Mechanistic inhibition of non-enzymatic glycation and aldose reductase activity by naringenin: Binding, enzyme kinetics and molecular docking analysis

Protective effect of colchicine on albumin glycation and cellular oxidative stress: Insights into diabetic cardiomyopathy

The present work elucidates the role of colchicine (COL) on albumin glycation and cellular oxidative stress in diabetic cardiomyopathy (DCM). Human serum albumin (HSA) was glycated with methylglyoxal in the presence of COL (2.5, 3.75, and 5 µM), whereas positive and negative control samples were maintained separately. The effects of COL on HSA glycation, structural and functional modifications in glycated HSA were analyzed using different spectroscopical and fluorescence techniques. Increased fructosamine, carbonyl, and pentosidine formation in glycated HSA samples were inhibited in the presence of COL. Structural conformation of HSA and glycated HSA samples was examined by field emission scanning electron microscopy, circular dichroism, Fourier transform infrared, and proton nuclear magnetic resonance analyses, where COL maintained both secondary and tertiary structures of HSA against glycation. Functional marker assays included ABTS•+ radical scavenging and total antioxidant activities, advanced oxidative protein product formation, and turbidimetry, which showed preserved functional properties of glycated HSA in COL-containing samples. Afterward, rat cardiomyoblast (H9c2 cell line) was treated with glycated HSA-COL complex (400 μg/mL) for examining various cellular antioxidants (nitric oxide, catalase, superoxide dismutase, and glutathione) and detoxification enzymes (aldose reductase, glyoxalase I, and II) levels. All three concentrations of COL exhibited effective anti-glycation properties, enhanced cellular antioxidant levels, and detoxification enzyme activities. The report comprehensively analyzes the potential anti-glycation and properties of COL during its initial assessment.

Development of nano-delivery systems for loaded bioactive compounds: using molecular dynamics simulations

Over the past decade, a remarkable surge in the development of functional nano-delivery systems loaded with bioactive compounds for healthcare has been witnessed. Notably, the demanding requirements of high solubility, prolonged circulation, high tissue penetration capability, and strong targeting ability of nanocarriers have posed interdisciplinary research challenges to the community. While extensive experimental studies have been conducted to understand the construction of nano-delivery systems and their metabolic behavior in vivo, less is known about these molecular mechanisms and kinetic pathways during their metabolic process in vivo, and lacking effective means for high-throughput screening. Molecular dynamics (MD) simulation techniques provide a reliable tool for investigating the design of nano-delivery carriers encapsulating these functional ingredients, elucidating the synthesis, translocation, and delivery of nanocarriers. This review introduces the basic MD principles, discusses how to apply MD simulation to design nanocarriers, evaluates the ability of nanocarriers to adhere to or cross gastrointestinal mucosa, and regulates plasma proteins in vivo. Moreover, we presented the critical role of MD simulation in developing delivery systems for precise nutrition and prospects for the future. This review aims to provide insights into the implications of MD simulation techniques for designing and optimizing nano-delivery systems in the healthcare food industry.

Inhibitory effect of Nifedipine on aldose reductase delays cataract progression

Aldose reductase (ALR2) is a rate-limiting component of the polyol pathway, which is essential for the NADPH-mediated conversion from glucose to sorbitol. ALR2 dysregulation has been linked to α-crystallin aggregation, increased oxidative stress, and calcium inflow, all of which contribute to a diabetic cataract. Given its crucial role in occular pathologies, ALR2 has emerged as a promising target to treat oxidative stress and hyperglycaemic condition which form the underlying cause of diabetic cataracts. However, several of them had issues with sensitivity and specificity to ALR2, despite being screened as effective ALR2 inhibitors from a wide range of structurally varied molecules. The current study investigates the inhibitory potential of Nifedipine, an analog of the dihydro nicotinamide class of compounds against ALR2 activity. The enzyme inhibition studies were supported by in vitro biomolecular interactions, molecular modeling approaches, and in vivo validation in diabetic rat models. Nifedipine demonstrated appreciable inhibitory potential with the purified recombinant hAR (human aldose reductase; with an IC50 value of 2.5 µM), which was further supported by Nifedipine-hAR binding affinity (Kd = 2.91 ± 1.87 × 10-4 M) by ITC and fluorescence quenching assays. In the in vivo models of STZ-induced diabetic rats, Nifedipine delayed the onset progression of cataracts by preserving the antioxidant enzyme activity (SOD, CAT, and GPX GSH, TBARS, and protein carbonyls) and was shown to retain the α-crystallin chaperone activity by reducing the calcium levels in the diabetic rat lens. In conclusion, our results demonstrate effective inhibition of ALR2 by Nifedipine, resulting in amelioration of diabetic cataract conditions by lowering oxidative and osmotic stress while retaining the chaperone activity of α-crystallins. The present study could be envisaged to improve the eye condition in older adults upon Nifedipine treatment.

Antiglycation potential of metal ions and polyphenolic extract of chickpea on thiol-protease inhibitor: A management for diabetic complications

Glycation is the non-enzymatic adduct formation between reducing sugars or dicarbonyls with proteins and is a crucial molecular event under hyperglycaemic conditions of diabetes. The accumulation of advanced glycation end products (AGEs) due to glycation of proteins has been implicated in several diseases associated with ageing and diabetes. Thus, investigating the antiglycation potential of some trace metal ions (Manganese; Mn2+, and Zinc; Zn2+) and polyphenolic extract of chickpea seeds (PEC) on the methylglyoxal (MGO) induced glycation of a phytocystatin isolated from chickpea was taken up to find an inexpensive and non-toxic therapeutic means of medicating protein glycation and associated diabetic complications. The current study focused on the comparative analyses of these micronutrients and herbal extracts in inhibiting protein glycation and AGEs formation in a quest to develop nutraceuticals for managing diabetes. The effect of metals (Mn2+, Zn2+) and PEC on protein glycation was assessed by different techniques, i.e., glycation-specific AGE fluorescence and absorbance, thiol protease inhibitory activity assay, and conformational alterations by spectroscopic assays. This study revealed the significant anti-glycation potencies of Mn2+, Zn2+, and PEC against the MGO-induced glycation of CPC, which might pave the way for resolving pathological complications of diabetes by combining higher levels of efficacy, selectivity, and safety in humans. Moreover, characterization and identification of different AGEs formed during the glycation process in diabetics was done to apply the same for determining the onset of glycation at the early stage so that appropriate steps be taken to address the menace of diabetic complications.

Cheminformatics identification of modulators of key carbohydrate-metabolizing enzymes from C. cujete for type-2 diabetes mellitus intervention

Purpose

The therapeutic use of oral hypoglycaemic agents in the management of type-2 diabetes mellitus (T2DM) is without adverse effects; thus, calls for alternative and novel candidates from natural products in medicinal plants.

Method

The study explored molecular docking and molecular dynamics (MD) simulation approaches to identify key antidiabetic metabolites from Crescentia cujete.

Results

Molecular docking results identified four and/or five best compounds against each target enzyme (alpha-glucosidase, dipeptidyl peptidase-IV, aldose reductase, and protein tyrosine phosphatase-1B (PTP-1B)) implicated in diabetes. The resulting complexes (except against PTP-1B) had higher docking scores above respective standards (acarbose, Diprotin A, ranirestat). The MD simulation results revealed compounds such as benzoic acid (-48.414 kcal/mol) and phytol (-45.112 kcal/mol) as well as chlorogenic acid (-42.978 kcal/mol) and naringenin (-31.292 kcal/mol) had higher binding affinities than the standards [acarbose (-28.248 kcal/mol), ranirestat (-21.042 kcal/mol)] against alpha-glucosidase and aldose reductase, respectively while Diprotin A (-45.112 kcal/mol) and ursolic acid (-18.740 kcal/mol) presented superior binding affinities than the compounds [luteolin (-41.957 kcal/mol and naringenin (-16.518 kcal/mol)] against DPP-IV and PTP-1B respectively.

Conclusion

While isoflavone (alpha-glucosidase), xylocaine (DPP-IV), luteolin (aldose reductase,) and chlorogenic acid (PTP-1B) were affirmed as the best inhibitors of respective enzyme targets, luteolin, and chlorogenic acid may be suggested and proposed as probable candidates against T2DM and related retinopathy complication based on their structural stability, compactness and affinity for three (DPP-IV, aldose reductase, and PTP-1B) of the four targets investigated. Further studies are warranted in vitro and in vivo on the antihyperglycaemic effects of these drug candidates.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01249-7.

Molecular insights into α-glucosidase inhibition and antiglycation properties affected by the galloyl moiety in (-)-epigallocatechin-3-gallate

BACKGROUND

Diabetes mellitus poses a substantial threat to public health due to rising morbidity and mortality. α-Glucosidase is one of the key enzymes affecting diabetes. Herein, (-)-epigallocatechin-3-gallate (EGCG) and (-)-epigallocatechin (EGC) were applied to clarify the role of the galloyl moiety of tea polyphenols in the inhibition of glycation and α-glucosidase activity. The structure-activity relationship of the galloyl moiety in EGCG on α-glucosidase was investigated in terms of inhibition kinetics, spectroscopy, atomic force microscopy and molecular docking. A bovine serum protein-fructose model was employed to determine the effect of the galloyl moiety on glycation.

RESULTS

The results indicated that the introduction of a galloyl moiety enhanced the capacity of EGCG to inhibit glycation and α-glucosidase activity. The IC50 value of EGC is approximately 2400 times higher than that of EGCG. Furthermore, the galloyl moiety in EGCG altered the microenvironment and secondary structure of α-glucosidase, resulting in a high binding affinity of EGCG to α-glucosidase. The binding constant of EGCG to α-glucosidase at 298 K is approximately 28 times higher than that of EGC.

CONCLUSION

Overall, the galloyl moiety of EGCG plays a crucial role in inhibiting glycation and α-glucosidase activity, which helps to enhance the molecular understanding of the structure and function of the polyphenol galloyl moiety in the science of food and agriculture. © 2023 Society of Chemical Industry.

Discovery of novel glucosinolates inhibiting advanced glycation end products: Virtual screening and molecular dynamic simulation

Protein glycation can result in the formation of advanced glycation end products (AGEs), which pose a potential health risk due to their association with diabetic complications. Natural products are a source of drugs discovery and the search for potential natural inhibitors of AGEs is of great significance. Glucosinolates (GSLs) mainly from cruciferous plants have potential antioxidant, anti-inflammatory, and anti-glycation activities. In this study, the inhibitory activity of GSLs on bovine serum albumin (BSA) along with its mechanism was investigated by virtual screening and various computational simulation techniques. Virtual screening revealed that 174 GSLs were screened using Maestro based on the glide score and 89% of the compounds were found to have potential anti-glycation ability with the docking scores less than -5 kcal/mol. Molecular docking showed that the top 10 GSLs were bound to the IIA structural domain of BSA. Among them, glucohesperin (1) and 2-hydroxyethyl glucosinolate (2) had the lowest docking scores of -9.428 and -9.333 kcal/mol, respectively, reflecting their good binding affinity. Molecular dynamics simulations of 1 (ΔG = -43.46 kcal/mol) and 2 (ΔG = -43.71 kcal/mol) revealed that the complexes of these two compounds with proteins had good stability. Further binding site analysis suggested that the mechanism of inhibition of protein glycation by these two active ingredients might be through competitive hydrogen bonding to maintain the structural integrity of the protein, thus inhibiting glycation reaction. Moreover, the ADMET values and CYP450 metabolism prediction data were within the recommended values. Therefore, it can be concluded that 1 and 2 may act as potential anti-glycation agents.

Rutin impedes human low-density lipoprotein from non-enzymatic glycation: A mechanistic insight against diabetes-related disorders

Glycation of human low-density protein (LDL) has an essential contribution to cardiovascular diseases. Natural compounds like rutin have been extensively studied in preventing glycation-induced oxidative stress. This study examined rutin's anti-glycation potential with glycated LDL utilizing spectroscopic and in silico methods. Glycated LDL treated with rutin, showed around 80 % inhibition in advanced glycation end-product production. Carbonyl content and lipid peroxidation like assays were used to establish the development of oxidative stress. Rutin was seen to lower the generation of oxidative stress in a dose-dependent manner. Using thioflavin t-test and electron microscopy, rutin was suggested to restore the structural disturbances in glycated LDL. Moreover, CD spectroscopy suggested reinstation of secondary structure of glycated LDL treated with rutin. Mechanistic insights between rutin and LDL were observed through spectroscopic measures. Molecular docking study confirmed the LDL-rutin binding with a binding energy of -10.0 kcal/mol. The rutin-LDL complex was revealed to be highly stable by molecular dynamics simulation, with RMSD, RMSF, Rg, SASA, and the secondary structure of LDL remaining essentially unchanged during the simulation period. Our study suggests that rutin possesses strong anti-glycating properties, which can be useful in therapeutics, as glycated LDL has an important role in atherosclerotic cardiovascular diseases.

Fishing the Targets of Bioactive Compounds from Psidium guajava L. Leaves in the Context of Diabetes

Psidium guajava L. (guava) leaves have demonstrated their in vitro and in vivo effect against diabetes mellitus (DM). However, there is a lack of literature concerning the effect of the individual phenolic compounds present in the leaves in DM disease. The aim of the present work was to identify the individual compounds in Spanish guava leaves and their potential contribution to the observed anti-diabetic effect. Seventy-three phenolic compounds were identified from an 80% ethanol extract of guava leaves by high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry. The potential anti-diabetic activity of each compound was evaluated with the DIA-DB web server that uses a docking and molecular shape similarity approach. The DIA-DB web server revealed that aldose reductase was the target protein with heterogeneous affinity for compounds naringenin, avicularin, guaijaverin, quercetin, ellagic acid, morin, catechin and guavinoside C. Naringenin exhibited the highest number of interactions with target proteins dipeptidyl peptidase-4, hydroxysteroid 11-beta dehydrogenase 1, aldose reductase and peroxisome proliferator-activated receptor. Compounds catechin, quercetin and naringenin displayed similarities with the known antidiabetic drug tolrestat. In conclusion, the computational workflow showed that guava leaves contain several compounds acting in the DM mechanism by interacting with specific DM protein targets.

Butein Inhibits the Glycation of α-Crystallin: An Approach in Prevention of Retinopathy

The aggregation of lens proteins induced by glycation is one of the key drivers of diabetic retinopathy and development of diabetic cataracts. Moreover, glycation also causes numerous alterations not only to the tertiary structure of lens proteins but also to serum proteins. There are also evidences of covalent crosslinking among lens crystallins resulting in development of cataract. In this article, the inhibitory potential of butein was tested against the glucose induced glycation and the aggregation α-crystallin (α-cry). The results showed that there was inhibition of advanced glycation products (78.28%) and early glycation products (86.30%) following the treatment of butein. Additionally, the presence of butein caused a significant improvement in the tested biochemical markers of glycation. The treatment with butein reduced the free lysine modification to 23.67%. The secondary and tertiary structural distortions of α-cry were also protected. The mechanism of inhibition further investigated at the molecular level using biophysical and computational techniques. The interaction data showed the butein exhibited strong affinity towards the α-cry. The binding event was entropically driven and energetically favourable. The Gibb's free energy of the interaction was found to be -5.99 to -7.17 kcal mol^-1. The binding site of butein in α-cry was deciphered by molecular docking and the dynamics was studied using molecular dynamics (MD) simulations. The simulation data showed that butein formed stable complex with α-cry under physiological conditions. Most of the tested parameters from molecular simulations, such as secondary structure, was found to be stable. The data clearly show the potential of butein in inhibiting the glycation induced aggregation of α-cry and hence can be developed as useful inhibitor in the management of diabetic cataract and retinopathy.

Celecoxib, Glipizide, Lapatinib, and Sitagliptin as potential suspects of aggravating SARS-CoV-2 (COVID-19) infection: a computational approach

COVID-19 caused by SARS-CoV-2 has emerged as a potential threat to human life, especially to people suffering from chronic diseases. In this study, we investigated the ability of selected FDA-approved drugs to inhibit TACE (tumor necrosis factor α converting enzyme), which is responsible for the shedding of membrane-bound ACE2 (angiotensin-converting enzyme2) receptors into soluble ACE2. The inhibition of TACE would lead to an increased population of membrane-bound ACE2, which would facilitate ACE2-Spike protein interaction and viral entry. A total of 50 drugs prescribed in treating various chronic diseases in Saudi Arabia were screened by performing molecular docking using AutoDock4.2. Based on docking energy (≤ -9.00 kcal mol^-1), four drugs (Celecoxib, Glipizide, Lapatinib, and Sitagliptin) were identified as potential inhibitors of TACE, with binding affinities up to 10⁶-10⁷ M^-1. Analysis of the molecular docking suggests that these drugs were bound to TACE's catalytic domain and interact with the key residues such as His405, Glu406, and His415, which are involved in active site Zn²⁺ ion chelation. Molecular dynamics simulation was performed to confirm the stability of TACE-drugs complexes. RMSD (root mean square deviation), RMSF (root mean square fluctuation), Rg (radius of gyration), and SASA (solvent accessible surface area) were within the acceptable limits. Free energy calculations using Prime-MM/GBSA suggest that Celecoxib formed the most stable complex with TACE, followed by Glipizide, Sitagliptin, and Lapatinib. The finding of this study suggests a mechanism for drugs to aggravate SARS-CoV-2 infection and hence high mortality in patients suffering from chronic diseases.Communicated by Ramaswamy H. Sarma.

Insight into the Interaction Mechanism of HSA with Aztreonam: A Multispectroscopic and Computational Approach

Aztreonam is a Gram-negative bacteria-targeting synthetic monobactam antibiotic. Human serum albumin (HSA) plays an important role in the transference of pharmaceuticals, hormones, and fatty acids, along with other compounds, determining their biodistribution and physiological fate. Using several biophysical and in silico approaches, we studied the interaction of aztreonam with HSA under physiological environments in this study. Results confirm the formation of HSA-aztreonam complex where aztreonam showed moderate affinity towards HSA. A static mode of quenching was confirmed from the steady state fluorescence data. FRET findings also showed that there was a significant feasibility of energy transfer between HSA and aztreonam. Site marker displacement experimental conclusion suggested the binding site of aztreonam was the sub-domain IB of HSA. Circular dichroic spectroscopic analysis suggested that aztreonam interaction decreases the α-helical content of HSA. Changes in microenvironment were studied through synchronous fluorescence data. According to molecular docking results, the HSA-aztreonam complex is mostly maintained by non-covalent forces, with a binding energy of 7.7 kcal mol^-1. The presence of a hydrogen bond, van der Waal interaction, and pi-anion interaction in the binding process, as well as conformational changes in HSA after binding with aztreonam, are all confirmed by molecular dynamic simulation.

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.

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.

Advanced Glycation End Products in the Skin: Molecular Mechanisms, Methods of Measurement, and Inhibitory Pathways

Advanced glycation end products (AGEs) are a series of stable compounds produced under non-enzymatic conditions by the amino groups of biomacromolecules and the free carbonyl groups of glucose or other reducing sugars commonly produced by thermally processed foods. AGEs can cause various diseases, such as diabetes, atherosclerosis, neurodegeneration, and chronic kidney disease, by triggering the receptors of AGE (RAGEs) in the human body. There is evidence that AGEs can also affect the different structures and physiological functions of the skin. However, the mechanism is complicated and cumbersome and causes various harms to the skin. This article aims to identify and summarise the formation and characteristics of AGEs, focussing on the molecular mechanisms by which AGEs affect the composition and structure of normal skin substances at different skin layers and induce skin issues. We also discuss prevention and inhibition pathways, provide a systematic and comprehensive method for measuring the content of AGEs in human skin, and summarise and analyse their advantages and disadvantages. This work can help researchers acquire a deeper understanding of the relationship between AGEs and the skin and provides a basis for the development of effective ingredients that inhibit glycation.

Investigation of antidiabetic properties of shikonin by targeting aldose reductase enzyme: In silico and in vitro studies

Diabetes is a complicated multifactorial disorder in which the patient generally observes polyphagia, polydipsia, and polyuria due to uncontrolled growth in blood sugar levels. For its management, the pharmaceutical industry is working day and night to find a better drug with no or least toxicity. That's why nowadays a more focused branch is to use herbal phytoconstituents for its prevention. Shikonin is a naphthoquinone natural dye that is isolated from the plants of the Boraginaceae family and has proven its role as an anti-cancer, anti-inflammatory, and anti-gonadotrophic agent. In our previous study, we have published its anti-diabetic action by inhibiting the enzyme protein tyrosine phosphatase 1B. In this study, we were more focused on finding out the role of Shikonin and its pharmacophores by inhibiting the action of aldose reductase (AR) enzyme. The study was conducted using pharmacophore modeling, molecular docking, and molecular dynamics simulation studies. The absorption, distribution, metabolism, excretion (ADME), and toxicity profile were also evaluated in this study. Along with all the computational biology parameters we also focused on the in vitro activity and kinetic study of inhibitory activity of Shikonin against aldose reductase.

Ameliorative effect of pioglitazone on glucose induced glycation of α-crystallin: Management of complications associated with diabetic retinopathy

The glycation and aggregation of lens proteins significantly contribute to the onset of diabetic cataracts as well as the retinopathy. The glycation exerts numerous alterations in the tertiary structural of proteins. Moreover, the covalent crosslinking of lens crystallins also contribute to the cataract formation. In this article, the effect of pioglitazone on glucose induced glycation and aggregation α-crystallin was examined. A remarkable inhibition of early glycation products (~80%) and advanced glycation products (~75%) was recorded by the treatment of pioglitazone. There was >75% recovery in biochemical marker (carbonyl content). The presence of 150 μM of pioglitazone reduced the free lysine modifications to 35%. Treatment of pioglitazone also protected the secondary structural alterations induced by glycation and inhibited the formation of protein aggregates. The interaction studies showed that pioglitazone interacted with α-crystallin via moderate binding affinity. The interaction between pioglitazone interacted and α-crystallin was energetically and entropically favourable. The complex of pioglitazone with studied protein stable in which RMSF, R_g, SASA, RMSD, and the secondary structural components was not affected. The findings show antiglycation activity of pioglitazone along with its mechanism of action highlighting the ability of drug to be possibly developed novel as glycation inhibitor.

Binding and thermodynamic study of thalidomide with calf thymus DNA: Spectroscopic and computational approaches

The thalidomide-DNA interactions have been investigated in detail by numerous biophysical techniques such as UV-vis, dye displacement assay, viscosity, cyclic voltammetry, circular dichroism, molecular docking, molecular dynamic simulation, FT-IR and ¹H NMR spectroscopy. CD spectroscopy, thermal denaturation and viscosity measurement explained that thalidomide is groove binder. Molecular docking analysis highlighted that thalidomide binds trough minor groove of calf thymus DNA which also confirmed from dye displacement experiment. To our knowledge, this is the first instance thalidomide was shown to binds with calf thymus DNA. Molecular dynamic simulation indicated that the thalidomide-DNA system was stabilized by electrostatic attraction as the main interaction and mode of binding is minor groove. Our study provides a better understanding to the DNA-thalidomide binding affinity and it mechanism. Overall, all these in formations can be used for further understanding the pharmacological effects of thalidomide.

Concatenation of molecular docking and molecular simulation of BACE-1, γ-secretase targeted ligands: in pursuit of Alzheimer's treatment

INTRODUCTION

Alzheimer's disease (AD), the most predominant cause of dementia, has evolved tremendously with an escalating frequency, mainly affecting the elderly population. An effective means of delaying, preventing, or treating AD is yet to be achieved. The failure rate of dementia drug trials has been relatively higher than in other disease-related clinical trials. Hence, multi-targeted therapeutic approaches are gaining attention in pharmacological developments.

AIMS

As an extension of our earlier reports, we have performed docking and molecular dynamic (MD) simulation studies for the same 13 potential ligands against beta-site APP cleaving enzyme 1 (BACE-1) and γ-secretase as a therapeutic target for AD. The In-silico screening of these ligands as potential inhibitors of BACE-1 and γ-secretase was performed using AutoDock enabled PyRx v-0.8. The protein-ligand interactions were analyzed in Discovery Studio 2020 (BIOVIA). The stability of the most promising ligand against BACE-1 and γ-secretase was evaluated by MD simulation using Desmond-2018 (Schrodinger, LLC, NY, USA).

RESULTS

The computational screening revealed that the docking energy values for each of the ligands against both the target enzymes were in the range of -7.0 to -10.1 kcal/mol. Among the 13 ligands, 8 (55E, 6Z2, 6Z5, BRW, F1B, GVP, IQ6, and X37) showed binding energies of ≤-8 kcal/mol against BACE-1 and γ-secretase. For the selected enzyme targets, BACE-1 and γ-secretase, 6Z5 displayed the lowest binding energy of -10.1 and -9.8 kcal/mol, respectively. The MD simulation study confirmed the stability of BACE-6Z5 and γ-secretase-6Z5 complexes and highlighted the formation of a stable complex between 6Z5 and target enzymes.

CONCLUSION

The virtual screening, molecular docking, and molecular dynamics simulation studies revealed the potential of these multi-enzyme targeted ligands. Among the studied ligands, 6Z5 seems to have the best binding potential and forms a stable complex with BACE-1 and γ-secretase. We recommend the synthesis of 6Z5 for future in-vitro and in-vivo studies.

Coumarin Exhibits Broad-Spectrum Antibiofilm and Antiquorum Sensing Activity against Gram-Negative Bacteria: In Vitro and In Silico Investigation

Quorum sensing (QS) and biofilm inhibition are recognized as the novel drug targets for the broad-spectrum anti-infective strategy to combat the infections caused by drug-resistant bacterial pathogens. Many compounds from medicinal plants have been found to demonstrate anti-infective activity. However, broad-spectrum anti-QS and antibiofilm efficacy and their mode of action are poorly studied. In this study, the efficacy of coumarin was tested against QS-regulated virulent traits of Gram-negative bacteria. Coumarin inhibited the production of violacein pigment in Chromobacterium violaceum 12472 by 64.21%. Similarly, there was 87.25, 70.05, 76.07, 58.64, 48.94, and 81.20% inhibition of pyocyanin, pyoverdin, and proteolytic activity, lasB elastase activity, swimming motility, and rhamnolipid production, respectively, in Pseudomonas aeruginosa PAO1. All tested virulence factors of Serratia marcescens MTCC 97 were also suppressed by more than 50% at the highest sub-minimum inhibitory concentration. Moreover, the biofilms of bacterial pathogens were also inhibited in a dose-dependent manner. Molecular docking and molecular dynamics (MD) simulation gave insights into the possible mode of action. The binding energy obtained by docking studies ranged from -5.7 to -8.1 kcal mol^-1. Coumarin was found to be docked in the active site of acylhomoserine lactone (AHL) synthases and regulatory proteins of QS. MD simulations further supported the in vitro studies where coumarin formed a stable complex with the tested proteins. The secondary structure of all proteins showed a negligible change in the presence of coumarin. Computational studies showed that the possible mechanisms of anti-QS activity were the inhibition of AHL synthesis, antagonization of QS-regulatory proteins, and blocking of the receptor proteins. The findings of this study clearly highlight the potency of coumarin against the virulence factors of Gram-negative bacterial pathogens that may be developed as an effective inhibitor of QS and biofilms.

Development of Aldose Reductase Inhibitors for the Treatment of Inflammatory Disorders and Cancer: Current Drug Design Strategies and Future Directions

Aldose Reductase (AR) is an enzyme that converts glucose to sorbitol during the polyol pathway of glucose metabolism. AR has been shown to be involved in the development of secondary diabetic complications due to its involvement in causing osmotic as well as oxidative stress. Various AR inhibitors have been tested for their use to treat secondary diabetic complications, such as retinopathy, neuropathy, and nephropathy in clinical studies. Recent studies also suggest the potential role of AR in mediating various inflammatory complications. Therefore, the studies on the development and potential use of AR inhibitors to treat inflammatory complications and cancer besides diabetes are currently on the rise. Further, genetic mutagenesis studies, computer modeling, and molecular dynamics studies have helped design novel and potent AR inhibitors. This review discussed the potential new therapeutic use of AR inhibitors in targeting inflammatory disorders and cancer besides diabetic complications. Further, we summarized studies on how AR inhibitors have been designed and developed for therapeutic purposes in the last few decades.

Bioflavonoid (Hesperidin) Restrains Protein Oxidation and Advanced Glycation End Product Formation by Targeting AGEs and Glycolytic Enzymes

Alpha-amylase (α-amylase) not long ago has acquire recognition as a possible drug target for the management of diabetes. Here, we have investigated the binding and enzyme activity of α-amylase by hesperidin; a naturally occurring flavanone having wide therapeutic potential. Hesperidin exerted an inhibitory influence on α-amylase activity with an IC₅₀ value of 16.6 µM. Hesperidin shows a significant binding toward α-amylase with a binding constant (K_a) of the order of 10⁴ M^-1. The evaluation of thermodynamic parameters (∆H and ∆S) suggested that van der Waals force and hydrogen bonding drive seemingly specific hesperidin-α-amylase complex formation. Glycation and oxidation studies were performed using human serum albumin (HSA) as ideal protein. Hesperidin inhibited fructosamine content ≈40% at 50 µM and inhibited advanced glycation end products (AGEs) formation by 71.2% at the same concentration. Moreover, significant recovery was evident in free -SH groups and carbonyl content of HSA. Additionally, molecular docking also entrenched in vitro observations and provided an insight into the important residues (Trp58, Gln63, His101, Glu233, Asp300, and His305) at the heart of hesperidin-α-amylase interaction. This study delineates mechanistic insight of hesperidin-α-amylase interaction and provides a platform for use of hesperidin to treat AGEs directed diseases.

Design, synthesis and molecular modeling studies of novel mesalamine linked coumarin for treatment of inflammatory bowel disease

Inflammatory bowel diseases (IBD) are continuous idiopathic inflammation of GIT. Ulcerative colitis, inflammation of the colonic or rectal mucosa has no known medical cure and its treatment is aimed at reducing the signs and symptoms associated with the disorders, induction and maintenance of remission. In this study, we have reported the synthesis of mesalamine and coumarin linked together by a diazo group. The compound was characterized by various spectroscopic methods. Therapeutic potential of the synthesized compound was investigated through acetic acid induced ulcerative rat model. Pharmacokinetic properties were predicted for the compounds by ADMET related descriptors. Molecular docking studies were conducted with four proteins (COX-2, MMP-9, TNF-α and MPO) to examine the interaction of mesalamine (MS) and mesalamine coumarin derivative (MS-CU). Moreover, molecular dynamic simulations were carried out to study the dynamics and stability of the complexes in solvent system. The binding energy of MS-CU with MPO, COX-2, MMP-9 and TNF-α was found to be -9.5, -10.4, -9.2 and -8.4 kcal/mol respectively. MS-CU exhibited higher binding affinity towards all tested proteins than MS. Molecular dynamic simulation reveals that both MS and MS-CU formed a stable complex with all test proteins in aqueous system. Overall binding energy of MS-CU was more than MS showing stronger affinity towards the test portions. In conclusion, Mesalamine-coumarin derivative reduces colonic damage in acetic acid induced ulcerative colitis in rat model, and therefore may prove to be effective in the management of IBD.

Purification and characterization of aldose reductase from jerboa (Jaculus orientalis) and evaluation of its inhibitory activity by Euphorbia regis-jubae (Webb & Berth) extracts

This study aimed, for the first time, to assess the purification of aldose reductase (AR) in Jaculus orientalis (Dipodidae family) kidney and to evaluate the in vitro aldose reductase inhibitory (ARI) effects of Euphorbia regis-jubae (Euphorbiaceae family) aqueous and hydroethanolic extracts. Initial screening assay of the enzymatic AR activity in different jerboa states (euthermic, prehibernating and hibernating) and tissues (brain, brown adipose tissue, liver and kidneys) was assessed. Then, AR has been purified to homogeneity from the kidneys of prehibernating jerboas by a series of chromatographic technics. Furthermore, the in vitro and in silico ARI effects of E. regis-jubae (Webb & Berth) extracts, characterized by hight performance liquid chromatography (HPLC) on the purified enzyme were evaluated. Our results showed that the highest enzyme activity was detected in the kidneys, followed by white adipose tissue and the lungs of pre-hibernating jerboa. The enzyme was purified to homogeneity from jerboa kidneys during prehibernating state with a purification factor of 53.4-fold and a yield of about 6%. AR is monomeric, active in D(+)-glyceraldehyde substrate and in disodium phosphate buffer. The pH and temperature for AR were determined to be 6.5-7.5 and 35 °C, respectively. Results of the in vitro ARI activity was strongest with both the hydroethanolic extract (IC₅₀ = 96.45 μg/mL) and aqueous extract (IC₅₀ = 140 μg/mL). Molecular docking study indicated that catechin might be the main component in both aqueous and hydroethanolic extracts to inhibited AR. This study provides new evidence on the ARI effect of E. regis-jubae (Webb & Berth), which may be related to its phenolic constituents.

Vitexin Inhibits Protein Glycation through Structural Protection, Methylglyoxal Trapping, and Alteration of Glycation Site

In this study, the antiglycation potential and mechanisms of vitexin were explored in vitro by multispectroscopy, microscope imaging, high-resolution mass spectrometry, and computational simulations. Vitexin was found to show much stronger antiglycation effects than aminoguanidine. The inhibition against the fluorescent advanced glycation end products was more than 80% at 500 μM vitexin in both bovine serum albumin (BSA)-fructose and BSA-methylglyoxal (MGO) models. Treated with 100 and 200 μM vitexin for 24 h, the contents of MGO were reduced to 4.97 and 0.2%, respectively, and only one vitexin-mono-MGO adduct was formed. LC-Orbitrap-MS/MS analysis showed that vitexin altered the glycated sites and reduced the glycation degree of some sites. The mechanisms of vitexin against protein glycation were mainly through BSA structural protection, MGO trapping, and alteration of glycation sites induced by interaction with BSA. These findings provided valuable information about the functional development of vitexin as a potential antiglycation agent.

Glyburide inhibits non-enzymatic glycation of HSA: An approach for the management of AGEs associated diabetic complications

Advanced glycation endproducts (AGEs) are the final product of glycation, highly reactive in nature and contribute directly or indirectly to numerous complications related to diabetes. In this study, the antiglycation activity of glyburide was investigated using HSA as model protein, both against glucose and methylglyoxal mediated glycation. The possible mechanism of action was also deciphered using biophysical and computational tools. Approximately 70% inhibition of both early and advanced glycation end products were recorded in the presence of glyburide. Free lysine modification was reduced by glyburide treatment and improvement in biochemical markers such as free thiol groups and carbonyl content was observed. Interaction studies revealed that glyburide showed moderate to strong binding affinity towards HSA with binding constant in the order of 10⁶ M^-1. The interaction of glyburide with HSA was entropically favourable and spontaneous in nature. Molecular dynamics simulation deciphered that glyburide-HSA complex was quite stable where RMSD, RMSF, R_g, SASA, and secondary structure of HSA remained approximately same over the entire simulation period. The average binding energy of the MD simulation for glyburide-HSA complex was found to be -15.386 kJ mol^-1. The findings demonstrate the antiglycation potential of glyburide and its possible mechanism of action.