The protective effects of oral low-dose quercetin on diabetic nephropathy in hypercholesterolemic mice

From Life's Essential 8 to metabolic syndrome: insights from NHANES database and network pharmacology analysis of quercetin

Background

Metabolic syndrome (MetS), or syndrome X, is a collection of metabolic illnesses that affect the body's health, particularly insulin resistance and obesity. The prevalence of MetS is on the rise, particularly among younger individuals. Quercetin, a natural flavonoid found in many traditional Chinese medicines, can impact various pathways to disrupt the pathological advancement of MetS with few negative effects. The American Heart Association recently introduced a cardiovascular health assessment termed Life's Essential 8 (LE8), which might impact the treatment of MetS.

Methods

Quercetin targets and their functions in MetS pathways were identified using a network pharmacology method and molecular docking techniques. The study examined quercetin's direct and indirect interactions with proteins linked to the pathogenic processes of MetS. Data were collected regarding the American Heart Association's LE8 cardiovascular health indicators, which include health behaviors (diet, physical activity, nicotine exposure, and sleep) and health factors (body mass index, non-high-density lipoprotein cholesterol, blood glucose, and blood pressure). The study assessed the connection between LE8 and the occurrence of MetS, taking into account dietary quercetin consumption as a variable of interest.

Results

The negative correlation between MetS and LE8 indicates that individuals with higher LE8 scores are less likely to develop MetS. Individuals in the fully adjusted highest group (LE8 ≥ 80) demonstrated a 79% lower likelihood of developing MetS than those in the lowest group (OR = 0.21; 95% CI, 0.17-0.26, p < 0.0001). Network pharmacology and molecular docking results show that quercetin may exert its therapeutic effects by modulating various biological response processes, including those related to xenobiotic stimuli, bacterial molecules, lipopolysaccharides, and oxidative stimuli. These processes involve key pathways associated with diabetic complications, such as the AGE-RAGE signaling pathway, pathways related to diabetic complications, and pathways involved in lipids and atherosclerosis. Therefore, quercetin may reduce cardiovascular risk, improve glucose-lipid metabolism, and alleviate insulin resistance and other biological processes by influencing multiple aspects of the lipid profile, blood glucose, and insulin resistance, ultimately impacting the links between LE8 score and MetS.

Conclusion

This study discovered that an optimal LE8 score is a marker of adopting a lifestyle of wellness and is connected with a reduced likelihood of developing MetS. Quercetin acts on core targets such as IL6, BCL2, TP53, IL1B, MAPK1, and CCL2, and then plays a therapeutic role in regulating lipid metabolism, anti-inflammation, immunomodulation, autophagy, etc., through the pathways of diabetic complications, lipids, atherosclerosis, etc., and has the characteristics of multi-targets, multi-pathways, and multi-functions in regulating interventions for MetS.

Tyrosine phenol-lyase inhibitor quercetin reduces fecal phenol levels in mice

Tyrosine phenol-lyase (TPL), which is expressed in intestinal bacteria, catalyzes the formation of phenol from the substrate L-Tyr. Bacterial metabolite phenol and the sulfate conjugate (phenyl sulfate) are known as a type of uremic toxins, some of which exert cytotoxicity. Therefore, pathologically elevated phenol and phenyl sulfate levels are strongly implicated in the etiology and outcome of uremia. In this study, we explored the inhibitory effects of dietary polyphenols on TPL-catalyzed phenol production using a TPL activity assay. Quercetin, one of the most popular polyphenols, exhibited the strongest inhibitory activity (Ki = 19.9 µM). Quercetin competitively inhibited TPL, and its activity was stronger than that of a known TPL inhibitor (Tyr analog; 2-aza-Tyr, Ki = 42.0 µM). Additionally, quercetin significantly inhibited phenol production in TPL-expressing bacterial cultures (Morganella morganii and Citrobacter koseri) and Tyr-rich (5%) diet-fed C57BL/6J mouse feces. Our findings suggest that quercetin is the most promising polyphenol for reducing phenol levels. Because quercetin has a low gastrointestinal absorption rate, TPL inhibition in the intestinal tract by quercetin may be an effective strategy for treating uremia.

Quercetin, a Plant Flavonol Attenuates Diabetic Complications, Renal Tissue Damage, Renal Oxidative Stress and Inflammation in Streptozotocin-Induced Diabetic Rats

Diabetes mellitus is a metabolic syndrome characterized by increased glucose levels, oxidative stress, hyperlipidemia, and frequently decreased insulin levels. The current research was carried out for eight consecutive weeks to evaluate the possible reno-protective effects of quercetin (50 mg/kg b.w.) on streptozotocin (STZ) (55 mg/kg b.w.) induced diabetes rat models. Various physiological, biochemical, and histopathological parameters were determined in control, diabetic control, and quercetin-treated diabetic rats. The current findings demonstrated that diabetes control rats showed significantly decreased body weights (198 ± 10 vs. 214 ± 13 g) and insulin levels (0.28 ± 0.04 vs. 1.15 ± 0.05 ng/mL) in comparison to normal control. Besides this, the other parameters showed increased values, such as fasting blood glucose, triglyceride (TG), and total cholesterol levels (99 ± 5 vs. 230 ± 7 mg/dL, 122.9 ± 8.7 vs. 230.7 ± 7.2 mg/dL, 97.34 ± 5.7 vs. 146.3 ± 8 mg/dL) (p < 0.05). In addition, the urea and creatinine levels (39.9 ± 1.8 mg/dL and 102.7 ± 7.8 μmol/L) were also high in diabetes control rats. After 8 weeks of quercetin treatment in STZ-treated animals, body weight, insulin, and fasting blood sugar levels were significantly restored (p < 0.05). The inflammatory markers (TNF-α, IL-6, and IL-1β) were significantly increased (52.64 ± 2, 95.64 ± 3, 23.3 ± 1.2 pg/mL) and antioxidant enzymes levels (SOD, GST, CAT, and GSH) were significantly decreased (40.3 ± 3 U/mg, 81.9 ± 10 mU/mg, 14.2 ± 2 U/mg, 19.9 ± 2 μmol/g) in diabetic rats. All the parameters in diabetic animals treated with quercetin were restored towards their normal values. Histopathological findings revealed that the quercetin-treated group showed kidney architecture maintenance, reduction of fibrosis, and decreased expression of COX-2 protein. These results determined that quercetin has reno-protective effects, and conclude that quercetin possesses a strong antidiabetic potential and might act as a therapeutic agent in the prevention or delay of diabetes-associated kidney dysfunction.

Effective dose/duration of natural flavonoid quercetin for treatment of diabetic nephropathy: A systematic review and meta-analysis of rodent data

BACKGROUND

Given the challenges on diabetic nephropathy (DN) treatment, research has been carried out progressively focusing on dietary nutrition and natural products as a novel option with the objective of enhancing curative effect and avoiding adverse reactions. As a representative, Quercetin (Qu) has proved to be of great value in current data.

PURPOSE

We aimed to synthetize the evidence regarding the therapeutic effect and specific mechanism of quercetin on DN via systematically reviewing and performing meta-analysis.

METHODS

Preclinical literature published prior to August 2021, was systematical retrieval and manually filtrated across four major databases including PubMed, Web of Science, EMBASE and Cochrane library. Pooled overall effect sizes of results were generated by STATA 16.0, and underlying mechanisms were summarized. Three-dimensional dose/time-effect analyses and radar maps were conducted to examine the dosage/time-response relations between Qu and DN.

RESULTS

This paper pools all current available evidence in a comprehensive way, and shows the therapeutic benefits as well as potential action mechanisms of Qu in protecting the kidney against damage. A total of 304 potentially relevant citations were identified, of which 18 studies were enrolled into analysis. Methodological quality was calculated, resulting in an average score of 7.06/10. This paper provided the preliminary evidence that consumption of Qu could induce a statistical reduction in mesangial index, Scr, BUN, 24-h urinary protein, serum urea, BG, kidney index, TC, TG, LDL-C, AST, MDA, AGE, TNF-α, TGF-β1, TGF-β1 mRNA, CTGF and IL-1β, whereas HDL-C, SOD, GSH, GSH-Px, CAT and smad-7 were significantly increased. Furthermore, Qu could remarkably improve the renal pathology. In terms of the mechanisms underlying therapy of DN, Qu exerts anti-diabetic nephropathy properties possibly through PI3K/PKB, AMPK-P38 MAPK, SCAP/SREBP2/LDLr, mtROS-TRX/TXNIP/NLRP3/IL-1β, TGF-β1/Smad, Nrf2/HO-1, Hippo, mTORC1/p70S6K and SHH pathways. Dose/time-response images predicted a modest association between Qu dosage consumption/administration length and therapeutic efficacy, with the optimal dosage at 90-150 mg/kg/d and administration length ranging from 8 weeks to 12 weeks.

CONCLUSIONS

Quercetin exhibit highly pleiotropic actions, which simultaneously contributes to prevent fundamental progression of DN, such as hyperglycemia, dyslipidemia, inflammation, fibrotic lesions and oxidative stress. The therapeutic effect becomes stronger when Qu administration at higher dosages lasts for longer durations. Taken together, quercetin could be used in patients with DN as a promising agent, which has well-established safety profiles and nontoxicity according to existing literature.

Quercetin supplementation alters adipose tissue and hepatic transcriptomes and ameliorates adiposity, dyslipidemia, and glucose intolerance in adult male rats

Quercetin, a flavonoid present in many fruits and vegetables, exhibits beneficial effects toward abnormalities related to metabolic syndrome. In this study, to further investigate metabolic and transcriptomic responses to quercetin supplementation, we used a genetic model of metabolic syndrome. Adult male rats of the PD/Cub strain were fed either a high-sucrose diet (HSD; control PD rats) or HSD fortified with quercetin (10 g quercetin/kg diet; PD-Q rats). Morphometric and metabolic parameters, along with transcriptomic profiles of the liver and retroperitoneal fat, were assessed. The relative weights of epididymal and retroperitoneal fat were significantly decreased in quercetin-treated animals. Furthermore, a smaller area under the glycemic curve along with a decreased level of fasting insulin were detected in PD-Q rats. While no changes in total cholesterol levels were observed, the overall level of triglycerides decreased in the serum and the liver of the PD-Q rats. The transcriptomic profile of the liver and the adipose tissue corroborated the metabolic and morphometric findings, revealing the pattern consistent with insulin-sensitizing changes, with major regulator nodes being Pparg, Adipoq, Nos2, and Mir378. In conclusion, quercetin supplementation improves abnormalities related to metabolic syndrome, namely adiposity, dyslipidemia and glucose intolerance.

The Regulatory Effects of Traditional Chinese Medicine on Ferroptosis

Traditional Chinese medicine (TCM) has significantly contributed to protecting human health and promoting the progress of world civilization. A total of 2,711 TCMs are included in the 2020 version of the Chinese Pharmacopoeia, which is an integral part of the world’s medical resources. Tu Youyou and her team discovered and purified artemisinin. And their contributions made the values and advantageous effects of TCM more and more recognized by the international community. There has been a lot of studies on TCM to treat diseases through antioxidant mechanisms, the reports on the new mechanisms beyond antioxidants of TCM has also increased year by year. Recently, many TCMs appear to have significant effects in regulating ferroptosis. Ferroptosis is an iron-dependent, non-apoptotic, regulated cell death characterized by intracellular lipid peroxide accumulation and oxidative membrane damage. Recently, accumulating studies have demonstrated that numerous organ injuries and pathophysiological process of many diseases are companied with ferroptosis, such as cancer, neurodegenerative disease, acute renal injury, arteriosclerosis, diabetes, and ischemia-reperfusion injury. This work mainly introduces dozens of TCMs that can regulate ferroptosis and their possible mechanisms and targets.

Protective effect of quercetin on kidney diseases: From chemistry to herbal medicines

Kidney injuries may trigger renal fibrosis and lead to chronic kidney disease (CKD), but effective therapeutic strategies are still limited. Quercetin is a natural flavonoid widely distributed in herbal medicines. A large number of studies have demonstrated that quercetin may protect kidneys by alleviating renal toxicity, apoptosis, fibrosis and inflammation in a variety of kidney diseases. Therefore, quercetin could be one of the promising drugs in the treatment of renal disorders. In the present study, we review the latest progress and highlight the beneficial role of quercetin in kidney diseases and its underlying mechanisms. The pharmacokinetics and bioavailability of quercetin and its proportion in herbal medicine will also be discussed.

Potential Pharmaceutical Applications of Quercetin in Cardiovascular Diseases

Quercetin, as a member of flavonoids, has emerged as a potential therapeutic agent in cardiovascular diseases (CVDs) in recent decades. In this comprehensive literature review, our goal was a critical appraisal of the pathophysiological mechanisms of quercetin in relation to the classical cardiovascular risk factors (e.g., hyperlipidemia), atherosclerosis, etc. We also assessed experimental and clinical data about its potential application in CVDs. Experimental studies including both in vitro methods and in vivo animal models mainly outline the following effects of quercetin: (1) antihypertensive, (2) hypolipidemic, (3) hypoglycemic, (4) anti-atherosclerotic, and (5) cardioprotective (suppressed cardiotoxicity). From the clinical point of view, there are human studies and meta-analyses implicating its beneficial effects on glycemic and lipid parameters. In contrast, other human studies failed to demonstrate consistent favorable effects of quercetin on other cardiometabolic risk factors such as MS, obesity, and hypertension, underlying the need for further investigation. Analyzing the reason of this inconsistency, we identified significant drawbacks in the clinical trials’ design, while the absence of pharmacokinetic/pharmacodynamic tests prior to the studies attenuated the power of clinical results. Therefore, additional well-designed preclinical and clinical studies are required to examine the therapeutic mechanisms and clinical efficacy of quercetin in CVDs.

The effect of quercetin on diabetic nephropathy (DN): a systematic review and meta-analysis of animal studies

Quercetin, a flavonoid possessing numerous biological activities, is reported to improve renal injury in diabetic animals. Here, the aim of this systematic review and meta-analysis is to assess the effect of quercetin on diabetic nephropathy and summarize its possible mechanisms. We searched in four databases PubMed, Web of Sciences (WOS), Cochrane and Embase from inception to May 2021 and ultimately included 20 animal studies in this review. A total of 12 outcome measurements including renal function indexes, oxidative stress biomarkers and inflammatory cytokines were extracted for meta-analysis using RevMan 5.4 software. Apart from creatinine clearance and uric acid with no significant difference, quercetin significantly decreased the levels of renal index, serum/plasma creatinine (SCr), blood urea nitrogen (BUN), urine protein, urine albumin, malondialdehyde (MDA), tumor necrosis factor (TNF)-α and interleukin (IL)-1β, and increased superoxide dismutase (SOD) and catalase (CAT) activity. In short, quercetin improves renal function and attenuates the renal oxidative stress level and inflammatory response in DN animal models. Its possible action mechanisms include anti-oxidation, anti-inflammation, anti-fibrosis, and regulation of renal lipid accumulation.

Inflammation, oxidative stress and altered heat shock response in type 2 diabetes: the basis for new pharmacological and non-pharmacological interventions

Type 2 diabetes mellitus (DM2) is a chronic disease characterised by variable degrees of insulin resistance and impaired insulin secretion. Besides, several pieces of evidence have shown that chronic inflammation, oxidative stress, and 70 kDa heat shock proteins (HSP70) are strongly involved in DM2 and its complications, and various pharmacological and non-pharmacological treatment alternatives act in these processes/molecules to modulate them and ameliorate the disease. Besides, uncontrolled hyperglycaemia is related to several complications as diabetic retinopathy, neuropathy and hepatic, renal and cardiac complications. In this review, we address discuss the involvement of different inflammatory and pro-oxidant pathways related to DM2, and we described molecular targets modulated by therapeutics currently available to treat DM2.

Quercetin for managing type 2 diabetes and its complications, an insight into multitarget therapy

BACKGROUND

Quercetin, a bioflavonoid abundant in grapefruit, onion, berries, etc., has vast therapeutic potential, especially against Type 2 diabetes and its complications. Quercetin showed similar effects as that of metformin, (widely prescribed antidiabetic drug) in cell lines models (Sajan et al., 2010; Dhanya et al., 2017). In vivo findings also showcase it as a promising agent against diabetes and its pathophysiological complications.

SCOPE AND APPROACH

Quercetin can be produced on a large scale through a novel fermentation-based glycosylation strategy from cheap substrates and can be utilized as a dietary supplement. The review focuses on the mounting evidence pointing to Quercetin as a promising candidate for managing type 2 diabetes and its oxidative stress mediated pathophysiological complications.

CONCLUSION

Quercetin acts on multiple targets of diabetes and regulates key signalling pathways which improve the symptoms as well as the complications of Type 2 diabetes. However further studies are needed to improve the bioavailability and to establish a dosing regimen for Quercetin.

Therapeutic Effects and Safe Uses of Plant-Derived Polyphenolic Compounds in Cardiovascular Diseases: A Review

Polyphenols have long been recognized as health-promoting entities, including beneficial effects on cardiovascular disease, but their reputation has been boosted recently following a number of encouraging clinical studies in multiple chronic pathologies, that seem to validate efficacy. Health benefits of polyphenols have been linked to their well-established powerful antioxidant activity. This review aims to provide comprehensive and up-to-date knowledge on the current therapeutic status of polyphenols having sufficient heed towards the treatment of cardiovascular diseases. Furthermore, data about the safety profile of highly efficacious polyphenols has also been investigated to further enhance their role in cardiac abnormalities. Evidence is presented to support the action of phenolic derivatives against cardiovascular pathologies by following receptors and signaling pathways which ultimately cause changes in endogenous antioxidant, antiplatelet, vasodilatory, and anti-inflammatory activities. In addition, in vitro antioxidant and pre-clinical and clinical experiments on anti-inflammatory as well as immunomodulatory attributes of polyphenols have revealed their role as cardioprotective agents. However, an obvious shortage of in vivo studies related to dose selection and toxicity of polyphenols makes these compounds a suitable target for clinical investigations. Further studies are needed for the development of safe and potent herbal products against cardiovascular diseases. The novelty of this review is to provide comprehensive knowledge on polyphenols safety and their health claims. It will help researchers to identify those moieties which likely exert protective and therapeutic effects towards cardiovascular diseases.

Quercetin alleviates acute kidney injury by inhibiting ferroptosis

INTRODUCTION

Ferroptosis is an iron-dependent regulated necrosis and has been proven to contribute to the progress of acute kidney injury (AKI). Quercetin (QCT), a natural flavonoid which is commonly found in numerous fruits and vegetables, has extensive pharmacological effects, such as anti-oxidant, anti-inflammatory and anti-senescence effects.

OBJECTIVES

This study aims to explain whether ferroptosis is a therapeutic strategy to AKI, and to explore the effect of QCT on AKI ferroptosis.

METHODS

NRK-52E cells and HK-2 cells were used for in vitro ferroptosis studies. Morphology of cells was detected by transmission electron microscopy. Lipid ROS was assayed using flow cytometry. In vivo, AKI was induced by ischemia-reperfusion (I/R) or folic acid (FA). To explore the molecular mechanisms, RNA-sequence analysis was performed. Transwell was used to detect macrophage migration.

RESULTS

We discovered that quercetin (QCT), a natural flavonoid, inhibited ferroptosis in renal proximal tubular epithelial cells. QCT blocked the typical morphologic changes of ferroptotic cells by reducing the levels of malondialdehyde (MDA) and lipid ROS and increasing the levels of glutathione (GSH). Moreover, QCT ameliorated AKI induced by I/R or FA. RNA-sequence analysis highlighted activation transcription factor 3 (ATF3), as it was the dominant one among all the 299 down-regulated genes by QCT. Knockdown of ATF3 could significantly increase the levels of SLC7A11, GPX4 and increased the cell viability. In addition, ferroptotic cells were found to be extremely pro-inflammatory by recruiting macrophages through CCL2, while QCT inhibited the chemotaxis of macrophages induced by ferroptosis in AKI.

CONCLUSIONS

Collectively, these results identify QCT as a ferroptosis inhibitor and provide new therapeutic strategies for diseases related to ferroptosis.

Using Network Pharmacology to Explore the Mechanism of Peach Kernel-Safflower in the Treatment of Diabetic Nephropathy

OBJECTIVE

The mechanism of peach kernel-safflower in treating diabetic nephropathy (DN) was investigated using network pharmacology.

METHODS

Network pharmacology methodology was applied to screen the effective compounds of peach kernel-safflower in the SymMap and TCMSP databases. Potential targets were then screened in the ETCM, SEA, and SymMap databases to construct a compound-target network. This was followed by screening of DN targets in OMIM, Gene, and GeneCards databases. The common targets of drugs and diseases were selected for analysis in the STRING database, and the results were imported into Cytoscape 3.8.0 to construct a protein-protein interaction network. Next, GO and KEGG enrichment analyses were performed. Finally, Schrödinger molecular docking verified the reliability of the results.

RESULTS

A total of 23 effective compounds and 794 potential targets resulted from our screening process. Quercetin and luteolin were identified as the main effective ingredients in peach kernel-safflower. Furthermore, five key targets (VEGFA, IL6, TNF, AKT1, and TP53), AGE-RAGE, fluid shear stress and atherosclerosis, IL-17, and HIF-1 signaling pathways may be involved in the treatment of DN using peach kernel-safflower.

CONCLUSIONS

This study embodies the complex network relationship of multicomponents, multitargets, and multipathways of peach kernel-safflower to treat DN and provides a basis for further research on its mechanism.

Potential effect of tropical fruits Phyllanthus emblica L. for the prevention and management of type 2 diabetic complications: a systematic review of recent advances

Phyllanthus emblica is a fruit widely consumed in subtropical areas, which is rich in polyphenols and other nutrients. There are increasing evidences that as a daily and nutritious fruit, it may have a positive role in controlling diabetic complications. According to the new study, its mechanisms include enhancing the functioning of insulin, reducing insulin resistance, activating the insulin-signaling pathway, protecting β-cells, scavenging free radicals, alleviating inflammatory reactions, and reducing the accumulation of advanced glycation end products. Owing to its few side effects, and low price, it should be easily accepted by patients and has potential for preventing diabetes. Taken together, Phyllanthus emblica may be an ideal fruit for controlling diabetic complications. This review highlights the latest findings of the role of Phyllanthus emblica in anti-diabetes and its complications, especially clarifies the molecular mechanism of the chemical components related to this effect, and prospects some existing problems and future research directions.

Therapeutic application of nutraceuticals in diabetic nephropathy: Current evidence and future implications

Diabetes mellitus (DM) is a common metabolic disease which may cause several complications, such as diabetic nephropathy (DN). The routine medical treatments used for DM are not effective enough and have many undesirable side effects. Moreover, the global increased prevalence of DM makes researchers try to explore potential complementary or alternative treatments. Nutraceuticals, as natural products with pharmaceutical agents, have a wide range of therapeutic properties in various pathologic conditions such as DN. However, the exact underlying mechanisms have not been fully understood. The purpose of this review is to summarize recent findings on the effect of nutraceuticals on DN.

Quercetin liposomes ameliorate streptozotocin-induced diabetic nephropathy in diabetic rats

The effects of quercetin liposomes (Q-PEGL) on streptozotocin (STZ)-induced diabetic nephropathy (DN) was investigated in rats. Male Sprague Dawley rats were used to establish a STZ induced DN model. DN rats randomly received one of the following treatments for 8 weeks: blank treatment (DN), free quercetin (Que), pegylated liposomes (PEGL) and pegylated quercetin liposomes (Q-PEGL). A group of healthy rats served as the normal control. The fasting blood glucose (FBG), body weights (BWs), renal hypertrophy index (rHI), serum and urine biochemistry, renal histopathology, oxidative stress and immunohistochemical measurements of AGEs were analyzed to compare the effect of different treatments. Que and Q-PEGL significantly improved DN biochemistry and pathological changes, although the treated rats still had some symptoms of DN. The therapeutic effect of Q-PEGL surpassed that of Que. Pegylated quercetin liposomes allow maintaining higher quercetin concentrations in plasma than non-encapsulated quercetin. In conclusion the use of quercetin liposomes allows to reduce disease symptoms in a rat model of DN.

Identifying Synergistic Mechanisms of Multiple Ingredients in Shuangbai Tablets against Proteinuria by Virtual Screening and a Network Pharmacology Approach

Shuangbai Tablets (SBT), a traditional herbal mixture, has shown substantial clinical efficacy. However, a systematic mechanism of its active ingredients and pharmacological mechanisms of action against proteinuria continues being lacking. A network pharmacology approach was effectual in discovering the relationship of multiple ingredients and targets of the herbal mixture. This study aimed to identify key targets, major active ingredients, and pathways of SBT against proteinuria by network pharmacology approach combined with thin layer chromatography (TLC). Human phenotype (HP) disease analysis, gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and molecular docking were used in this study. To this end, a total of 48 candidate targets of 118 active ingredients of SBT were identified. Network analysis showed PTGS2, ESR1, and NOS2 to be the three key targets, and beta-sitosterol, quercetin, and berberine were the three major active ingredients; among them one of the major active ingredients, quercetin, was discriminated by TLC. These results of the functional enrichment analysis indicated that the most relevant disease including these 48 candidate proteins is proteinuria, SBT treated proteinuria by sympathetically regulating multiple biological pathways, such as the HIF-1, RAS, AGE-RAGE, and VEGF signaling pathways. Additionally, molecular docking validation suggested that major active ingredients of SBT were capable of binding to HIF-1A and VEGFA of the main pathways. Consequently, key targets, major active ingredients, and pathways based on data analysis of SBT against proteinuria were systematically identified confirming its utility and providing a new drug against proteinuria.

Association between LXR-α and ABCA1 Gene Polymorphisms and the Risk of Diabetic Kidney Disease in Patients with Type 2 Diabetes Mellitus in a Chinese Han Population

We designed a case-control study and selected LXR-α rs7120118 C>T and ABCA1 rs2230806 A>G polymorphisms to determine the correlation between these polymorphisms and diabetic kidney disease (DKD) susceptibility in a Chinese Han population. Three hundred DKD patients and 346 type 2 diabetes mellitus (DM) patients without kidney disease were recruited. Our results showed that rs7120118 was associated with DKD (genotype, P = .027; allele, P < .011). rs7120118 was associated with a higher risk of DKD under a dominant model adjustment by age and sex (P = .015) and an additive model (P = .040); rs2230806 was associated with a higher risk of DKD under an recessive model (P < .03); the combined effect of rs7120118 CC+rs2230806 GG genotype showed an association of DKD adjustment for age and sex (P = .009). In subgroup analysis of patients without hypercholesterolemia, the rs2230806 genotype frequencies were different between the two groups (P = .042). rs2230806 was associated with increased risk of DKD under a recessive model adjustment for age and sex (P = .013) and an additive model (P = .031). Our results suggest that LXR-α rs7120118 is significantly associated with a higher risk of DKD, and ABCA1 rs2230806 is significantly associated with a higher risk of DKD without hypercholesterolemia in Chinese Han individuals.

Tangshen Formula Attenuates Diabetic Nephropathy by Promoting ABCA1-Mediated Renal Cholesterol Efflux in db/db Mice

The commonly prescribed Tangshen Formula (TSF) is a traditional Chinese formulation that has been shown to reduce plasma lipid metabolism and proteinuria and improve the estimated glomerular filtration rate (eGFR) in patients with diabetic kidney disease. This study investigated the underlying mechanism whereby TSF regulates renal lipid accumulation and ameliorates diabetic renal injuries in spontaneous diabetic db/db mice and in vitro in sodium palmitate (PA)-stimulated and Abca1-SiRNA-transfected mouse tubular epithelial cells (mTECs). The results revealed that TSF treatment significantly ameliorated the renal injuries by lowering urinary albumin excretion and improving renal tissue injuries in diabetic (db/db) mice. Interestingly, the treatment with TSF also resulted in decreased cholesterol levels in the renal tissues of db/db mice, which was associated with increased expression of the peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α), the Liver X receptors (LXR), and ATP-binding cassette subfamily A member 1 (ABCA1), suggesting that TSF might attenuate diabetic kidney injury via a mechanism associated with improving cholesterol efflux in the diabetic kidney. This was investigated in vitro in mTECs, and the results showed that TSF reduced the PA-stimulated cholesterol accumulation in mTECs. Mechanistically, the addition of TSF was capable of reversing PA-induced downregulation of PGC-1α, LXR, and ABCA1 expression and cholesterol accumulation in mTECs, suggesting that TSF might act the protection via the PGC-1α-LXR-ABCA1 pathway to improve the cholesterol efflux in the renal tissues of db/db mice. This was further confirmed by silencing ABCA1 to block the promotive effect of TSF on cholesterol efflux in vitro. In conclusion, TSF might ameliorate diabetic kidney injuries by promoting ABCA1-mediated renal cholesterol efflux.

Quercetin ameliorates podocyte injury via inhibition of oxidative stress and the TGF-β1/Smad pathway in DN rats

This is the first study to demonstrate that quercetin ameliorates podocyte injury via inhibition of the TGF-β1/Smad pathway.

Quercetin nanoparticle complex attenuated diabetic nephropathy via regulating the expression level of ICAM-1 on endothelium

The purpose of the study was to reveal the therapeutic effect of quercetin (QUE) nanoparticle complex on diabetic nephropathy (DN) by regulating the expression of intercellular adhesion molecular-1 (ICAM-1) on endothelium as compared to free QUE. QUE 10 mg/kg as a single abdominal subcutaneous injection daily for 8 weeks continuously in diabetic rats and 10 mg/kg QUE nanoparticle complex as a single abdominal subcutaneous injection every 5 days, continuously administered for 8 weeks to diabetic rats. Blood and left kidneys were collected; pathological change of kidney, renal function, oxidative stress level, blood glucose level, serum lipid, urine protein, and albumin/creatinine ratio were measured; and neutrophil adhesion, ICAM-1 expression, and CD11b⁺ cells infiltration were observed. Both QUE and QUE nanoparticle complex preconditioning ameliorated the pathological damage of kidney and improved renal function, alleviated renal oxidative stress injury, restricted inflammatory cells infiltration, and downregulated the ICAM-1 expression as compared to DN group, while QUE nanoparticle complex significantly alleviated this effect.

The effect of hesperidin and quercetin on oxidative stress, NF-κB and SIRT1 levels in a STZ-induced experimental diabetes model

OBJECTIVE

The aim of this study is to investigate the roles of SIRT1 and NF-κB in the pathogenesis of diabetes mellitus in rats with STZ-induced diabetes and determine the effects of hesperidin and quercetin on oxidative stress and on the levels of SIRT1 and NF-κB.

MATERIALS AND METHODS

The experimental animals were divided into four groups, each group comprising ten rats designated as follows: group 1 served as control rats (C); group 2 served as diabetic rats (DM); group 3 served as diabetic rats administered hesperidin (DM+HSP) (100mg/kg b.w.) in aqueous suspension orally for 15 days; and group 4 served as diabetic rats administered quercetin (DM+Q) (100mg/kg b.w.) in aqueous suspension orally for 15 days.

RESULTS

In diabetic group, liver and kidney SIRT1, SOD and CAT activities were significantly lower than control group (p<0.05). Hesperidin and quercetin caused significant increase in the SIRT1, SOD and CAT activities of both DM+HP and DM+Q groups kidney tissues compared to DM group (p<0.05). Liver SOD activies were not found to differ significantly between DM, DM+Q and DM+HP groups (p>0.05). In DM+HP group, liver CAT activities were significantly higher than DM (p<0.05), but there was no significant difference in liver CAT activities between DM and DM+Q (p>0.05). In diabetic group, liver and kidney NF-κB and MDA levels were increased compared to control group (p<0.05), and groups of DM+HP and DM+Q had lower NF-κB and MDA levels than diabetic group (p<0.05).

CONCLUSION

As a conclusion, based on the results we obtained from this study and the literature data discussed above, we determined in STZ-induced diabetic rats that, increased glucose levels and liver and kidney damage markers decreased significantly after administration of hesperedin and quercetin, and that oxidative stress and NF-κB levels increased while SIRT1 levels decreased in the diabetic group.

A Novel Non-Peptidic Agonist of the Ghrelin Receptor with Orexigenic Activity In vivo

Loss of appetite in the medically ill and ageing populations is a major health problem and a significant symptom in cachexia syndromes, which is the loss of muscle and fat mass. Ghrelin is a gut-derived hormone which can stimulate appetite. Herein we describe a novel, simple, non-peptidic, 2-pyridone which acts as a selective agonist for the ghrelin receptor (GHS-R1a). The small 2-pyridone demonstrated clear agonistic activity in both transfected human cells and mouse hypothalamic cells with endogenous GHS-R1a receptor expression. In vivo tests with the hit compound showed significant increased food intake following peripheral administration, which highlights the potent orexigenic effect of this novel GHS-R1a receptor ligand.

Coadjuvants in the Diabetic Complications: Nutraceuticals and Drugs with Pleiotropic Effects

Because diabetes mellitus (DM) is a multifactorial metabolic disease, its prevention and treatment has been a constant challenge for basic and clinical investigators focused on translating their discoveries into clinical treatment of this complex disorder. In this review, we highlight recent experimental and clinical evidences of potential coadjuvants in the management of DM, such as polyphenols (quercetin, resveratrol and silymarin), cultured probiotic microorganisms and drugs acting through direct/indirect or pleiotropic effects on glycemic control in DM. Among several options, we highlight new promising therapeutic coadjuvants, including chemical scavengers, the probiotic kefir and the phosphodiesterase 5 inhibitors, which besides the reduction of hyperglycemia and ameliorate insulin resistance, they reduce oxidative stress and improve endothelial dysfunction in the systemic vascular circulation. In the near future, experimental studies are expected to clear the intracellular pathways involving coadjuvants. The design of clinical trials may also contribute to new strategies with coadjuvants against the harmful effects of diabetic complications.

Protective effect of sildenafil on the genotoxicity and cytotoxicity in apolipoprotein E-deficient mice bone marrow cells

BACKGROUND

The pharmacological inhibitor of phosphodiesterase 5 (PDE5), sildenafil, is a promising candidate for antioxidant therapy that can result in cardiovascular protection. In addition to its known effects on the cardiovascular system, hypercholesterolemia leads to increased oxidative stress and DNA damage in the bone marrow, which is a non-classical target organ of atherosclerosis. In the present study, we evaluate oxidative stress and assess the effect of genomic instability on cell cycle kinetics in atherosclerotic animals and determine if sildenafil reverses these detrimental effects in bone marrow cells.

METHODS

Experiments were performed in male wild-type (WT) and apolipoprotein E knockout mice (apoE(-/-)) (9 weeks of age). apoE(-/-) mice were randomly distributed into the following 2 groups: sildenafil-treated (40 mg/kg/day for 3 weeks, n = 8) and vehicle-treated (n = 8), by oral gavage. After treatment, bone marrow cells were isolated to assess the production of superoxide anions and hydrogen peroxide, determine cell cycle kinetics and evaluate the presence of micronucleated cells.

RESULTS

Sildenafil treatment reduced the cytoplasmic levels of superoxide anion (~95% decrease, p < 0.05) and decreased hydrogen peroxide (~30% decrease, p < 0.05). Moreover, we observed protective effects on the DNA of bone marrow cells, including normal cell cycling, decreased DNA fragmentation and a diminished frequency of micronucleated cells.

CONCLUSION

Our data reveal that the excessive production of ROS in atherosclerotic mice overcome the DNA repair pathways in bone marrow cells. The novelty of the present study is that the administration of sildenafil reduced ROS to baseline levels and, consequently, reverted the DNA damage and its outcomes in bone marrow cells.

Resin from Virola oleifera Protects Against Radiocontrast-Induced Nephropathy in Mice

Contrast-induced nephropathy (CIN) is an iatrogenic medical event for which there is not yet a successful therapy. Increasing evidence in rodents has suggested that this disease is associated with renal tubular and vascular injury that is triggered directly by oxidative stress. In the present study, we evaluated whether the antioxidant resin from Virola oleifera (RV) could attenuate renal damage in an experimental mouse model of CIN. Adult male Swiss mice were divided into six groups and pre-treated orally with RV (10, 100 and 300 mg/kg), N-acetylcysteine (200 mg/kg) or vehicle for 5 days before the induction of CIN and Control group. Renal function was assessed by measuring plasma creatinine and urea levels. Additionally, renal oxidative stress and apoptosis/cell viability were determined with flow cytometry. Finally, kidney tissues were sectioned for histopathological examination. In this CIN model, pre-treatment with RV improved renal function, lowered the mortality rate, and reduced oxidative stress and apoptosis in both the medulla and cortex renal cells in a dose-dependent manner. Moreover, the RV treatment had beneficial effects on kidney histopathology that were superior to the standard treatment with N-acetylcysteine. These data suggest that because of its antioxidative and antiapoptotic effects and its ability to preserve renal function, resin from Virola oleifera may have potential as a new therapeutic approach for preventing CIN.