Effects of N-Acetylcysteine, Quercetin, and Phytic Acid on Spontaneous Hepatic and Renal Lesions in LEC Rats

Metabolic Derangement of Essential Transition Metals and Potential Antioxidant Therapies

Essential transition metals have key roles in oxygen transport, neurotransmitter synthesis, nucleic acid repair, cellular structure maintenance and stability, oxidative phosphorylation, and metabolism. The balance between metal deficiency and excess is typically ensured by several extracellular and intracellular mechanisms involved in uptake, distribution, and excretion. However, provoked by either intrinsic or extrinsic factors, excess iron, zinc, copper, or manganese can lead to cellular damage upon chronic or acute exposure, frequently attributed to oxidative stress. Intracellularly, mitochondria are the organelles that require the tightest control concerning reactive oxygen species production, which inevitably leaves them to be one of the most vulnerable targets of metal toxicity. Current therapies to counteract metal overload are focused on chelators, which often cause secondary effects decreasing patients' quality of life. New therapeutic options based on synthetic or natural antioxidants have proven positive effects against metal intoxication. In this review, we briefly address the cellular metabolism of transition metals, consequences of their overload, and current therapies, followed by their potential role in inducing oxidative stress and remedies thereof.

A High-Calorie Diet Aggravates Mitochondrial Dysfunction and Triggers Severe Liver Damage in Wilson Disease Rats

BACKGROUND & AIMS

In Wilson disease, ATP7B mutations impair copper excretion into bile. Hepatic copper accumulation may induce mild to moderate chronic liver damage or even acute liver failure. Etiologic factors for this heterogeneous phenotype remain enigmatic. Liver steatosis is a frequent finding in Wilson disease patients, suggesting that impaired copper homeostasis is linked with liver steatosis. Hepatic mitochondrial function is affected negatively both by copper overload and steatosis. Therefore, we addressed the question of whether a steatosis-promoting high-calorie diet aggravates liver damage in Wilson disease via amplified mitochondrial damage.

METHODS

Control Atp7b+/- and Wilson disease Atp7b-/- rats were fed either a high-calorie diet (HCD) or a normal diet. Copper chelation using the high-affinity peptide methanobactin was used in HCD-fed Atp7b-/- rats to test for therapeutic reversal of mitochondrial copper damage.

RESULTS

In comparison with a normal diet, HCD feeding of Atp7b-/- rats resulted in a markedly earlier onset of clinically apparent hepatic injury. Strongly increased mitochondrial copper accumulation was observed in HCD-fed Atp7b-/- rats, correlating with severe liver injury. Mitochondria presented with massive structural damage, increased H2O2 emergence, and dysfunctional adenosine triphosphate production. Hepatocellular injury presumably was augmented as a result of oxidative stress. Reduction of mitochondrial copper by methanobactin significantly reduced mitochondrial impairment and ameliorated liver damage.

CONCLUSIONS

A high-calorie diet severely aggravates hepatic mitochondrial and hepatocellular damage in Wilson disease rats, causing an earlier onset of the disease and enhanced disease progression.

Chemo-mapping and biochemical-modulatory and antioxidant/prooxidant effect of Galium verum extract during acute restraint and dark stress in female rats

Galium verum is a well-known medicinal plant which is used in various pathologies. G. verum extracts are characterized here using chromatography, where among the rich pool of phenolic acids of flavonoids two known anti-stress modulators, chlorogenic acid and rutin are identified in high quantities. Additionally, the extracts are characterized using a series of in vitro assays (EPR, DPPH, TPC and TEAC). Considering the chemical findings, the potential beneficial effects of the G. verum extract are explored here in a living organism exposed to stress induced oxidative damages. Thus, the biochemical-modulatory and antioxidant roles of two doses of G. verum extract are examined in animals exposed to acute restraint and dark stress (S). The animals were divided in groups [control, S, SG1 (exposed to 25 mg G. verum extract), SG2 (50 mg extract)]. Increased levels of lipid peroxidation (TBARS from 4.43 to 8.06 nmol/mL), corticosterone from 0.43 to 1.96 μg/dL and epinephrine from 44.43 to 126.7 μg/mL, as well as decreased antioxidant enzymes activities (SOD/CAT) were observed in the S group. The G. verum extract afforded a near-normal equilibrium within the biochemical parameters of animals exposed to RS, by reducing oxidative damage (TBARS at a 3.73 nmol/mL; CS at 0.90 μg/dL; EP at 63.72 μg/mL) and by restoring the antioxidant balance.

Mitochondria and Reactive Oxygen Species in Aging and Age-Related Diseases

Aging has been linked to several degenerative processes that, through the accumulation of molecular and cellular damage, can progressively lead to cell dysfunction and organ failure. Human aging is linked with a higher risk for individuals to develop cancer, neurodegenerative, cardiovascular, and metabolic disorders. The understanding of the molecular basis of aging and associated diseases has been one major challenge of scientific research over the last decades. Mitochondria, the center of oxidative metabolism and principal site of reactive oxygen species (ROS) production, are crucial both in health and in pathogenesis of many diseases. Redox signaling is important for the modulation of cell functions and several studies indicate a dual role for ROS in cell physiology. In fact, high concentrations of ROS are pathogenic and can cause severe damage to cell and organelle membranes, DNA, and proteins. On the other hand, moderate amounts of ROS are essential for the maintenance of several biological processes, including gene expression. In this review, we provide an update regarding the key roles of ROS-mitochondria cross talk in different fundamental physiological or pathological situations accompanying aging and highlighting that mitochondrial ROS may be a decisive target in clinical practice.

Molecular mechanisms of action of quercetin in cancer: recent advances

In the last few decades, the scientific community has discovered an immense potential of natural compounds in the treatment of dreadful diseases such as cancer. Besides the availability of a variety of natural bioactive molecules, efficacious cancer therapy still needs to be developed. So, to design an efficacious cancer treatment strategy, it is essential to understand the interactions of natural molecules with their respective cellular targets. Quercetin (Quer) is a naturally occurring flavonol present in many commonly consumed food items. It governs numerous intracellular targets, including the proteins involved in apoptosis, cell cycle, detoxification, antioxidant replication, and angiogenesis. The weight of available synergistic studies vigorously fortifies the utilization of Quer as a chemoprevention drug. This extensive review covers various therapeutic interactions of Quer with their recognized cellular targets involved in cancer treatment.

Redox-proteomics of the effects of homogentisic acid in an in vitro human serum model of alkaptonuric ochronosis

Alkaptonuria (AKU) is a rare inborn error of metabolism associated with a deficient activity of homogentisate 1,2-dioxygenase (HGO), an enzyme involved in tyrosine and phenylalanine metabolism. Such a deficiency leads to the accumulation of homogentisic acid (HGA) and its oxidized/polymerized products in connective tissues, where melanin-like pigments accumulate (ochronosis). Ochronosis involves especially joints, where an ochronotic arthropathy develops. Little is known on the molecular mechanisms leading to ochronosis and ochronotic arthropathy in AKU. Previous works of ours showed that HGA in vitro propagates oxidative stress through its conversion into benzoquinone acetate (BQA). We hence used an in vitro model consisting of human serum treated with HGA and evaluated the activities of glutathione related anti-oxidant enzymes and levels of compounds indexes of oxidative stress. Proteomics and redox-proteomics were used to identify oxidized proteins and proteins more likely able to bind BQA. Overall, we found that the production of ochronotic pigment in HGA-treated serum is accompanied by lipid peroxidation, decreased activity of the enzyme glutathione peroxidase and massive depletion of thiol groups, together with increased protein carbonylation and thiol oxidation. We also found that BQA was likely to bind carrier proteins and naturally abundant serum proteins, eventually altering their chemico-physical properties. Concluding, our work points towards a critical importance of thiol compounds in counteracting HGA- and BQA- mediated stress in AKU, so that future research for disease biomarkers and pharmacological treatments for AKU and ochronosis will be more easily addressed.

Final Report of the Cosmetic Ingredient Review Expert Panel Amended Safety Assessment of Calendula officinalis—Derived Cosmetic Ingredients

Calendula officinalis extract, C officinalis flower, C officinalis flower extract, C officinalis flower oil, and C officinalis seed oil are cosmetic ingredients derived from C officinalis. These ingredients may contain minerals, carbohydrates, lipids, phenolic acids, flavonoids, tannins, coumarins, sterols and steroids, monoterpenes, sesquiterpenes, triterpenes, tocopherols, quinones, amino acids, and resins. These ingredients were not significantly toxic in single-dose oral studies using animals. The absence of reproductive/developmental toxicity was inferred from repeat-dose studies of coriander oil, with a similar composition. Overall, these ingredients were not genotoxic. They also were not irritating, sensitizing, or photosensitizing in animal or clinical tests but may be mild ocular irritants. The Cosmetic Ingredient Review (CIR) Expert Panel concluded that these ingredients are safe for use in cosmetics in the practices of use and concentration given in this amended safety assessment.

Evaluation of anti-oxidant treatments in an in vitro model of alkaptonuric ochronosis

OBJECTIVES

Alkaptonuria (AKU) is a rare genetic disease associated with deficient homogentisate 1,2-dioxygenase activity in the liver. This leads to the accumulation of homogentisic acid (HGA) and its oxidized/polymerized products in connective tissues, which in turn become characterized by the presence of melanin-like pigments (ochronosis). Since at present, further studies are necessary to support the use of drugs for the treatment of AKU, we investigated the effects of various anti-oxidants in counteracting melanin-like pigmentation and oxidative stress related to HGA and its metabolites.

METHODS

We set up an in vitro model using human serum treated with 0.33 mM HGA and tested the anti-oxidants ascorbic acid, N-acetylcysteine, phytic acid (PHY), taurine (TAU), ferulic acid (FER) and lipoic acid (LIP) for their ability to prevent or delay the production of melanin-like pigments, as well as to reduce oxidative post-translational modifications of proteins. Monitoring of intrinsic fluorescence of HGA-induced melanin-like pigments was used to evaluate the efficacy of compounds.

RESULTS

Our model allowed us to prove efficacy especially for PHY, TAU, LIP and FER in counteracting the production of HGA-induced melanin-like pigments and protein oxidation induced by HGA and its metabolites.

CONCLUSIONS

Our model allows the opening of new anti-oxidant therapeutic strategies to treat alkaptonuric ochronosis.

Iron (III) chelation and antioxidant properties of myo-inositol phosphorylated polymeric microspheres

New chelating and antioxidant polymeric microspheres were synthesized through precipitation polymerization of 4-O-(4-vinylbenzyl)-myo-inositol 1,3,5-orthoformate with ethylene glycol dimethacrylate and subsequent exhaustive phosphorylation of the myo-inositol groups with phosphoric acid. Three different microspheres using different molar ratios of the two co-monomers were prepared. The antioxidant properties of these polymers were evaluated in rat liver microsomal membranes. This study showed that the macromolecular systems are very effective at inhibiting iron-dependent lipid peroxidation of the membranes. This antioxidant effect is due to the chelating properties of polyphosphorylated inositol residues in the polymeric devices toward ferric ions. The amount of polyphosphorylated inositol in the microspheres was found to play a crucial role in determining the chelating efficiency of the polymers: the polymer with the greatest amount of polyphosphorylated inositol was the most powerful antioxidant polymer.

The effect of quercetin on neointima formation in a rat artery balloon injury model

This study aimed at investigating the effect of quercetin on neointima hyperplasia in the abdominal aorta of rats after balloon injury and expressions of related growth factors. Fifty-four healthy male Sprague-Dawley rats were randomly divided into five groups: a sham-operation group (sham, n=6), a control group (control, n=12), and three quercetin-treated groups: Q50 group (50mg/kg body weight/day, n=12), Q100 group (100mg/kg body weight/day, n=12), and Q200 group (200mg/kg body weight/day, n=12) 3 days before balloon injury until the end of the experiment. Fourteen days after injury, rats were killed, and the abdominal aortas were harvested. Hematoxylin-eosin staining showed that quercetin significantly reduced the neointimal areas and the intimal to medial ratio in the Q100 and Q200 groups 14 days after injury. Immunohistochemical analysis showed that quercetin significantly inhibited PCNA, PDGF-BB, b-FGF, and TGF-beta1 expressions in the neointima. Masson's trichrome showed that quercetin significantly reduced collagen deposition in the neointima. We concluded that quercetin significantly inhibited neointimal hyperplasia in rat abdominal aorta 14 days after injury in relatively high doses. This effect of quercetin might be partially attributed to the suppression of PDGF-BB, b-FGF, and TGF-beta1 expressions.

Food flavor cinnamaldehyde-induced biochemical and histological changes in the kidney of male albino wistar rat

Rats were given food flavor cinnamaldehyde (CNMA) orally by gavage at the dose of 2.14, 6.96, 22.62 and 73.5mg/kg body weight/day for 10, 30 and 90 days. Only the group of rats treated with CNMA at the dose 73.5mg/kg body weight/day for 90 days showed histological changes in the kidney followed by increased activities of renal, serum and urinary enzymes. CNMA-induced glucosuria in these rats was accompanied by marked proteinuria and creatinuria. Increased serum blood urea nitrogen and serum creatinine and decreased serum protein and glucose levels were observed in these rats. Thus, CNMA at the dose of 73.5mg/kg body weight/day for 90 days exert its effect on kidney of male albino wistar rat and its effect is time and dose dependent.

A critical review of the data related to the safety of quercetin and lack of evidence of in vivo toxicity, including lack of genotoxic/carcinogenic properties

Quercetin is a naturally-occurring flavonol (a member of the flavonoid family of compounds) that has a long history of consumption as part of the normal human diet. Because a number of biological properties of quercetin may be beneficial to human health, interest in the addition of this flavonol to various traditional food products has been increasing. Prior to the use of quercetin in food applications that would increase intake beyond that from naturally-occurring levels of the flavonol in the typical Western diet, its safety needs to be established or confirmed. This review provides a critical examination of the scientific literature associated with the safety of quercetin. Results of numerous genotoxicity and mutagenicity, short- and long-term animal, and human studies are reviewed in the context of quercetin exposure in vivo. To reconcile results of in vitro studies, which consistently demonstrated quercetin-related mutagenicity to the absence of carcinogenicity in vivo, the mechanisms that lead to the apparent in vitro mutagenicity, and those that ensure absence of quercetin toxicity in vivo are discussed. The weight of the available evidence supports the safety of quercetin for addition to food.

The LEC rat: a useful model for studying liver carcinogenesis related to oxidative stress and inflammation

Growing evidence indicates oxidative stress as a mechanism of several diseases including cancer. Oxidative stress can be defined as the imbalance between cellular oxidant species production and antioxidant capability shifted towards the former. Lipid peroxidation is one of the processes that takes place during oxidative stress. Lipid peroxidation products, such as malondialdehyde (MDA) and 4-hydroxy-2-nonenal (HNE), are closely related to carcinogenesis as they are potent mutagens and they have been suggested as modulators of signal pathways related to proliferation and apoptosis, two processes implicated in cancer development. Mechanisms by which oxidative stress leads to tumor formation are still under investigation. The need of suitable in vivo models that could reflect that inflammation-related human carcinogenesis is evident. In this regard, the mutant strain Long Evans Cinnamon-like (LEC) rat provides a promising model for investigation of the relationship between hepatitis induced by oxidative stress and hepatocarcinogenesis because it has been demonstrated to develop spontaneous liver tumor formation related to copper accumulation and oxidative stress. In this review, the findings regarding oxidative stress and its relation with liver pathologies in LEC rats are discussed; we focus on the mechanisms proposed for HNE carcinogenesis.

Inhibition of acrolein-induced apoptosis by the antioxidant N-acetylcysteine

Acrolein is a highly electrophilic alpha,beta-unsaturated aldehyde to which humans are exposed in many situations. It is an environmental pollutant that is responsible for multiple respiratory diseases and has been implicated in neurodegenerative diseases such as Alzheimer's disease. The hypothesis of the study is that the antioxidant N-acetylcysteine (NAC), a precursor of glutathione, could protect cells against acrolein-induced apoptosis. Exposure of Chinese hamster ovary cells to a noncytotoxic dose of acrolein (4 fmol/cell) depleted intracellular glutathione to 45% of initial levels. NAC, which increased intracellular glutathione levels by 30%, afforded protection against acrolein-induced cytotoxicity (loss of cell proliferation) and apoptosis. NAC protected against apoptosis by diminishing acrolein-induced activation of the mitochondrial death pathway. NAC inhibited acrolein-induced Bad translocation from the cytosol to the mitochondria, as well as Bcl-2 translocation from mitochondria to the cytosol, as evaluated by Western blot analysis. However, NAC had no effect on acrolein-induced Bax translocation to mitochondria and cytochrome c liberation into the cytosol. Meanwhile, NAC inhibited depolarization of mitochondrial membrane potential, as evaluated by rhodamine fluorescence using flow cytometry. NAC also inhibited procaspase-9 processing, activation of enzymatic activity of caspase-9, -7, and -8, and poly(ADP-ribose) polymerase cleavage induced by acrolein. Inhibition of acrolein-induced apoptosis using NAC was confirmed morphologically by diminished condensation of nuclear chromatin, as evaluated by fluorescence microscopy. These findings suggest that NAC could be potentially useful as a protective agent for people exposed to acrolein.

Flavonoid-induced acute nephropathy by Cupressus funebris Endl (Mourning Cypress)

Worldwide use of herbal therapy has increased dramatically in recent years. Most herbal therapies were not regulated as medicines, and their adverse effects often were underreported. We report a patient who developed acute renal failure, acute hepatic failure, autoimmune hemolytic anemia, and thrombocytopenia after oral intake of hot-water extract of Cupressus funebris Endl (Mourning Cypress), which is rich in flavonoids. Her renal biopsy showed acute tubular necrosis, interstitial nephritis, and hemoglobin casts. The clinical course and pathological findings were consistent with flavonoid-induced acute nephropathy. We emphasize that flavonoids are not harmless and may induce acute life-threatening renal damage.