Modulatory role of HMG-CoA reductase inhibitors and ezetimibe on LDL-AGEs-induced ROS generation and RAGE-associated signalling in HEK-293 Cells

Mitigation of ROS-triggered endoplasmic reticulum stress by upregulating Nrf2 retards diabetic nephropathy

Endoplasmic reticulum stress (ERS) plays a crucial role in the pathogenesis of diabetic nephropathy (DN), and it is often accompanied by an increase in reactive oxygen species (ROS) production. However, the precise relationship between NFE2-related factor-2 (Nrf2), a key regulator of ROS balance, and ERS in DN remains elusive. This study aimed to investigate the impact of Nrf2 on ERS and its therapeutic potential in DN. Herein, ERS-related changes, including increased activating transcription factor-6 (ATF6), glucose-regulated protein 78 (GRP78), and transcription factor C/EBP homologous protein (CHOP) expression, were observed in the renal tissues of streptozotocin-induced DN mice and high glucose cultured human renal proximal tubular (HK-2) cells. Nrf2 knockdown increased the sensitivity of HK-2 cells to ERS under high glucose conditions, underscoring the regulatory role of Nrf2 in ERS modulation. Notably, upregulating Nrf2 in ezetimibe-treated diabetic mice restored ERS markers and ameliorated albuminuria, glomerular hypertrophy, mesangial expansion, and tubulointerstitial fibrosis. Furthermore, the inhibition of ERS in HK-2 cells by the ROS scavenger, N-acetylcysteine, highlights the interplay between ROS and ERS. This study, for the first time, elucidates that the upregulation of Nrf2 may alleviate the negative influence of ROS-mediated ERS, presenting a promising therapeutic avenue for delaying the progression of DN. These findings suggest a potential strategy for targeting Nrf2 and ERS in developing novel therapeutic interventions for DN.

Attenuation of albumin glycation and oxidative stress by minerals and vitamins: An in vitro perspective of dual-purpose therapy

Nonenzymatic glycation of proteins is accelerated in the context of elevated blood sugar levels in diabetes. Vitamin and mineral deficiencies are strongly linked to the onset and progression of diabetes. The antiglycation ability of various water- and fat-soluble vitamins, along with trace minerals like molybdenum (Mo), manganese (Mn), magnesium (Mg), chromium, etc., have been screened using Bovine Serum Albumin (BSA) as in vitro model. BSA was incubated with methylglyoxal (MGO) at 37 °C for 48 h, along with minerals and vitamins separately, along with controls and aminoguanidine (AG) as a standard to compare the efficacy of the minerals and vitamins. Further, their effects on renal cells' (HEK-293) antioxidant potential were examined. Antiglycation potential is measured by monitoring protein glycation markers, structural and functional modifications. Some minerals, Mo, Mn, and Mg, demonstrated comparable inhibition of protein-bound carbonyl content and ß-amyloid aggregation at maximal physiological concentrations. Mo and Mg protected the thiol group and free amino acids and preserved the antioxidant potential. Vitamin E, D, B1 and B3 revealed significant glycation inhibition and improved antioxidant potential in HEK-293 cells as assessed by estimating lipid peroxidation, SOD and glyoxalase activity. These results emphasize the glycation inhibitory potential of vitamins and minerals, indicating the use of these micronutrients in the prospect of the therapeutic outlook for diabetes management.

Oxidative stress in intervertebral disc degeneration: Molecular mechanisms, pathogenesis and treatment

Low back pain (LBP) is a leading cause of labour loss and disability worldwide, and it also imposes a severe economic burden on patients and society. Among symptomatic LBP, approximately 40% is caused by intervertebral disc degeneration (IDD). IDD is the pathological basis of many spinal degenerative diseases such as disc herniation and spinal stenosis. Currently, the therapeutic approaches for IDD mainly include conservative treatment and surgical treatment, neither of which can solve the problem from the root by terminating the degenerative process of the intervertebral disc (IVD). Therefore, further exploring the pathogenic mechanisms of IDD and adopting targeted therapeutic strategies is one of the current research hotspots. Among the complex pathophysiological processes and pathogenic mechanisms of IDD, oxidative stress is considered as the main pathogenic factor. The delicate balance between reactive oxygen species (ROS) and antioxidants is essential for maintaining the normal function and survival of IVD cells. Excessive ROS levels can cause damage to macromolecules such as nucleic acids, lipids, and proteins of cells, affect normal cellular activities and functions, and ultimately lead to cell senescence or death. This review discusses the potential role of oxidative stress in IDD to further understand the pathophysiological processes and pathogenic mechanisms of IDD and provides potential therapeutic strategies for the treatment of IDD.

Novel Functionalized Spiro [Indoline-3,5'-pyrroline]-2,2'dione Derivatives: Synthesis, Characterization, Drug-Likeness, ADME, and Anticancer Potential

A highly stereo-selective, one-pot, multicomponent method was chosen to synthesize the novel functionalized 1, 3-cycloaddition spirooxindoles (SOXs) (4a-4h). Synthesized SOXs were analyzed for their drug-likeness and ADME parameters and screened for their anticancer activity. Our molecular docking analysis revealed that among all derivatives of SOXs (4a-4h), 4a has a substantial binding affinity (∆G) -6.65, -6.55, -8.73, and -7.27 Kcal/mol with CD-44, EGFR, AKR1D1, and HER-2, respectively. A functional study demonstrated that SOX 4a has a substantial impact on human cancer cell phenotypes exhibiting abnormality in cytoplasmic and nuclear architecture as well as granule formation leading to cell death. SOX 4a treatment robustly induced reactive oxygen species (ROS) generation in cancer cells as observed by enhanced DCFH-DA signals. Overall, our results suggest that SOX (4a) targets CD-44, EGFR, AKR1D1, and HER-2 and induces ROS generation in cancer cells. We conclude that SOX (4a) could be explored as a potential chemotherapeutic molecule against various cancers in appropriate pre-clinical in vitro and in vivo model systems.

Association of circulatory PCSK-9 with biomarkers of redox imbalance and inflammatory cascades in the prognosis of diabetes and associated complications: a pilot study in the Indian population

AbstractsBesides the profound role of proprotein convertase subtilisin/kexin type-9 (PCSK-9) in LDL-C regulation, its association with other metabolic complications cannot be disregarded. The co-existence of redox imbalance and inflammatory cascades has greatly reflected the etiology of hyperglycemia. Therefore, we studied the association of PCSK-9 with inflammation and oxidative stress biomarkers to predict its role in the prognosis of diabetes and its associated complications in the Indian population. This pilot study examined a total of n = 187 subjects: healthy controls (HC; n = 50), diabetic without complication (T2DM; n = 49), diabetic nephropathy (T2DM-N; n = 43), and diabetic dyslipidemic (T2DM-DL; n = 45) subjects. The relationship between circulatory PCSK-9 levels and inflammation and redox imbalance biomarkers has been explored. The significant positive association of elevated PCSK-9 level with the inflammatory (i.e. IL-1β, IL-6, TNF-α, and CRP) and oxidative stress marker (i.e. XOD, CD, LOOH, and MDA) was observed in T2DM-N and T2DM-DL subjects. Whereas single regression analysis depicted that PCSK-9 was inversely associated with the FRAP and PON-1 in T2DM-N and T2DM-DL subjects. Furthermore, no significant correlation was detected in both T2DM and HC subjects. We found a significant relationship between these prognostic biomarkers with an elevated level of PCSK-9 in T2DM-N and T2DM-DL subjects. PCSK-9 is a nontraditional biomarker in diabetes that may help identify patients at risk of developing secondary complications of diabetes in the Indian population. However, further large cohort validation studies are needed.

Secondary Metabolite Profiling, Antioxidant, Antidiabetic and Neuroprotective Activity of Cestrum nocturnum (Night Scented-Jasmine): Use of In Vitro and In Silico Approach in Determining the Potential Bioactive Compound

This study aims to describe the therapeutic potential of C. nocturnum leaf extracts against diabetes and neurological disorders via the targeting of α-amylase and acetylcholinesterase (AChE) activities, followed by computational molecular docking studies to establish a strong rationale behind the α-amylase and AChE inhibitory potential of C. nocturnum leaves-derived secondary metabolites. In our study, the antioxidant activity of the sequentially extracted C. nocturnum leaves extract was also investigated, in which the methanolic fraction exhibited the strongest antioxidant potential against DPPH (IC₅₀ 39.12 ± 0.53 µg/mL) and ABTS (IC₅₀ 20.94 ± 0.82 µg/mL) radicals. This extract strongly inhibited the α-amylase (IC₅₀188.77 ± 1.67 µg/mL) and AChE (IC₅₀ 239.44 ± 0.93 µg/mL) in a non-competitive and competitive manner, respectively. Furthermore, in silico analysis of compounds identified in the methanolic extract of the leaves of C. nocturnum using GC-MS revealed high-affinity binding of these compounds with the catalytic sites of α-amylase and AChE, with binding energy ranging from -3.10 to -6.23 kcal/mol and from -3.32 to -8.76 kcal/mol, respectively. Conclusively, the antioxidant, antidiabetic, and anti-Alzheimer activity of this extract might be driven by the synergistic effect of these bioactive phytoconstituents.

Differential gene expression analysis of RAGE-S100A6 complex for target selection and the design of novel inhibitors for anticancer drug discovery

Receptor for advanced glycation end products (RAGE), a member of the immunoglobulin family, interactions with its ligands trigger downstream signaling and induce an inflammatory response linked to diabetes, inflammation, carcinogenesis, cardiovascular disease, and a variety of other human disorders. The interaction of RAGE and S100A6 has been associated with a variety of malignancies. For the control of RAGE-related illnesses, there is a great demand for more specialized drug options. To identify the most effective target for combating human malignancies associated with RAGE-S100A6 complex, we conducted single and differential gene expression analyses of S100A6 and RAGE, comparing normal and malignant tissues. Further, a structure-based virtual screening was conducted using the ZINC15 database. The chosen compounds were then subjected to a molecular docking investigation on the RAGE active site region, recognized by the various cancer-related RAGE ligands. An optimized RAGE structure was screened against a library of drug-like molecules. The screening results suggested that three promising compounds were presented as the top acceptable drug-like molecules with a high binding affinity at the RAGE V-domain catalytic region. We depicted that these compounds may be potential RAGE inhibitors and could be used to produce a successful medication against human cancer and other RAGE-related diseases based on their various assorted parameters, binding energy, hydrogen bonding, ADMET characteristics, etc. MD simulation on a time scale of 50 ns was used to test the stability of the RAGE-inhibitor complexes. Therefore, targeting RAGE and its ligands using these drug-like molecules may be an effective therapeutic approach.

Metformin encapsulated gold nanoparticles (MTF-GNPs): A promising antiglycation agent

The generation of advanced glycation end products (AGEs) through nonenzymatic protein glycation contributes to the pathogenesis of long-lived diabetic problems. Metformin (MTF) is the very first drug having antihyperglycemic effects on type II diabetes mellitus which also possess interaction with dicarbonyl compounds and blocks the formation of AGEs. In the current study, MTF is bioconjugated with glycation-derived synthesized gold nanoparticles (GNPs) of significant size. Additionally, using various biophysical and biochemical approaches, we investigated the antiglycating capacity MTF-GNPs in contrast to MTF against d-ribose-derived glycation of bovine serum albumin. Our key findings via utilizing various assays demonstrated that MTF-GNPs were able to inhibit AGEs development by reducing hyperchromicity, early glycation products, carbonyl content, hydxoxymethylfurfural content, production of fluorescent AGEs, normalizing the loss of secondary structure (i.e., α-helix and β-sheets) of proteins, elevating the levels of free lysine and free arginine more efficiently compared to pure MTF. Based on these results, we concluded that MTF-GNPs possess a considerable antiglycation property and may be developed as an outstanding anti-AGEs treatment drug. Further in vivo and clinical research are necessary to determine the therapeutic effects of MTF-GNPs against AGE-related and metabolic disorders.

Therapeutic potential of targeting the receptor for advanced glycation end products (RAGE) by small molecule inhibitors

Receptor for advanced glycation end products (RAGE) is a 45 kDa transmembrane receptor of immunoglobulin family that can bind to various endogenous and exogenous ligands and initiate the inflammatory downstream signaling pathways. RAGE is involved in various disorders including cardiovascular and neurodegenerative diseases, cancer, and diabetes. This review summarizes the structural features of RAGE and its various isoforms along with their pathological effects. Mainly, the article emphasized on the translational significance of antagonizing the interactions of RAGE with its ligands using small molecules reported in the last 5 years and discusses future approaches that could be employed to block the interactions in the treatment of chronic inflammatory ailments. The RAGE inhibitors described in this article could prove as a powerful approach in the management of immune‐inflammatory diseases. A critical review of the literature suggests that there is a dire need to dive deeper into the molecular mechanism of action to resolve critical issues that must be addressed to understand RAGE‐targeting therapy and long‐term blockade of RAGE in human diseases.

Carvacrol protects against carbonyl osmolyte-induced structural modifications and aggregation to serum albumin: Insights from physicochemical and molecular interaction studies

The robust use of osmolytes (i.e., polyols and sugars) in the key therapeutic regimens/formulations has questioned their impact beyond the stability of therapeutic proteins as these osmolytes trigger structural alterations into proteins including misfolding and subsequent aggregation into amyloid fibrils. Therefore, the current study is the first to delineate the inhibitory effect of carvacrol (CRV) on the carbonyl osmolyte-induced aggregation as well as structural alterations to the bovine serum albumin (BSA) via a set of physicochemical as well as artificial intelligence (AI)-based molecular docking studies. Our initial findings from physicochemical investigations revealed that CRV exhibits substantial protection to BSA under carbonyl osmolyte stress as evident by the compromised hyperchromicity, Schiff's bases, carbonyl and hydroxymethyl furfural content, reduced fluorescent signals, low Rayleigh scattering and prevention of covalent modifications at Lys and Arg residues. The protection against aggregate formation by CRV was further confirmed through the reduced amyloid-specific congo red absorbance as well as fluorescent signals recorded after adding the fibril-specific extrinsic fluorophore probes (i.e., ThT and ANS). The AI-based molecular docking analysis further revealed that CRV (ΔG: -4.96 kcal/mol) competes with d-fructose (ΔG: -4.40 kcal/mol) to mask the Lys and Arg residues to restrict the osmolyte-mediated protein modifications. In conclusion, CRV exhibits substantial protective impact against carbonyl osmolyte-induced structural alterations and protein misfolding and aggregation.

Potential dual inhibitors of PCSK-9 and HMG-R from natural sources in cardiovascular risk management

Atherosclerotic cardiovascular disease (ASCVD) stands amongst the leading causes of mortality worldwide and has attracted the attention of world's leading pharmaceutical companies in order to tackle such mortalities. The low-density lipoprotein-cholesterol (LDL-C) is considered the most prominent biomarker for the assessment of ASCVD risk. Distinct inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-R), the chief hepatic cholesterogenic enzyme, are being used since last seven decades to manage hypercholesterolemia. On the other hand, discovery and the association of proprotein convertase subtilisin/kexin type-9 (PCSK-9) with increased ASCVD risk have established PCSK-9 as a novel therapeutic target in cardiovascular medicine. PCSK-9 is well reckoned to facilitate the LDL-receptor (LDL-R) degradation and compromised LDL-C clearance leading to the arterial atherosclerotic plaque formation. The currently available HMG-R inhibitors (statins) and PCSK-9 inhibitors (siRNA, anti-sense oligonucleotides, and monoclonal antibodies) have shown great promises in achieving LDL-C lowering goals, however, their life long prescriptions have raised significant concerns. These deficits associated with the synthetic HMG-R and PCSK-9 inhibitors called for the discovery of alternative therapeutic candidates with potential dual HMG-R and PCSK-9 inhibitory activities from natural origins. Therefore, this report firstly describes the mechanistic insights into the cholesterol homeostasis through HMG-R, PCSK-9, and LDL-R functionality and then compiles the pharmacological effects of natural secondary metabolites with special emphasis on their dual HMG-R and PCSK-9 inhibitory action. In conclusion, various natural products exhibit atheroprotective effects via targeting HMG-R and PCSK-9 activities and lipoprotein metabolism, however, further clinical assessments are still warranted prior their approval for ASCVD risk management in hypercholesterolemic patients.

Physicochemical Characterization of In Vitro LDL Glycation and Its Inhibition by Ellagic Acid (EA): An In Vivo Approach to Inhibit Diabetes in Experimental Animals

Hundreds of millions of people around the globe are afflicted by diabetes mellitus. The alteration in glucose fixation process might result into hyperglycaemia and could affect the circulating plasma proteins to undergo nonenzymatic glycation reaction. If it is unchecked, it may lead to diabetes with increase in advanced glycation end products (AGEs). Therefore, the present study was designed to inhibit the diabetes and glycation by using natural antioxidant “ellagic acid” (EA). In this study, we explored the antidiabetes and antiglycation potential of EA in both in vitro (EA at micromolar concentration) and in vivo systems. The EA concentrations of 10 and 20 mg kg⁻¹B.W./day were administered orally for 25 days to alloxan-induced diabetic rats, a week after confirmation of stable diabetes in animals. Intriguingly, EA supplementation in diabetic rats reversed the increase in fasting blood sugar (FBS) and hemoglobin A1c (HbA1c) level. EA also showed an inhibitory role against glycation intermediates including dicarbonyls, as well as AGEs, investigated in a glycation mixture with in vitro and in vivo animal plasma samples. Additionally, EA treatment resulted in inhibition of lipid peroxidation-mediated malondialdehyde (MDA) and conjugated dienes (CD). Furthermore, EA exhibited an antioxidant property, increased the level of plasma glutathione (GSH), and also helped to decrease histological changes evaluated by histoimmunostaining of animal kidney tissues. The results from our investigation clearly indicates the antiglycative property of EA, suggesting EA as an adequate inhibitor of glycation and diabetes, which can be investigated further in preclinical settings for the treatment and management of diabetes-associated complications.

Exploring the Binding Pattern of Geraniol with Acetylcholinesterase through In Silico Docking, Molecular Dynamics Simulation, and In Vitro Enzyme Inhibition Kinetics Studies

Acetylcholinesterase (AChE) inhibition is a key element in enhancing cholinergic transmission and subsequently relieving major symptoms of several neurological and neuromuscular disorders. Here, the inhibitory potential of geraniol and its mechanism of inhibition against AChE were elucidated in vitro and validated via an in silico study. Our in vitro enzyme inhibition kinetics results show that at increasing concentrations of geraniol and substrate, Vmax did not change significantly, but Km increased, which indicates that geraniol is a competitive inhibitor against AChE with an IC₅₀ value 98.06 ± 3.92 µM. All the parameters of the ADME study revealed that geraniol is an acceptable drug candidate. A docking study showed that the binding energy of geraniol (−5.6 kcal mol⁻¹) was lower than that of acetylcholine (−4.1 kcal mol⁻¹) with AChE, which exhibited around a 12.58-fold higher binding affinity of geraniol. Furthermore, molecular dynamics simulation revealed that the RMSD of AChE alone or in complex with geraniol fluctuated within acceptable limits throughout the simulation. The mean RMSF value of the complex ensures that the overall conformation of the protein remains conserved. The average values of Rg, MolSA, SASA, and PSA of the complex were 3.16 Å, 204.78, 9.13, and 51.58 Ų, respectively. We found that the total SSE of AChE in the complex was 38.84% (α-helix: 26.57% and β-sheets: 12.27%) and remained consistent throughout the simulation. These findings suggest that geraniol remained inside the binding cavity of AChE in a stable conformation. Further in vivo investigation is required to fully characterize the pharmacokinetic properties, optimization of dose administration, and efficacy of this plant-based natural compound.

Glycyrrhizic Acid Scavenges Reactive Carbonyl Species and Attenuates Glycation-Induced Multiple Protein Modification: An In Vitro and In Silico Study

The current study is aimed at studying the inhibitory effect of glycyrrhizic acid (GA) on D-ribose-mediated protein glycation via various physicochemical analyses and in silico approaches. Being a potent free radical scavenger and a triterpenoid saponin, GA plays a vital role in diminishing the oxidative stress and thus could be an effective inhibitor of the nonenzymatic glycation process. Our data showed that varying concentrations of GA inhibited the in vitro BSA-AGEs via inhibiting the formation of fructosamines, fluorescent AGEs, scavenging protein carbonyl and hydroxymethyl furfural (HMF) content, and protection against D-ribose-induced modification of BSA as evident by increased free Arg and Lys residues in GA-treated Gly-BSA samples. Moreover, GA also attenuated D-ribose-induced alterations in the secondary structure of BSA by protecting the α-helix and β-sheet conformers and amide-I band delocalization. In addition, GA attenuated the modification in β-cross amyloid structures of BSA and in silico molecular interaction study too showed strong binding of GA with higher number of Lys and Arg residues of BSA and binding energy (ΔG) of -8.8 Kcal/mol, when compared either to reference standard aminoguanidine (AG)-BSA complex (ΔG: -4.3 Kcal/mol) or D-ribose-BSA complex (ΔG: -5.2 Kcal/mol). Therefore, GA could be a new and favorable inhibitor of the nonenzymatic glycation process that ameliorates AGEs-related complications via attenuating the AGE formation and glycation-induced multiple protein modifications with a reduced risk of adverse effects on protein structure and functionality; hence, it could be investigated at further preclinical settings for the treatment and management of diabetes and age-associated complications.

AGE/RAGE in diabetic kidney disease and ageing kidney

Diabetic kidney disease (DKD) is the primary cause of chronic kidney disease that inevitably progress to end-stage kidney disease. Intervention strategies such as blood glucose control is effective for preventing DKD, but many patients with DKD still reach end-stage kidney disease. Although comprehensive mechanisms shed light on the progression of DKD, the most compelling evidence has highlighted that hyperglycemia-related advanced glycation end products (AGEs) formation plays a central role in the pathogenesis of DKD. Pathologically, accumulation of AGEs-mediated receptor for AGEs (RAGE) triggers oxidative stress and inflammation, which is the major deleterious effect of AGEs in host and intestinal microenvironment of diabetic and ageing conditions. The activation of AGEs-mediated RAGE could evoke nicotinamide adenine dinucleotide phosphate oxidase-induced reactive oxygen and nitrogen species production and subsequently give rise to oxidative stress in DKD and ageing kidney. Therefore, targeting RAGE with its ligands mediated oxidative stress and chronic inflammation is considered as an additional intervention strategy for DKD and ageing kidney. In this review, we summarize AGEs/RAGE-mediated oxidative stress and inflammation signaling pathways in DKD and ageing kidney, discussing opportunities and challenges of targeting at AGEs/RAGE-induced oxidative stress that could hold the promising potential approach for improving DKD and ageing kidney.

Ezetimibe attenuates experimental diabetes and renal pathologies via targeting the advanced glycation, oxidative stress and AGE-RAGE signalling in rats

The current in-vivo study was premeditated to uncover the protective role of ezetimibe (EZ) against advanced glycation endproducts (AGEs)-related pathologies in experimental diabetes. Our results showed that EZ markedly improved the altered biochemical markers of diabetes mellitus (DM) (FBG, HbA1c, insulin, microalbumin, and creatinine) and cardiovascular disease (in-vivo lipid/lipoprotein level and hepatic HMG-CoA reductase activity) along with diminished plasma carboxymethyl-lysine (CML) and renal fluorescent AGEs level. Gene expression study revealed that EZ significantly down-regulated the renal AGEs-receptor (RAGE), nuclear factor-κB (NFκB-2), transforming growth factor-β (TGF-β1), and matrix metalloproteinase-2 (MMP-2) mRNA expression, however, the neuropilin-1 (NRP-1) mRNA expression was up-regulated. In addition, EZ also maintained the redox status via decreasing the lipid peroxidation and protein-bound carbonyl content (CC) and increasing the activity of high-density lipoprotein (HDL)-associated-paraoxonase-1 (PON-1) and renal antioxidant enzymes as well as also protected renal histopathological features. We conclude that EZ exhibits antidiabetic and reno-protective properties in diabetic rats.