Quercetin supplementation suppresses the secretion of pro-inflammatory cytokines in the lungs of Mongolian gerbils and in A549 cells exposed to benzo[a]pyrene alone or in combination with β-carotene: in vivo and ex vivo studies

Au/Doc/Quer@PDA/A10-3.2 Nanoparticles for targeted treatment of docetaxel-resistant prostate cancer

Docetaxel (Doc), as a first-line chemotherapy drug for prostate cancer (PC), often loses its therapeutic efficacy due to acquired resistance and lack of targeting specificity. Therefore, there is a need to develop a novel drug that can overcome Doc resistance and enhance its targeting ability to inhibit PC progression. In this study, we prepared Au/Doc/Quer@PDA/A10-3.2 nanoparticles (NPs) composite drug by encapsulating Doc and quercetin (Quer) within polydopamine (PDA)-coated Au NPs and further modifying them with RNA oligonucleotide aptamer A10-3.2. A10-3.2 was used for specific targeting of prostate-specific membrane antigen (PSMA)-positive PC cells (LNCaP). Quer was employed to reverse the resistance of Doc-resistant cell line (LNCaP/R) to Doc. Physical characterization using ultraviolet-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR) confirmed the successful preparation of Au/Doc/Quer@PDA/A10-3.2 NPs. Fluorescence imaging and flow cytometry experiments demonstrated the targeting ability of Au/Doc/Quer@PDA/A10-3.2 NPs towards PSMA-positive LNCaP/R cells. Cell proliferation, apoptosis, invasion, and migration experiments revealed that Quer reversed the resistance of LNCaP/R cells to Doc. Immunoblotting experiments further confirmed the mechanism behind sensitization of chemotherapy by Quer. Finally, we evaluated the therapeutic efficacy of Au/Doc/Quer@PDA/A10-3.2 NPs in a mouse model of PC. In conclusion, this study synthesized and validated a novel nano-composite drug (Au/Doc/Quer@PDA/A10-3.2 NPs) for combating Doc-resistant PC, which could potentially be applied in clinical treatment of PC.

Neuroprotective effects of quercetin on the cerebellum of zinc oxide nanoparticles (ZnoNps)-exposed rats

Engineered nanomaterials induce hazardous effects at the cellular and molecular levels. We investigated different mechanisms underlying the neurotoxic potential of zinc oxide nanoparticles (ZnONPs) on cerebellar tissue and clarified the ameliorative role of Quercetin supplementation. Forty adult male albino rats were divided into control group (I), ZnONPs-exposed group (II), and ZnONPs and Quercetin group (III). Oxidative stress biomarkers (MDA & TOS), antioxidant biomarkers (SOD, GSH, GR, and TAC), serum interleukins (IL-1β, IL-6, IL-8), and tumor necrosis factor alpha (TNF-α) were measured. Serum micro-RNA (miRNA): miRNA-21-5p, miRNA-122-5p, miRNA-125b-5p, and miRNA-155-3p expression levels were quantified by real-time quantitative polymerase-chain reaction (RT-QPCR). Cerebellar tissue sections were stained with Hematoxylin & Eosin and Silver stains and examined microscopically. Expression levels of Calbindin D28k, GFAP, and BAX proteins in cerebellar tissue were detected by immunohistochemistry. Quercetin supplementation lowered oxidative stress biomarkers levels and ameliorated the antioxidant parameters that were decreased by ZnONPs. No significant differences in GR activity were detected between the study groups. ZnONPs significantly increased serum IL-1β, IL-6, IL-8, and TNF-α which were improved with Quercetin. Serum miRNA-21-5p, miRNA-122-5p, miRNA-125b-5p, and miRNA-155-p expression levels showed significant increase in ZnONPs group, while no significant difference was observed between Quercetin-treated group and control group. ZnONPs markedly impaired cerebellar tissue structure with decreased levels of calbindin D28k, increased BAX and GFAP expression. Quercetin supplementation ameliorated cerebellar tissue apoptosis, gliosis and improved calbindin levels. In conclusion: Quercetin supplementation ameliorated cerebellar neurotoxicity induced by ZnONPs at cellular and molecular basis by different studied mechanisms.Abbreviations: NPs: Nanoparticles, ROS: reactive oxygen species, ZnONPs: Zinc oxide nanoparticles, AgNPs: silver nanoparticles, BBB: blood-brain barrier, ncRNAs: Non-coding RNAs, miRNA: Micro RNA, DMSO: Dimethyl sulfoxide, LPO: lipid peroxidation, MDA: malondialdehyde, TBA: thiobarbituric acid, TOS: total oxidative status, ELISA: enzyme-linked immunosorbent assay, H2O2: hydrogen peroxide, SOD: superoxide dismutase, GR: glutathione reductase, TAC: total antioxidant capacity, IL-1: interleukin-1, TNF: tumor necrosis factor alpha, cDNA: complementary DNA, RT-QPCR: Real-time quantitative polymerase-chain reaction, ABC: Avidin biotin complex technique, DAB: 3', 3-diaminobenzidine, SPSS: Statistical Package for Social Sciences, ANOVA: One way analysis of variance, Tukey's HSD: Tukey's Honestly Significant Difference, GFAP: glial fiberillar acitic protein, iNOS: Inducible nitric oxide synthase, NO: nitric oxide, HO-1: heme oxygenase-1, Nrf2: nuclear factor erythroid 2-related factor 2, NF-B: nuclear factor-B, SCI: spinal cord injury, CB: Calbindin.

A comprehensive and current review on the role of flavonoids in lung cancer-Experimental and theoretical approaches

BACKGROUND

It is well-known that flavonoids, which can be easily obtained from many fruits and vegetables are widely preferred in the treatment of some important diseases. Some researchers noted that these chemical compounds exhibit high inhibition effect against various cancer types. Many experimental studies proving this ability of the flavonoids with high antioxidant activity are available in the literature.

PUROPOSE

The main aim of this review is to summarize comprehensively anticancer properties of flavonoids against the lung cancer in the light of experimental studies and well-known theory and electronic structure principles. In this review article, more detailed and current information about the using of flavonoids in the treatment of lung cancer is presented considering theoretical and experimental approaches.

STUDY DESIGN

In addition to experimental studies including the anticancer effects of flavonoids, we emphasized the requirement of the well-known electronic structure principle in the development of anticancer drugs. For this aim, Conceptual Density Functional Theory should be considered as a powerful tool. Searching the databases including ScienceDirect, PubMed and Web of Science, the suitable reference papers for this project were selected.

METHODS

Theoretical tools like DFT and Molecular Docking provides important clues about anticancer behavior and drug properties of molecular systems. Conceptual Density Functional Theory and CDFT based electronic structure principles and rules like Hard and Soft Acid-Base Principle (HSAB), Maximum Hardness Principle, Minimum Polarizability, Minimum Electrophilicity Principles and Maximum Composite Hardness Rule introduced by one of the authors of this review are so useful to predict the mechanisms and powers of chemical systems. Especially, it cannot be ignored the success of HSAB Principle in the explanations and highlighting of biochemical interactions.

RESULTS

Both theoretical analysis and experimental studies confirmed that flavonoids have higher inhibition effect against lung cancer. In addition to many superior properties like anticancer activity, antimicrobial activity, antioxidant activity, antidiabetic effect of flavonoids, their toxicities are also explained with the help of published popular papers. Action modes of the mentioned compounds are given in detail.

CONCLUSION

The review includes detailed information about the mentioned electronic structure principles and rules and their applications in the cancer research. In addition, the epidemiology and types of lung cancer anticancer activity of flavonoids in lung cancer are explained in details.

Target-Specific Drug Discovery of Natural Products against SARS-CoV-2 Life Cycle and Cytokine Storm in COVID-19

Coronavirus disease 2019 (COVID-19) is currently a worldwide pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently, there are no drugs that can specifically combat SARS-CoV-2. Besides, multiple SARS-CoV-2 variants are circulating globally. These variants may lead to immune escape or drug resistance. Natural products may be appropriate for this need due to their cost efficiency, fewer side effects, and antiviral activities. Considering these circumstances, there is a need to develop or discover more compounds that have potential to target SARS-CoV-2. Therefore, we searched for articles on natural products describing anti-SARS-CoV-2 activities by targeting the SARS-CoV-2 life cycle and the cytokine storm in COVID-19 from academic databases. We reviewed anti-SARS-CoV-2 activities of natural products, especially those that target the SARS-CoV-2 life cycle (angiotensin-converting enzyme 2, transmembrane serine protease 2, cathepsin L, 3CL protease, PL protease, RNA-dependent RNA polymerase, and helicase) and cytokine storm in COVID-19. This review may provide a repurposed approach for the discovery of specific medications using natural products to treat COVID-19 through targeting the SARS-CoV-2 life cycle and the cytokine storm in COVID-19.

Natural Products Targeting Cancer Stem Cells for Augmenting Cancer Therapeutics

Cancer stem cells (CSC) have been identified in several types of solid tumors. In some cases, CSC may be the source of all the tumor cells, the cause of the tumor's resistance to chemotherapeutic agents, and the source of metastatic cells. Thus, a combination therapy targeting non-CSC tumor cells as well as specifically targeting CSCs holds the potential to be highly effective. Natural products (NPs) have been a historically rich source of biologically active compounds and are known for their ability to influence multiple signaling pathways simultaneously with negligible side effects. In this review, we discuss the potential of NPs in targeting multiple signaling pathways in CSC and their potential to augment the efficacy of standard cancer therapy. Specifically, we focus on the anti-CSC activities of flavonoids, FDA-approved drugs originating from natural sources. Additionally, we emphasize the potential of NPs in targeting microRNA-mediated signaling, given the roles of microRNA in the maintenance of the CSC phenotype.

Observable Protective Activities of Quercetin on Aluminum Chloride-Induced Testicular Toxicity in Adult Male Wistar Rat

Background:

Aluminum chloride (AlCl3 ) present in many manufactured consumable is considered as a toxic element.

Aim:

Our study evaluates the toxic effects induced by AlCl3 on the testes as well as the therapeutic tendency of Quercetin (QUE) agent as an antioxidant.

Setting and Design:

In the department of Anatomy of Medical School.

Methods and Materials:

Thirty-two male Wistar rats weighing approximately 170 ± 10 g were assigned into four groups with eight each, fed with rat chow and water ad-libitum. Group A served as control and was given distilled water throughout; Group B was given only QUE (200 mg/kg body weight) for 21 days; Group C was given only AlCl3 (300 mg/kg body weight) for 14 days; and Group D was given AlCl3 (300 mg/kg body weight) for 14 days followed with QUE (200 mg/kg body weight) for 21 days. Substance administrations were done orally.

Statistical analysis:

One-way analysis of variance was used to analyze the data, in GraphPad Prism 6.0 being the statistical software.

Results:

AlCl3 significantly reduced the relative organ (testes) weight, correlating the decrease in sperm count, sperm motility and sperm viability. Furthermore, there was a decrease in luteinizing hormone with an increase in follicle-stimulating hormone which accounted for a significant reduction in testosterone level that plays a great role in spermatogenesis, following AlCl3 treatment. The cytoarchitecture of the testes showed degenerative changes in the seminiferous tubules and leydin cells, nitric oxide synthases immunoreactivity was intense in the seminiferous epithelium of rat in Group C.

Conclusion:

These suggest that QUE antioxidant property could reverse the decrease in sperm status, hormonal effects, and functional deficit induced by aluminum chloride on the testes of Wistar rats.

Effects of supplementation with β-carotene on the growth performance and intestinal mucosal barriers in layer-type cockerels

β-carotene is a robust modulator of mucosal barriers, and it can amplify the immunoglobulin A (IgA) response via the retinoic acid (RA)-mediated pathway. We investigated the influence of β-carotene on intestinal barriers in layer-type cockerels. In this study, β-carotene has a positive influence on growth performance and intestinal morphology. β-carotene remarkably enhanced serum secretory immunoglobulin A (sIgA) levels, jejunal mucosal sIgA, and IgA concentrations. β-Carotene significantly enhanced mRNA expression levels of IgA, CC chemokine receptor-9 (CCR9), polymeric immunoglobulin receptor (pIgR), and retinoic acid receptor α (RARα) in the ileal tissues and pIgR in the jejunal tissues. β-Carotene improves mRNA expression of intestinal barrier-related proteins including: mucin-2 (MUC-2), zonula occludens-2 (ZO-2), occludins (OCLN), and zonula occludens-1 (ZO-1) in the ileal tissues. Moreover, β-carotene decreased the levels of Escherichia coli and elevates the levels of Lactobacillus. The results indicate that β-carotene can promote growth performance and contribute to the gradual development of intestinal barriers in Hyline Brown chicks. This study enriches our knowledge about the effects of β-carotene on intestinal barrier and highlights a theoretical basis of β-carotene application in the poultry industry.

Fisetin and Quercetin: Promising Flavonoids with Chemopreventive Potential

Despite advancements in healthcare facilities for diagnosis and treatment, cancer remains the leading cause of death worldwide. As prevention is always better than cure, efficient strategies are needed in order to deal with the menace of cancer. The use of phytochemicals as adjuvant chemotherapeutic agents in heterogeneous human carcinomas like breast, colon, lung, ovary, and prostate cancers has shown an upward trend during the last decade or so. Flavonoids are well-known products of plant derivatives that are reportedly documented to be therapeutically active phytochemicals against many diseases encompassing malignancies, inflammatory disorders (cardiovascular disease, neurodegenerative disorder), and oxidative stress. The current review focuses on two key flavonols, fisetin and quercetin, known for their potential pharmacological relevance. Also, efforts have been made to bring together most of the concrete studies pertaining to the bioactive potential of fisetin and quercetin, especially in the modulation of a range of cancer signaling pathways. Further emphasis has also been made to highlight the molecular action of quercetin and fisetin so that one could explore cancer initiation pathways and progression, which could be helpful in designing effective treatment strategies.

Quercetin and Idebenone Ameliorate Oxidative Stress, Inflammation, DNA damage, and Apoptosis Induced by Titanium Dioxide Nanoparticles in Rat Liver

Titanium dioxide nanoparticles (TiO₂-NPs) are extensively used in a wide range of applications; however, many reports have investigated their nanotoxicological effect at the molecular level either in vitro or in vivo systems. The defensive roles of quercetin (Qur) or idebenone (Id) against the hepatotoxicity induced by TiO₂-NPs were evaluated in the current study. The results showed that the coadministration of Qur or Id to rats intoxicated with TiO₂-NPs markedly ameliorated the elevation in hepatic malondialdehyde (MDA), serum alanine amino-transferase (ALT), glucose, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), immunoglobin G (IgG), and C-reactive protein (CRP) levels compared to their levels in TiO₂-NPs-treated rats. The aforementioned antioxidants also effectively modulated the changes in the levels of serum vascular endothelial growth factor (VEGF), nitric oxide (NO), hepatic DNA breakage, caspase-3, and inhibition of drug metabolizing enzymes (cytochrome P450s; CYP4502E12E1) in rat livers induced by TiO₂-NPs toxicity. The histopathological examination of the liver section showed that TiO₂-NPs caused severe degeneration of most hepatocytes with an increase in collagen in the portal region, while treatment with the antioxidants in question improved liver architecture. These outcomes supported the use of Qur and Id as protective agents against the hepatotoxicity induced by TiO₂-NPs and other hepatotoxic drugs.

Stability of dietary polyphenols: It's never too late to mend?

We have comprehensively investigated the structure-stability relationship of natural polyphenols in DMEM medium without cells. Polyphenols with catechol or pyrogallol structure were evidently instable in DMEM medium without cells. Herein, we further investigate stability of polyphenols when incubated with cancer cells and its related mechanism. After incubated with SK-28 cells and A549 cells at 37 °C in 5% CO₂ for 72 h, the new products of quercetin and 5,7,3',4'-tetrahydroxyflavone were found to quite different from different cells. It is time to investigate what really happened for polyphenols and the new products of polyphenols in cancer cells, as well as the related mechanism. It is very important to further check the bioactivity of these new products, which will avoid erroneous conclusions for what's the really bioactive compounds.

Combined effect of tris(2-chloroethyl)phosphate and benzo (a) pyrene on the release of IL-6 and IL-8 from HepG2 cells via the EGFR-ERK1/2 signaling pathway

Tris(2-chloroethyl)phosphate plus benzo (a) pyrene induced inflammatory response in HepG2 cells through the activation of EGFR-ERK1/2 signaling pathway.

Chitosan nanoparticles plus quercetin suppress the oxidative stress, modulate DNA fragmentation and gene expression in the kidney of rats fed ochratoxin A-contaminated diet

This study aimed to evaluate the protective role of chitosan nanoparticles (COS-NPs) singly or plus quercetin (Q) against OTA-induced oxidative stress and renal genotoxicity. Twelve groups of male Sprague-Dawley rats were treated orally for 3 weeks included the control group, animals fed OTA-contaminated diet (3 mg/kg diet); COS-NPs-treated groups at low (140 mg/kg b.w.) or high (280 mg/kg b.w.) dose, Q-treated group (50 mg/kg b.w.), Q plus low or high dose of COS-NPs-treated groups and OTA plus Q and/or COS-NPs at the two tested doses-treated groups. The results indicated that COS-NPs were roughly rod in shape with average particle size of 200 nm and zeta potential 31.4 ± 2.8 mV. Animals fed OTA-contaminated diet showed significant changes in serum biochemical parameters, increase kidney MDA and DNA fragmentation and decreased GPx and SOD gene expression accompanied with severe histological changes. Q and/or COS-NPs at the two tested doses induced significant improvements in all tested parameters and succeeded to overcome these effects especially in the animals treated with Q plus the high dose of COS-NPs. It could be concluded that COS-NPs are promise candidate to enhance the antioxidant effect of Q and protect against the nephrotoxicity of OTA in high endemic areas.

Rutin inhibits proliferation, attenuates superoxide production and decreases adhesion and migration of human cancerous cells

Lung and colorectal cancer are the principal causes of death in the world. Rutin, an active flavonoid compound, is known for possessing a wide range of biological activities. In this study, we examined the effect of rutin on the viability, superoxide anion production, adhesion and migration of human lung (A549) and colon (HT29 and Caco-2) cancer cell lines. In order to control the harmlessness of the tested concentrations of rutin, the viability of cancer cell lines was assessed using a 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. ROS generation was measured by lucigenin chemiluminescence detecting superoxide ions. To investigate the effect of rutin on the behavior of human lung and colon cancer cell lines, we performed adhesion assays, using various purified extracellular matrix (ECM) proteins. Finally, in vitro cell migration assays were explored using modified Boyden chambers. The viability of cancerous cells was inhibited by rutin. It also significantly attenuated the superoxide production in HT29 cells. In addition, rutin affected adhesion and migration of A549 and HT29 cell. These findings indicate that rutin, a natural molecule, might have potential as anticancer agent against lung and colorectal carcinogenesis.

Alleviation of bone markers in rats induced nano-zinc oxide by qurecetin and α-lipolic acid

The purpose of this study was to evaluate the potential protective effect of qurecetin (Qur) and α-lipolic acid (ALA) to modulate the perturbation of bone turnover which is induced by nano-zinc oxide (n-ZnO). Rats were fasted overnight and randomly divided into two groups: G1, normal healthy animals and the other rats were administered zinc oxide nanoparticles orally by guava in a dose of 600 mg/kg body weight/d for 5 sequential days in Wistar albino male rats. N-ZnO-exposed animals were randomly sub-divided into three groups: G2, n-ZnO-exposed animals; G3, n-ZnO-exposed animals co-treated with Qur (200 mg/kg daily); and G4, n-ZnO-exposed animals co-treated with ALA (200 mg/kg). Qur and ALA were administered orally by guava daily for three sequential weeks from the beginning of the experiment. The results revealed a significant reduction of nitiric oxide (NO) and serum level and comet assay in n-ZnO exposure rats after treatment of Qur and ALA. It was found the alteration of pro-inflammatory markers (tumor necrosis factor alpha; TNF-α, interleukin-6; IL-6 and C-reactive protein; CRP), bone alkaline phosphatase (B-ALP, bone formation marker), and C-terminal peptide type I collagen (CTx, bone resorption marker) levels compared with the normal group. Co-administration of Qur and ALA in n-ZnO-exposed rats significantly alleviated the mentioned alterations of biochemical parameters. These results suggest that Qur and ALA as antioxidant agents may be a candidate for preventive and treatment applications of impaired bone markers induced bone loss caused by nano-particles of metal oxide.

Plant Polyphenols as Chemopreventive Agents for Lung Cancer

Lung cancer may be prevented by a diet rich in fruits and vegetables as they are enriched with dietary antioxidant polyphenols, such as flavonoids, proanthocyanidins, lignans, stilbenes, and phenolic acids. Dietary polyphenols exert a wide range of beneficial biological functions beyond their antioxidative properties and are involved in regulation of cell survival pathways leading to anticarcinogenic and antimutagenic functions. There are sufficient evidence from in vitro, in vivo, and epidemiological studies to suggest that the dietary intervention of polyphenols in cancer prevention, including the chemopreventive ability of dietary polyphenols, act against lung carcinogens. Cohort and epidemiological studies in selected risk populations have evaluated clinical effects of polyphenols. Polyphenols have demonstrated three major actions: antioxidative activity, regulation of phase I and II enzymes, and regulation of cell survival pathways against lung carcinogenesis. They have also shown an inverse association of lung cancer occurrences among high risk populations who consumed considerable amounts of fruits and vegetables in their daily diet. In in vitro cell culture experimental models, polyphenols bind with electrophilic metabolites from carcinogens, inactivate cellular oxygen radicals, prevent membrane lipid peroxidation and DNA oxidative damage, and adduct formation. Further, polyphenols enhance the detoxifying enzymes such as the phase II enzymes, glutathione transferases and glucuronosyl transferases.

SIRT1 in B[a]P-induced lung tumorigenesis

Benzo[a]pyrene (B[a]P) is a carcinogen in cigarette smoke. We found that B[a]P induced SIRT1 in human bronchial epithelial BEAS-2B cell. SIRT1 was overexpressed in the lung of B[a]P-exposed mice and in human lung cancer biopsies. SIRT1 up-regulated TNF-α and β-catenin and down-regulated the membrane fraction of E-cadherin. In addition, SIRT1 promoted invasion, migration and tumorigenesis of BEAS-2B cells in nude mice upon B[a]P exposure. Thus, SIRT1 is involved in B[a]P-induced transformation associated with activation of the TNF-α/β-catenin axis and is as a potential therapeutic target for lung cancer.

Quercetin Mediates β-Catenin in Pancreatic Cancer Stem-Like Cells

OBJECTIVE

The aim of this study is to explore how quercetin interacts with pancreatic cancer stem-like cells and the mechanism underlying the effective quercetin-mediated suppression.

METHODS

A model of pancreatic cancer stem-like cells was generated by using a sphere formation culture system. A comparative analysis was performed between the parent cells and pancreatic cancer stem-like cells with a related treatment strategy focusing on cancer stem cell (CSC) properties and drug-resistance-related mechanisms in vitro.

RESULTS

Our data show that pancreatic cancer stem-like cells have greater resistance to gemcitabine and stronger CSC properties compared with the parent cells. In contrast to the pancreatic cancer stem-like cells, overexpression of β-catenin was observed in the parent cells. Quercetin suppressed proliferation, invasion and self-renewal capacity, and CSC surface markers expression, with alterations of β-catenin in pancreatic cancer stem-like cells. The combination of quercetin and gemcitabine can reduce tumor growth and decrease drug resistance in pancreatic cancer.

CONCLUSIONS

β-Catenin plays an important role in maintenance and progression of pancreatic cancer. Targeting β-catenin using quercetin combined with gemcitabine may be a treatment strategy to improve prognosis in patients with pancreatic cancer.

Chitosan nanoparticles and quercetin modulate gene expression and prevent the genotoxicity of aflatoxin B1 in rat liver

The aims of the current study were to prepare chitosan nanoparticles (CNPs) and to evaluate its protective role alone or in combination with quercetin (Q) against AFB₁-induce cytotoxicity in rats. Male Sprague-Dawley rats were divided into 12 groups and treated orally for 4 weeks as follow: the control group, the group treated with AFB₁ (80 μg/kg b.w.) in corn oil, the groups treated with low (140 mg/kg b.w.) or high (280 mg/kg b.w.) dose of CNPs, the group treated with Q (50 mg/kg b.w.), the groups treated with Q plus the low or the high dose of CNPs and the groups treated with AFB₁ plus Q and/or CNPs at the two tested doses. The results also revealed that administration of AFB₁ resulted in a significant increase in serum cytokines, Procollagen III, Nitric Oxide, lipid peroxidation and DNA fragmentation accompanied with a significant decrease in GPx I and Cu–Zn SOD-mRNA gene expression. Q and/or CNPs at the two tested doses overcome these effects especially in the group treated with the high dose of CNPs plus Q. It could be concluded that CNPs is a promise candidate as drug delivery enhances the protective effect of Q against the cytogenetic effects of AFB₁ in high endemic areas.

Potential impact of quercetin and idebenone against immuno- inflammatory and oxidative renal damage induced in rats by titanium dioxide nanoparticles toxicity

The aim of this study was to investigate the toxic impacts of titanium dioxide nanoparticles (TiO₂-NPs) on rat kidneys and the possible prophylactic role of either quercetin or idebenone. TiO₂-NPs were administered orally at either 600 mg or 1 g/kg body weight for 5 consecutive days to evaluate dose-dependent toxicity referred to the OECD guidelines for testing of chemicals. The results showed that administration of either low or high repeated doses of TiO₂-NPs to rats significantly increases serum kideney function biomarkers (urea, creatinine and uric acid) as well as increases in serum glucose and serum immuno- inflammatory biomarkers including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), immunoglobin g (IGg), vascular endothelial growth factor (VEGF, angiogenic factor) and nitric oxide (NO) with a concomitant decrease in renal GSH content versus normal control values. The increase in these biomarkers was more evident in rats intoxicated with high TiO₂-NPs repeated doses. Oral co- administration of either quercetin or idebenone (each 200mg/Kg body weight) daily for three weeks to rats intoxicated by either of the two doses markedly ameliorated TiO₂-NPs induced alteration in the above biomarkers. The prophylactic impacts of both agents on biochemical markers were more pronounced in rats received low TiO₂-NPs repeated doses. The biochemical investigation was supported by histological examination. In conclusion, The data showed the severity in renotoxicity of TiO₂-NPs was dose-dependent and the protective effect of quercetin and idebenone may be related to their antioxidant and anti-inflammatory properties.

Oral and intraperitoneal administration of quercetin decreased lymphocyte DNA damage and plasma lipid peroxidation induced by TSA in vivo

Our previous study showed that quercetin enhances the anticancer effect of trichostatin A (TSA) in xenograft mice given quercetin intraperitoneally (10 mg/kg, 3 times/week). Herein, we investigate whether quercetin administered orally exerts such an effect and prevents the cytotoxic side effects of TSA. We found that quercetin given orally (20 and 100 mg/kg, 3 times/week) failed to enhance the antitumor effect of TSA although it increased the total quercetin concentration more than quercetin administered intraperitoneally in the plasma. The compound quercetin-3-glucuronide (Q3G) increased the most. However, quercetin administered intraperitoneally increased the total quercetin level in tumor tissues more than oral quercetin. Oral and intraperitoneal administration of quercetin similarly decreased lymphocyte DNA damage and plasma lipid peroxidation level induced by TSA. Furthermore, we found that the enhancing effect of Q3G on the antitumor effect of TSA and the incorporation of Q3G was less than that of quercetin in A549 cells. However, we found that A549 cells possessed the ability to convert Q3G to quercetin. In conclusion, different from quercetin administered intraperitoneally, quercetin administered orally failed to enhance the antitumor effect of TSA because of its metabolic conversion. However, it prevented TSA-induced DNA damage and lipid peroxidation.

Quercetin enhances the antitumor activity of trichostatin A through upregulation of p53 protein expression in vitro and in vivo

This study investigated the effects of quercetin on the anti-tumor effect of trichostatin A (TSA), a novel anticancer drug, in vitro and in vivo and the possible mechanisms of these effects in human lung cancer cells. We first showed that quercetin (5 µM) significantly increased the growth arrest and apoptosis in A549 cells (expressing wild-type p53) induced by 25 ng/mL of (82.5 nM) TSA at 48 h by about 25% and 101%, respectively. However, such enhancing effects of quercetin (5 µM) were not significant in TSA-exposed H1299 cells (a p53 null mutant) or were much lower than in A549 cells. In addition, quercetin significantly increased TSA-induced p53 expression in A549 cells. Transfection of p53 siRNA into A549 cells significantly but not completely diminished the enhancing effects of quercetin on TSA-induced apoptosis. Furthermore, we demonstrated that quercetin enhanced TSA-induced apoptosis through the mitochondrial pathway. Transfection of p53 siRNA abolished such enhancing effects of quercetin. However, quercetin increased the acetylation of histones H3 and H4 induced by TSA in A549 cells, even with p53 siRNA transfection as well as in H1299 cells. In a xenograft mouse model of lung cancer, quercetin enhanced the antitumor effect of TSA. Tumors from mice treated with TSA in combination with quercetin had higher p53 and apoptosis levels than did those from control and TSA-treated mice. These data indicate that regulation of the expression of p53 by quercetin plays an important role in enhancing TSA-induced apoptosis in A549 cells. However, p53-independent mechanisms may also contribute to the enhancing effect of quercetin.

Effects of quercetin metabolites on the enhancing effect of β-carotene on DNA damage and cytochrome P1A1/2 expression in benzo[a]pyrene-exposed A549 cells

A549 cells were pre-incubated with β-carotene (BC) alone or in combination with quercetin or three major quercetin metabolites in human plasma, quercetin 3-glucuronide (Q3G), quercetin 3'-sulphate (Q3'S) and isorhamnetin, followed by incubation with benzo[a]pyrene (BaP), to investigate the effects of these compounds on the BaP-induced harmful effects of BC. All the quercetin metabolites at 10μM inhibited BaP+BC-induced cell death. Q3'S, Q3G and isorhamnetin also significantly decreased BaP±BC-induced DNA damage by 64%, 60% and 24%, respectively. In a similar order, these compounds suppressed BaP+BC-induced cytochrome P450 (CYP)1A1/1A2 expression by 10-50%. Q3G and Q3'S significantly decreased the intracellular reactive oxygen species formation induced by BaP+BC; however, Q3G had the best effect on decreasing the loss of BC induced by Fe/NTA. The combined effects of quercetin metabolites were additive. This study indicates that quercetin metabolites decrease the BaP-induced harmful effect of β-carotene in A549 cells by downregulating the expression of CYP1A1/1A2, at least in part.