Quercetin and Its Role in Chronic Diseases

Polymer lipid hybrid nanoparticles for phytochemical delivery: challenges, progress, and future prospects

Phytochemicals, naturally occurring compounds in plants, possess a wide range of therapeutic properties, including antioxidant, anti-inflammatory, anticancer, and antimicrobial activities. However, their clinical application is often hindered by poor water solubility, low bioavailability, rapid metabolism, and instability under physiological conditions. Polymer lipid hybrid nanoparticles (PLHNPs) have emerged as a novel delivery system that combines the advantages of both polymeric and lipid-based nanoparticles to overcome these challenges. This review explores the potential of PLHNPs to enhance the delivery and efficacy of phytochemicals for biomedical applications. We discuss the obstacles in the conventional delivery of phytochemicals, the fundamental architecture of PLHNPs, and the types of PLHNPs, highlighting their ability to improve encapsulation efficiency, stability, and controlled release of the encapsulated phytochemicals. In addition, the surface modification strategies to improve overall therapeutic efficacy by site-specific delivery of encapsulated phytochemicals are also discussed. Furthermore, we extensively discuss the preclinical studies on phytochemical encapsulated PLHNPs for the management of different diseases. Additionally, we explore the challenges ahead and prospects of PLHNPs regarding their widespread use in clinical settings. Overall, PLHNPs hold strong potential for the effective delivery of phytochemicals for biomedical applications. As per the findings from pre-clinical studies, this may offer a promising strategy for managing various diseases.

Effect of quercetin and mirtazapine on spermatogenesis and testis structure in phenylhydrazine-induced hemolytic anemia mice: An experimental study

Anemia poses a significant healthcare challenge across different socioeconomic groups and can result in reproductive system damage through the generation of free radicals and lipid peroxidation. This study examines the protective effects of quercetin (QUE) and mirtazapine (MIR) against the reproductive damage caused by phenylhydrazine (PHZ) in mice. Fifty NMRI mice, aged 8-10 weeks with an average weight of 27.0 ± 2.0 g, were randomly divided into five groups. The control group (Group 1) received oral administration of 10 mL/kg/day of normal saline. Group 2 (PHZ group) received an initial intraperitoneal dose of 8 mg/100 g body weight of PHZ, followed by subsequent doses of 6 mg/100 g every 48 h. Group 3 received PHZ along with oral QUE at a dosage of 50 mg/kg/day. Group 4 received PHZ along with oral MIR at a dosage of 30 mg/kg/day. Group 5 received PHZ along with oral QUE at a dosage of 50 mg/kg/day and MIR at a dosage of 30 mg/kg/day. The treatment duration was 35 days. Sperm samples were collected from the caudal region of the epididymis post-euthanasia to assess the total mean sperm count, sperm viability, motility, DNA damage, and morphology. Testicular tissue was employed to quantify total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione peroxidase (GPx), and malondialdehyde (MDA) concentrations, while serum levels of testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were analyzed. Additionally, various aspects, including testicular histopathology, oxidative enzyme levels, gene expression related to apoptosis and antiapoptotic pathways, and in vivo fertility index, were evaluated after 35 days. The QUE, MIR, and QUE + MIR groups showed less abnormal morphology and DNA damage, as well as better total and progressive sperm motility, motility characteristics, viability, and plasma membrane function compared to the PHZ group. QUE, MIR, and QUE + MIR administration increased TAC, SOD, and GPx activities in testicular tissue, while reducing MDA levels compared to the PHZ group. Furthermore, QUE, MIR, and QUE + MIR significantly reduced Bax, and caspase-3 expression levels, and increased Bcl-2 expression levels, compared to the PHZ group. Mice treated with QUE, MIR, and QUE + MIR exhibited an increased in vivo fertility index and plasma sex hormone levels compared to the PHZ group. These results show that QUE, MIR, and QUE + MIR might be able to improve the fertility index, boost the testicular antioxidant defense system, and control the death of germ cells. This could mean that they could be used to treat mice with PHZ-induced testicular damage.

Therapeutic implications of quercetin and its derived-products in COVID-19 protection and prophylactic

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel human coronavirus, which has triggered a global pandemic of the coronavirus infectious disease 2019 (COVID-19). Outbreaks of emerging infectious diseases continue to challenge human health worldwide. The virus conquers human cells through the angiotensin-converting enzyme 2 receptor-driven pathway by mostly targeting the human respiratory tract. Quercetin is a natural flavonoid widely represented in the plant kingdom. Cumulative evidence has demonstrated that quercetin and its derivatives have various pharmacological properties including anti-cancer, anti-hypertension, anti-hyperlipidemia, anti-hyperglycemia, anti-microbial, antiviral, neuroprotective, and cardio-protective effects, because it is a potential treatment for severe inflammation and acute respiratory distress syndrome. Furthermore, it is the main life-threatening condition in patients with COVID-19. This article provides a comprehensive review of the primary literature on the predictable effectiveness of quercetin and its derivatives docked to multi-target of SARS-CoV-2 and host cells via in silico and some of validation through in vitro, in vivo, and clinically to fight SARS-CoV-2 infections, contribute to the reduction of inflammation, which suggests the preventive and therapeutic latency of quercetin and its derived-products against COVID-19 pandemic, multisystem inflammatory syndromes (MIS), and long-COVID.

Exploring the therapeutic potential of quercetin: A focus on its sirtuin-mediated benefits

As the global population ages, preventing lifestyle- and aging-related diseases is increasing, necessitating the search for safe and affordable therapeutic interventions. Among nutraceuticals, quercetin, a flavonoid ubiquitously present in various plants, has garnered considerable interest. This review aimed to collate and analyze existing literature on the therapeutic potentials of quercetin, especially its interactions with SIRTs and its clinical applicability based on its bioavailability and safety. This narrative review was based on a literature survey spanning from 2015 to 2023 using PUBMED. The keywords and MeSH terms used were: "quercetin" AND "bioavailability" OR "metabolism" OR "metabolites" as well as "quercetin" AND "SIRTuin" OR "SIRT*" AND "cellular effects" OR "pathway" OR "signaling" OR "neuroprotective" OR "cardioprotective" OR "nephroprotective" OR "antiatherosclerosis" OR "diabetes" OR "antidiabetic" OR "dyslipidemia" AND "mice" OR "rats". Quercetin demonstrates multiple therapeutic activities, including neuroprotective, cardioprotective, and anti-atherosclerotic effects. Its antioxidant, anti-inflammatory, antiviral, and immunomodulatory properties are well-established. At a molecular level, it majorly interacts with SIRTs, particularly SIRT1 and SIRT6, and modulates numerous signaling pathways, contributing to its therapeutic effects. These pathways play roles in reducing oxidative stress, inflammation, autophagy regulation, mitochondrial biogenesis, glucose utilization, fatty acid oxidation, and genome stability. However, clinical trials on quercetin's effectiveness in humans are scarce. Quercetin exhibits a wide range of SIRT-mediated therapeutic effects. Despite the compelling preclinical data, more standardized clinical trials are needed to fully understand its therapeutic potential. Future research should focus on addressing its bioavailability and safety concerns.

Investigation of the combined cytotoxicity induced by sodium butyrate and a flavonoid quercetin treatment on MCF-7 breast cancer cells

Quercetin (QUE) belonging to the flavonoid class is a common phytochemical present in the daily diet of some individuals. Quercetin is an important source of free radical scavengers. This property makes this flavonoid a reliable antioxidant with the following properties: anti-inflammatory, anti-diabetic, antimicrobial and anti-carcinogenic. Sodium butyrate (NaBu) acts as a histone deacetylase inhibitor (HDACi) and is known to regulate apoptosis in cancer cells. Combining natural flavonoids such as QUE with different substances may synergistically enhance their anti-carcinogenic capacity. Thus, the aim of this study was to examine the combined treatment effects of QUE and NaBu in hormone-sensitive breast cancer cells in vitro. MCF-7 breast cancer cells were treated with QUE alone, NaBu alone, as well as QUE and NaBu combined to determine the following: cell proliferation, levels of protein annexin A5 (ANXA5) and reactive oxygen species (ROS), mRNA protein expression, as well as cell and nuclear morphology. Data demonstrated that either QUE or NaBu alone inhibited cell proliferation, and reduced levels protein ANXA5, ROS and mRNA protein expression, The combination of QUE and NaBu produced a significant synergistic inhibitory effect compared to treatment groups of QUE or NaBu alone. In conclusion, our findings showed that the combination treatment of QUE and NaBu may constitute a promising therapeutic approach to breast cancer treatment but this needs further molecular and in vivo investigations.

Quercetin attenuates deoxynivalenol-induced intestinal barrier dysfunction by activation of Nrf2 signaling pathway in IPEC-J2 cells and weaned piglets

The presence of deoxynivalenol (DON), one of the most frequently occurring mycotoxin, in food and feed has been considered a risk factor to both human and animal health. Molecular mechanisms that regulate DON effects in tissues are still poorly understood. However, recent evidence suggests that nuclear factor erythroid 2-like 2 (Nrf2) may be a major target during mycotoxin-induced intestinal barrier dysfunction. Although quercetin, a plant-derived flavonoid, is known to induce the activation of Nrf2 signaling pathway, its potential to mitigate effects of DON and the implication of Nrf2 in its physiological effects is poorly understood. Therefore, this study was conducted to investigate the protective effects of quercetin in alleviating the DON-induced barrier loss and intestinal injuries in IPEC-J2 cells and weaned piglets and determine the potential role of Nrf2. Quercetin treatment dose-dependently increased mRNA expression of Nrf2 target gene, NQO-1, and concomitantly increased the expression of claudin-4 at both mRNA and protein levels. Quercetin supplementation also reversed the reduction of claudin-4 caused by DON exposure in vivo and in vitro. The decreased membrane presence of claudin-4 and ZO-1 induced by DON was also blocked by quercetin. Furthermore, quercetin attenuated the endocytosis and degradation of claudin-4 caused by DON exposure. The effects of quercetin also included the restoration of transepithelial electrical resistance (TEER) and reduction of FITC-dextran permeability that have been perturbed by DON. However, the protective effects of quercetin against DON exposure were abolished by a specific Nrf2 inhibitor (brusatol), confirming the importance of Nrf2 in the regulation of TJP expression and barrier function by quercetin. In vivo study in weaned pigs showed that DON exposure impaired villus-crypt morphology as indicated by diffuse apical villus necrosis, villus atrophy and fusion. Notably, intestinal injuries caused by DON administration were partly mitigated by quercetin supplementation. Collectively, this study shows that quercetin could be used to prevent the DON-induced gut barrier dysfunction in humans and animals and the protective effects of quercetin against DON-induced intestinal barrier disruption is partly through Nrf2-dependent signaling pathway.

Targeted delivery of nutraceuticals derived from food for the treatment of obesity and its related complications

Nutraceuticals which are abundant in foods have attracted much attention due to their bioactive activities of anti-obesity, anti-hyperlipidemia and anti-atherosclerosis. Unfortunately, the poor bioavailability severely undermines their envisioned benefits. Therefore, there is an urgent need to develop suitable delivery systems to promote the benefits of their biological activity. Targeted drug delivery system (TDDS) is a novel drug delivery system that can selectively concentrate drugs on targets in the body, improve the bioavailability of agents and reduce side effects. This emerging drug delivery system provides a new strategy for the treatment of obesity with nutraceuticals and would be a promising alternative to be widely used in the food field. This review summarizes the recent studies on the application in the targeted delivery of nutraceuticals for treating obesity and its related complications, especially the available receptors and their corresponding ligands for TDDS and the evaluation methods of the targeting ability.

Recent Advances in Potential Health Benefits of Quercetin

Quercetin, a flavonoid found in fruits and vegetables, has been a part of human diets for centuries. Its numerous health benefits, including antioxidant, antimicrobial, anti-inflammatory, antiviral, and anticancer properties, have been extensively studied. Its strong antioxidant properties enable it to scavenge free radicals, reduce oxidative stress, and protect against cellular damage. Quercetin's anti-inflammatory properties involve inhibiting the production of inflammatory cytokines and enzymes, making it a potential therapeutic agent for various inflammatory conditions. It also exhibits anticancer effects by inhibiting cancer cell proliferation and inducing apoptosis. Finally, quercetin has cardiovascular benefits such as lowering blood pressure, reducing cholesterol levels, and improving endothelial function, making it a promising candidate for preventing and treating cardiovascular diseases. This review provides an overview of the chemical structure, biological activities, and bioavailability of quercetin, as well as the different delivery systems available for quercetin. Incorporating quercetin-rich foods into the diet or taking quercetin supplements may be beneficial for maintaining good health and preventing chronic diseases. As research progresses, the future perspectives of quercetin appear promising, with potential applications in nutraceuticals, pharmaceuticals, and functional foods to promote overall well-being and disease prevention. However, further studies are needed to elucidate its mechanisms of action, optimize its bioavailability, and assess its long-term safety for widespread utilization.

Histone deacetylase functions and therapeutic implications for adult skeletal muscle metabolism

Skeletal muscle is a highly adaptive organ that sustains continuous metabolic changes in response to different functional demands. Healthy skeletal muscle can adjust fuel utilization to the intensity of muscle activity, the availability of nutrients and the intrinsic characteristics of muscle fibers. This property is defined as metabolic flexibility. Importantly, impaired metabolic flexibility has been associated with, and likely contributes to the onset and progression of numerous pathologies, including sarcopenia and type 2 diabetes. Numerous studies involving genetic and pharmacological manipulations of histone deacetylases (HDACs) in vitro and in vivo have elucidated their multiple functions in regulating adult skeletal muscle metabolism and adaptation. Here, we briefly review HDAC classification and skeletal muscle metabolism in physiological conditions and upon metabolic stimuli. We then discuss HDAC functions in regulating skeletal muscle metabolism at baseline and following exercise. Finally, we give an overview of the literature regarding the activity of HDACs in skeletal muscle aging and their potential as therapeutic targets for the treatment of insulin resistance.

Quercetin protects endothelial function from inflammation induced by localized disturbed flow by inhibiting NRP2 -VEGFC complex

Atherosclerosis is a focal chronic inflammatory disease, the initial pathogenic event of which is endothelial dysfunction, and disturbed flow (DF) is the primary and vital factor underlying endothelial dysfunction. The present research aims to elucidate the mechanism underlying the regulation of Neuropilin (NRP)2 under DF in endothelial cells (ECs) in an inflammatory state. We observed that NRP2 expression was significantly upregulated in DF-stimulated human umbilical vein endothelial cells (HUVECs). Knockdown of NRP2 in HUVECs significantly ameliorated cell inflammation induced by DF. In addition, quercetin inhibited NRP2 expression as well as endothelial inflammation. Animal experiments suggested that NRP2 knockdown or intraperitoneal injection of quercetin affected the expression of inflammation-related genes. Moreover, the upstream transcription factor GATA2 was found to regulate NRP2 transcription by binding to the -1100 to +100 bp region of the NRP2 promoter. Further studies showed that quercetin inhibited NRP2-VEGFC complex formation induced by disturbed flow, although did not inhibit GATA2 expression. These findings suggest that NRP2 plays an important role in promoting inflammation. Quercetin antagonizes atherosclerosis by inhibiting NRP2 and the formation of NRP2-VEGFC complex by inhibiting the inflammatory effects induced by disordered flow.

Potential Role of Quercetin Glycosides as Anti-Atherosclerotic Food-Derived Factors for Human Health

Quercetin is a monomeric polyphenol of plant origin that belongs to the flavonol-type flavonoid subclass. Extensive studies using cultured cells and experimental model animals have demonstrated the anti-atherosclerotic effects of dietary quercetin in relation to the prevention of cardiovascular disease (CVD). As quercetin is exclusively present in plant-based foods in the form of glycosides, this review focuses on the bioavailability and bioefficacy of quercetin glycosides in relation to vascular health effects. Some glucose-bound glycosides are absorbed from the small intestine after glucuronide/sulfate conjugation. Both conjugated metabolites and deconjugated quercetin aglycones formed by plasma β-glucuronidase activity act as food-derived anti-atherogenic factors by exerting antioxidant, anti-inflammatory, and plasma low-density lipoprotein cholesterol-lowering effects. However, most quercetin glycosides reach the large intestine, where they are subject to gut microbiota-dependent catabolism resulting in deglycosylated aglycone and chain-scission products. These catabolites also affect vascular health after transfer into the circulation. Furthermore, quercetin glycosides may improve gut microbiota profiles. A variety of human cohort studies and intervention studies support the idea that the intake of quercetin glycoside-rich plant foods such as onion helps to prevent CVD. Thus, quercetin glycoside-rich foods offer potential benefits in terms of cardiovascular health and possible clinical applications.

Quercetin alleviates ferroptosis accompanied by reducing M1 macrophage polarization during neutrophilic airway inflammation

Ferroptosis is a kind of regulated cell death, supporting the pathological process of lung inflammation, including asthma. Quercetin (QCT), a kind of natural dietary flavonoid, exerts anti-inflammatory and anti-ferroptosis effects in various diseases. However, the role of QCT in ferroptosis-associated airway inflammation of neutrophilic asthma remains to be described. Our study aimed to investigate the therapeutic effects of QCT on neutrophilic airway inflammation of asthma. Ferrostatin-1 (Fer-1), as a kind of ferroptosis inhibitor, was used to demonstrate whether neutrophilic airway inflammation of asthma relied on ferroptosis. In our study, the alleviation effect of QCT on neutrophilic airway inflammation was similar to Fer-1. Moreover, the significantly decreased levels of ferroptosis anti-oxidant protein (GPX4 and SLC7A11), increased malondialdehyde (MDA) levels, upregulated levels of 4-hydroxynonenal (4-HNE) expression by immunohistochemistry, and distorted mitochondria morphological changes in the lung tissues suggested lung ferroptosis in neutrophilic airway inflammation, which could be reversed by QCT treatment. In vitro experiments showed that QCT reduced LPS-induced ferroptosis through upregulating cell viability and levels of ferroptosis anti-oxidant protein (SLC7A11 and GPX4), reducing inflammatory cytokines, and decreasing the levels of MDA. Furthermore, ferroptosis was accompanied by enhancing M1 phenotype in neutrophilic airway inflammation, and QCT suppressed ferroptosis by inhibiting the pro-inflammatory M1 profile in vitro and in vivo, just as Fer-1 did. In conclusion, our study found that QCT ameliorated ferroptosis-associated neutrophilic airway inflammation accompanied by inhibiting M1 macrophage polarization. QCT may be a promising ferroptosis inhibitor for neutrophilic airway inflammation.

Ultrasmall iron-quercetin metal natural product nanocomplex with antioxidant and macrophage regulation in rheumatoid arthritis

Oxidative stress, due to the disruption of the balance between reactive oxygen species (ROS) generation and the antioxidant defense system, plays an important role in the pathogenesis of rheumatoid arthritis (RA). Excessive ROS leads to the loss of biological molecules and cellular functions, release of many inflammatory mediators, stimulate the polarization of macrophages, and aggravate the inflammatory response, thus promoting osteoclasts and bone damage. Therefore, foreign antioxidants would effectively treat RA. Herein, ultrasmall iron-quercetin natural coordination nanoparticles (Fe-Qur NCNs) with excellent anti-inflammatory and antioxidant properties were constructed to effectively treat RA. Fe-Qur NCNs obtained by simple mixing retain the inherent ability to remove ROS of quercetin and have a better water-solubility and biocompatibility. In vitro experiments showed that Fe-Qur NCNs could effectively remove excess ROS, avoid cell apoptosis, and inhibit the polarization of inflammatory macrophages by reducing the activation of the nuclear factor-κ-gene binding (NF-κB) pathways. In vivo experiments showed that the swollen joints of mice with rheumatoid arthritis treated with Fe-Qur NCNs significantly improved, with Fe-Qur NCNs largely reducing inflammatory cell infiltration, increasing anti-inflammatory macrophage phenotypes, and thus inhibiting osteoclasts, which led to bone erosion. This study demonstrated that the new metal-natural coordination nanoparticles could be an effective therapeutic agent for the prevention of RA and other diseases associated with oxidative stress.

Potential active compounds and molecular mechanism of Xuefu Zhuyu decoction for atherosclerosis, based on network pharmacology and molecular docking

To explore the potential active compounds and molecular mechanism of Xuefu Zhuyu decoction (XFZYD) in the treatment of atherosclerosis (AS) based on network pharmacology and molecular docking. The effective components and action targets of XFZYD were screened by using TCMSP database. And then, the action targets of AS were collected by GeneCards database. The intersection targets between the effective components' targets of XFZYD and AS-related action targets were used to construct PPI networks. GO and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were performed on these intersection targets. Finally, molecular docking software was used to excavate the active compounds of the core targets VEGFA and AKT1. We detected 225 active components of XFZYD, and found that quercetin, kaempferol, luteolin, naringenin, β-sitosterol, isorhamnetin, stigmasterol, baicalein, nobiletin, and β-carotene are the potential active compounds of XFZYD; STAT3, IL6, JUN, VEGFA, MAPK14, and AKT1 are the core target proteins of the active compounds, among which VEGFA and AKT1 are the key target proteins. PPI network results showed that β-carotene, quercetin, kaempferol, luteolin, and naringenin had higher degree values and more corresponding targets than other 5 active compounds and had the stable binding ability to regulatory proteins VEGFA and AKT1. The core components β-carotene, quercetin, kaempferol, and luteolin exerted their therapeutic effects on AS by acting on the key target proteins VEGFA and AKT1 to regulate fluid shear stress and the AGE-RAGE signaling pathway and IL-17 signaling pathway of diabetic complications of AS. The molecular docking results showed that VEGFA and AKT1 had great docking ability with the targeted active compounds, and β-carotene is the best. The active components of XFZYD, including β -carotene, quercetin, kamanol, and luteolin, can act on VEGFA and AKT1. These active ingredients play a role in alleviating and treating AS by regulating fluid shear stress and participating in signaling pathways such AS AGE-RAGE of atherosclerosis and diabetes mellitus complicated with AS. β-carotene is a potential inhibitor of VEGFA and AKT1 and treats AS through antioxidant action.

Quercetin: A Molecule of Great Biochemical and Clinical Value and Its Beneficial Effect on Diabetes and Cancer

Quercetin belongs to the broader category of polyphenols. It is found, in particular, among the flavonols, and along with kaempferol, myricetin and isorhamnetin, it is recognized as a foreign substance after ingestion in contrast to vitamins. Quercetin occurs mainly linked to sugars with the most common compounds being quercetin-3-O-glucoside or as an aglycone, especially in the plant population. The aim of this review is to present a recent bibliography on the mechanisms of quercetin absorption and metabolism, bioavailability, and antioxidant and the clinical effects in diabetes and cancer. The literature reports a positive effect of quercetin on oxidative stress, cancer, and the regulation of blood sugar levels. Moreover, research-administered drug dosages of up to 2000 mg per day showed mild to no symptoms of overdose. It should be noted that quercetin is no longer considered a carcinogenic substance. The daily intake of quercetin in the diet ranges 10 mg-500 mg, depending on the type of products consumed. This review highlights that quercetin is a valuable dietary antioxidant, although a specific daily recommended intake for this substance has not yet been determined and further studies are required to decide a beneficial concentration threshold.

Recent Advances in Managing Spinal Intervertebral Discs Degeneration

Low back pain (LBP) represents a frequent and debilitating condition affecting a large part of the global population and posing a worldwide health and economic burden. The major cause of LBP is intervertebral disc degeneration (IDD), a complex disease that can further aggravate and give rise to severe spine problems. As most of the current treatments for IDD either only alleviate the associated symptoms or expose patients to the risk of intraoperative and postoperative complications, there is a pressing need to develop better therapeutic strategies. In this respect, the present paper first describes the pathogenesis and etiology of IDD to set the framework for what has to be combated to restore the normal state of intervertebral discs (IVDs), then further elaborates on the recent advances in managing IDD. Specifically, there are reviewed bioactive compounds and growth factors that have shown promising potential against underlying factors of IDD, cell-based therapies for IVD regeneration, biomimetic artificial IVDs, and several other emerging IDD therapeutic options (e.g., exosomes, RNA approaches, and artificial intelligence).

Neuroprotective Effects of Quercetin on Ischemic Stroke: A Literature Review

Ischemic stroke (IS) is characterized by high recurrence and disability; however, its therapies are very limited. As one of the effective methods of treating acute attacks of IS, intravenous thrombolysis has a clear time window. Quercetin, a flavonoid widely found in vegetables and fruits, inhibits immune cells from secreting inflammatory cytokines, thereby reducing platelet aggregation and limiting inflammatory thrombosis. In pre-clinical studies, it has been shown to exhibit neuroprotective effects in patients with ischemic brain injury. However, its specific mechanism of action remains unknown. Therefore, this review aims to use published data to elucidate the potential value of quercetin in patients with ischemic brain injury. This article also reviews the plant sources, pharmacological effects, and metabolic processes of quercetin in vivo, thus focusing on its mechanism in inhibiting immune cell activation and inflammatory thrombosis as well as promoting neuroprotection against ischemic brain injury.

Quercetin extracted from Sophora japonica flower improves growth performance, nutrient digestibility, cecal microbiota, organ indexes, and breast quality in broiler chicks

Objective

The objective of this study was to evaluate the effects of supplementing quercetin extracted from Sophora japonica flower (QS) to the diet of broiler chicks on their growth performance, apparent nutrient digestibility, cecal microbiota, serum lipid profiles, relative organ weight, and breast muscle quality.

Method

A total of 1088 1-day-old broiler chicks (mixed sex) were randomly assigned to four groups based on the initial body weight (43.00 ± 0.29 g). The experimental period was 35 days (starter, days 0-7; grower, days 7-21; finisher, days 21-35). There were 17 replicate cages per treatment and 16 birds per cage. Dietary treatments consisted of birds receiving basal diet without quercetin as the control group and treatment groups consisted of birds fed basal diet supplemented with 0.2, 0.4, or 0.6 g/kg QS.

Results

With the increase of the QS dosage, body weight gain during days 0-7 (P = 0.021), 7-21 (P = 0.010), and 1-35 (P = 0.045), feed intake during days 0-7 (P = 0.037) and 1-35 (P = 0.025), apparent dry matter digestibility (P = 0.008), apparent energy retention (P = 0.004), cecal lactic acid bacteria counts (P = 0.023), the relative weight of breast muscle (P = 0.014), pH value from breast muscle (P < 0.001), and the water holding capacity of breast muscle (P = 0.012) increased linearly, whereas the drip loss from breast muscle (P = 0.001) decreased linearly.

Conclusion

The addition of QS in the diet of broiler chicks had positive effects on the breast muscle yield and breast muscle quality, and improved the dry matter digestibility and energy retention by increasing cecal beneficial bacteria counts, thus improving growth performance.

Human Sirtuin Regulators: The "Success" Stories

The human sirtuins are a group of NAD⁺-dependent protein deacylases. They “erase” acyl modifications from lysine residues in various cellular targets including histones, transcription factors, and metabolic enzymes. Through these far-reaching activities, sirtuins regulate a diverse array of biological processes ranging from gene transcription to energy metabolism. Human sirtuins have been intensely pursued by both academia and industry as therapeutic targets for a broad spectrum of diseases such as cancer, neurodegenerative diseases, and metabolic disorders. The last two decades have witnessed a flood of small molecule sirtuin regulators. However, there remain relatively few compounds targeting human sirtuins in clinical development. This reflects the inherent issues concerning the development of isoform-selective and potent molecules with good drug-like properties. In this article, small molecule sirtuin regulators that have advanced into clinical trials will be discussed in details as “successful” examples for future drug development. Special attention is given to the discovery of these compounds, the mechanism of action, pharmacokinetics analysis, formulation, as well as the clinical outcomes observed in the trials.

Effects of preheating and drying methods on pyridoxine, phenolic compounds, ginkgolic acids, and antioxidant capacity of Ginkgo biloba nuts

Although ginkgo nuts are very nutritious and loaded with numerous bioactive compounds, the nuts contain significant levels of unwanted compounds (ginkolic acids) which are toxic to consumption. To reduce or eliminate these toxic compounds without impacting the nutritional value and the bioactivity of the final product, an appropriate processing technology is needed. Thus, the effect of preheating (90 and 120°C) prior to drying (freeze drying: FD, hot air drying: HAD, and HAD in tandem with FD: HAD-FD) was evaluated on ginkgolic acids, pyridoxine analogues, phenolic compounds, and antioxidant properties of ginkgo nuts. Our results pointed out a significant decrease (below 50%) of ginkgolic acids in ginkgo nuts samples processed at 90°C compared to the control. The major compounds found after treatments were respectively, kaempferol (36.66-354.38 µg/g), quercetin (9.04-183.71 µg/g), and caffeic acid (19.66-106.88 µg/g). Principal component analysis (PCA) revealed that preheating at 90°C prior to HAD-FD would be a proper and reasonable approach for preserving the bioactive compounds and antioxidant capacity of ginkgo nuts (EC₅₀ ranged from 2.25 to 4.60 mg/mL) while significantly reducing their content in toxic compounds.

The impact of the phytotherapeutic agent quercetin on expression of genes and activity of signaling pathways

Quercetin is a flavonoid existing in different herbs, fruits, seeds, nuts and tea. It has beneficial effects on human health through mediating antioxidant activities, immune-modulatory impacts and regulating metabolic pathways. These effects are most probably induced through modulation of activity of signaling pathways and expression of genes. Several in vitro studies have verified anti-proliferative effects of quercetin and its effect on expression of apoptotic genes and cell cycle-related genes. Moreover, through modulation of a number of proteins such as NF-kB, PARP, STAT3, Bax, Bcl-2, COX2, and cytokines, quercetin has beneficial effects in neurodegenerative disorders, liver diseases and diabetes. PI3K/AKT is the mostly linked pathway with beneficial effects of quercetin. In the current manuscript, we explain the impact of quercetin on expression of genes and function of cellular signaling cascades in different contexts.

Potential Implications of Quercetin in Autoimmune Diseases

Autoimmune diseases are a worldwide health problem with growing rates of morbidity, and are characterized by breakdown and dysregulation of the immune system. Although their etiology and pathogenesis remain unclear, the application of dietary supplements is gradually increasing in patients with autoimmune diseases, mainly due to their positive effects, relatively safety, and low cost. Quercetin is a natural flavonoid that is widely present in fruits, herbs, and vegetables. It has been shown to have a wide range of beneficial effects and biological activities, including anti-inflammation, anti-oxidation, and neuroprotection. In several recent studies quercetin has reportedly attenuated rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, and systemic lupus erythematosus in humans or animal models. This review summarizes the evidence for the pharmacological application of quercetin for autoimmune diseases, which supports the view that quercetin may be useful for their prevention and treatment.

Protective Effects of Quercetin on Oxidative Stress-Induced Tubular Epithelial Damage in the Experimental Rat Hyperoxaluria Model

Background and Objectives: The most common kidney stones are calcium stones and calcium oxalate (CaOx) stones are the most common type of calcium stones. Hyperoxaluria is an essential risk factor for the formation of these stones. Quercetin is a polyphenol with antioxidant, anti-inflammatory, and many other physiological effects. The aim of this study was to investigate the protective effect of quercetin in hyperoxaluria-induced nephrolithiasis. Materials and Methods: Male Wistar-Albino rats weighing 250–300 g (n = 24) were randomized into three groups: Control (n = 8), ethylene glycol (EG) (n = 8), and EG + quercetin (n = 8). One percent EG-water solution was given to all rats except for the control group as drinking water for five weeks. Quercetin-water solution was given to the EG + quercetin group by oral gavage at a dose of 10 mg/kg/day. Malondialdehyde (MDA), catalase (CAT), urea, calcium, and oxalate levels were analyzed in blood and urine samples. Histopathological assessments and immunohistochemical analyses for oxidative stress and inflammation indicators p38 mitogen-activated protein kinase (p38-MAPK) and nuclear factor kappa B (NF-kB) were performed on renal tissues. Results: The MDA levels were significantly lower in the quercetin-treated group than in the EG-treated group (p = 0.001). Although CAT levels were higher in the quercetin-treated group than the EG-administered group, they were not significantly different between these groups. The expression of p38 MAPK was significantly less in the quercetin-treated group than the EG group (p < 0.004). There was no statistically significant difference between the quercetin and EG groups in terms of NF-kB expression. Conclusions: We conclude that hyperoxaluria activated the signaling pathways, which facilitate the oxidative processes leading to oxalate stone formation in the kidneys. Our findings indicated that quercetin reduced damage due to hyperoxaluria. These results imply that quercetin can be considered a therapeutic agent for decreasing oxalate stone formation, especially in patients with recurrent stones due to hyperoxaluria.

Quercetin Alleviates Neuropathic Pain in the Rat CCI Model by Mediating AMPK/MAPK Pathway

Context

Quercetin (que) is one abundant flavonol with a variety of biological activities. Previous studies have shown quercetin can reduce neuropathic pain in rats with chronic constriction injury (CCI).

Objective

To evaluate the effects of quercetin on neuropathic pain in CCI model and explore its underlying mechanism in vivo.

Materials and Methods

CCI model was established by ligating the sciatic nerve of right leg on the SD rats. They were divided into ten groups: sham group, CCI model, sham+ que, CCI+ que group (30, 60, 120 mg/kg), CCI+ AICAR, CCI+ que+ compound C, CCI+etoricoxib, and the control group. They were administered for 28 days, and were performed the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) during the experiment. At the end of the experiment, sciatic nerves and spinal cord segments of rats were collected, ELISA detected the expression of inflammatory factors, detected the microglia and astrocytes with fluorescence, and Western blot detected AMPK/MAPK pathway.

Results

Que could increase the MWT of CCI rats, improve the TWL of plantar, and reduce the inflammatory cells at the ligation site of the sciatic nerve. Also, que could reduce the levels of TNF-α, IL-6, and IL-1β. Western blotting results showed that p-38 MAPK, p-ERK, and p-JNK were activated in the spinal dorsal horn of CCI model group. After treatment with que and AMPK agonists, the phosphorylation levels of related proteins were inhibited. In addition, the analgesic effect of que was abolished when the AMPK inhibitor was added.

Discussion and Conclusion

Quercetin alleviated the inflammatory response of sciatic nerve and spinal dorsal horn in rats induced by CCI. Quercetin alleviates neuralgia in CCI rats by activating AMPK pathway and inhibiting MAPK pathway and its downstream targets, p-38, p-ERK, and p-JNK.

Molecular and Biological Functions of Quercetin as a Natural Solution for Cardiovascular Disease Prevention and Treatment

Cardiovascular disease (CVD) is a worldwide health problem with growing up rates of mortality and morbidity. Many risk factors, including high blood pressure, cigarette smoking, diabetes, obesity, and dyslipidemia are responsible for CVD. CVD can be prevented by some simple and cost-effective steps such as smoking cessation, normalizing body weight, regular physical activity, and dietary changes, including decreasing saturated fats, increasing the intake of vegetables and fruits, and reducing sugar intake. In the last decades, growing up number of studies were performed to explain the possible function of non-nutrient substances from the diet which might prevent CVD. One of these natural compounds is quercetin which is widely present in vegetables, tea, fruits and wine. Many in vitro, in vivo and clinical studies have indicated the cardioprotective functions of quercetin. They can be explained by quercetin's reducing blood pressure, antioxidant potential and some other activities. This review evaluates the experimental and clinical studies that have studied the effect of quercetin in CVD and summarizes the molecular mechanisms of action as well as clinical effects of quercetin in CVD.

SIRT1 Activation by Natural Phytochemicals: An Overview

Sirtuins are class III histone deacetylases, whose enzymatic activity is dependent on NAD⁺ as a cofactor. Sirtuins are reported to modulate numerous activities by controlling gene expression, DNA repair, metabolism, oxidative stress response, mitochondrial function, and biogenesis. Deregulation of their expression and/or action may lead to tissue-specific degenerative events involved in the development of several human pathologies, including cancer, neurodegeneration, and cardiovascular disease. The most studied member of this class of enzymes is sirtuin 1 (SIRT1), whose expression is associated with increasing insulin sensitivity. SIRT1 has been implicated in both tumorigenic and anticancer processes, and is reported to regulate essential metabolic pathways, suggesting that its activation might be beneficial against disorders of the metabolism. Via regulation of p53 deacetylation and modulation of autophagy, SIRT1 is implicated in cellular response to caloric restriction and lifespan extension. In recent years, scientific interest focusing on the identification of SIRT1 modulators has led to the discovery of novel small molecules targeting SIRT1 activity. This review will examine compounds of natural origin recently found to upregulate SIRT1 activity, such as polyphenolic products in fruits, vegetables, and plants including resveratrol, fisetin, quercetin, and curcumin. We will also discuss the potential therapeutic effects of these natural compounds in the prevention and treatment of human disorders, with particular emphasis on their metabolic impact.

Quercetin alleviates rheumatoid arthritis by inhibiting neutrophil inflammatory activities

Rheumatoid arthritis (RA) is a prototypical autoimmune disorder mainly characterized by joint inflammation and cartilage destruction. Neutrophils actively take part in the initiation and progression of RA. Neutrophils express inflammatory mediators, including cytokines and chemokines. Aberrant formation of neutrophil extracellular traps (NETs) has been demonstrated in the pathogenesis of RA. Thus, neutrophils are regarded as important therapeutic targets in RA treatment. Quercetin is one of the major flavonoids found in fruits and vegetables. Previous studies have demonstrated that quercetin is a potential agent for the treatment of RA. However, the underlying antiarthritic mechanism of quercetin has not been investigated clearly. In this study, we analyzed the therapeutic mechanism of quercetin for RA. Our results showed that quercetin ameliorates inflammation in RA mice by inhibiting neutrophil activities. Quercetin inhibited neutrophil infiltration and reduced the plasma levels of inflammatory cytokines. Quercetin promoted the apoptosis of activated neutrophils. In addition, quercetin inhibited NET formation by suppressing autophagy. These findings suggest that quercetin may be an alternative agent for the treatment of RA by inhibiting neutrophil activities.

Effect of Quercetin on PC12 Alzheimer's Disease Cell Model Induced by Aβ 25-35 and Its Mechanism Based on Sirtuin1/Nrf2/HO-1 Pathway

Objective

This study is aimed at studying the effect of quercetin on the Alzheimer disease cell model induced by Aβ_25-35 in PC12 cells and its mechanism of action.

Methods

The AD cell model was established by Aβ_25-35. Quercetin was used at different concentrations (0, 10, 20, 40, and 80 μmol/L). The morphology of cells was observed, and the effect on cell survival rate was detected by the MTT method. Cell proliferation was detected by the SRB method. The contents of LDH, SOD, MDA, GSH-Px, AChE, CAT, and T-AOC were detected by kits. The expression of sirtuin1/Nrf2/HO-1 was detected by RT-qPCR and Western blot.

Results

PC12 cells in the control group grew quickly and adhered well to the wall, most of which had extended long axons and easily grew into clusters. In the model group, cells were significantly damaged and the number of cells was significantly reduced. It was found that PC12 cells were swollen, rounded, protruding, and retracting, with reduced adherent function and floating phenomenon. Quercetin could increase the survival rate and proliferation rate of PC12 cells; reduce the levels of LDH, AChE, MDA, and HO-1 protein; and increase the levels of SOD, GSH-Px, CAT, T-AOC, sirtuin1, and Nrf2 protein.

Conclusion

Quercetin can increase the survival rate of PC12 injured by Aβ_25-35, promote cell proliferation, and antagonize the toxicity of Aβ; it also has certain neuroprotective effects. Therefore, quercetin is expected to become a drug for the treatment of AD.

Effect of Roasting on the Phytochemical Properties of Three Varieties of Marble Vine (Dioclea reflexa) Using Response Surface Methodology

This study assessed the optimum roasting conditions on the phytochemical properties of three varieties of Dioclea reflexa seeds using response surface methodology. Roasting conditions were varied using temperature (110°C~200°C) and time (10~40 min). Phytochemical components (phenolics, tannin, flavonoids, cardiac glycoside, and steroids) of the seeds were screened and estimated. The study showed that availability of phytochemical activities was heat-dependent. An increase in roasting temperature beyond 110°C for 10 min resulted in a decrease in total phenolic (TP) and flavonoid (TF) contents. However, prolonged durations of roasting favored increased amounts of TP and TF in dark and light varieties. Total sterol, tannin, and cardiac glycoside contents increased with increasing roasting temperature and time. The desirability of the models were 0.76, 0.74, and 0.72 for black, dark brown, and light brown, respectively. The coefficients of regression (R2), ranged from 0.66 to 0.98 signifying accuracy of the model. The following models (cubic, quadratic, and 2 factor interaction) were significant (P≤0.05). We found that roasting time influenced the phytochemical properties of D. reflexa to a greater extent than temperature. The optimum roasting temperature and time was found to beat 110°C, 35 min, 40 min, and 32 min in black, dark brown, and light brown varieties, respectively. Roasting conditions significantly affects the phytochemical contents of three varieties of D. reflexa seed flour (P<0.05). Therefore, D. reflexa holds the potential to be used in development of functional foods and in therapeutic applications to promote health.

Antitumor Effects of Quercetin in Hepatocarcinoma In Vitro and In Vivo Models: A Systematic Review

Quercetin is a flavonoid present in fruits, vegetables and plants with antioxidant, anti-inflammatory and anticancer properties. Its beneficial activities have been demonstrated in different human pathologies, including hepatoprotective effects against liver disorders. High mortality and late diagnosis of the primary liver tumor hepatocarcinoma (HCC) makes this cancer an interesting target for the study of quercetin effects. Our aim was to systematically review antitumor activities of quercetin in HCC preclinical studies employing single, encapsulated, combined or derived quercetin forms. Literature search was conducted in PubMed, Scopus and Web of Science (WOS), and 39 studies were finally included. We found that 17 articles evaluated quercetin effects alone, six used encapsulated strategy, 10 combined this flavonoid, two decided to co-encapsulate it and only four studied effects of quercetin derivatives, highlighting that only nine included in vivo models. Results evidence the quercetin antiproliferative and proapoptotic properties against HCC either alone and with the mentioned strategies; nevertheless, few investigations assessed specific activities on different processes related with cancer progression. Overall, further studies including animal models are needed to deeper investigate the precise mechanisms of action of quercetin as antitumor agent, as well as the potential of novel strategies aimed to improve quercetin effects in HCC.

Curcumin and quercetin synergistically attenuate subacute diazinon-induced inflammation and oxidative neurohepatic damage, and acetylcholinesterase inhibition in albino rats

The ubiquitous use of diazinon (DZN, an organophosphorus insecticide) has increased the probability of occupational, public, and the ecosystem exposure; these exposures are linked to negative health outcomes. The flavonoids curcumin (CUR) and quercetin (QUE) exert significant anti-inflammatory and antioxidant activities against toxicants, including insecticides. However, it is unclear whether their combination enhances these activities. Therefore, 40 albino rat were divided randomly into the CTR, DZN, CUR + DZN, QUE + DZN, and CUR + QUE + DZN groups, which are treated daily via gavage for 28 days. DZN induced neurohepatic inflammation and oxidative damage, which was confirmed by significant (P < 0.05) induction of aspartate and alanine aminotransferases, alkaline phosphatase, lactate dehydrogenase, γ-glutamyl transferase, and tumor necrosis factor-α and inhibition of acetylcholinesterase activity. Furthermore, the liver and brain of DZN-exposed rats exhibited a notable elevation in MDA level paralleled with reduction in antioxidant molecules, i.e., glutathione, superoxide dismutase, glutathione peroxidase, and catalase. The pretreatment of DZN-intoxicated rats with CUR or QUE substantially mitigated neurohepatic dysfunction and inflammation and improved liver and brain antioxidant status with reducing oxidative stress levels. Furthermore, pretreatment with CUR + QUE synergistically restored the neurohepatic dysfunction and oxidative levels to approximately normal levels. The overall results suggested that CUR or QUE inhibits DZN-mediated neurohepatic toxicity via their favorable anti-inflammatory, antioxidant, and free radical-scavenging activities. Moreover, both QUE and CUR may be mutual adjuvant agents against oxidative stress neurohepatic damages.

Polyalthia Clerodane Diterpene Potentiates Hypoglycemia via Inhibition of Dipeptidyl Peptidase 4

Serine protease dipeptidyl peptidase 4 (DPP-4) is involved in self/non-self-recognition and insulin sensitivity. DPP-4 inhibitors are conventional choices for diabetic treatment; however, side effects such as headache, bronchus infection, and nasopharyngitis might affect the daily lives of diabetic patients. Notably, natural compounds are believed to have a similar efficacy with lower adverse effects. This study aimed to validate the DPP-4 inhibitory activity of clerodane diterpene 16-hydroxycleroda-3,13-dien-15,16-olide (HCD) from Polyalthia longifolia, rutin, quercetin, and berberine, previously selected through molecular docking. The inhibitory potency of natural DPP-4 candidates was further determined by enzymatic, in vitro Caco-2, and ERK/PKA activation in myocyte and pancreatic cells. The hypoglycemic efficacy of the natural compounds was consecutively analyzed by single-dose and multiple-dose administration in diet-induced obese diabetic mice. All the natural-compounds could directly inhibit DPP-4 activity in enzymatic assay and Caco-2 inhibition assay, and HCD showed the highest inhibition of the compounds. HCD down-regulated LPS-induced ERK phosphorylation in myocyte but blocked GLP-1 induced PKA expression. For in vivo tests, HCD showed hypoglycemic efficacy only in single-dose administration. After 28-days administration, HCD exhibited hypolipidemic and hepatoprotective efficacy. These results revealed that HCD performed potential antidiabetic activity via inhibition of single-dose and long-term administrations, and could be a new prospective anti-diabetic drug candidate.

Small Library of Triazolyl Polyphenols Correlating Antioxidant Activity and Stability with Number and Position of Hydroxyl Groups

Polyphenolic compounds have attracted much interest because of their antioxidant properties and multiple applications, from food or cosmetic preservatives to free radical scavengers as therapeutic agents. Inspired by common OH substitutions in natural products, here we describe a small library of 1,2,3-triazoles disubstituted with polyphenol groups at 1,4-positions, in an attempt to correlate the number and position of hydroxyl groups in the aromatic rings with the antioxidant activity. Some compounds from this library exhibit strong radical scavenging activities in the oxygen radical absorbance capacity assay, similar to or even higher than resveratrol and other well-kwon flavonoids. The antioxidant activity for selected compounds was confirmed in vitro through the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) test and in vivo by a Saccharomyces cerevisiae model organism assay. The activity depends on the number and position of the hydroxyl groups, with compounds bearing a 2″5″-hydroxyl substituents on the phenyl ring at position 4 showing the best antioxidant values. The presence of two quinone-forming phenolic groups at the same molecule is behind the instability of some of these compounds in aqueous media.

Actions of Brain-Derived Neurotrophin Factor in the Neurogenesis and Neuronal Function, and Its Involvement in the Pathophysiology of Brain Diseases

It is well known that brain-derived neurotrophic factor, BDNF, has an important role in a variety of neuronal aspects, such as differentiation, maturation, and synaptic function in the central nervous system (CNS). BDNF stimulates mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK), phosphoinositide-3kinase (PI3K), and phospholipase C (PLC)-gamma pathways via activation of tropomyosin receptor kinase B (TrkB), a high affinity receptor for BDNF. Evidence has shown significant contributions of these signaling pathways in neurogenesis and synaptic plasticity in in vivo and in vitro experiments. Importantly, it has been demonstrated that dysfunction of the BDNF/TrkB system is involved in the onset of brain diseases, including neurodegenerative and psychiatric disorders. In this review, we discuss actions of BDNF and related signaling molecules on CNS neurons, and their contributions to the pathophysiology of brain diseases.

Effects of quercetin on the pharmacokinetics of losartan and its metabolite EXP3174 in rats

1. This study investigates the influence of quercetin on the pharmacokinetics of losartan and its metabolite EXP3174 in rats. 2. The pharmacokinetic profiles of losartan and EXP3174 of orally administered losartan (10 mg/kg) with or without pretreatment with quercetin (20 mg/kg/day for 7 days) were investigated. Additionally, Caco-2 cell transwell model and rat liver microsome incubation experiments were also conducted to investigate its potential mechanism. 3. The results showed that when the rats were pretreated with quercetin, the C_max (2.16 ± 0.40 vs. 1.33 ± 0.21 mg/L) and the AUC_(0-t) (13.89 ± 1.22 vs. 7.34 ± 0.75 mg·h/L) of losartan increased significantly (p < .05), and while the C_max (0.76 ± 0.09 vs. 1.14 ± 0.18 mg/L) of EXP3174 decreased significantly compared to the control (p < .05). The t_1/2 of losartan was prolonged from 3.27 ± 0.45 h to 4.74 ± 0.51 h (p < .05). The results also indicated that quercetin could increase losartan absorption rate by inhibiting the activity of P-gp and decrease its metabolic stability by inhibiting the activity of CYP450 enzyme. 4. These results indicated that the herb-drug interaction between quercetin and losartan might occur when they are co-administered in rats, quercetin could increase the systemic exposure of losartan and decrease the plasma concentration of EXP3174, possibly by inhibiting the activity of P-gp or CYP450 enzyme.

Quercetin suppresses the chymotrypsin-like activity of proteasome via inhibition of MEK1/ERK1/2 signaling pathway in hepatocellular carcinoma HepG2 cells

The proteasomal system is a promising target for cancer treatment. Quercetin (Que), a flavonoid compound with antitumor ability, displays the inhibitory effect on proteasome activity. However, the underlying molecular mechanisms are ill defined. The present study found that Que treatment significantly reduced the chymotrypsin-like protease activity of proteasome whereas the trypsin- and caspase-like protease activities remained unchanged in HepG2 cancer cells, along with activation of p38 MAPK and JNK and reduction of ERK1/2 phosphorylation. Que-reduced proteasome activity could not be reverted by inhibition of p38 MAPK and JNK signaling pathway. In addition, MEK1 overexpression or knockdown upregulated or downregulated the chymotrypsin-like protease activity of proteasome, respectively. Both Que and MEK1/ERK1/2 inhibitor attenuated the expression levels of proteasome β subunits. These results indicate that Que-induced suppression of MEK1/ERK1/2 signaling and subsequent reduction of proteasome β subunits is responsible for its inhibitory impacts on proteasome activity.

Regulation of Aquaporin Functional Properties Mediated by the Antioxidant Effects of Natural Compounds

Some aquaporins (AQPs) have been recently demonstrated to facilitate the diffusion of hydrogen peroxide (H₂O₂) from the producing cells to the extracellular fluid, and their reactive oxygen species scavenging properties have been defined. Nevertheless, the identification of different AQPs acting as peroxiporins, their functional role in eustress and distress, and the identification of antioxidant compounds able to regulate AQP gating, remain unsolved. This study aims to investigate, in HeLa cells: (1) the expression of different AQPs; (2) the evaluation of naringenin, quercetin, (R)-aloesaponol III 8-methyl ether, marrubiin, and curcumin antioxidant profiles, via α,α-diphenyl-β-picrylhydrazyl assay; (3) the effect of the compounds on the water permeability in the presence and in the absence of oxidative stress; and (4) the effect of pre- and post-treatment with the compounds on the H₂O₂ content in heat-stressed cells. Results showed that HeLa cells expressed AQP1, 3, 8, and 11 proteins. The oxidative stress reduced the water transport, and both pre- and post-treatment with the natural compounds recovering the water permeability, with the exception of curcumin. Moreover, the pre- and post-treatment with all the compounds reduced the H₂O₂ content of heat-stressed cells. This study confirms that oxidative stress reduced water AQP-mediated permeability, reversed by some chemical antioxidant compounds. Moreover, curcumin was shown to regulate AQP gating. This suggests a novel mechanism to regulate cell signaling and survival during stress, and to manipulate key signaling pathways in cancer and degenerative diseases.

An Asian traditional herbal complex containing Houttuynia cordata Thunb, Perilla frutescens Var. acuta and green tea stimulates hair growth in mice

BACKGROUND

Houttuynia cordata Thunb (HC) is a traditional herbal medicine widely used in Asia for the treatment of patients with alopecia, usually in combination with other two herbal medicines (Perilla frutescens var. acuta (PFVA) and green tea (GT)). However, the effect of this herbal complex has not been clearly demonstrated. We sought to determine the hair growth-promoting effect of this herbal complex (HC, PFVA, and GT) in the animal model.

METHODS

Six-week-old male C57BL/6 mice were randomly divided into four groups (negative control, finasteride (1 mg/kg) as a positive control, and two (200 and 400 mg/kg) concentrations of the herbal complex as experimental groups) and were fed its corresponding medications orally for 25 days. Hair growth was evaluated visually and microscopically. Western blot analysis for insulin-like growth factor (IGF)-1 and transforming growth factor (TGF)-β1 was performed.

RESULTS

The herbal complex exhibited hair growth-promoting activity in C57BL/6 mice. Grossly, the area of hair regrowth was 55.1 (±3.8) %, 70.2 (±6.3) % and 83.5 (±5.7) % in negative control, herbal complex 200 mg/kg and 400 mg/kg group, respectively. In histologic examination, the hair follicle count in deep subcutis was 2.6 (±0.7), 5.8 (±0.7) and 8.6 (±1.2) and the diameter of hair follicles was 11.9 (±5.0) μm, 17.4 (±3.9) μm and 22.8 (±5.2) μm in negative control, herbal complex 200 and 400 mg/kg group, respectively. The expression of IGF-1 was 0.14 (±0.01), 0.23 (±0.02) and 0.24 (±0.01) and the expression of TGF-β1 was 0.26 (±0.01), 0.19 (±0.02) and 0.15 (±0.01) in negative control, the 200 and 400 mg/kg group, respectively.

CONCLUSIONS

This data provides adequate preliminary experimental evidence to support the hair regeneration effect of this herbal complex.

Nuts and Dried Fruits: An Update of Their Beneficial Effects on Type 2 Diabetes

Nuts and dried fruit are essential foods in the Mediterranean diet. Their frequent consumption has been associated with the prevention and/or the management of such metabolic conditions as type 2 diabetes (T2D), metabolic syndrome and cardiovascular diseases. Several previous reviews of epidemiological studies and clinical trials have evaluated the associations of nuts and/or dried fruit with various metabolic disorders. However, no reviews have focused on the mechanisms underlying the role of nuts and/or dried fruit in insulin resistance and T2D. This review aims to report nut and dried-fruit nutritional interventions in animals and humans, and to focus on mechanisms that could play a significant role in the prevention and treatment of insulin resistance and T2D.

Antioxidants Mediate Both Iron Homeostasis and Oxidative Stress

Oxidative stress is a common denominator in the pathogenesis of many chronic diseases. Therefore, antioxidants are often used to protect cells and tissues and reverse oxidative damage. It is well known that iron metabolism underlies the dynamic interplay between oxidative stress and antioxidants in many pathophysiological processes. Both iron deficiency and iron overload can affect redox state, and these conditions can be restored to physiological conditions using iron supplementation and iron chelation, respectively. Similarly, the addition of antioxidants to these treatment regimens has been suggested as a viable therapeutic approach for attenuating tissue damage induced by oxidative stress. Notably, many bioactive plant-derived compounds have been shown to regulate both iron metabolism and redox state, possibly through interactive mechanisms. This review summarizes our current understanding of these mechanisms and discusses compelling preclinical evidence that bioactive plant-derived compounds can be both safe and effective for managing both iron deficiency and iron overload conditions.