, and protein structural protection activities of garlic. Results from spectral (UV and fluorescence) and circular dichroism (CD) analysis helped ascertain protein conformation and secondary structure protection against glycation to a significant extent. Further, garlic showed heat-induced protein denaturation inhibition activity (52.17%). It also inhibited glycation, advanced glycation end products (AGEs) formation as well as lent human serum albumin (HSA) protein structural stability, as revealed by reduction in browning intensity (65.23%), decrease in protein aggregation index (67.77%), and overall reduction in cross amyloid structure formation (33.26%) compared with positive controls (100%). The significant antioxidant nature of garlic was revealed by FRAP assay (58.23%) and DPPH assay (66.18%). Using molecular docking analysis, some of the important garlic metabolites were investigated for their interactions with the HSA molecule. Molecular docking analysis showed quercetin, a phenolic compound present in garlic, appears to be the most promising inhibitor of glucose interaction with the HSA molecule. Our findings show that garlic can prevent oxidative stress and glycation-induced biomolecular damage and that it can potentially be used in the treatment of several health conditions, including diabetes and other inflammatory diseases.