Protective Effect of Carnosine During Nitrosative Stress in Astroglial Cell Cultures

Formation of nitric oxide by astrocytes has been suggested to contribute, via impairment of mitochondrial function, to the neurodegenerative process. Mitochondria under oxidative stress are thought to play a key role in various neurodegenerative disorders; therefore protection by antioxidants against oxidative stress to mitochondria may prove to be beneficial in delaying the onset or progression of these diseases. Carnosine has been recently proposed to act as antioxidant in vivo. In the present study, we demonstrate its neuroprotective effect in astrocytes exposed to LPS- and INFγ-induced nitrosative stress. Carnosine protected against nitric oxide-induced impairment of mitochondrial function. This effect was associated with decreased formation of oxidatively modified proteins and with decreased up-regulation oxidative stress-responsive genes, such as Hsp32, Hsp70 and mt-SOD. Our results sustain the possibility that carnosine might have anti-ageing effects to brain cells under pathophysiological conditions leading to degenerative damage, such as aging and neurodegenerative disorders.     

Protective effects of carnosine and homocarnosine on ferritin and hydrogen peroxide-mediated DNA damage

Previous studies have shown that one of the primary causes of increased iron content in the brain may be the release of excess iron from intracellular iron storage molecules such as ferritin. Free iron generates ROS that cause oxidative cell damage. Carnosine and related compounds such as endogenous histidine dipetides have antioxidant activities. We have investigated the protective effects of carnosine and homocarnosine against oxidative damage of DNA induced by reaction of ferritin with H(2)O(2). The results show that carnosine and homocarnosine prevented ferritin/H(2)O(2)-mediated DNA strand breakage. These compounds effectively inhibited ferritin/H(2)O(2)-mediated hydroxyl radical generation and decreased the mutagenicity of DNA induced by the ferritin÷H(2)O(2) reaction. Our results suggest that carnosine and related compounds might have antioxidant effects on DNA under pathophysiological conditions leading to degenerative damage such as neurodegenerative disorders.     

Carnosine: biological role and prospects for use in medicine]

The biological role of the histidine-containing dipeptide carnosine (beta-alanyl-L-histidine) has been reviewed. The properties and putative biological role of the dipeptide in vertebrate tissues are considered. The antioxidative activity of carnosine and related compounds is described. The author's conception of the membranoprotective effect of carnosine on cells, tissues, and whole organism has been formulated. The properties of carnosine as an antistressory radioprotective agent are discussed. The data presented suggest that carnosine is a perspective immunomodulating tool which has many applications in medicine.     

Effect of carnosine supplementation on apoptosis and irisin,total oxidant and antioxidants levels in the serum,liver and lung tissues in rats exposed to formaldehyde inhalation

The main objective of the study has been to show whether carnosine has positive effects on liver and lung tissues of rats exposed to a range of formaldehyde concentrations, and to explore how irisin expression and antioxidant capacity are altered in these tissues by carnosine supplementation. Sprague-Dawley type male rats were divided into 8 groups with 6 animals in each: (I) Control; no chemical supplementation); (II) sham (100 mg/kg/day carnosine); (III) low dose formaldehyde (LDFA) for 5 days/week; (IV) LDFA for 5 days/week and carnosine); (V) moderate dose formaldehyde (MDFA) for 5 days/week); (VI) MDFA for 5 days/week and carnosine; (VII) high dose formaldehyde (HDFA) for 5 days/week; (VIII) and HDFA for 5 days/week and carnosine. Sham and control groups were exposed to normal air. Irisin levels of the serum, liver and lung tissue supernatants were analyzed by ELISA, while the REL method was used to determine total oxidant/antioxidant capacity. Irisin production by the tissues was detected immunohistochemically. Increasing doses of FA decreased serum/tissue irisin and total antioxidant levels relative to the controls, as also to increases in TUNEL expressions, total oxidant level, oxidant and apoptosis index. Irisin expression was detected in hepatocyte and sinusoidal cells of the liver and parenchymal cells of the lung. In conclusion, while FA exposure reduces irisin and total oxidant in the serum, liver and lung tissues in a dose-dependent manner and increases the total antioxidant capacity, carnosine supplementation reduces the oxidative stress and restores the histopathological and biochemical signs.     

Protective effects of histidine dipeptides on the modification of neurofilament-L by the cytochrome c/hydrogen peroxide system

Neurofilament-L (NF-L) is a major element of the neuronal cytoskeleton and is essential for neuronal survival. Moreover, abnormalities in NF-L result in neurodegenerative disorders. Carnosine and the related endogeneous histidine dipeptides prevent protein modifications such as oxidation and glycation. In the present study, we investigated whether histidine dipeptides, carnosine, homocarnosine, or anserine protect NF-L against oxidative modification during reaction between cytochrome c and H(2)O(2). Carnosine, homocarnosine and anserine all prevented cytochrome c/H(2)O(2)-mediated NF-L aggregation. In addition, these compounds also effectively inhibited the formation of dityrosine, and this inhibition was found to be associated with the reduced formations of oxidatively modified proteins. Our results suggest that carnosine and histidine dipeptides have antioxidant effects on brain proteins under pathophysiological conditions leading to degenerative damage, such as, those caused by neurodegenerative disorders.     

New glycoside derivatives of carnosine and analogs resistant to carnosinase hydrolysis: synthesis and characterization of their copper(II) complexes

Carnosine (β-alanyl-L-histidine) is an endogenous dipeptide widely and abundantly distributed in muscle and nervous tissues of several animal species. Many functions have been proposed for this compound, such as antioxidant and metal ion-chelator properties. However, the main limitation on therapeutic use of carnosine on pathologies related to increased oxidative stress and/or metal ion dishomeostasis is associated with the hydrolysis by the specific dipeptidase carnosinase. Several attempts have been made to overcome this limitation. On this basis, we functionalized carnosine and its amide derivative with small sugars such as glucose and lactose. The resistance of these derivatives to the carnosinase hydrolysis was tested and compared with that of carnosine. We found that the glycoconjugation protects the dipeptide moiety from carnosinase hydrolysis, thus potentially improving the availability of carnosine. The copper(II) binding properties of all the new synthesized compounds were investigated by spectroscopic (UV-Visible and circular dichroism) and ESI-MS studies. Particularly, the new family of amide derivatives that are not significantly hydrolyzed by carnosinase is a very promising class of carnosine derivatives. The sugar moiety can act as a recognition element. These new derivatives are potentially able to act as chelating agents in the development of clinical approaches for the regulation of metal homeostasis in the field of medicinal inorganic chemistry.     

Carnosine derivatives: new multifunctional drug-like molecules

Carnosine (β-alanyl-L-histidine) is an endogenous dipeptide widely and abundantly distributed in the muscle and nervous tissues of several animal species. Many functions have been proposed for this compound because of its antioxidant and metal ion-chelator properties. Many potential therapeutic properties have been recognized especially related to the antioxidant activity, but the therapeutic uses are strongly limited by the mechanism governing its homeostasis. This fact has been the main reason for developing the synthesis of carnosine derivatives with interesting potentiality, but until now there have been very few applications. These derivatives could represent the future drugs for many pathologies related to oxidative stress and metal ion dyshomeostasis.     

Role of carnosine in preventing thioacetamide-induced liver injury in the rat

Carnosine (beta-alanyl-L-histidine) is a dipeptide with antioxidant properties. Free radicals are involved in the pathogenesis of acute liver injury induced by thioacetamide (TAA). In this study, we investigated the effect of carnosine treatment on TAA-induced oxidative stress and hepatotoxicity. Rats were injected intraperitoneally with TAA (500 mg/kg) and carnosine (250 mg/kg, intraperitoneal) was co-administered with TAA. All animals were killed 24 h after injections. TAA administration resulted in hepatic necrosis, significant increases in plasma transaminase activities as well as hepatic lipid peroxide levels. In addition, hepatic antioxidant system was found to be depressed following TAA administration. When carnosine was co-administered with TAA in rats, plasma transaminase activities were found to approach to normal values in rats. Histological findings also suggested that carnosine has preventive effect on TAA-induced hepatic necrosis. Carnosine treatment caused significant decreases in lipid peroxide levels in TAA-treated rats without any changes in enzymatic and non-enzymatic antioxidants except vitamin E in the liver of rats. Our findings indicate that carnosine, in vivo may have a preventive effect on TAA-induced oxidative stress and hepatotoxicity by acting as an non-enzymatic antioxidant itself.     

Antioxidant effect of carnosine treatment on renal oxidative stress in streptozotocin-induced diabetic rats

Nitric oxide (NO) plays a significant role in the development of diabetic nephropathy. We investigated the effects of an antioxidant, carnosine, on streptozotocin (STZ)-induced renal injury in diabetic rats. We used four groups of eight rats: group 1, control; group 2, carnosine treated; group 3, untreated diabetic; group 4, carnosine treated diabetic. Kidneys were removed and processed, and sections were stained with periodic acid-Schiff (PAS) and subjected to eNOS immunohistochemistry. Examination by light microscopy revealed degenerated glomeruli, thickened basement membrane and glycogen accumulation in the tubules of diabetic kidneys. Carnosine treatment prevented the renal morphological damage caused by diabetes. Moreover, administration of carnosine decreased somewhat the oxidative damage of diabetic nephropathy. Appropriate doses of carnosine might be a useful therapeutic option to reduce oxidative stress and associated renal injury in diabetes mellitus.     

Chronic exposure to U18666A is associated with oxidative stress in cultured murine cortical neurons

Findings that antioxidant treatment may be beneficial in Alzheimer's disease indicate that oxidative stress is an important factor in its pathogenesis. Studies have also suggested that cholesterol imbalance in the brain might be related to the development of neurological disorders. Previously, we have reported that U18666A, a cholesterol transport-inhibiting agent, leads to apoptosis and intracellular cholesterol accumulation in primary cortical neurons. In this study, we found that neuronal apoptosis mediated by U18666A is associated with oxidative stress in the treated cortical neurons. Cortical neurons treated with U18666A also showed decreased secretion and increased intraneuronal accumulation of beta-amyloid. The association of neuronal apoptosis with oxidative stress and Abeta accumulation may provide clues to the pathogenesis of Alzheimer's disease, as well as the role oxidative stress plays in other neurodegenerative diseases.     

The grape antioxidant resveratrol for skin disorders: promise, prospects, and challenges

Resveratrol, a phytoalexin antioxidant found in red grapes, has been shown to have both chemopreventive and therapeutic effects against many diseases and disorders, including those of the skin. Studies have shown protective effects of resveratrol against ultraviolet radiation-mediated oxidative stress and cutaneous damages including skin cancer. Because many of the skin conditions stem from ultraviolet radiation and oxidative stress, this antioxidant appears to have promise and prospects against a wide range of cutaneous disorders including skin aging and skin cancers. However, there are a few roadblocks in the way of this promising agent regarding its translation from the bench to the bedside. This review discusses the promise and prospects of resveratrol in the management of skin disorders and the associated challenges.     

Distribution of carnosine-like peptides in the nervous system of developing and adult zebrafish (Danio rerio) and embryonic effects of chronic carnosine exposure

Carnosine-like peptides (carnosine-LP) are a family of histidine derivatives that are present in the nervous system of various species and that exhibit antioxidant, anti-matrix-metalloproteinase, anti-excitotoxic, and free-radical scavenging properties. They are also neuroprotective in animal models of cerebral ischemia. Although the function of carnosine-LP is largely unknown, the hypothesis has been advanced that they play a role in the developing nervous system. Since the zebrafish is an excellent vertebrate model for studying development and disease, we have examined the distribution pattern of carnosine-LP in the adult and developing zebrafish. In the adult, immunoreactivity for carnosine-LP is specifically concentrated in sensory neurons and non-sensory cells of the olfactory epithelium, the olfactory nerve, and the olfactory bulb. Robust staining has also been observed in the retinal outer nuclear layer and the corneal epithelium. Developmental studies have revealed immunostaining for carnosine-LP as early as 18 h, 24 h, and 7 days post-fertilization in, respectively, the olfactory, corneal, and retinal primordia. These data suggest that carnosine-LP are involved in olfactory and visual function. We have also investigated the effects of chronic (7 days) exposure to carnosine on embryonic development and show that 0.01 μM to 10 mM concentrations of carnosine do not elicit significant deleterious effects. Conversely, treatment with 100 mM carnosine results in developmental delay and compromised larval survival. These results indicate that, at lower concentrations, exogenously administered carnosine can be used to explore the role of carnosine in development and developmental disorders of the nervous system. This research was supported in part by an Intramural Research Grant Program Award from Michigan State University (no. 06-IRGP-899 to M.C.S.) and a grant from the National Institutes of Health (no. DC-03112 to F.L.M.).     

Effects of nutritional antioxidants on AAPH- or AGEs-induced oxidative stress in human SW872 liposarcoma cells

High levels of oxidative stress were reported in obesity-linked type 2 diabetes and were associated with elevated formation of advanced glycation end products (AGEs). Many studies have focused on the effect of antioxidants on vascular and circulating cells such as macrophages. However, despite the major role of adipocytes in the etiology of diabetes, little is known about the effect of natural antioxidants on adipocyte response to oxidative stress. The present study reports the differential protective effects of plant nutrients toward adipose cells subjected to oxidative stress. Caffeic acid, quercetin, l-ascorbic acid, and α-tocopherol were tested on SW872 liposarcoma cells subjected to a free radical generator or to AGEs. Proliferation, viability, free radical formation, and superoxide dismutase expression were assessed in treated cells. Caffeic acid and quercetin appeared as the most potent antioxidant nutrients. Our findings clearly show a novel antioxidant role for caffeic acid and quercetin at the adipose tissue level. These new data confirm the beneficial role of phytotherapy as an interesting alternative mean for the development of novel therapeutical and nutritional strategy to prevent metabolic disorders inherent to obesity-linked diabetes.     

Anti-ischemic activity of carnosine

This review summarizes the data on anti-ischemic activity of carnosine. The pronounced anti-ischemic effects of carnosine in the brain and heart are due to the combination of antioxidant and membrane-protecting activity, proton buffering capacity, formation of complexes with transition metals, and regulation of macrophage function. In experimental cerebral ischemia, carnosine decreases mortality and is beneficial for neurological conditions of the animals. In cardiac ischemia, carnosine protects cardiomyocytes from damage and improves contractility of the heart. The data indicate that carnosine can be used as an anti-ischemic drug.     

Antioxidant Activity of Diethyldithiocarbamate

Diethyldithiocarbamate (DDC), a potent copper chelating agent, has long been used for the treatment of oxygen toxicity to the central nervous system, as an immunomodulator to treat cancer, and in HIV-infected patients. We evaluated the antioxidant properties of DDC, including its scavenging of reactive oxygen species, its reducing properties, its iron-chelating properties, and its protective effects on oxidant-induced damage to brain tissue, protein, human LDL, and DNA. It is found that DDC is a powerful reductant and antioxidant since it scavenges hypochlorous acid, hydroxyl radical and peroxynitrite; it chelates, then oxidizes ferrous ions; it blocks the generation of hydroxyl radicals and inhibits oxidative damage to deoxyribose, protein, DNA, and human LDL. These findings may provide an explanation for the apparent beneficial effects of DDC against oxidative stress-related diseases that have been observed in experimental and clinical studies.     

Haematococcus astaxanthin: applications for human health and nutrition

The carotenoid pigment astaxanthin has important applications in the nutraceutical, cosmetics, food and feed industries. Haematococcus pluvialis is the richest source of natural astaxanthin and is now cultivated at industrial scale. Astaxanthin is a strong coloring agent and a potent antioxidant - its strong antioxidant activity points to its potential to target several health conditions. This article covers the antioxidant, UV-light protection, anti-inflammatory and other properties of astaxanthin and its possible role in many human health problems. The research reviewed supports the assumption that protecting body tissues from oxidative damage with daily ingestion of natural astaxanthin might be a practical and beneficial strategy in health management.     

Nrf2-induced antioxidant protection: a promising target to counteract ROS-mediated damage in neurodegenerative disease?

Neurodegenerative diseases share various pathological features, such as accumulation of aberrant protein aggregates, microglial activation, and mitochondrial dysfunction. These pathological processes are associated with generation of reactive oxygen species (ROS), which cause oxidative stress and subsequent damage to essential molecules, such as lipids, proteins, and DNA. Hence, enhanced ROS production and oxidative injury play a cardinal role in the onset and progression of neurodegenerative disorders. To maintain a proper redox balance, the central nervous system is endowed with an antioxidant defense mechanism consisting of endogenous antioxidant enzymes. Expression of most antioxidant enzymes is tightly controlled by the antioxidant response element (ARE) and is activated by nuclear factor E2-related factor 2 (Nrf2). In past years reports have highlighted the protective effects of Nrf2 activation in reducing oxidative stress in both in vitro and in vivo models of neurodegenerative disorders. Here we provide an overview of the involvement of ROS-induced oxidative damage in Alzheimer's disease, Parkinson's disease, and Huntington's disease and we discuss the potential therapeutic effects of antioxidant enzymes and compounds that activate the Nrf2-ARE pathway.     

Controlling oxidative stress as a novel molecular approach to protecting the vascular wall in diabetes

PURPOSE OF REVIEW: In diabetes, oxidative stress plays a key role in the pathogenesis of vascular complications; therefore an antioxidant therapy would be of great interest in this disease. RECENT FINDINGS: Hyperglycemia directly promotes an endothelial dysfunction--inducing process of overproduction of superoxide at the mitochondrial level. This is the first and key event able to activate all the pathways involved in the development of vascular complications of diabetes. It has recently been shown that statins, angiotensin-converting enzyme inhibitors, angiotensin II type 1 blockers, calcium channel blockers, and thiazolidinediones have a strong intracellular antioxidant activity. SUMMARY: Classic antioxidants, such as vitamin E, failed to show beneficial effects on diabetic complications probably because their action is only "symptomatic". The preventive activity against hyperglycemia-induced oxidative stress shown by statins, angiotensin-converting enzyme inhibitors, angiotensin II type 1 blockers, calcium channel blockers, and thiazolidinediones justifies use of these compounds for preventing complications in patients with diabetes, in whom antioxidant defences have been shown to be defective.     

Neuroprotective effect of carnosine on primary culture of rat cerebellar cells under oxidative stress

Dipeptide carnosine (β-alanyl-L-histidine) is a natural antioxidant, but its protective effect under oxidative stress induced by neurotoxins is studied insufficiently. In this work, we show the neuroprotective effect of carnosine in primary cultures of rat cerebellar cells under oxidative stress induced by 1 mM 2,2′-azobis(2-amidinopropane)dihydrochloride (AAPH), which directly generates free radicals both in the medium and in the cells, and 20 nM rotenone, which increases the amount of intracellular reactive oxygen species (ROS). In both models, adding 2 mM carnosine to the incubation medium decreased cell death calculated using fluorescence microscopy and enhanced cell viability estimated by the MTT assay. The antioxidant effect of carnosine inside cultured cells was demonstrated using the fluorescence probe dichlorofluorescein. Carnosine reduced by half the increase in the number of ROS in neurons induced by 20 nM rotenone. Using iron-induced chemiluminescence, we showed that preincubation of primary neuronal cultures with 2 mM carnosine prevents the decrease in endogenous antioxidant potential of cells induced by 1 mM AAPH and 20 nM rotenone. Using liquid chromatographymass spectrometry, we showed that a 10-min incubation of neuronal cultures with 2 mM carnosine leads to a 14.5-fold increase in carnosine content in cell lysates. Thus, carnosine is able to penetrate neurons and exerts an antioxidant effect. Western blot analysis revealed the presence of the peptide transporter PEPT2 in rat cerebellar cells, which suggests the possibility of carnosine transport into the cells. At the same time, Western blot analysis showed no carnosine-induced changes in the level of apoptosis regulating proteins of the Bcl-2 family and in the phosphorylation of MAP kinases, which suggests that carnosine could have minimal or no side effects on proliferation and apoptosis control systems in normal cells.