Molecular mechanisms of oxygen radical carcinogenesis and mutagenesis: the role of DNA base damage

Aryl hydrocarbon receptor (AHR) and nuclear factor erythroid-derived 2-like 2 (NRF2): An important crosstalk in the gut-liver axis

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor, mainly involved in detoxification. However, in the intestine, metabolites derived from the diet, which are converted by a wide range of bacteria can also activate the AHR. This intestinal AHR activation plays a key role in maintaining the gut barrier by, for example, upregulating antimicrobial peptides and anti-inflammatory cytokines. Since the gut barrier influences the gut-liver axis by regulating the leaking of metabolites, bacteria, and endotoxins into circulation and particularly into the liver, the AHR is a key factor in the gut-liver axis. Vice versa, certain liver pathologies also influence the gut microbiome, thereby altering bacteria-derived activation of the AHR. Additionally, bile acids can impact the gut via the liver and thereby also affect the AHR. The aryl hydrocarbon receptor (AHR) interacts with several molecular factors, one of which is the nuclear factor erythroid-derived 2-like 2 (NRF2), a transcription factor primarily associated with regulating antioxidant stress responses. The interplay between AHR and NRF2 has been investigated in the context of various diseases; this review highlights the significance of this interaction within the framework of the gut-liver axis.

The Functional Significance of McMafF_G_K in Molluscs: Implications for Nrf2-Mediated Oxidative Stress Response

The nuclear factor erythroid 2-related factor 2 (Nrf2) is a pivotal regulator of antioxidant gene expression in mammals, forming heterodimer complexes with small Maf proteins through its BZip domain. However, the underlying mechanism of Nrf2 action in molluscs remains poorly understood. The thick shell mussel, Mytilus coruscus, represents a model organism for the marine environment and molluscs interaction research. In this study, we used in silico cloning to obtain a small Maf homologue called McMafF_G_K from M. coruscus. McMafF_G_K possesses a typical BZip domain, suggesting its affiliation with the traditional small Maf family and its potential involvement in the Nrf2 signaling pathway. Transcriptional analysis revealed that McMafF_G_K exhibited a robust response to benzo[a]pyrene (Bap) in the digestive glands. However, this response was down-regulated upon interference with McMafF_G_K-siRNA. Interestingly, the expression levels of Nrf2, NAD(P)H: quinone oxidoreductase (NQO-1), and Glutathione Peroxidase (GPx), which are key players in oxidative stress response, showed a positive correlation with McMafF_G_K in digested adenocytes of M. coruscus. Furthermore, in vitro analysis of antioxidant capacity in digestive gland cells demonstrated that Bap exposure led to an increase in reactive oxygen species (ROS) levels, accompanied by an elevation in total antioxidant capacity (T-AOC), potentially counterbalancing the excessive ROS. Strikingly, transfection of McMafF_G_K siRNA resulted in a significant rise in ROS level and a down-regulation of T-AOC level. To validate the functional relevance of McMafF_G_K, a glutathione S-transferase (GST) pull-down assay confirmed its interaction with McNrf2, providing compelling evidence of their protein interaction. This study significantly contributes to our understanding of the functional role of McMafF_G_K in the Nrf2 signaling pathway and sheds light on its potential as a target for further research in oxidative stress response.

Stromal inflammation, fibrosis and cancer: An old intuition with promising potential

It is now well established that the biology of cancer is influenced by not only malignant cells but also other components of the tumour microenvironment. Chronic inflammation and fibrosis have long been postulated to be involved in carcinogenesis. Chronic inflammation can promote tumorigenesis via growth factor/cytokine-mediated cellular proliferation, apoptotic resistance, immunosuppression; and free-radical-induced oxidative deoxyribonucleic acid damage. Fibrosis could cause a perturbation in the dynamics of the tumour microenvironment, potentially damaging the genome surveillance machinery of normal epithelial cells. In this review, we will provide an in-depth discussion of various diseases characterised by inflammation and fibrosis that have been associated with an increased risk of malignancy. In particular, we will present a comprehensive overview of the impact of alterations in stromal composition on tumorigenesis, induced as a consequence of inflammation and/or fibrosis. Strategies including the application of various therapeutic agents with stromal manipulation potential and targeted cancer screening for certain inflammatory diseases which can reduce the risk of cancer will also be discussed.

Hydrogen-Bonding Interactions of 8-Substituted Purine Derivatives

Hydrogen bonding between nucleobases is a crucial noncovalent interaction for life on Earth. Canonical nucleobases form base pairs according to two main geometries: Watson-Crick pairing, which enables the static functions of nucleic acids, such as the storing of genetic information; and Hoogsteen pairing, which facilitates the dynamic functions of these biomacromolecules. This precisely tuned system can be affected by oxidation or substitution of nucleobases, leading to changes in their hydrogen-bonding patterns. This paper presents an investigation into the intermolecular interactions of various 8-substituted purine derivatives with their hydrogen-bonding partners. The systems were analyzed using nuclear magnetic resonance spectroscopy and density functional theory calculations. Our results demonstrate that the stability of hydrogen-bonded complexes, or base pairs, depends primarily on the number of intermolecular H-bonds and their donor-acceptor alternation. No strong preferences for a particular geometry, either Watson-Crick or Hoogsteen, were found.

Multivitamins in the prevention of cancer and cardiovascular disease: the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) randomized clinical trial

BACKGROUND

Although older adults commonly take multivitamin-multimineral (MVM) supplements to promote health, evidence on the use of daily MVMs on invasive cancer is limited.

OBJECTIVES

The study objective was to determine if a daily MVM decreases total invasive cancer among older adults.

METHODS

We performed a randomized, double-blind, placebo-controlled, 2-by-2 factorial trial of a daily MVM and cocoa extract for prevention of cancer and cardiovascular disease (CVD) among 21,442 US adults (12,666 women aged ≥65 y and 8776 men aged ≥60 y) free of major CVD and recently diagnosed cancer. The intervention phase was from June 2015 through December 2020. This article reports on the MVM intervention. Participants were randomly assigned to daily MVM or placebo. The primary outcome was total invasive cancer, excluding nonmelanoma skin cancer. Secondary outcomes included major site-specific cancers, total CVD, all-cause mortality, and total cancer risk among those with a baseline history of cancer.

RESULTS

During a median follow-up of 3.6 y, invasive cancer occurred in 518 participants in the MVM group and 535 participants in the placebo group (HR: 0.97; 95% CI: 0.86, 1.09; P = 0.57). We observed no significant effect of a daily MVM on breast cancer (HR: 1.06; 95% CI: 0.79, 1.42) or colorectal cancer (HR: 1.30; 95% CI: 0.80, 2.12). We observed a protective effect of a daily MVM on lung cancer (HR: 0.62; 95% CI: 0.42, 0.92). The composite CVD outcome occurred in 429 participants in the MVM group and 437 participants in the placebo group (HR: 0.98; 95% CI: 0.86, 1.12). MVM use did not significantly affect all-cause mortality (HR: 0.93; 95% CI: 0.81, 1.08). There were no safety concerns.

CONCLUSIONS

A daily MVM supplement, compared with placebo, did not significantly reduce the incidence of total cancer among older men and women. Future studies are needed to determine the effects of MVMs on other aging-related outcomes among older adults. This trial is registered at www.clinicaltrials.gov as NCT02422745.

Antioxidant Aryl-Substituted Phthalan Derivatives Produced by Endophytic Fungus Cytospora rhizophorae

Six new phthalan derivatives cytorhizophins D-I (1-6) as well as three known derivatives cytorhizophin C, pestacin and rhizophol B were isolated from Cytospora rhizophorae. Among them, cytorhizophins D-E (1-2) and F-G (3-4) were two pairs of diastereoisomers, all of them featuring a 1-phenyl-1,3-dihydroisobenzofuran scaffold with a highly oxygenated O-linked isopentenyl unit. Besides, cytorhizophins H-I (5-6) represent the first examples of phthalide family with fascinating 6/6/6/5 tetracyclic ring system fusing as unprecedented furo [4,3,2-kl]xanthen-2 (10bH)-one skeleton. The structures of the new phthalan derivatives were extensively confirmed by detail spectroscopic analysis. The partial absolute configurations of compounds 1-6 were established through electronic circular dichroism (ECD) calculations. Moreover, compounds 1-4 showed remarkable antioxidant activities with EC₅₀ values ranging from 5.86 to 26.80 μM, which were better than or comparable to that of ascorbic acid (positive control).

Ferulic acid: A review of its pharmacology, pharmacokinetics and derivatives

Ferulic acid, a kind of phenolic substance widely existing in plants, is an important active component of many traditional Chinese medicines. So far, it has been proved that ferulic acid has a variety of biological activities, especially in oxidative stress, inflammation, vascular endothelial injury, fibrosis, apoptosis and platelet aggregation. Many studies have shown that ferulic acid can inhibit PI3K/AKT pathway, the production of ROS and the activity of aldose reductase. The anti-inflammatory effect of ferulic acid is mainly related to the levels of PPAR γ, CAM and NF-κ B and p38 MAPK signaling pathways. Ferulic acid not only protects vascular endothelium by ERK1/2 and NO/ET-1 signal, but also plays an anti-fibrosis role by TGF-β/Smad and MMPs/TIMPs system. Moreover, ferulic acid has ant-apoptotic and anti-platelet effects. In addition to the pharmacological effects of ferulic acid, its pharmacokinetics and derivatives were also discussed in this paper. This review provides the latest summary of the latest research on ferulic acid.

Toxic effects of octocrylene on zebrafish larvae and liver cell line (ZFL)

Octocrylene (OC) is a broad-spectrum ultraviolet-absorbing chemical used in sunscreen and other personal care products. Its health effects are a concern because it has been detected in water, fish, humans, and food chains. In vivo and in vitro investigations were performed in zebrafish (Danio rerio) larvae and a zebrafish liver cell line (ZFL), respectively, to understand the potential risks and molecular mechanisms of OC toxicity. The 96-h median lethal concentration (LC₅₀) of OC was determined to be 251.8 μM in larvae and 5.5 μM in ZFL cells. Quantitative real-time PCR (qRT-PCR) showed that OC induced the expression of genes for CYPs (CYP1A, CYP3A65), estrogen receptors (ERα, ERβ1, GPER), vitellogenin (VTG1), and sex determination (BRCA2, CYP19A, DMRT1, SOX9A), both in vitro and in vivo. A whole-transcriptome sequencing method was used to evaluate the gene expression profile of larvae exposed to OC. OC was found to mediate the biosynthesis of estrogens (such as estriol) and affect the antioxidant pathway (glutathione transferases and peroxisome). These findings clarify the toxic effects and molecular mechanisms of OC and support banning its use in cosmetics.

Predicting oxidative stress induced by organic chemicals by using quantitative Structure-Activity relationship methods

Cellular exposure to xenobiotic human-made products will lead to oxidative stress that gives rise to DNA damage, as well as chemical or mechanical damage. Distinguishing the chemicals that will induce oxidative stress and predicting their toxicity is necessary. In the present study, 4270 compounds in the ARE-bla assay were investigated to predict active and inactive compounds by using simple algorithms, namely, recursive partitioning (RP) and binomial logistic regression, and to develop the quantitative structure-activity relationship (QSAR) models of chemicals that activate the ARE pathway to induce oxidative stress and exert toxic effects on cells. A decision tree based on scaffold-based fragments obtained through RP analysis showed the best identification accuracy. However, the overall identification accuracy of this model for active compounds was unsatisfactory due to limited fragments. Furthermore, a binomial logistic regression model was developed from 638 active compounds and 3632 inactive chemicals. The model with a cutoff of 0.15 could predict chemicals that were active or inactive with the prediction accuracy of 69.1%. Its area under the receiver operating characteristic (ROC) curve metric (AUROC) was 0.762, which indicated the acceptable predictive ability of this model. The parameters nBM (number of multiple bonds) and H% (percentage of H atom) played dominant roles in the prediction of the activity (inactive or active) of chemicals. A global QSAR model was developed to predict the toxicity of active chemicals. However, the model displayed an unsatisfactory result with R² = 0.316 and R²_ext = 0.090. Active chemicals were then classified on the basis of structure. A total of 79 compounds with carbon chains could be predicted with acceptable performance by using a QSAR model with six descriptors (R² = 0.722, R²_ext = 0.798, Q²_Loo = 0.654, Q²_Boot = 0.755, Q²_ext = 0.721). The simple models established here contribute to efforts on identification compounds inducing oxidative stress and provide the scientific basis for risk assessment to organisms in the environment.

REM sleep loss-induced elevated noradrenaline could predispose an individual to psychosomatic disorders: a review focused on proposal for prediction, prevention, and personalized treatment

Historically and traditionally, it is known that sleep helps in maintaining healthy living. Its duration varies not only among individuals but also in the same individual depending on circumstances, suggesting it is a dynamic and personalized physiological process. It has been divided into rapid eye movement sleep (REMS) and non-REMS (NREMS). The former is unique that adult humans spend the least time in this stage, when although one is physically asleep, the brain behaves as if awake, the dream state. As NREMS is a pre-requisite for appearance of REMS, the latter can be considered a predictive readout of sleep quality and health. It plays a protective role against oxidative, stressful, and psychopathological insults. Several modern lifestyle activities compromise quality and quantity of sleep (including REMS) affecting fundamental physiological and psychopathosomatic processes in a personalized manner. REMS loss-induced elevated brain noradrenaline (NA) causes many associated symptoms, which are ameliorated by preventing NA action. Therefore, we propose that awareness about personalized sleep hygiene (including REMS) and maintaining optimum brain NA level should be of paramount significance for leading physical and mental well-being as well as healthy living. As sleep is a dynamic, multifactorial, homeostatically regulated process, for healthy living, we recommend addressing and treating sleep dysfunctions in a personalized manner by the health professionals, caregivers, family, and other supporting members in the society. We also recommend that maintaining sleep profile, optimum level of NA, and/or prevention of elevation of NA or its action in the brain must be seriously considered for ameliorating lifestyle and REMS disturbance-associated dysfunctions.

Overexpression of Nrf2 promotes colon cancer progression via ERK and AKT signaling pathways

PURPOSE

We investigated the expression of Nrf2 in colorectal cancer and its correlation with clinicopathological characteristics as well as mechanisms and roles of Nrf2 expression including cell signaling pathway, survival, proliferation, and migration.

METHODS

Nrf2 expression was measured in 12 and 30 different colorectal cancer (CRC) tissues by western blot (WB) and immunohistochemistry (IHC), respectively. SW480 cells were used for cell proliferation and cell migration tests. The correlation between the expression of Nrf2 and clinicopathologic parameters were evaluated using the chi-square or Fisher exact test. Data are expressed as the mean ± standard deviation for 3 independent experiments. P < 0.05 was considered statistically significant.

RESULTS

Analysis of WB demonstrated that Nrf2 proteins were increased in CRC tissues, and decreased in normal tissues. IHC staining showed that the Nrf2 expression was elevated in CRC tissues, compared to matched normal tissues. When SW480 cells were suppressed with small interfering RNA of Nrf2, cell viability was inhibited, and cell apoptosis was increased. These results were found along with suppression of the phosphorylated form of extracellular signal-regulated kinase 1/2 and AKT.

CONCLUSION

This study suggests that overexpression of Nrf2 may be related to carcinogenesis and progression of CRC.

Exosomal Nrf2: From anti-oxidant and anti-inflammation response to wound healing and tissue regeneration in aged-related diseases

Accumulation of oxidative stress in cells is an essential feature of cellular senescence and aging. This phenomenon is involved in different age-related diseases through dysregulation of homeostasis and impairing repair and regeneration (wound healing) capacity, which can suppress antioxidant responses such as the activity of antioxidant enzymes and damaged protein clearance system. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor which regulates basal and inducible expression pattern of specific genes (antioxidants and detoxifications) through antioxidant element response (ARE) sites in the stress condition, specifically in chronic and age-related stresses. Nrf2 maintains cellular redox hemostasis and promotes rejuvenation. Exosomes are nanoscale vesicles that are released by various cells to actively regulate the complex cellular signaling networks. Exosomal-Nrf2 and exosomal-Nrf2-mediated products can modulate oxidative hemostasis in target cells to induce tissue repairing with therapeutic proposes, and regeneration capability. In this study, we summarized the role of exosomal-Nrf2 in different age-related diseases, including diabetic foot ulcers, atherosclerosis, chronic heart failure, reproductive cell failures, and neurodegenerative diseases. In addition, we briefly explained the crosstalk between plant exosomes and mammalian cell metabolism in the benefit of cellular stress suppression.

Molecular Mechanisms of the Efficacy of Cold Atmospheric Pressure Plasma (CAP) in Cancer Treatment

Recently, the potential use of cold atmospheric pressure plasma (CAP) in cancer treatment has gained increasing interest. Especially the enhanced selective killing of tumor cells compared to normal cells has prompted researchers to elucidate the molecular mechanisms for the efficacy of CAP in cancer treatment. This review summarizes the current understanding of how CAP triggers intracellular pathways that induce growth inhibition or cell death. We discuss what factors may contribute to the potential selectivity of CAP towards cancer cells compared to their non-malignant counterparts. Furthermore, the potential of CAP to trigger an immune response is briefly discussed. Finally, this overview demonstrates how these concepts bear first fruits in clinical applications applying CAP treatment in head and neck squamous cell cancer as well as actinic keratosis. Although significant progress towards understanding the underlying mechanisms regarding the efficacy of CAP in cancer treatment has been made, much still needs to be done with respect to different treatment conditions and comparison of malignant and non-malignant cells of the same cell type and same donor. Furthermore, clinical pilot studies and the assessment of systemic effects will be of tremendous importance towards bringing this innovative technology into clinical practice.

Chrysanthemum Morifolium Extract And Ascorbic Acid-2-Glucoside (AA2G) Blend Inhibits UVA-Induced Delayed Cyclobutane Pyrimidine Dimer (CPD) Production In Melanocytes

Background

Solar ultraviolet radiation (UV) induces DNA damages in skin via direct absorption of UVB or indirectly by photosensitization mediated through UVA. Recent findings have revealed that UVA induces cyclobutane pyrimidine dimer (CPD) generation via chemiexcitation in melanocytes hours after the exposure. This UVA-induced delayed CPD (dark CPD) constitutes the majority of CPD in melanocytes. These findings indicate that sun light can damage the skin hours after the exposure, suggesting the need for skin care products post sun exposure. The main objective of this study was to investigate whether a blend of Chrysanthemum Morifolium flower extract (Chrys) and vitamin C derivative, Ascorbic Acid-2-Glucoside (AA2G), can provide protective effects against reactive oxygen species, melanin formation and UVA-induced dark CPD.

Methods

Intracellular ROS levels were measured in epidermal keratinocytes using DHR123 dye. Melanogenesis inhibition efficacy was determined using B16 cells. As for the dark CPD measurement, Melan-a cells were treated with or without actives for 6 days, then irradiated with UVA at various doses. Cells were exposed with anti-CPD mAb followed by secondary Ab. CPD levels were determined by measuring fluorescent intensity using a high content imaging analysis.

Results

Chrys, AA2G and their blend at various concentrations demonstrated ROS scavenging activity. Though Chrys alone did not show significant melanogenesis inhibition in B16 assay, the blend of Chrys with AA2G demonstrated additive effects in comparison with AA2G alone. The blend of AA2G and Chrys at various concentrations exhibited enhanced efficacy for inhibiting dark CPD compared to AA2G alone.

Conclusion

The results from this study indicate that the use of natural antioxidant, Chrys in combination with AA2G, provides protection against UVA-induced delayed CPD formation by enhancing ROS scavenging activity and melanogenesis inhibition. These findings could potentially be applied for formulating post-sun exposure skin care products, possibly extending to evening-after care products.

Protective effects of raspberry on the oxidative damage in HepG2 cells through Keap1/Nrf2-dependent signaling pathway

The aim of the present study was to explore the protective effects of raspberry and its bioactive compound cyanidin 3-O-glucoside against H2O2-induced oxidative stress in HepG2 cells. We established a model of oxidative stress in HepG2 cells induced by H2O2 and examined the protein expression of Keap1/Nrf2. The antioxidant activity of raspberry extract was carried out measuring the level of reactive oxygen species (ROS), and the changes of phase II detoxification elements such as GSH level and CAT activity. Also the expression of proteins related to the Keap1/Nrf2 signaling was tested. The results revealed that raspberry extract significantly reduced the ROS levels in oxidative injured cells, increased GSH content and CAT activity, and activated the expression of proteins Keap1, Nrf2, HO-1, NQO1, and γ-GCS. These results taken together indicated that raspberry treatment could ameliorate H2O2-induced oxidative stress in HepG2 cells via Keap1/Nrf2 pathway.

Chemoprevention by Probiotics During 1,2-Dimethylhydrazine-Induced Colon Carcinogenesis in Rats

BACKGROUND

Probiotics are believed to have properties that lower the risk of colon cancer. However, the mechanisms by which they exert their beneficial effects are relatively unknown.

AIM

To assess the impact of probiotics in preventing induction of colon carcinogenesis in rats.

METHODS

The rats were divided into six groups viz., normal control, Lactobacillus plantarum (AdF10)-treated, Lactobacillus rhamnosus GG (LGG)-treated, 1,2-dimethylhydrazine (DMH)-treated, L. plantarum (AdF10) + DMH-treated and L. rhamnosus GG (LGG) + DMH-treated. Both the probiotics were supplemented daily at a dose of 2 × 10¹⁰ cells per day. DMH at a dose of 30 mg/kg body weight was administered subcutaneously twice a week for the first 4 weeks and then once every week for a duration of 16 weeks. Glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and catalase as protein expression of genes involved in apoptosis were assessed during DMH-induced colon carcinogenesis in rats.

RESULTS

DMH treatment decreased the activity of GSH, GPx, GST, SOD and catalase. However, AdF10 and LGG supplementation to DMH-treated rats significantly increased the activity of these enzymes. Further, DMH treatment revealed alterations in the protein expressions of various genes involved in the p53-mediated apoptotic pathway such as p53, p21, Bcl-2, Bax, caspase-9 and caspase-3, which, however, were shifted towards normal control levels upon simultaneous supplementation with probiotics.

CONCLUSION

The present study suggests that probiotics can provide protection against oxidative stress and apoptotic-related protein disregulation during experimentally induced colon carcinogenesis.

Protective effects of curcumin against aflatoxicosis: A comprehensive review

Aflatoxicosis is a deleterious medical condition that results from aflatoxins (AFs) or ochratoxins (OTs). Contamination with these toxins exerts detrimental effects on the liver, kidneys, reproductive organs, and also on immunological and cardiovascular systems. Aflatoxicosis is closely associated with overproduction of reactive oxygen species (ROS) as key contributors to oxidative and nitrosative stress responses, and subsequent damages to lipids, proteins, RNA, and DNA. The main target organ for AF toxicity is the liver, where DNA adducts, degranulation of endoplasmic reticulum, increased hepatic lipid peroxide, GSH depletion, mitochondrial dysfunction, and reduction of enzymatic and non-enzymatic antioxidants are manifestations of aflatoxicosis. Curcuma longa L. (turmeric) is a medicinal plant widely utilized all over the world for culinary and phytomedical purposes. Considering the antioxidant characteristic of curcumin, the main active component of turmeric, this review is intended to critically summarize the available evidence supporting possible effectiveness of curcumin against aflatoxicosis. Curcumin can serve as a promising candidate for attenuation of the adverse consequences of aflatoxicosis, acting mainly through intrinsic antioxidant effects aroused from its structure, modulation of the immune system as reflected by interleukin-1β and transforming growth factor-β, and interfering with AF's biotransformation by cytochrome P450 isoenzymes CYP1A, CYP3A, CYP2A, CYP2B, and CYP2C.

Supplementation with Achyrocline satureioides Inflorescence Extracts to Pregnant and Breastfeeding Rats Induces Tissue-Specific Changes in Enzymatic Activity and Lower Neonatal Survival

Achyrocline satureioides (AS, family Asteraceae) is a plant widely used in traditional medicine for stomach, digestive, and gastrointestinal disorders during pregnancy. Studies regarding the indiscriminate use of plant infusions during pregnancy are limited. Recent reports have shown that chronic flavonoid supplementation induces toxicity in vivo and raises the mortality rates of healthy subjects. Therefore, we investigated whether supplementation of pregnant and lactating Wistar rats with two AS inflorescence extracts, consisting of an aqueous (AQ) extract similar to a tea (47 mg·kg^-1·day) and a hydroethanolic (HA) extract (35 mg·kg^-1·day^-1) with a higher flavonoid content, could induce redox-related side effects. Total reactive antioxidant potential (TRAP), thiobarbituric reactive species (TBARS), and total reduced thiol (SH) content were evaluated. Superoxide dismutase (SOD) and catalase (CAT) activities were additionally quantified. Our data suggest that both AQ and HA of AS inflorescence extracts may induce symptoms of toxicity in concentrations of (47 mg·kg^-1·day) and (35 mg·kg^-1·day^-1), respectively, in mothers regarding the delivery index and further decrease of neonatal survival. Of note, significant tissue-specific changes in maternal (liver, kidney, heart, and hippocampus) and pups (liver and kidney) biochemical oxidative parameters were observed. Our findings provide evidence that may support the need to control supplementation with the AQ of AS inflorescence extracts during gestation due to potential toxicity in vivo, which might be related, at least in part, to changes in tissue-specific redox homeostasis and enzymatic activity.

In silico genotoxicity of coumarins: application of the Phenol-Explorer food database to functional food science

Coumarins are a group of phytochemicals that may be beneficial or harmful to health depending on their type and dosage and the matrix that contains them. Some of these compounds have been proven to display pro-oxidant and clastogenic activities. Therefore, in the current work, we have studied the coumarins that are present in food sources extracted from the Phenol-Explorer database in order to predict their clastogenic activity and identify the structure-activity relationships and genotoxic structural alerts using alternative methods in the field of computational toxicology. It was necessary to compile information on the type and amount of coumarins in different food sources through the analysis of databases of food composition available online. A virtual screening using a clastogenic model and different software, such as MODESLAB, ChemDraw and STATISTIC, was performed. As a result, a table of food composition was prepared and qualitative information from this data was extracted. The virtual screening showed that the esterified substituents inactivate molecules, while the methoxyl and hydroxyl substituents contribute to their activity and constitute, together with the basic structures of the studied subclasses, clastogenic structural alerts. Chemical subclasses of simple coumarins and furocoumarins were classified as active (xanthotoxin, isopimpinellin, esculin, scopoletin, scopolin and bergapten). In silico genotoxicity was mainly predicted for coumarins found in beer, sherry, dried parsley, fresh parsley and raw celery stalks. The results obtained can be interesting for the future design of functional foods and dietary supplements. These studies constitute a reference for the genotoxic chemoinformatic analysis of bioactive compounds present in databases of food composition.

Protective Effects of Sweet Orange, Unshiu Mikan, and Mini Tomato Juice Powders on t-BHP-Induced Oxidative Stress in HepG2 Cells

The aim of this study was to investigate the protective effects of juice powders from sweet orange [Citrus sinensis (L.) Osbeck], unshiu mikan (Citrus unshiu Marcow), and mini tomato (Solanum lycopersicum L.), and their major flavonoids, hesperidin, narirutin, and rutin in tert-butyl hydroperoxide (t-BHP)-induced oxidative stress in HepG2 cells. The increased reactive oxygen species and decreased glutathione levels observed in t-BHP-treated HepG2 cells were ameliorated by pretreatment with juice powders, indicating that the hepatoprotective effects of juice powders and their major flavonoids are mediated by induction of cellular defense against oxidative stress. Moreover, pretreatment with juice powders up-regulated phase-II genes such as heme oxygenase-1 (HO-1), thereby preventing cellular damage and the resultant increase in HO-1 expression. The high-performance liquid chromatography profiles of the juice powders confirmed that hesperidin, narirutin, and rutin were the key flavonoids present. Our results suggest that these fruit juice powders and their major flavonoids provide a significant cytoprotective effect against oxidative stress, which is most likely due to the flavonoid-related bioactive compounds present, leading to the normal redox status of cells. Therefore, these fruit juice powders could be advantageous as bioactive sources for the prevention of oxidative injury in hepatoma cells.

Improved Hepatoprotective Effect of Liposome-Encapsulated Astaxanthin in Lipopolysaccharide-Induced Acute Hepatotoxicity

Lipopolysaccharide (LPS)-induced acute hepatotoxicity is significantly associated with oxidative stress. Astaxanthin (AST), a xanthophyll carotenoid, is well known for its potent antioxidant capacity. However, its drawbacks of poor aqueous solubility and low bioavailability have limited its utility. Liposome encapsulation is considered as an effective alternative use for the improvement of bioavailability of the hydrophobic compound. We hypothesized that AST encapsulated within liposomes (LA) apparently shows improved stability and transportability compared to that of free AST. To investigate whether LA administration can efficiently prevent the LPS-induced acute hepatotoxicity, male Sprague-Dawley rats (n = six per group) were orally administered liposome-encapsulated AST at 2, 5 or 10 mg/kg-day (LA-2, LA-5, and LA-10) for seven days and then were LPS-challenged (i.p., 5 mg/kg). The LA-10 administered group, but not the other groups, exhibited a significant amelioration of serum glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), blood urea nitrogen (BUN), creatinine (CRE), hepatic malondialdehyde (MDA) and glutathione peroxidase (GSH-Px), IL-6, and hepatic nuclear NF-κB and inducible nitric oxide synthase (iNOS), suggesting that LA at a 10 mg/kg-day dosage renders hepatoprotective effects. Moreover, the protective effects were even superior to that of positive control N-acetylcysteine (NAC, 200 mg/kg-day). Histopathologically, NAC, free AST, LA-2 and LA-5 partially, but LA-10 completely, alleviated the acute inflammatory status. These results indicate that hydrophobic AST after being properly encapsulated by liposomes improves bioavailability and can also function as potential drug delivery system in treating hepatotoxicity.

Isotetrandrine ameliorates tert-butyl hydroperoxide-induced oxidative stress through upregulation of heme oxygenase-1 expression

1R, 1'S-isotetrandrine, a naturally occurring plant alkaloid found in Mahonia of Berberidaceae, possesses anti-inflammatory, antibacterial, and antiviral properties, but the antioxidative activity and mechanism action remain unclear. In this study, we demonstrated the antioxidative effect and mechanism of 1R, 1'S-isotetrandrine against tert-butyl hydroperoxide-induced oxidative damage in HepG2 cells. We found that 1R, 1'S-isotetrandrine suppressed cytotoxicity, reactive oxygen species generation, and glutathione depletion. Additionally, our study confirmed that 1R, 1'S-isotetrandrine significantly increased the antioxidant enzyme heme oxygenase-1 expression and nuclear translocation of factor-erythroid 2 p45-related factor 2 (Nrf2). Specifically, the nuclear translocation of Nrf2 induced by 1R, 1'S-isotetrandrine was associated with Nrf2 negative regulatory protein Keap1 inactivation and phosphorylation of both extracellular signal-regulated protein kinase and c-Jun NH2-terminal kinase. Preincubation with thiol-reducing agents reduced 1R, 1'S-isotetrandrine-induced heme oxygenase-1 expression, and treatment with either extracellular signal-regulated protein kinase or c-Jun NH2-terminal kinase inhibitors attenuated the levels of 1R, 1'S-isotetrandrine-induced Nrf2 activation and heme oxygenase-1 expression. Furthermore, the cytoprotective effect of 1R, 1'S-isotetrandrine was abolished by heme oxygenase-1, extracellular signal-regulated protein kinase, and c-Jun NH2-terminal kinase inhibitors. These results indicated that the 1R, 1'S-isotetrandrine ameliorated tert-butyl hydroperoxide-induced oxidative damage through upregulation of heme oxygenase-1 expression by the dissociation of Nrf2 from Nrf2-Keap1 complex via extracellular signal-regulated protein kinase and c-Jun NH2-terminal kinase activation and Keap1 inactivation.

Protective effects of germinated and fermented soybean extract against tert-butyl hydroperoxide-induced hepatotoxicity in HepG2 cells and in rats

The aim of the current study is to investigate the antioxidant and hepatoprotective effects of germinated and fermented soybean extract (GFSE) on tert-butyl hydroperoxide (t-BHP)-induced oxidative stress in HepG2 cells and in the rat liver. High performance liquid chromatography (HPLC) analysis showed that genistin (3.40 ± 0.14 μg mg(-1)) was the most abundant isoflavone in the GFSE. Coumestrol (1.00 ± 0.04 μg mg(-1)), daidzin (0.78 ± 0.14 μg mg(-1)), genistein (0.68 ± 0.05 μg mg(-1)), glycitin (0.54 ± 0.02 μg mg(-1)), glycitein (0.41 ± 0.02 μg mg(-1)), and daidzein (0.02 ± 0.0 g mg(-1)) are also contained in decreasing order of content. GFSE significantly inhibited t-BHP-induced reactive oxygen species (ROS) production in HepG2 cells. This GFSE-induced ROS reduction was associated with the down-regulation of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4), a pro-oxidant enzyme, and the up-regulation of the mRNA levels of antioxidant enzymes, including catalase, superoxide dismutase (SOD), glutathione reductase (GR), and glutathione peroxidase (Gpx) in the rat liver. In addition, increased levels of antioxidant enzyme mRNAs correlated with the enhanced enzymatic activities of SOD, catalase, and glutathione-S-transferase (GST). The antioxidant effect of GFSE was supported by the reduction in the levels of malondialdehyde (MDA), a hydroperoxide, and the serum levels of lactate dehydrogenase (LDH), a biomarker of cell damage, were also lowered by GFSE. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST), which are clinical biomarkers of liver function, were shown to be improved with GFSE administration. The effects of GFSE were attributable to an improvement in liver tissue morphology. Taken together, GFSE protected the liver from t-BHP-induced oxidative stress by regulating ROS-related enzymes. Our results suggest that GFSE might be a hepatoprotective source against oxidative stress.

Lico A Enhances Nrf2-Mediated Defense Mechanisms against t-BHP-Induced Oxidative Stress and Cell Death via Akt and ERK Activation in RAW 264.7 Cells

Licochalcone A (Lico A) exhibits various biological properties, including anti-inflammatory and antioxidant activities. In this study, we investigated the antioxidative potential and mechanisms of Lico A against tert-butyl hydroperoxide- (t-BHP-) induced oxidative damage in RAW 264.7 cells. Our results indicated that Lico A significantly inhibited t-BHP-induced cytotoxicity, apoptosis, and reactive oxygen species (ROS) generation and reduced glutathione (GSH) depletion but increased the glutamate-cysteine ligase modifier (GCLM) subunit and the glutamate-cysteine ligase catalytic (GCLC) subunit genes expression. Additionally, Lico A dramatically upregulated the antioxidant enzyme heme oxygenase 1 (HO-1) and nuclear factor erythroid 2-related factor 2 (Nrf2), which were associated with inducing Nrf2 nuclear translocation, decreasing Keap1 protein expression and increasing antioxidant response element (ARE) promoter activity. Lico A also obviously induced the activation of serine/threonine kinase (Akt) and extracellular signal-regulated kinase (ERK), but PI3K/Akt and ERK inhibitors treatment displayed clearly decreased levels of LicoA-induced Nrf2 nuclear translocation and HO-1 expression, respectively. Furthermore, Lico A treatment markedly attenuated t-BHP-induced oxidative damage, which was reduced by treatment with PI3K/Akt, ERK, and HO-1 inhibitors. Therefore, Lico A might have a protective role against t-BHP-induced cytotoxicity by modulating HO-1 and by scavenging ROS via the activation of the PI3K/Akt and ERK/Nrf2 signaling pathways.

Expression of nuclear factor erythroid 2 protein in malignant cutaneous tumors

Background

Reactive oxygen species (ROS) damages cell molecules, and modifies cell signaling. The nuclear factor E2-related factor (Nrf2) is a critical transcription regulator, which protects cells against oxidative damage. Nrf2 expression is increased in a large number of cancers. However, little information has been reported regarding the expression of Nrf2 in skin cancers. Hence, we explored the expression of Nrf2 protein in skin cancers.

Methods

The Nrf2 protein expression in 24 specimens, including 6 malignant melanomas (MM), 6 squamous cell carcinomas (SCC), 6 basal cell carcinomas (BCC), and 6 normal skin tissues, was evaluated by western blotting. Immunohistochemical staining was performed. The expression of Kelch-like ECH-associated protein 1 (Keap1), the key regulator of Nrf2, was also analyzed by western blotting.

Results

Small interfering RNA transfection to the melanoma cell line G361 confirmed that an approximately 66 kDa band was the true Nrf2 band. The western blot revealed that the Nrf2 protein was definitely expressed in normal skin tissues, but the Nrf2 expression was decreased in MM, SCC, and BCC. Immunohistochemical examination showed that expression of Nrf2 was decreased in all skin cancer tissues compared to the normal skin tissues. Keap1 was not expressed in all malignant skin tumors and normal skin tissues by western blot.

Conclusions

ROS was increased in various types of cancers which proteins were highly expressed or underexpressed. This study demonstrated that the expression of Nrf2 protein was down-regulated in human malignant skin tumors. We suggest that decreased expression of Nrf2 is related to skin cancers.

Intracellular generation of ROS by 3,5-dimethylaminophenol: persistence, cellular response, and impact of molecular toxicity

Epidemiological studies have demonstrated extensive human exposure to the monocyclic aromatic amines, particularly to 3,5-dimethylaniline, and found an association between exposure to these compounds and risk for bladder cancer. Little is known about molecular mechanisms that might lead to the observed risk. We previously suggested that the hydroxylated 3,5-dimethylaniline metabolite, 3,5-dimethylaminophenol (3,5-DMAP), played a central role in effecting genetic change through the generation of reactive oxygen species (ROS) in a redox cycle with 3,5-dimethylquinoneimine. Experiments here characterize ROS generation by 3,5-DMAP exposure in nucleotide repair-proficient and -deficient Chinese hamster ovary cells as a function of time. Besides, various cellular responses discussed herein indicate that ROS production is the principal cause of cytotoxicity. Fluorescence microscopy of cells exposed to 3,5-DMAP confirmed that ROS production occurs in the nuclear compartment, as suggested by a previous study demonstrating covalent linkage between 3,5-DMAP and histones. 3,5-DMAP was also compared with 3,5-dimethylhydroquinone to determine whether substitution of one of the phenolic hydroxyl groups by an amino group had a significant effect on some of the investigated parameters. The comparatively much longer duration of observable ROS produced by 3,5-DMAP (7 vs. 1 day) provides further evidence that 3,5-DMAP becomes embedded in the cellular matrix in a form capable of continued redox cycling. 3,5-DMAP also induced dose-dependent increase of H2O2 and ·OH, which were determined as the major free radicals contributing to the cytotoxicity and apoptosis mediated via caspase-3 activation. Overall, this study provides insight into the progression of alkylaniline-induced toxicity.

Genotoxic and oxidative damage potentials in human lymphocytes after exposure to terpinolene in vitro

Terpinolene (TPO) is a monocyclic monoterpene found in the essential oils of various fir and pine species. Recent reports indicated that several monoterpenes could exhibit antioxidant effects in both human and animal experimental models. However, so far, the nature and/or biological roles of TPO have not been elucidated in human models yet. The aim of this study was to investigate the genetic, oxidative and cytotoxic effects of TPO in cultured human blood cells (n = 5) for the first time. Human blood cells were treated with TPO (0-200 mg/L) for 24 and 48 h, and then cytotoxicity was detected by lactate dehydrogenase (LDH) release and [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay, while DNA damage was also analyzed by micronucleus assay, sister chromatid exchanges assay and 8-oxo-2-deoxyguanosine (8-OH-dG) level. In addition, biochemical parameters [total antioxidant capacity (TAC) and total oxidative stress (TOS)] were examined to determine oxidative effects. The results of LDH and MTT assays showed that TPO (at concentrations greater than 100 mg/L) decreased cell viability. In our in vitro test systems, it was observed that TPO had no genotoxicity on human lymphocytes. Again, TPO (at 10, 25, 50 and 75 mg/L) treatment caused statistically important (p < 0.05) increases of TAC levels in human lymphocytes without changing TOS levels. In conclusion, TPO can be a new resource of therapeutics as recognized in this study with its non-genotoxic and antioxidant features.

Investigation of cytotoxic, genotoxic and oxidative properties of carvacrol in human blood cells

Carvacrol (CVC), a major constituent of genera Origanum and Thymus, is such a substance that has attracted attention because of its wide variety of beneficial biological activities such as antibacterial, antifungal, and anticancer effects. However, there are limited data on the cytogenetic and antioxidant effects of CVC in cultured human blood cells. The aim of this study was to investigate for the first time the genetic, oxidative, and cytotoxic effects of CVC in cultured human blood cells ( n = 5). Human blood cells were treated with CVC (0–200 mg/L) for 24 and 48 h and then cytotoxicity detected by lactate dehydrogenase (LDH) release and (3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide) (MTT) assay, while DNA damage was also analyzed by micronucleus (MN) assay, chromosomal aberration (CA) assay and 8-oxo-2-deoxyguanosine (8-OH-dG) level. In addition, biochemical parameters (total antioxidant capacity [TAC] and total oxidative stress [TOS]) were examined to determine the oxidative effects. The results of LDH and MTT assays showed that CVC (at concentrations above 100 mg/L) decreased cell viability. In our in vitro test systems, it was observed that CVC had no mutagenic effects on human lymphocytes. On the other hand, CVC (at 50, 75, and 100 mg/L) treatment caused statistically important ( p < 0.05) increases in TAC and TOS levels (at 150 and 200 mg/L) on human lymphocytes. In conclusion, CVC can be a new resource of therapeutics as recognized in this study with their nonmutagenic and antioxidant features.

The active site of TthPolX is adapted to prevent 8-oxo-dGTP misincorporation

Full genome sequencing of bacterial genomes has revealed the presence of numerous genes encoding family X DNA polymerases. These enzymes play a variety of biological roles and, accordingly, display often striking functional differences. Here we report that the PolX from the heat-stable organism Thermus thermophilus (TthPolX) inserts the four dNTPs with strong asymmetry. We demonstrate that this behaviour is related to the presence of a single divergent residue in the active site of TthPolX. Mutation of this residue (Ser²⁶⁶) to asparagine, the residue present in most PolXs, had a strong effect on TthPolX polymerase activity, increasing and equilibrating the insertion efficiencies of the 4 dNTPs. Moreover, we show that this behaviour correlates with the ability of TthPolX to insert 8-oxo-dGMP. Although the wild-type enzyme inefficiently incorporates 8-oxo-dGMP, the substitution of Ser²⁶⁶ to asparagine resulted in a dramatic increase in 8-oxo-dGMP incorporation opposite dA. These results suggest that the presence of a serine at position 266 in TthPolX allows the enzyme to minimize the formation of dA:8-oxo-dGMP at the expense of decreasing the insertion rate of pyrimidines. We discuss the structural basis for these effects and the implications of this behaviour for the GO system (BER of 8-oxo-dG lesions).

Isoliquiritigenin enhances radiosensitivity of HepG2 cells via disturbance of redox status

Redox balance plays an important role in the maintenance of cell growth and survival. Disturbance of this equilibrium can alter normal cellular processes. Excessive reactive oxygen species (ROS) are often found in cancer cells. However, cancer cells have an efficient antioxidant system to counteract the increased generation of ROS. This high antioxidant capacity also favors resistance to drugs and radiation. Here, we show that isoliquiritigenin (ISL), a natural antioxidant, effectively decreased ROS in HepG2 cells in a time-dependant manner at 0.5, 1, and 2 h of treatment. The decreased ROS caused redox imbalance and reductive stress. To adapt to this state, nuclear factor erythroid-2-related factor 2, which regulates the antioxidant enzyme system, was significantly decreased. Antioxidant enzymes reached their lowest level at 6 h after ISL treatment. Endogenous ROS were still being generated so after 6 h of ISL treatment, ROS were clearly higher than before ISL treatment, causing redox imbalance in the HepG2 cells which changed from reductive to oxidative stress. At this stage, cells were irradiated with X-rays. The excess ROS induced serious oxidative stress, resulting in radiosensitization. Therefore, we concluded that ISL induced oxidative stress by disturbing the redox status and ultimately enhancing the radiosensitivity of HepG2 cells.

Oxidative stress, cancer, and sleep deprivation: is there a logical link in this association?

INTRODUCTION

Sleep disorders are associated with various human pathologies and interfere with biological processes essential for health and quality of life. On the other hand, cancer is one of the most common diseases worldwide with an average of 1,500 deaths per day in the USA. Is there a factor common to both sleep disorders and cancer that serves to link these conditions?

DISCUSSION

It is a normal process for cellular metabolism to produce reactive oxidant series (ROS). However, when the production of ROS overcomes the antioxidant capacity of the cell to eliminate these products, the resulting state is called oxidative stress. Oxidative DNA damage may participate in ROS-induced carcinogenesis. Moreover, ROS are also produced in the sleep deprivation process. The aim of this article is to review pathways and mechanisms that may point to oxidative stress as a link between sleep deprivation and cancer.

Oxidative damage and genotoxicity biomarkers in transfused and untransfused thalassemic subjects

Chronic anemia and tissue hypoxia increase intestinal iron absorption and mitochondrial impairment in thalassemic patients. Regular blood transfusions improve hemoglobin levels but determine an iron overload that induces reactive oxygen species (ROS) overproduction. The aim of this study was to assess cellular oxidative damage by detection of ROS, lipid peroxidation, 8-oxo-dG, and mitochondrial transmembrane potential (Δψ(m)) in transfused and untransfused thalassemic patients. We have also evaluated genotoxicity by CBMN and comet assay. Our data show that ROS and lipid hydroperoxides are significantly higher in thalassemic patients than in controls, especially in untransfused thalassemia intermedia patients. Moreover, the latter have a significant decrease in Δψ(m) that highlights the energetic failure in hypoxic state and the ROS overproduction in the respiratory chain. 8-OHdG levels are higher in thalassemics than in controls, but do not differ significantly between the two patient groups. Both genotoxicity biomarkers highlight the mutagenic potential of hydroxyl radicals released by iron in the Fenton reaction. Values for percentage of DNA in the comet tail and micronuclei frequency, significantly higher in transfused patients, could also be due to active hepatitis C virus infection and to the many drug treatments. Our biomonitoring study confirms the oxidative damage in patients with thalassemia major and shows an unexpected cellular oxidative damage in untransfused thalassemic patients. In addition to iron overload, the results highlight the important role played by hypoxia-driven mitochondrial ROS overproduction in determining oxidative damage in β-thalassemias.

Genotoxicity of 2,6- and 3,5-dimethylaniline in cultured mammalian cells: the role of reactive oxygen species

Several alkylanilines with structures more complex than toluidines have been associated epidemiologically with human cancer. Their mechanism of action remains largely undetermined, and there is no reported evidence that it replicates that of multicyclic aromatic amines even though the principal metabolic pathways of P450-mediated hydroxylation and phase II conjugation are very similar. As a means to elucidate their mechanisms of action, lethality and mutagenicity in the adenine phosphoribosyltransferase (aprt (+/-)) gene induced in several Chinese hamster ovary cell types by 2,6- and 3,5-dimethylaniline (2,6-DMA, 3,5-DMA) and their N- and ring-hydroxyl derivatives (N-OH-2,6-DMA, N-OH-3,5-DMA, 2,6-DMAP, 3,5-DMAP) were assessed. Dose-response relationships were determined in the parental AA8 cell line, its repair-deficient UV5 subclone and other repair-deficient 5P3NAT2 or -proficient 5P3NAT2R9 subclones engineered to express mouse cytochrome P4501A2 (CYP1A2) and human N-acetyltransferase (NAT2), and also in AS52 cells harboring the bacterial guanine-hypoxanthine phosphoribosyltransferase (gpt) gene. Mutations in the gpt gene of AS52 cells were characterized and found to be dominated by G:C to A:T and A:T to G:C transitions. Separately, treatment of AS52 cells with N-OH-2,6-DMA, N-OH-3,5-DMA, 2,6-DMAP, 3,5-DMAP, and 3,5-DMAP led to intracellular production of reactive oxygen species (ROS) for at least 24h after removal of the mutagens in every case. Using the comet assay, DNA strand breaks were observed in a dose-dependent manner in AS52 cells when treated with each of the four N-OH-2,6-DMA, N-OH-3,5-DMA, 2,6-DMAP, and 3,5-DMAP derivatives. Comparative evaluation of the results indicates that the principal mechanism of mutagenic action is likely to be through redox cycling of intracellularly bound aminophenol/quinone imine structures to generate ROS rather than through formation of covalent DNA adducts.

Testing the efficacy of quercetin in mitigating bisphenol A toxicity in liver and kidney of mice

Quercetin (3,5,7,3',4'-pentahydroxy flavone) is a potent antioxidant found in various fruits and vegetables. The present investigation was an attempt to evaluate the mitigatory effect of quercetin on the damage caused by bisphenol A (BPA; 2,2-bis (4-hydroxyphenyl) propane), a well-known xenoestrogen, on liver and kidney of mice. Swiss strain adult male albino mice were orally administered with 120 and 240 mg/kg body weight (bw)/day BPA with or without quercetin (60 mg/kg bw/day) for 30 days. On the completion of the treatment period, animals were killed; organs were isolated and used for the study. Results revealed that oral administration of BPA for 30 days caused significant and dose-dependent decrease in body weight. Absolute and relative organ weights, total lipid and cholesterol contents were significantly increased in liver and kidney of mice when compared with vehicle control. BPA treatment also caused, when compared with vehicle control, a statistically significant reductions in the activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase as well as in glutathione and total ascorbic acid contents; however, significant increase was found in malondialdehyde (MDA) levels. Histopathological studies revealed hepatocellular necrosis, cytoplasmic vacuolization and decrease in hepatocellular compactness in liver as well as distortion of the tubules, increased vacuolization, necrosis and disorganization of glomerulus in the kidney of BPA-treated mice. All these effects were dose-dependent. Co-treatment with quercetin (60 mg/kg bw) and BPA (low dose and high dose) alleviates the changes in body weight, as well as absolute and relative organ weights of mice. It also ameliorates the oxidative stress created by BPA by lowering MDA levels and by increasing enzymatic and nonenzymatic antioxidants as well as it brings back the normal histoarchitecture of liver and kidney of mice. The present results revealed that graded doses of BPA caused oxidative damage in liver and kidney of mice, which is mitigated by quercetin.

The role of Fpg protein in UVC-induced DNA lesions

We previously demonstrated that reactive oxygen species (ROS) could be involved in ultraviolet-C (UVC)-induced DNA damage in Escherichia coli cells. In the present study, we evaluated the involvement of the GO system proteins in the repair of the 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxoG, GO) lesion, which is ROS-induced oxidative damage. We first found that the mutant strain Δfur, which produces an accumulation of iron, and the cells treated with 2,2'-dipyridyl, a iron chelator, were both as resistant to UVC-induced lethality as the wild strain. The 8-oxoG could be mediated by singlet oxygen ((1)O(2)). The Fpg protein repaired this lesion when it was linked to C (cytosine), whereas the MutY protein repaired 8-oxoG when it was linked to A (adenine). The survival assay showed that the Fpg protein, but not the MutY protein, was important to UVC-induced lethality and interacted with the UvrA protein, a nucleotide excision repair (NER) protein involved in UVC repair. The GC-TA reversion assay in the mutant strains from the '8-oxoG-repair' GO system showed that UVC-induced mutagenesis in the fpg mutants, but not in the MutY strain. The transformation assay demonstrated that the Fpg protein is important in UVC repair. These results suggest that UVC could also cause indirect ROS-mediated DNA damage and the Fpg protein plays a predominant role in repairing this indirect damage.

Dihydroquercetin: More than just an impurity?

Dihydroquercetin (taxifolin) is a potent flavonoid found in onions, French maritime bark, milk thistle, tamarind seeds and commercially available semi-synthetic monoHER marketed as Venoruton. This review focuses on the therapeutic promise of dihydroquercetin in major disease states such as cancer, cardiovascular disease and liver disease by reviewing the proposed mechanism(s) of action, including the activation of the antioxidant response element (ARE) and detoxifying phase II enzymes, inhibition of cytochrome P(450) and fatty acid synthase in carcinogenesis. TNF-alpha and NF-ĸB dependent transcription in hepatitis C infections, the scavenging effect of myeloperoxidase (MPO) derived reactive nitrogen species and subsequent effects on cholesterol biosynthesis as well as the effects on apob/apoA-I, HMG-CoA reductase and apoptosis are reviewed. The stereochemistry and pro-oxidant effect of dihydroquercetin are also considered. Although the majority of research on dihydroquercetin to date has focused on the identification of molecular targets in vitro, this review will bring together evidence of the potency and mode of action of dihydroquercetin and will propose a role for the therapeutic potential of flavonoid antioxidants.

Ameliorative effects of tinospora cordifolia root extract on histopathological and biochemical changes induced by aflatoxin-b(1) in mice kidney

The present study was planned to investigate the ability of the Tinospora cordifolia to scavenge free radicals generated during aflatoxicosis. A total no. of 48 male Swiss albino mice (30 ± 5 g) were exposed to Aflatoxin B(1)(AFB(1)) (2 μg/30 g b.wt, orally) either individually or in combination with T. cordifolia (50, 100, 200 mg/kg, orally) once daily for 25 days. AFB(1) exposure led to significant rise in thiobarbituric acid reactive substances (TBARS) and fall in superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione-S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR), ascorbic acid, and protein content. T. cordifolia was found to show protective effect by lowering down the content of TBARS and enhancing the GSH, ascorbic acid, protein, and the activities of antioxidant enzymes viz., SOD, CAT, glutathione peroxidase, GST, and GR in kidney. Histopathological analysis of kidney samples also confirmed the protective values and antioxidant activity of ethanolic extract of herb. T. cordifolia showed protection against aflatoxin-induced nephrotoxicity due to the presence of alkaloids such as a choline, tinosporin, isocolumbin, palmatine, tetrahydropalmatine, and magnoflorine.