Curcumin eliminates the effect of advanced glycation end-products (AGEs) on the divergent regulation of gene expression of receptors of AGEs by interrupting leptin signaling

Fructose-mediated AGE-RAGE axis: approaches for mild modulation

Fructose is a valuable and healthy nutrient when consumed at normal levels (≤50 g/day). However, long-term consumption of excessive fructose and elevated endogenous production can have detrimental health impacts. Fructose-initiated nonenzymatic glycation (fructation) is considered as one of the most likely mechanisms leading to the generation of reactive species and the propagation of nonenzymatic processes. In the later stages of glycation, poorly degraded advanced glycation products (AGEs) are irreversibly produced and accumulated in the organism in an age- and disease-dependent manner. Fructose, along with various glycation products-especially AGEs-are present in relatively high concentrations in our daily diet. Both endogenous and exogenous AGEs exhibit a wide range of biological effects, mechanisms of which can be associated with following: (1) AGEs are efficient sources of reactive species in vivo, and therefore can propagate nonenzymatic vicious cycles and amplify glycation; and (2) AGEs contribute to upregulation of the specific receptor for AGEs (RAGE), amplifying RAGE-mediated signaling related to inflammation, metabolic disorders, chronic diseases, and aging. Therefore, downregulation of the AGE-RAGE axis appears to be a promising approach for attenuating disease conditions associated with RAGE-mediated inflammation. Importantly, RAGE is not specific only to AGEs; it can bind multiple ligands, initiating a complex RAGE signaling network that is not fully understood. Maintaining an appropriate balance between various RAGE isoforms with different functions is also crucial. In this context, mild approaches related to lifestyle-such as diet optimization, consuming functional foods, intake of probiotics, and regular moderate physical activity-are valuable due to their beneficial effects and their ability to mildly modulate the fructose-mediated AGE-RAGE axis.

The association between plant-based diet indices and risk of mortality in patients with cirrhosis: a cohort study

BACKGROUND

Following a plant-based diet is associated with a wide range of health benefits. The current study aimed to investigate the association between plant-based diet indices, specifically the plant-based diet index (PDI), healthful PDI (hPDI), and unhealthful PDI (uPDI) and risk of mortality in cirrhotic patients.

METHODS

This cohort study included a total of 121 patients with cirrhosis, who were followed for four years. Plant-based diet indices were calculated based on a validated semi-quantitative food frequency questionnaire consisting of 168 items. The Hazard ratio (HR) with their corresponding 95% confidence intervals (CIs) were estimated using the Cox proportional risk models.

RESULTS

During 414 person-year of follow-up, 43 deaths (7 women, 36 men) were documented. After adjusting all confounders, it has been found that the PDI (HR T3 vs. T1 = 0.16, 95% CI = 0.03-0.89, P trend = 0.024) and hPDI (HR T3 vs. T1 = 0.04, 95% CI = 0.02-0.61, P trend = 0.020) were inversely associated with the risk of mortality. While uPDI was directly associated with a significant increase in mortality risk (HR T3 vs. T1 = 8.74, 95% CI = 0.33-17.14, P trend = 0.018). The 4-year survival rate among patients showed a significant relationship with all three indices.

CONCLUSIONS

Our findings highlight that higher scores of PDI and hPDI can significantly reduce the risk of mortality in patients with cirrhosis, while a significant increase in mortality risk was found in those with higher uPDI. However, confirmation of these findings requires further studies.

The effectiveness of antioxidant agents in delaying progression of diabetic nephropathy: A systematic review of randomized controlled trials

Introduction

Oxidative stress plays a central role in the pathophysiology of diabetes mellitus and its complications, including diabetic nephropathy. Excessive production of reactive oxygen species (ROS) alters renal metabolic pathways, leading to inflammation, endothelial dysfunction, and fibrosis, ultimately resulting in end-stage renal disease (ESRD). Studies have shown that exogenous antioxidants can improve the pathophysiological condition of patients with diabetic nephropathy. Objective: This systematic review aims to investigate the types of antioxidant agents that inhibit the development of diabetic nephropathy and the effectiveness of antioxidant agent interventions to repair kidney structure and function.

Methods

A systematic review of randomized controlled trials that examined the role of antioxidants in improving diabetic nephropathy was conducted. The literature search was performed on PubMed, ScienceDirect, and EBSCO. The inclusion criteria covered articles on the antioxidant activity of herbal extracts and compounds that inhibit the progression of diabetic nephropathy in humans. In addition, the articles were written in English and published between 2012 and 2022. The reporting of the systematic review followed the Preferred Reporting Elements for Systematic Review and Meta-Analysis (PRISMA) guideline. The full texts of all potentially relevant systematic reviews were assessed for quality using the Risk of Bias 2 (RoB 2) tool.

Results

A total of 2,367 articles were identified in the three databases, of which only 15 articles met the inclusion criteria. Antioxidant agents that inhibit diabetic nephropathy can be classified as single antioxidants (silymarin, baicalin, epigallocatechin gallate, vitamin E, selenium, curcumin, α-lipoic acid, and tocotrienol-rich vitamin E) and combined antioxidants (α-lipoic acid with vitamin B6, and resveratrol with losartan). Antioxidant agents have been shown to reduce oxidative stress and inflammation, but their role in the progression of fibrosis remains unclear. The oxidative stress marker MDA was significantly reduced by silymarin, curcumin, vitamin E, tocotrienol-rich vitamin E, selenium, ALA, vitamin B, resveratrol and losartan. Silymarin was found to be the most effective (-3.43 µmol/L; 6.02 to 0.83). Compared to silymarin and epigallocatechin gallate, vitamin E was more effective (at -35.4 ng/L; P < 0.001) in reducing inflammation by decreasing TNF-α levels. In addition, tocotrienol-rich vitamin E, silymarin, baicalin, and selenium showed a decrease TGF-β levels, but did not show statistically significant differences between the placebo and intervention groups.

Conclusion

Potential antioxidant agents, such as flavonoids, vitamins, fatty acids, and antioxidant minerals, were examined in this systematic review. These agents contribute to reducing markers of oxidative stress and hyperglycemia-induced inflammation. Although several antioxidants play a role in reducing fibrosis markers, the effect does not appear to be statistically significant.

The effect of curcumin supplementation on circulating adiponectin and leptin concentration in adults: a GRADE-assessed systematic review and meta-analysis of randomised controlled trials

Curcumin is a phytocompound found in the root of turmeric, a common herbal ingredient in many Asian cuisines. The compound contains anti-inflammatory activity, which is mediated through an upregulation of adiponectin and reduction of leptin. Results of randomised controlled trials (RCT) have shown that the effects of curcumin on adipokines are conflicting. Therefore, the current systematic review and meta-analysis of RCT were conducted with the aim of elucidating the role of curcumin supplementation on serum adiponectin and leptin. The search included PubMed, Embase, Cochrane Library, Scopus, Web of Science and Google Scholar from inception to August 2023. For net changes in adipokines, standardised mean differences (SMD) were calculated using random effects models. Thirteen RCT with fourteen treatment arms were eligible for inclusion in this meta-analysis. Curcumin supplementation was effective in increasing serum adiponectin (SMD = 0·86, 95 % CI (0·33, 1·39), P < 0·001; I2 = 93·1 %, P < 0·001) and reducing serum leptin (SMD = -1·42, 95 % CI (-2·29, -0·54), P < 0·001; I2 = 94·7 %, P < 0·001). In conclusion, curcumin supplementation significantly increased circulating adiponectin and decreased leptin levels in adults.

Non-enzymatic glycation and diabetic kidney disease

Chronic diabetes leads to various complications including diabetic kidney disease (DKD). DKD is a major microvascular complication and the leading cause of morbidity and mortality in diabetic patients. Varying degrees of proteinuria and reduced glomerular filtration rate are the cardinal clinical manifestations of DKD that eventually progress into end-stage renal disease. Histopathologically, DKD is characterized by renal hypertrophy, mesangial expansion, podocyte injury, glomerulosclerosis, and tubulointerstitial fibrosis, ultimately leading to renal replacement therapy. Amongst the many mechanisms, hyperglycemia contributes to the pathogenesis of DKD via a mechanism known as non-enzymatic glycation (NEG). NEG is the irreversible conjugation of reducing sugars onto a free amino group of proteins by a series of events, resulting in the formation of initial Schiff's base and an Amadori product and to a variety of advanced glycation end products (AGEs). AGEs interact with cognate receptors and evoke aberrant signaling cascades that execute adverse events such as oxidative stress, inflammation, phenotypic switch, complement activation, and cell death in different kidney cells. Elevated levels of AGEs and their receptors were associated with clinical and morphological manifestations of DKD. In this chapter, we discussed the mechanism of AGEs accumulation, AGEs-induced cellular and molecular events in the kidney and their impact on the pathogenesis of DKD. We have also reflected upon the possible options to curtail the AGEs accumulation and approaches to prevent AGEs mediated adverse renal outcomes.

GLP-1/Sigma/RAGE receptors: An evolving picture of Alzheimer's disease pathology and treatment

According to the facts and figures 2023stated that 6.7 million Americans over the age of 65 have Alzheimer's disease (AD). The scenario of AD has reached up to the maximum, of 4.1 million individuals, 2/3rd are female patients, and approximately 1 in 9 adults over the age of 65 have dementia with AD dementia. The fact that there are now no viable treatments for AD indicates that the underlying disease mechanisms are not fully understood. The progressive neurodegenerative disease, AD is characterized by amyloid plaques and neurofibrillary tangles (NFTs) of abnormally hyperphosphorylated tau protein and senile plaques (SPs), which are brought on by the buildup of amyloid beta (Aβ). Numerous attempts have been made to produce compounds that interfere with these characteristics because of significant research efforts into the primary pathogenic hallmark of this disorder. Here, we summarize several research that highlights interesting therapy strategies and the neuroprotective effects of GLP-1, Sigma, and, AGE-RAGE receptors in pre-clinical and clinical AD models.

Role of polyphenols in the management of diabetic complications

BACKGROUND

Diabetes Mellitus is an endocrine disorder that will affect, about 693 million adults by 2045 worldwide, (>50% increase from 2017). The conventional treatment of the disease, include the oral hypoglycemic drugs which are given in combination with other drugs and are known to possess various adverse effects like gastrointestinal disturbance, nausea, water retention etc. PURPOSE: Due to the urgent need of combating this disorder without side effects, the alternative and complementary therapies should be explored due to their natural origins and comparable safety. Herbal sources serve as new leads, due to the presence of phytoconstituents with potential therapeutic properties, efficacy and safety. In this review, we tried to summarise the polyphenolic phytoconstituents effective in the treatment of diabetic complications.

METHODS

A systematic literature search was conducted using 4 databases (Google scholar, Pubmed, Scopus, Embase) for the identification of relevant data. Search was performed using various key words such as "diabetes", "polyphenols", "marine sources","anti-diabetic polyphenols". The in vitro studies involving the cell lines used in diabetes and animal models were also considered for inclusion. Additional research papers were identified by reviewing abstracts, scrutinizing reference lists, and reviewing previously published review articles.

RESULTS

Polyphenols, a group of phytoconstituents are known worldwide for their tremendous antioxidant potential. So, various research groups have explored their mechanism and therapeutic value in diabetic complications, to improve the insulin sensitivity and glucose metabolism, in controlling the glycemic conditions.

CONCLUSION

Polyphenols exhibit effective therapeutic potential in managing diabetic complications through their multifaceted mechanism of action. They exhibit antioxidative, anti-inflammatory, and anti-glycemic properties, which collectively contribute to their beneficial effects in mitigating diabetic complications. Thus, the inclusion of polyphenols into the diet, may be cosidered as an approach of managing diabetes on long term basis. In this review, we have tried to identify polyphenols effective in diabetes and summarize their mechanism of action along with their potential, for the treatment of diabetic complications.

An immune-related multi-omics analysis of dolichyl-diphosphooligosaccharide protein glycosyltransferase in glioma: Prognostic value exploration and competitive endogenous RNA network identification

Dolichyl-diphosphooligosaccharide protein glycosyltransferase (DDOST) plays a pivotal role in the glycosylation of asparagine residues on nascent polypeptides. However, the biological role of DDOST in glioma remains unclear. The mRNA expression of DDOST in glioma was identified using TCGA, CGGA, GEO and Rembrandt datasets. Immunohistochemistry assay was conducted to examine the protein level of DDOST. Cox regression analysis, nomograms and calibration plots were used to evaluate the prognostic value of DDOST. The association between DDOST and immune cell infiltration was evaluated using CIBERSORT algorithm. Additionally, DNA methylation and ceRNA regulatory network of DDOST expression were investigated using the LinkedOmics and ENCORI databases. The authors found that DDOST was substantially expressed at the mRNA and protein levels. Functional enrichment analysis revealed close associations between DDOST and immune-related pathways, as well as immune cell infiltration. In addition, DDOST exhibited synergistic effects with tumour mutational burden (TMB) and other immune checkpoints. For expression regulation mechanisms, DDOST had low DNA methylation levels in high-grade gliomas and may be involved in multiple ceRNA networks in glioma. Thus, DDOST may serve as an unfavourable biomarker for gliomas. DNA methylation and ceRNA regulatory networks of DDOST expression were identified for the first time in this multi-omics study.

Inhibition of advance glycation end products formation, gastrointestinal digestion, absorption and toxicity: A comprehensive review

Advanced glycation end-products (AGEs) are the final products of the non-enzymatic interaction between reducing sugars and amino groups in proteins, lipids and nucleic acids. In numerous diseases, such as diabetes, neuropathy, atherosclerosis, aging, nephropathy, retinopathy, and chronic renal illness, accumulation of AGEs has been proposed as a pathogenic mechanism of inflammation, oxidative stress, and structural tissue damage leading to chronic vascular issues. Current studies on the inhibition of AGEs mainly focused on food processing. However, there are few studies on the inhibition of AGEs during digestion, absorption and metabolism although there are still plenty of AGEs in our body with our daily diet. This review comprehensively expounded AGEs inhibition mechanism based on the whole process of digestion, absorption and metabolism by polyphenols, amino acids, hydrophilic colloid, carnosine and other new anti-glycation agents. Our study will provide a ground-breaking perspective on mediation or inhibition AGEs.

Selected Plant-Derived Polyphenols as Potential Therapeutic Agents for Peripheral Artery Disease: Molecular Mechanisms, Efficacy and Safety

Vascular diseases, such as peripheral artery disease (PAD), are associated with diabetes mellitus and a higher risk of cardiovascular disease and even death. Surgical revascularization and pharmacological treatments (mainly antiplatelet, lipid-lowering drugs, and antidiabetic agents) have some effectiveness, but the response and efficacy of therapy are overly dependent on the patient’s conditions. Thus, the demand for new cures exists. In this regard, new studies on natural polyphenols that act on key points involved in the pathogenesis of vascular diseases and, thus, on PAD are of great urgency. The purpose of this review is to take into account the mechanisms that lead to endothelium dysfunction, such as the glycoxidation process and the production of advanced glycation end-products (AGEs) that result in protein misfolding, and to suggest plant-derived polyphenols that could be useful in PAD. Thus, five polyphenols are considered, baicalein, curcumin, mangiferin, quercetin and resveratrol, reviewing the literature in PubMed. The key molecular mechanisms and preclinical and clinical studies of each selected compound are examined. Furthermore, the safety profiles of the polyphenols are outlined, together with the unwanted effects reported in humans, also by searching the WHO database (VigiBase).

Effect of Curcumin on Attenuation of Liver Cirrhosis via Genes/Proteins and Pathways: A System Pharmacology Study

Background: Liver cirrhosis is a life-threatening seqsuel of many chronic liver disorders of varying etiologies. In this study, we investigated protein targets of curcumin in liver cirrhosis based on a bioinformatics approach. Methods: Gene/protein associations with curcumin and liver cirrhosis were probed in drug−gene and gene−diseases databases including STITCH/DGIdb/DisGeNET/OMIM/DISEASES/CTD/Pharos and SwissTargetPrediction. Critical clustering groups (MCODE), hub candidates and critical hub genes in liver cirrhosis were identified, and connections between curcumin and liver cirrhosis-related genes were analyzed via Venn diagram. Interaction of hub genes with curcumin by molecular docking using PyRx-virtual screening tools was performed. Results: MCODE analysis indicated three MCODEs; the cluster (MCODE 1) comprised 79 nodes and 881 edges (score: 22.59). Curcumin database interactions recognized 318 protein targets. Liver cirrhosis genes and curcumin protein targets analysis demonstrated 96 shared proteins, suggesting that curcumin may influence 20 candidate and 13 hub genes, covering 81% of liver cirrhosis critical genes and proteins. Thirteen shared proteins affected oxidative stress regulation, RNA, telomerase activity, cell proliferation, and cell death. Molecular docking analysis showed the affinity of curcumin binding hub genes (Binding affinity: ΔG < −4.9 kcal/mol). Conclusions: Curcumin impacted on several critical liver cirrhosis genes mainly involved in extracellular matrix communication, focal adhesion, and the response to oxidative stress.

Accumulation of Advanced Glycation End-Products in the Body and Dietary Habits

The formation of advanced glycation end-products (AGE) in tissues is a physiological process; however, excessive production and storage are pathological and lead to inflammation. A sedentary lifestyle, hypercaloric and high-fructose diet and increased intake of processed food elements contribute to excessive production of compounds, which are created in the non-enzymatic multi-stage glycation process. The AGE’s sources can be endogenous and exogenous, mainly due to processing food at high temperatures and low moisture, including grilling, roasting, and frying. Accumulation of AGE increases oxidative stress and initiates various disorders, leading to the progression of atherosclerosis, cardiovascular disease, diabetes and their complications. Inborn defensive mechanisms, recovery systems, and exogenous antioxidants (including polyphenols) protect from excessive AGE accumulation. Additionally, numerous products have anti-glycation properties, occurring mainly in fruits, vegetables, herbs, and spices. It confirms the role of diet in the prevention of civilization diseases.

Therapeutic Role of Curcumin in Diabetes: An Analysis Based on Bioinformatic Findings

BACKGROUND

Diabetes is an increasingly prevalent global disease caused by the impairment in insulin production or insulin function. Diabetes in the long term causes both microvascular and macrovascular complications that may result in retinopathy, nephropathy, neuropathy, peripheral arterial disease, atherosclerotic cardiovascular disease, and cerebrovascular disease. Considerable effort has been expended looking at the numerous genes and pathways to explain the mechanisms leading to diabetes-related complications. Curcumin is a traditional medicine with several properties such as being antioxidant, anti-inflammatory, anti-cancer, and anti-microbial, which may have utility for treating diabetes complications. This study, based on the system biology approach, aimed to investigate the effect of curcumin on critical genes and pathways related to diabetes.

METHODS

We first searched interactions of curcumin in three different databases, including STITCH, TTD, and DGIdb. Subsequently, we investigated the critical curated protein targets for diabetes on the OMIM and DisGeNET databases. To find important clustering groups (MCODE) and critical hub genes in the network of diseases, we created a PPI network for all proteins obtained for diabetes with the aid of a string database and Cytoscape software. Next, we investigated the possible interactions of curcumin on diabetes-related genes using Venn diagrams. Furthermore, the impact of curcumin on the top scores of modular clusters was analysed. Finally, we conducted biological process and pathway enrichment analysis using Gene Ontology (GO) and KEGG based on the enrichR web server.

RESULTS

We acquired 417 genes associated with diabetes, and their constructed PPI network contained 298 nodes and 1651 edges. Next, the analysis of centralities in the PPI network indicated 15 genes with the highest centralities. Additionally, MCODE analysis identified three modular clusters, which highest score cluster (MCODE 1) comprises 19 nodes and 92 edges with 10.22 scores. Screening curcumin interactions in the databases identified 158 protein targets. A Venn diagram of genes related to diabetes and the protein targets of curcumin showed 35 shared proteins, which observed that curcumin could strongly interact with ten of the hub genes. Moreover, we demonstrated that curcumin has the highest interaction with MCODE1 among all MCODs. Several significant biological pathways in KEGG enrichment associated with 35 shared included the AGE-RAGE signaling pathway in diabetic complications, HIF-1 signaling pathway, PI3K-Akt signaling pathway, TNF signaling, and JAK-STAT signaling pathway. The biological processes of GO analysis were involved with the cellular response to cytokine stimulus, the cytokine-mediated signaling pathway, positive regulation of intracellular signal transduction and cytokine production in the inflammatory response.

CONCLUSION

Curcumin targeted several important genes involved in diabetes, supporting the previous research suggesting that it may have utility as a therapeutic agent in diabetes.

Design of Hepatic Targeted Drug Delivery Systems for Natural Products: Insights into Nomenclature Revision of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic-dysfunction-associated fatty liver disease (MAFLD), affects a quarter of the worldwide population. Natural products have been extensively utilized in treating NAFLD because of their distinctive advantages over chemotherapeutic drugs, despite the fact that there are no approved drugs for therapy. Notably, the limitations of many natural products, such as poor water solubility, low bioavailability in vivo, low hepatic distribution, and lack of targeted effects, have severely restricted their clinical application. These issues could be resolved via hepatic targeted drug delivery systems (HTDDS) that boost clinical efficacy in treating NAFLD and decrease the adverse effects on other organs. Herein an overview of natural products comprising formulas, single medicinal plants, and their crude extracts has been presented to treat NAFLD. Also, the clinical efficacy and molecular mechanism of active monomer compounds against NAFLD are systematically discussed. The targeted delivery of natural products via HTDDS has been explored to provide a different nanotechnology-based NAFLD treatment strategy and to make suggestions for natural-product-based targeted nanocarrier design. Finally, the challenges and opportunities put forth by the nomenclature update of NAFLD are outlined along with insights into how to improve the NAFLD therapy and how to design more rigorous nanocarriers for the HTDDS. In brief, we summarize the up-to-date developments of the NAFLD-HTDDS based on natural products and provide viewpoints for the establishment of more stringent anti-NAFLD natural-product-targeted nanoformulations.

Deletion of RAGE fails to prevent hepatosteatosis in obese mice due to impairment of other AGEs receptors and detoxifying systems

Advanced glycation endproducts (AGEs) are involved in several diseases, including NAFLD and NASH. RAGE is the main receptor mediating the pro-inflammatory signalling induced by AGEs. Therefore, targeting of RAGE has been proposed for prevention of chronic inflammatory diseases. However, the role of RAGE in the development of NAFLD and NASH remains poorly understood. We thus aimed to analyse the effect of obesity on AGEs accumulation, AGE-receptors and AGE-detoxification, and whether the absence of RAGE might improve hepatosteatosis and inflammation, by comparing the liver of lean control, obese (LeptrDb-/-) and obese RAGE-deficient (RAGE-/- LeptrDb-/-) mice. Obesity induced AGEs accumulation and RAGE expression with hepatosteatosis and inflammation in LeptrDb-/-, compared to lean controls. Despite the genetic deletion of RAGE in the LeptrDb-/- mice, high levels of intrahepatic AGEs were maintained accompanied by decreased expression of the protective AGE-receptor-1, impaired AGE-detoxifying system glyoxalase-1, and increased expression of the alternative AGE-receptor galectin-3. We also found sustained hepatosteatosis and inflammation as determined by persistent activation of the lipogenic SREBP1c and proinflammatory NLRP3 signalling pathways. Thus, RAGE targeting is not effective in the prevention of NAFLD in conditions of obesity, likely due to the direct liver specific crosstalk of RAGE with other AGE-receptors and AGE-detoxifying systems.

Diet-Derived Antioxidants and Their Role in Inflammation, Obesity and Gut Microbiota Modulation

It is generally accepted that gut microbiota, inflammation and obesity are linked to the development of cardiovascular diseases and other chronic/non-communicable pathological conditions, including cancer, neurodegenerative diseases and ageing-related disorders. In this scenario, oxidative stress plays a pivotal role. Evidence suggests that the global dietary patterns may represent a tool in counteracting oxidative stress, thus preventing the onset of diseases related to oxidative stress. More specifically, dietary patterns based on the regular consumption of fruits and vegetables (i.e., Mediterranean diet) have been licensed by various national nutritional guidelines in many countries for their health-promoting effects. Such patterns, indeed, result in being rich in specific components, such as fiber, minerals, vitamins and antioxidants, whose beneficial effects on human health have been widely reported. This suggests a potential nutraceutical power of specific dietary components. In this manuscript, we summarize the most relevant evidence reporting the impact of dietary antioxidants on gut microbiota composition, inflammation and obesity, and we underline that antioxidants are implicated in a complex interplay between gut microbiota, inflammation and obesity, thus suggesting their possible role in the development and modulation of chronic diseases related to oxidative stress and in the maintenance of wellness. Do all roads lead to Rome?

Macrocarquinoids A-C, new meroterpenoids from Sargassum macrocarpum

The production and accumulation of advanced glycation end products (AGEs) have been implicated in diabetes and diabetic complication. This study was conducted as a search for an AGE inhibitor from brown alga, Sargassum macrocarpum. Separation and purification were performed using AGEs inhibitory activity as an index, yielding isolation of 11 meroterpenoids, of which 3 were new compounds: macrocarquinoids A (1), B (6), and C (9). Their structures were elucidated using NMR spectral analysis with 2D techniques. All tested compounds showed AGEs inhibitory activity. Particularly, macrocarquinoid C (9) possessed the strongest activity (IC50: 1.0 mM) of isolated compounds. This activity was stronger than that of aminoguanidine (positive control).

Omaveloxolone and TX63682 are hepatoprotective in the STAM mouse model of nonalcoholic steatohepatitis

Omaveloxolone is a potent activator of Nrf2, a master transcriptional regulator of a multitude of cytoprotective functions, including antioxidative, anti-inflammatory, and mitochondrial bioenergetic effects. Some of the most potent known effects of Nrf2 involve hepatoprotective functions. The purpose of this study was to evaluate the effects of omaveloxolone and TX63682, a closely related structural analog with similar oral bioavailability, in the STAM mouse model of nonalcoholic steatohepatitis (NASH). C57Bl/6 mice received a single subcutaneous injection of streptozotocin two days after birth and were fed a high-fat diet from 4 to 9 weeks of age. Omaveloxolone and TX63682 were orally administered at doses of 1, 3, and 10 mg/kg/d from 6 to 9 weeks of age. Consistent with the beneficial effects of Nrf2 on hepatoprotection and improved lipid handling, both omaveloxolone and TX63682 decreased hepatic fat deposition, hepatocellular ballooning, inflammatory cell infiltration, and collagen deposition. Omaveloxolone and TX63682 also improved blood glucose control, as evidenced by reductions in nonfasting blood glucose and glycated hemoglobin A1C concentrations. Reductions in liver and serum triglycerides with omaveloxolone and TX63682 treatment were also observed. Both omaveloxolone and TX63682 decreased leptin and increased adiponectin in serum, which is consistent with the anti-inflammatory and antifibrotic effects observed in the liver. These results were associated with significant induction of Nrf2 target gene expression in the liver, including NAD(P)H:quinone oxidoreductase 1, sulfiredoxin 1, and ferritin heavy chain 1. Overall, these data suggest that omaveloxolone and related Nrf2 activators may be useful for the treatment of NASH.

The Close Interplay of Nitro-Oxidative Stress, Advanced Glycation end Products and Inflammation in Inflammatory Bowel Diseases

BACKGROUND

Inflammatory Bowel Disease (IBD) exhibits no defined aetiology. However, factors such as genetic and nitro-oxidative stress are associated with chronic inflammation and IBD progression to Colorectal Cancer (CRC). The present review discusses the association of nitro-oxidative stress, inflammation and Advanced Glycation End products (AGE) and their corresponding receptor (RAGE) in IBD and examines the connection between these factors and nuclear factors, such as Nuclear Factor Kappa B (NF-κB), factorerythroid 2-related factor-2 (Nrf2), and p53 Mutant (p53M).

METHODS

We searched the PubMed, ScienceDirect and Web of Science databases using a combination of the following terms: IBD, CRC, oxidative stress, inflammation, NF-κB, Nrf2, p53M, AGE and RAGE.

RESULTS

Oxidative stress and inflammation activated two cellular pathways, the nuclear expression of pro-inflammatory, pro-oxidant and pro-oncogenic genes based on NF-κB and p53M, which is associated with NF-κB activation, Deoxyribonucleic acid (DNA) damage and the expression of pro-oncogenic genes. Nrf2 stimulates the nuclear expression of enzymatic and non-enzymatic antioxidant systems and anti-inflammatory genes, and is inhibited by chronic oxidative stress, NF-κB and p53M. AGE/RAGE are involved in inflammation progression because RAGE polymorphisms and increased RAGE levels are found in IBD patients. Alterations of these pathways in combination with oxidative damage are responsible for IBD symptoms and the progression to CRC.

CONCLUSION

IBD is an inflammatory and nitro-oxidative stress-based bowel disease. Achieving a molecular understanding of the biochemical events and their complicated interactions will impact basic and applied research, animal models, and clinical trials.

Curcumin, Alone or in Combination with Aminoguanidine, Increases Antioxidant Defenses and Glycation Product Detoxification in Streptozotocin-Diabetic Rats: A Therapeutic Strategy to Mitigate Glycoxidative Stress

Both oxidative stress and the exacerbated generation of advanced glycation end products (AGEs) have crucial roles in the onset and progression of diabetic complications. Curcumin has antioxidant and antidiabetic properties; its combination with compounds capable of preventing the advanced glycation events, such as aminoguanidine, is an interesting therapeutic option to counteract diabetic complications. This study is aimed at investigating the effects of treatments with curcumin or aminoguanidine, alone or in combination, on metabolic alterations in streptozotocin-diabetic rats; the focus was mainly on the potential of these bioactive compounds to oppose the glycoxidative stress. Curcumin (90 mg/kg) or aminoguanidine (50 and 100 mg/kg), alone or in combination, slightly decreased glycemia and the biomarkers of early protein glycation, but markedly decreased AGE levels (biomarkers of advanced glycation) and oxidative damage biomarkers in the plasma, liver, and kidney of diabetic rats. Some novel insights about the in vivo effects of these bioactive compounds are centered on the triggering of cytoprotective machinery. The treatments with curcumin and/or aminoguanidine increased the activities of the antioxidant enzymes (paraoxonase 1, superoxide dismutase, and catalase) and the levels of AGE detoxification system components (AGE-R1 receptor and glyoxalase 1). In addition, combination therapy between curcumin and aminoguanidine effectively prevented dyslipidemia in diabetic rats. These findings demonstrate the combination of curcumin (natural antioxidant) and aminoguanidine (prototype therapeutic agent with anti-AGE activity) as a potential complementary therapeutic option for use with antihyperglycemic agents, which may aggregate beneficial effects against diabetic complications.

AGE-RAGE Axis in the Pathophysiology of Chronic Lower Limb Ischemia and a Novel Strategy for Its Treatment

This review focuses on the role of advanced glycation end products (AGEs) and its cell receptor (RAGE) and soluble receptor (sRAGE) in the pathogenesis of chronic lower limb ischemia (CLLI) and its treatment. CLLI is associated with atherosclerosis in lower limb arteries. AGE-RAGE axis which comprises of AGE, RAGE, and sRAGE has been implicated in atherosclerosis and restenosis. It may be involved in atherosclerosis of lower limb resulting in CLLI. Serum and tissue levels of AGE, and expression of RAGE are elevated, and the serum levels of sRAGE are decreased in CLLI. It is known that AGE, and AGE-RAGE interaction increase the generation of various atherogenic factors including reactive oxygen species, nuclear factor-kappa B, cell adhesion molecules, cytokines, monocyte chemoattractant protein-1, granulocyte macrophage-colony stimulating factor, and growth factors. sRAGE acts as antiatherogenic factor because it reduces the generation of AGE-RAGE-induced atherogenic factors. Treatment of CLLI should be targeted at lowering AGE levels through reduction of dietary intake of AGE, prevention of AGE formation and degradation of AGE, suppression of RAGE expression, blockade of AGE-RAGE binding, elevation of sRAGE by upregulating sRAGE expression, and exogenous administration of sRAGE, and use of antioxidants. In conclusion, AGE-RAGE stress defined as a shift in the balance between stressors (AGE, RAGE) and antistressor (sRAGE) in favor of stressors, initiates the development of atherosclerosis resulting in CLLI. Treatment modalities would include reduction of AGE levels and RAGE expression, RAGE blocker, elevation of sRAGE, and antioxidants for prevention, regression, and slowing of progression of CLLI.

Curcumin's Nanomedicine Formulations for Therapeutic Application in Neurological Diseases

The brain is the body's control center, so when a disease affects it, the outcomes are devastating. Alzheimer's and Parkinson's disease, and multiple sclerosis are brain diseases that cause a large number of human deaths worldwide. Curcumin has demonstrated beneficial effects on brain health through several mechanisms such as antioxidant, amyloid β-binding, anti-inflammatory, tau inhibition, metal chelation, neurogenesis activity, and synaptogenesis promotion. The therapeutic limitation of curcumin is its bioavailability, and to address this problem, new nanoformulations are being developed. The present review aims to summarize the general bioactivity of curcumin in neurological disorders, how functional molecules are extracted, and the different types of nanoformulations available.

Herbal drug discovery for the treatment of nonalcoholic fatty liver disease

Few medications are available for meeting the increasing disease burden of nonalcoholic fatty liver disease (NAFLD) and its progressive stage, nonalcoholic steatohepatitis (NASH). Traditional herbal medicines (THM) have been used for centuries to treat indigenous people with various symptoms but without clarified modern-defined disease types and mechanisms. In modern times, NAFLD was defined as a common chronic disease leading to more studies to understand NAFLD/NASH pathology and progression. THM have garnered increased attention for providing therapeutic candidates for treating NAFLD. In this review, a new model called “multiple organs-multiple hits” is proposed to explain mechanisms of NASH progression. Against this proposed model, the effects and mechanisms of the frequently-studied THM-yielded single anti-NAFLD drug candidates and multiple herb medicines are reviewed, among which silymarin and berberine are already under U.S. FDA-sanctioned phase 4 clinical studies. Furthermore, experimental designs for anti-NAFLD drug discovery from THM in treating NAFLD are discussed. The opportunities and challenges of reverse pharmacology and reverse pharmacokinetic concepts-guided strategies for THM modernization and its global recognition to treat NAFLD are highlighted. Increasing mechanistic evidence is being generated to support the beneficial role of THM in treating NAFLD and anti-NAFLD drug discovery.

The fate of dietary advanced glycation end products in the body: from oral intake to excretion

Advanced glycation end products (AGEs), which are closely associated with various chronic diseases, are formed through the Maillard reaction when aldehydes react with amines in heated foods or in living organisms. The fate of dietary AGEs after oral intake plays a crucial role in regulating the association between dietary AGEs and their biological effects. However, the complexity and diversity of dietary AGEs make their fate ambiguous. Glycated modifications can impair the digestion, transport and uptake of dietary AGEs. High and low molecular weight AGEs may exhibit individual differences in their distribution, metabolism and excretion. Approximately 50-60% of free AGEs are excreted after dietary intake, whereas protein-bound AGEs exhibit a limited excretion rate. In this article, we summarize several AGE classification criteria and their abundance in foods, and in the body. A standardized static in vitro digestion method is strongly recommended to obtain comparable results of AGE digestibility. Sophisticated hypotheses regarding the intestinal transportation and absorption of drugs, as well as calculated physicochemical parameters, are expected to alleviate the difficulties determining the digestion, transport and uptake of dietary AGEs. Orally supplied AGEs with low or high molecular weights must be supported by well-defined amounts in investigations of excretion. Furthermore, unequivocal evidence should be obtained regarding the degradation and metabolism products of dietary AGEs.

Advanced Glycation End Products in Chinese Medicine Mediated Aging Diseases: A Review

Aging has become a worldwide problem. During this process, the incidence of related diseases such as diabetes and atherosclerosis increases dramatically. Studies within the most recent two decades suggest a pivotal role of Advanced Glycation End Products (AGEs) in the aging process. This review aims to systemically summarize the effects and potential mechanism of Chinese Medicines on inhibiting AGEs-related aging diseases.

Advanced Glycation End Products (AGEs), Glutathione and Breast Cancer: Factors, Mechanism and Therapeutic Interventions

Background:

Advanced Glycation End products (AGEs) are basically the end result of glycation of proteins and/or lipids in the presence of sugars. Specific cases of hyperglycemia have been reported with increased propensity of generation of AGEs. Many chronic and deadly diseases such as diabetes, cancer and neurodegenerative disorders have been known to be caused as a result of generation of AGEs. The role of glutathione (GSH) metabolism and its intricate association with AGEs have also been well established in breast cancer prognosis and treatment. To understand the etiology, mechanism and production of AGEs along with clinical relevance of Receptors for Advanced Glycation End-products (RAGE) and RAGE ligands, their interplay with GSH is of paramount importance especially in relation to breast cancer.

Methods:

The available literature using PubMed, National Library of Medicine database, Web of Science and SCOPUS indexed, Science Direct and other prestigious journals have been systematically reviewed using the keywords: advanced glycation end-products, breast cancer, glutathione RAGE, and AGEs inhibitors. This narrative review of all the relevant papers with significant citations has led us to have greater insight into the action mechanism and potential therapeutic significance of AGEs inhibitors.

Results:

Targeting breast cancer with the specific immunoglobulins and with other therapeutic interventions is needed to inhibit the generation of AGEs and manage glutathione expression, thus having strong implications in the management of breast cancer. Many RAGE ligands such as HMGB1, S100P, S100A8, S100A9 etc. have been known to enhance RAGE expression which may further lead to increased proliferation, migration and metastatic nature of tumor cells. Hence, RAGE and RAGE ligands in a close linkup with GSH may prove to be effective therapeutic markers of severity of breast cancer and for angiogenesis of tumor.

Conclusion:

This review provides a strong platform to comprehend the etiology, mechanism and production of AGEs and glutathione along with the agents which can block their production, paving a way for the therapeutic intervention and an amicable solution to treat and manage breast cancer.

Effect of 660 nm visible red light on cell proliferation and viability in diabetic models in vitro under stressed conditions

The current study evaluated the photobiomodulatory effect of visible red light on cell proliferation and viability in various fibroblast diabetic models in vitro, namely, unstressed normal (N) and stressed normal wounded (NW), diabetic wounded (DW), hypoxic wounded (HW) and diabetic hypoxic wounded (DHW). Cells were irradiated at a wavelength of 660 nm with a fluence of 5 J/cm² (11.23 mW/cm²), which related to an irradiation time of 7 min and 25 s. Control cells were not irradiated (0 J/cm²). Cells were incubated for 48 h and cellular proliferation was determined by measuring 5-bromo-2'-deoxyuridine (BrdU) in the S-phase (flow cytometry), while viability was assessed by the Trypan blue exclusion test and Apoptox-glo triplex assay. In comparison with the respective controls, PBM increased viability in N- (P ≤ 0.001), HW- (P ≤ 0.01) and DHW-cells (P ≤ 0.05). HW-cells showed a significant progression in the S-phase (P ≤ 0.05). Also, there was a decrease in the G2M phase in HW- and DHW-cells (P ≤ 0.05 and P ≤ 0.05, respectively). This study concludes that hypoxic wounded and diabetic hypoxic wounded models responded positively to PBM, and PBM does not damage stressed cells but has a stimulatory effect on cell viability and proliferation to promote repair and wound healing. This suggests that the more stressed the cells are the better they responded to photobiomodulation (PBM).

AGE-RAGE Stress, Stressors, and Antistressors in Health and Disease

Adverse effects of advanced glycation end-products (AGEs) on the tissues are through nonreceptor- and receptor-mediated mechanisms. In the receptor-mediated mechanism, interaction of AGEs with its cell-bound receptor of AGE (RAGE) increases generation of oxygen radicals, activates nuclear factor-kappa B, and increases expression and release of pro-inflammatory cytokines resulting in the cellular damage. The deleterious effects of AGE and AGE-RAGE interaction are coined as "AGE-RAGE stress." The body is equipped with defense mechanisms to counteract the adverse effects of AGE and RAGE through endogenous enzymatic (glyoxalase 1, glyoxalase 2) and AGE receptor-mediated (AGER1, AGER2) degradation of AGE, and through elevation of soluble receptor of AGE (sRAGE). Exogenous defense mechanisms include reduction in consumption of AGE, prevention of AGE formation, and downregulation of RAGE expression. We have coined AGE and RAGE as "stressors" and the defense mechanisms as "anti-stressors." AGE-RAGE stress is defined as a shift in the balance between stressors and antistressors in the favor of stressors. Measurements of stressors or antistressors alone would not assess AGE-RAGE stress. For true assessment of AGE-RAGE stress, the equation should include all the stressors and antistressors. The equation for AGE-RAGE stress, therefore, would be the ratio of AGE + RAGE/sRAGE + glyoxalase1 + glyoxalase 2 + AGER1 +AGER2. This is, however, not practical in patients. AGE-RAGE stress may be assessed simply by the ratio of AGE/sRAGE. A high ratio of AGE/sRAGE indicates a relative shift in stressors from antistressors, suggesting the presence of AGE-RAGE stress, resulting in tissue damage, initiation, and progression of the diseases and their complications.

The Role of Glyoxalase-I (Glo-I), Advanced Glycation Endproducts (AGEs), and Their Receptor (RAGE) in Chronic Liver Disease and Hepatocellular Carcinoma (HCC)

Glyoxalase-I (Glo-I) and glyoxalase-II (Glo-II) comprise the glyoxalase system and are responsible for the detoxification of methylglyoxal (MGO). MGO is formed non-enzymatically as a by-product, mainly in glycolysis, and leads to the formation of advanced glycation endproducts (AGEs). AGEs bind to their receptor, RAGE, and activate intracellular transcription factors, resulting in the production of pro-inflammatory cytokines, oxidative stress, and inflammation. This review will focus on the implication of the Glo-I/AGE/RAGE system in liver injury and hepatocellular carcinoma (HCC). AGEs and RAGE are upregulated in liver fibrosis, and the silencing of RAGE reduced collagen deposition and the tumor growth of HCC. Nevertheless, data relating to Glo-I in fibrosis and cirrhosis are preliminary. Glo-I expression was found to be reduced in early and advanced cirrhosis with a subsequent increase of MGO-levels. On the other hand, pharmacological modulation of Glo-I resulted in the reduced activation of hepatic stellate cells and therefore reduced fibrosis in the CCl₄-model of cirrhosis. Thus, current research highlighted the Glo-I/AGE/RAGE system as an interesting therapeutic target in chronic liver diseases. These findings need further elucidation in preclinical and clinical studies.

Impact of intracellular glyceraldehyde-derived advanced glycation end-products on human hepatocyte cell death

Hepatocyte cell death is a key feature of nonalcoholic steatohepatitis (NASH); however, the pathogenesis of NASH currently remains unclear. We aimed to investigate the effects of intracellular glyceraldehyde (GA)-derived advanced glycation end-products (GA-AGEs) on human hepatocyte cell death. The accumulation of intracellular GA-AGEs has been associated with the induction of DNA damage and hepatocyte necrotic cell death. Among intracellular GA-AGEs, caspase-3 has been identified as a GA-AGE-modified protein with abrogated protein function. Furthermore, the activation of caspase-3 and induction of hepatocyte apoptosis by camptothecin, a DNA-damaging agent, was suppressed by a treatment with GA. These results suggest the inhibitory effects of GA-AGE-modified caspase-3 on the induction of DNA-damage-induced apoptosis, which is associated with hepatocyte necrosis. Therefore, the suppression of necrosis, the inflammatory form of cell death, by the accumulation of GA-AGEs and GA-AGE-modified caspase-3 may represent a novel therapeutic target for the pathogenesis of NASH.

Huang Gan Formula Eliminates the Oxidative Stress Effects of Advanced Oxidation Protein Products on the Divergent Regulation of the Expression of AGEs Receptors via the JAK2/STAT3 Pathway

Chronic kidney disease (CKD) has a high prevalence and low cure rate and represents a significant health issue. Oxidative stress is common in CKD due to metabolic disorders, inflammation, and impaired renal function changing normal proteins into advanced oxidation protein products (AOPPs). Huang Gan formula (HGF) is a new type of traditional Chinese herbal medicine. Although we previously investigated the protective effects of HGF against oxidative stress, the mechanism of HGF in CKD is still not fully understood. In this study, we used western blotting, quantitative polymerase chain reaction, and biochemical assays to show that HGF significantly decreased AOPP-induced oxidative stress damage. Moreover, the protective effects of HGF might be associated with upregulation of the advanced glycation end product receptor 1 (AGE-R1) and downregulation of the receptor for advance glycation end products (RAGE). Treatment with HGF and the Janus kinase 2 (JAK2) inhibitor, AG4-90, significantly attenuated AOPP-induced JAK2/STAT3 protein levels. These findings indicate that HGF inhibits AOPP-mediated biological responses by inactivating the JAK2/STAT3 pathway. In conclusion, HGF eliminated AOPP-induced effects in human mesangial cells (HMCs) by interrupting JAK2/STAT3 signaling, which altered RAGE/AGE-R1 expression and reduced oxidative stress in CKD.

Do Advanced Glycation End Products and Its Receptor Play a Role in Pathophysiology of Hypertension?

There is a close relationship between arterial stiffness and blood pressure. The studies suggest that the advanced glycation end products (AGEs) and its cell receptor (RAGE) are involved in the arterial stiffness in two ways: changes in arterial structure and vascular function. Plasma levels of AGEs and expression of RAGE are elevated, while the levels of soluble RAGE (sRAGE) and endogenous secretory RAGE (esRAGE) are lowered in patients with hypertension (HTN). There is a positive correlation between plasma levels of AGEs and arterial stiffness, and an inverse association between arterial stiffness/HTN, and serum levels of sRAGE and esRAGE. Various measures can reduce the levels of AGEs and expression of RAGE, and elevate sRAGE. Arterial stiffness and blood pressure could be reduced by lowering the serum levels of AGEs, and increasing the levels of sRAGE. Levels of AGEs can be lowered by reducing the consumption of AGE-rich diet, short duration of cooking in moist heat at low temperature, and cessation of cigarette smoking. Drugs such as aminoguanidine, vitamins, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II receptor blockers, statins, and metformin inhibit AGE formation. Alagebrium, an AGE breakers reduces levels of AGEs. Clinical trials with some drugs tend to reduce stiffness. Systemic administration of sRAGE has beneficial effect in animal studies. In conclusion, AGE-RAGE axis is involved in arterial stiffness and HTN. The studies suggest that inhibition of AGEs formation, reduction of AGE consumption, blockade of AGE-RAGE interaction, suppression of RAGE expression, and exogenous administration of sRAGE may be novel therapeutic strategies for treatment of arterial stiffness and HTN.

Advanced glycation end-products produced systemically and by macrophages: A common contributor to inflammation and degenerative diseases

Advanced glycation end products (AGEs) and their receptor have been implicated in the progressions of many intractable diseases, such as diabetes and atherosclerosis, and are also critical for pathologic changes in chronic degenerative diseases, such as Alzheimer's disease, Parkinson's disease, and alcoholic brain damage. Recently activated macrophages were found to be a source of AGEs, and the most abundant form of AGEs, AGE-albumin excreted by macrophages has been implicated in these diseases and to act through common pathways. AGEs inhibition has been shown to prevent the pathogenesis of AGEs-related diseases in human, and therapeutic advances have resulted in several agents that prevent their adverse effects. Recently, anti-inflammatory molecules that inhibit AGEs have been shown to be good candidates for ameliorating diabetic complications as well as degenerative diseases. This review was undertaken to present, discuss, and clarify current understanding regarding AGEs formation in association with macrophages, different diseases, therapeutic and diagnostic strategy and links with RAGE inhibition.

Hepatoprotective Effects of Chinese Medicinal Herbs: A Focus on Anti-Inflammatory and Anti-Oxidative Activities

The liver is intimately connected to inflammation, which is the innate defense system of the body for removing harmful stimuli and participates in the hepatic wound-healing response. Sustained inflammation and the corresponding regenerative wound-healing response can induce the development of fibrosis, cirrhosis and eventually hepatocellular carcinoma. Oxidative stress is associated with the activation of inflammatory pathways, while chronic inflammation is found associated with some human cancers. Inflammation and cancer may be connected by the effect of the inflammation-fibrosis-cancer (IFC) axis. Chinese medicinal herbs display abilities in protecting the liver compared to conventional therapies, as many herbal medicines have been shown as effective anti-inflammatory and anti-oxidative agents. We review the relationship between oxidative stress and inflammation, the development of hepatic diseases, and the hepatoprotective effects of Chinese medicinal herbs via anti-inflammatory and anti-oxidative mechanisms. Moreover, several Chinese medicinal herbs and composite formulae, which have been commonly used for preventing and treating hepatic diseases, including Andrographis Herba, Glycyrrhizae Radix et Rhizoma, Ginseng Radix et Rhizoma, Lycii Fructus, Coptidis Rhizoma, curcumin, xiao-cha-hu-tang and shi-quan-da-bu-tang, were selected for reviewing their hepatoprotective effects with focus on their anti-oxidative and ant-inflammatory activities. This review aims to provide new insight into how Chinese medicinal herbs work in therapeutic strategies for liver diseases.

Potential Dual Role of Eugenol in Inhibiting Advanced Glycation End Products in Diabetes: Proteomic and Mechanistic Insights

Medicinally important genus Ocimum harbors a vast pool of chemically diverse metabolites. Current study aims at identifying anti-diabetic candidate compounds from Ocimum species. Major metabolites in O. kilimandscharicum, O. tenuiflorum, O. gratissimum were purified, characterized and evaluated for anti-glycation activity. In vitro inhibition of advanced glycation end products (AGEs) by eugenol was found to be highest. Preliminary biophysical analysis and blind docking studies to understand eugenol-albumin interaction indicated eugenol to possess strong binding affinity for surface exposed lysines. However, binding of eugenol to bovine serum albumin (BSA) did not result in significant change in secondary structure of protein. In vivo diabetic mice model studies with eugenol showed reduction in blood glucose levels by 38% likely due to inhibition of α-glucosidase while insulin and glycated hemoglobin levels remain unchanged. Western blotting using anti-AGE antibody and mass spectrometry detected notably fewer AGE modified peptides upon eugenol treatment both in vivo and in vitro. Histopathological examination revealed comparatively lesser lesions in eugenol-treated mice. Thus, we propose eugenol has dual mode of action in combating diabetes; it lowers blood glucose by inhibiting α-glucosidase and prevents AGE formation by binding to ε-amine group on lysine, protecting it from glycation, offering potential use in diabetic management.

Curcumin Mimics the Neurocognitive and Anti-Inflammatory Effects of Caloric Restriction in a Mouse Model of Midlife Obesity

Dietary curcumin was studied for its potential to decrease adiposity and reverse obesity- associated cognitive impairment in a mouse model of midlife sedentary obesity. We hypothesized that curcumin intake, by decreasing adiposity, would improve cognitive function in a manner comparable to caloric restriction (CR), a weight loss regimen. 15-month-old male C57BL/6 mice were assigned in groups to receive the following dietary regimens for 12 weeks: (i) a base diet (Ain93M) fed ad libitum (AL), (ii) the base diet restricted to 70% of ad libitum (CR) or (iii) the base diet containing curcumin fed AL (1000 mg/kg diet, CURAL). Blood markers of inflammation, interleukin 6 (IL-6) and C-reactive protein (CRP), as well as an indicator of redox stress (GSH: GSSG ratio), were determined at different time points during the treatments, and visceral and subcutaneous adipose tissue were measured upon completion of the experiment. After 8 weeks of dietary treatment, the mice were tested for spatial cognition (Morris water maze) and cognitive flexibility (discriminated active avoidance). The CR group showed significant weight loss and reduced adiposity, whereas CURAL mice had stable weight throughout the experiment, consumed more food than the AL group, with no reduction of adiposity. However, both CR and CURAL groups took fewer trials than AL to reach criterion during the reversal sessions of the active avoidance task, suggesting an improvement in cognitive flexibility. The AL mice had higher levels of CRP compared to CURAL and CR, and GSH as well as the GSH: GSSG ratio were increased during curcumin intake, suggesting a reducing shift in the redox state. The results suggest that, independent of their effects on adiposity; dietary curcumin and caloric restriction have positive effects on frontal cortical functions that could be linked to anti-inflammatory or antioxidant actions.

Small interfering RNA targeting receptor for advanced glycation end products suppresses the generation of proinflammatory cytokines

The aim of the present study was to investigate the effect of receptor for advanced glycation end products (RAGE)-specific small interfering (si)RNA on the generation of proinflammatory cytokines in primary rat hepatic stellate cells (HSCs) and hepatic fibrotic (HF) rats. The RAGE-specific siRNA expression vector pAKD-GR126 was constructed, and then transfected into primary rat HSCs. Reverse transcription-quantitative polymerase chain reaction and western blot analyses were conducted to determine the mRNA and protein expression levels, respectively, of RAGE, tumor necrosis factor (TNF)-α and interleukin (IL)-6 in the primary HSCs. In addition, a CCl₄-induced Sprague Dawley (SD) rat model of hepatic fibrosis was established, and pAKD-GR126 was injected into the SD rats via the tail vein. Serum TNF-α and IL-6 concentrations were determined using radioimmunoassay. The mRNA and protein expression levels of RAGE (mRNA, F=7.791; protein, F=36.513), TNF-α (mRNA, F=474.568; protein, F=123.500) and IL-6 (mRNA, F=203.463; protein, F=320.555) in the pAKD-GR126-transfected primary HSCs were significantly reduced compared with those in the control and pAKD-NC groups (P<0.05). Serum TNF-α and IL-6 levels in the low-, medium- and high-dose pAKD-GR126 treatment groups were reduced compared with those in the fibrotic model group (TNF-α, F=416.397; IL-6, F=1,716.659; P<0.05). In summary, the RAGE-specific siRNA was able to effectively suppress the generation of the proinflammatory cytokines TNF-α and IL-6 in primary rat HSCs and HF rats.

Curcumin targets multiple pathways to halt hepatic stellate cell activation: updated mechanisms in vitro and in vivo

Nonalcoholic steatohepatitis (NASH) is the advanced form of nonalcoholic fatty liver disease, which is often accompanied by obese and/or type II diabetes mellitus. Approximately one-third of NASH patients develop hepatic fibrosis. Hepatic stellate cells are the major effector cells during liver fibrogenesis. Advanced liver fibrosis usually proceeds to cirrhosis and even hepatocellular carcinoma, leading to liver failure, portal hypertension and even death. Currently, there are no approved agents for treatment and prevention of liver fibrosis in human beings. Curcumin, the principal curcuminoid of turmeric, has been reported to show antitumor, antioxidant, and anti-inflammatory properties both in in vitro and in vivo systems. Accumulating data shows that curcumin plays a critical role in combating liver fibrogenesis. This review will discuss the inhibitory roles of curcumin and update the underlying mechanisms by which curcumin targets in inhibiting hepatic stellate cell activation.

Leptin, adipocytes and breast cancer: Focus on inflammation and anti-tumor immunity

More than one million new cases of breast cancer are diagnosed worldwide each year and more than 400,000 deaths are caused by the disease. The origin of this pathology is multifactorial and involved genetic, hormonal, environmental and nutritional factors including obesity in postmenopausal women. The role played by the adipose tissue and their secretions, ie adipokines, is beginning to be recognized. Plasma adipokine levels, which are modulated during obesity, could have “remote” effects on mammary carcinogenesis. Breast cancer cells are surrounded and locally influenced by an adipocyte microenvironment, which is probably more extensive in obese people. Hence, leptin appears to be strongly involved in mammary carcinogenesis and may contribute to the local pro-inflammatory mechanisms, especially in obese patients, who have increased metastatic potential and greater risk of mortality. This review presents the multifaceted role of leptin in breast cancer development and the different molecular pathways involved such as inflammation, oxidative stress and antitumor immunity.

Role of receptor for advanced glycation end products (RAGE) in liver disease

Receptor for advanced glycation end products (RAGE) belongs to a immunoglobulin superfamily of cell surface molecules that could bind to a number of ligands such as advanced glycation end products, high-mobility group protein box-1, S-100 calcium-binding protein, and amyloid-β-protein, inducing a series of signal transduction cascades, and being involved in a variety of cellular function, including inflammation, proliferation, apoptosis, angiogenesis, migration, and fibrosis. RAGE is expressed in hepatic stellate cells and hepatocytes and hepatoma cells. There is accumulating evidence that engagement of RAGE with various ligands elicits oxidative stress generation and subsequently activates the RAGE downstream pathway in the liver, thereby contributing to the development and progression of numerous types of hepatic disorders. These observations suggest that inhibition of the RAGE signaling pathway could be a novel therapeutic target for liver diseases. This article summarizes the pathological role of RAGE in hepatic insulin resistance, steatosis and fibrosis, ischemic and non-ischemic liver injury, and hepatocellular carcinoma growth and metastasis and its therapeutic interventions for these devastating disorders.

Leptin in nonalcoholic fatty liver disease: a narrative review

Leptin, the first described adipokine, interplays with hepatic metabolism. The aim of this review was to summarize available data on the association between leptin and nonalcoholic fatty liver disease (NAFLD). Leptin has a potential dual action on NAFLD experimental models, exerting a possible anti-steatotic, but also a proinflammatory and profibrogenic action. Observational clinical studies have shown higher or similar leptin levels between simple steatosis and nonalcoholic steatohepatitis (NASH) compared with controls. Interventional studies showed that circulating leptin diminishes together with body mass index after successful weight loss following lifestyle modifications or bariatric surgery. Studies providing evidence for the effect of other medications on leptin levels in NAFLD populations are limited and of low power. Data from small studies claim that recombinant leptin administration had a possibly beneficial effect on steatosis, but not fibrosis, in NAFLD patients with hypoleptinemia. Although the aforementioned dual leptin action has not yet been validated in humans, leptin administration in NAFLD patients with normoleptinemia or hyperleptinemia is discouraged. Further well-controlled studies in cautiously selected populations are needed to elucidate whether leptin has any prognostic and therapeutic role in NAFLD patients.