Protective role of antioxidative food factors in oxidative stress caused by hyperglycemia

Ameliorative potential of resveratrol on proinflammatory cytokines, hyperglycemia mediated oxidative stress, and pancreatic beta-cell dysfunction in streptozotocin-nicotinamide-induced diabetic rats

Chronic exposure of pancreatic beta-cells to supraphysiologic glucose causes adverse beta-cell dysfunction. Thus, the present study was aimed to investigate the hypothesis that oral administration of resveratrol attenuates hyperglycemia, proinflammatory cytokines and antioxidant competence and protects beta-cell ultrastructure in streptozotocin-nicotinamide-induced diabetic rats. Oral administration of resveratrol (5 mg/kg body weight) to diabetic rats for 30 days showed a significant decline in the levels of blood glucose, glycosylated hemoglobin (HbA1c), TNF-alpha, IL-1beta, IL-6, NF-kappaB p65 unit and nitric oxide (NO) with concomitant elevation in plasma insulin. Further, resveratrol treated diabetic rats elicited a notable attenuation in the levels of lipid peroxides, hydroperoxides and protein carbonyls in both plasma and pancreatic tissues. The diminished activities of pancreatic superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and glutathione-S-transferase (GST) as well as the decreased levels of plasma ceruloplasmin, vitamin C, vitamin E and reduced glutathione (GSH) in diabetic rats were reverted to near normalcy by resveratrol administration. Based on histological and ultrastructural observations, it is first-time reported that the oral administration of resveratrol may effectively rescue beta-cells from oxidative damage without affecting their function and structural integrity. The results of the present investigation demonstrated that resveratrol exhibits significant antidiabetic potential by attenuating hyperglycemia, enhancing insulin secretion and antioxidant competence in pancreatic beta-cells of diabetic rats.

A characterization of the antioxidant enzyme activity and reproductive toxicity in male rats following sub-chronic exposure to areca nut extracts

In the present study, areca nut extracts (ANE) administered to male rats by gavage at a dose of 100mg/kg/day for a period of 15, 30, or 45 days resulted in signs of reproductive toxicity. ANE administration resulted in a significant decline (30-57% in epididymal sperm count and 27-61% in sperm motility) as well as substantial abnormalities in sperm morphology. Significant variances in activities of antioxidant enzymes were also observed. Malondialdehyde (MDA) levels, which represent the level of lipid peroxidation, increased by 16-188% and levels of sialic acid decreased by 2-46% compared with that in controls. These results indicate that ANE induced spermatogenic damage, as indicated by a decrease in sperm counts and sperm motility as well as the activity of antioxidant enzymes, an increase in sperm abnormalities, and alterations in sialic acid and MDA levels. Such effects reflect that ANE administration resulted in reactive oxygen species (ROS)-induced oxidative stress in the testis, cauda epididymis, and sperm of male rats.

Curcumin modulates dopaminergic receptor, CREB and phospholipase C gene expression in the cerebral cortex and cerebellum of streptozotocin induced diabetic rats

Curcumin, an active principle component in rhizome of Curcuma longa, has proved its merit for diabetes through its anti-oxidative and anti-inflammatory properties. This study aims at evaluating the effect of curcumin in modulating the altered dopaminergic receptors, CREB and phospholipase C in the cerebral cortex and cerebellum of STZ induced diabetic rats. Radioreceptor binding assays and gene expression was done in the cerebral cortex and cerebellum of male Wistar rats using specific ligands and probes. Total dopaminergic receptor binding parameter, B_max showed an increase in cerebral cortex and decrease in the cerebellum of diabetic rats. Gene expression studies using real time PCR showed an increased expression of dopamine D1 and D2 receptor in the cerebral cortex of diabetic rats. In cerebellum dopamine D1 receptor was down regulated and D2 receptor showed an up regulation. Transcription factor CREB and phospholipase C showed a significant down regulation in cerebral cortex and cerebellum of diabetic rats. We report that curcumin supplementation reduces diabetes induced alteration of dopamine D1, D2 receptors, transcription factor CREB and phospholipase C to near control. Our results indicate that curcumin has a potential to regulate diabetes induced malfunctions of dopaminergic signalling, CREB and Phospholipase C expression in cerebral cortex and cerebellum and thereby improving the cognitive and emotional functions associated with these regions. Furthermore, in line with these studies an interaction between curcumin and dopaminergic receptors, CREB and phospholipase C is suggested, which attenuates the cortical and cerebellar dysfunction in diabetes. These results suggest that curcumin holds promise as an agent to prevent or treat CNS complications in diabetes.

Mitigating effects of antioxidant properties of Artemisia campestris leaf extract on hyperlipidemia, advanced glycation end products and oxidative stress in alloxan-induced diabetic rats

Artemisia campestris is used as antivenom and anti-inflammatory Tunisian folk medicine. Recently, increased oxidative stress was shown to play an important role in the etiology and pathogenesis of diabetes mellitus and its complications. This study was designed to examine the effects of A. campestris leaf aqueous extract (Ac) on alloxan-induced diabetic rats by measuring glycemia, lipid profile, lipid peroxidation (MDA), protein carbonyl content (PCO), advanced oxidation protein products (AOPP), activities of both non-enzymatic and enzymatic antioxidants. Results of our study showed an increase in blood glucose levels, total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-c), a decrease in high-density lipoprotein cholesterol (HDL-c) level and disturbed antioxidant enzyme activities (CAT, SOD, GPx) in the pancreatic tissue of diabetic rats. Furthermore, MDA, PCO and AOPP were elevated in the pancreas of the diabetic rats. The administration of Ac to diabetic rats at a dose of 200mgkg(-1)bw resulted in a significant reduction in glycemia, TC, TG, LDL-c, pancreas LPO, PCO and AOPP levels, CAT and GPx activities associated with an elevation of GSH content and SOD activity in comparison with diabetic group. We conclude that A. campestris aqueous extract may be effective for correcting hyperglycemia and preventing diabetic complications.

Effect of curcumin on selenite-induced cataractogenesis in Wistar rat pups

PURPOSE

The present study was aimed at investigating the possible antioxidant potential of curcumin at a dose of 75 mg/kg body weight on selenite-induced cataract in experimental rat pups.

METHODS

Group I: Control rat pups receiving physiological saline; Group II: Selenite-induced group (15 microM/kg body wt); Group III: Selenite-induced group co-treated with curcumin (single dose of curcumin orally 75 mg/kg body wt); Group IV: Selenite-induced animals post-treated (after 24 hrs) with curcumin at a dose mentioned for group III; Group V: Rat pups were pretreated with curcumin (dose as mentioned in Group III), 24 hrs before the administration of selenite. Encapsulated lenses liver, kidney, and serum were analyzed for antioxidant enzymes and malondialdehyde, a marker of lipid peroxidation.

RESULTS

Intraperitoneal injection of sodium selenite (15 microM/kg body wt) to 8-10-day-old rat pups led to severe oxidative stress in eye lens as evidenced by enhanced LPO levels that led to cataract formation. Sodium selenite also led to decrease in activities of SOD, GST, GPx, CAT with simultaneous decrease in the levels of GSH, vitamin C, and vitamin E. Treatment with curcumin (75 mg/kg body wt) led to a significant decrease in the levels of LPO, enzymic antioxidants, and nonenzymic antioxidants, which were similar to that of control.

CONCLUSIONS

Curcumin suppressed selenite-induced oxidative stress and cataract formation in rat pups. The presence of oxidative stress in selenite cataract development and its prevention by curcumin support the possibility that the natural consumption of curcumin in food can help prevent the onset of senile cataract.

Protective and anticataract effects of the aqueous extract of Cleistocalyx operculatus flower buds on beta-cells of streptozotocin-diabetic rats

The aim of the present study was to examine whether an aqueous extract of Cleistocalyx operculatus flower buds (COB) had protective and anticataract effects on beta-cells in experimental streptozotocin (STZ)-induced diabetes in rats. After 9 weeks of COB supplementation (500 mg/kg bw), the COB group had a significantly more stable insulin level as compared with the control diabetic group. Increased staining of insulin and preservation of islet cells were apparent in the COB-treated diabetic rats, whereas islet cell degeneration and weak insulin immunohistochemical staining were observed in the control diabetic rats. In addition, COB significantly delayed diabetic cataract formation and caused significant reductions in the glucose, sorbitol, and fructose levels in diabetic rat lenses. Furthermore, as compared to the control diabetic group, the COB group also showed antihyperglycemic effects (reductions in plasma glucose and HbA1c levels).

Assessing the neuroprotective effect of antioxidative food factors by application of lipid-derived dopamine modification adducts

Advances in understanding the neurodegenerative pathologies are creating new opportunities for the development of neuroprotective therapies, such as antioxidant food factors, lifestyle modification, and drugs. However, the biomarker by which to determine the effect of the agent on neurodegeneration is limited. We here address hexanoyl dopamine (HED), one of novel dopamine adducts derived from brain polyunsaturated acid, referring to its in vitro formation, potent toxicity to SH-SY5Y cells, and application to assess the neuroprotective effect of antioxidative food factors. Dopamine is a neurotransmitter and its deficiency is a characterized feature in Parkinson's disease (PD), thereby HED represents a new addition to understanding of dopamine biology and pathophysiology of PD and a novel biomarker for the assessment of neuroprotective therapies. We have established an analytical system using for the detection of HED and its toxicity to the neuroblstoma cell line, SH-SY5Y cells. Here, we discuss the characteristics of the system and its applications to investigate the neuroprotective effect of several antioxidants that originate from food.

Amelioration of lead-induced hepatotoxicity by Allium sativum extracts in Swiss albino mice

Lead is a blue-gray and highly toxic divalent metal that occurs naturally in the earth's crust and is spread throughout the environment by various human activities. The efficacy of garlic (Allium sativum) to reduce hepatotoxicity induced by lead nitrate was evaluated experimentally in male mice. Oral treatment with lead nitrate at a dose of 50 mg/kg body weight daily for 40 days (1/45 of LD₅₀) induced a significant increase in the levels of hepatic aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, acid phosphatase, cholesterol, lipid peroxidation, and lead nitrate. In parallel, hepatic protein levels in lead-exposed mice were significantly depleted. Lead nitrate exposure also produced detrimental effects on the redox status of the liver indicated by a significant decline in the levels of liver antioxidants such as superoxide dismutase, catalase, and glutathione. After exposure to lead nitrate (50 mg/kg body weight for 10 days), the animals received aqueous garlic extract (250 mg/kg body weight and 500 mg/kg body weight) and ethanolic garlic extract (100 mg/kg body weight and 250 mg/kg body weight), and partially restored the deranged parameters significantly. Histological examination of the liver also revealed pathophysiological changes in lead nitrate-exposed group and treatment with garlic improved liver histology. Our data suggest that garlic is a phytoantioxidant that can counteract the deleterious effects of lead nitrate.

Amelioration of lead-induced hepatotoxicity by Allium sativum extracts in Swiss albino mice

Lead is a blue-gray and highly toxic divalent metal that occurs naturally in the earth's crust and is spread throughout the environment by various human activities. The efficacy of garlic (Allium sativum) to reduce hepatotoxicity induced by lead nitrate was evaluated experimentally in male mice. Oral treatment with lead nitrate at a dose of 50 mg/kg body weight daily for 40 days (1/45 of LD(50)) induced a significant increase in the levels of hepatic aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, acid phosphatase, cholesterol, lipid peroxidation, and lead nitrate. In parallel, hepatic protein levels in lead-exposed mice were significantly depleted. Lead nitrate exposure also produced detrimental effects on the redox status of the liver indicated by a significant decline in the levels of liver antioxidants such as superoxide dismutase, catalase, and glutathione. After exposure to lead nitrate (50 mg/kg body weight for 10 days), the animals received aqueous garlic extract (250 mg/kg body weight and 500 mg/kg body weight) and ethanolic garlic extract (100 mg/kg body weight and 250 mg/kg body weight), and partially restored the deranged parameters significantly. Histological examination of the liver also revealed pathophysiological changes in lead nitrate-exposed group and treatment with garlic improved liver histology. Our data suggest that garlic is a phytoantioxidant that can counteract the deleterious effects of lead nitrate.

Assessing the neuroprotective effect of antioxidant food factors by application of lipid-derived dopamine modification adducts

Advances in understanding the neurodegenerative pathologies are creating new opportunities for the development of neuroprotective therapies, such as antioxidant food factors, lifestyle modification and drugs. However, the biomarker by which the effect of the agent on neurodegeneration is determined is limited. We here address hexanoyl dopamine (HED), one of novel dopamine adducts derived from brain polyunsaturated acid, referring to its in vitro formation, potent toxicity to SH-SY5Y cells, and application to assess the neuroprotective effect of antioxidative food factors. Dopamine is a neurotransmitter, and its deficiency is a characterized feature in Parkinson's disease (PD); thus, HED provides a new insight into the understanding of dopamine biology and pathophysiology of PD and a novel biomarker for the assessment of neuroprotective therapies. We have established an analytical system for the detection of HED and its toxicity to the neuroblstoma cell line, SH-SY5Y cells. Here, we discuss the characteristics of the system and its applications to investigate the neuroprotective effect of several antioxidants that originate from food.

Maillard reaction, mitochondria and oxidative stress: potential role of antioxidants

Glycation and oxidative stress are two important processes known to play a key role in complications of many disease processes. Oxidative stress, either via increasing reactive oxygen species (ROS), or by depleting the antioxidants may modulate the genesis of early glycated proteins in vivo. Maillard Reactions, occur in vivo as well as in vitro and are associated with the chronic complications of diabetes, aging and age-related diseases. Hyperglycaemia causes the autoxidation of glucose, glycation of proteins, and the activation of polyol metabolism. These changes facilitate the generation of reactive oxygen species and decrease the activity of antioxidant enzymes such as Cu,Zn-superoxide dismutase, resulting in a remarkable increase of oxidative stress. A large body of evidence indicates that mitochondria alteration is involved and plays a central role in various oxidative stress-related diseases. The damaged mitochondria produce more ROS (increase oxidative stress) and less ATP (cellular energy) than normal mitochondria. As they are damaged, they cannot burn or use glucose or lipid and cannot provide cell with ATP. Further, glucose, amino acids and lipid will not be correctly used and will accumulate outside the mitochondria; they will undergo more glycation (as observed in diabetes, obesity, HIV infection and lipodystrophia). The objective of this paper is to discuss how to stop the vicious circle established between oxidative stress, Maillard Reaction and mitochondria. The potential application of some antioxidants to reduce glycation phenomenon and to increase the antioxidant defence system by targeting mitochondria will be discussed. Food and pharmaceutical companies share the same challenge, they must act now, urgently and energetically.

Hyperlipidemia: a new therapeutic target for diabetic neuropathy

Emerging data establish dyslipidemia as a significant contributor to the development of diabetic neuropathy. In this review, we discuss how separate metabolic imbalances, including hyperglycemia and hyperlipidemia, converge on mechanisms leading to oxidative stress in dorsal root ganglia (DRG) sensory neurons. We conclude with suggestions for novel therapeutic strategies to prevent or reverse diabetes-induced nerve degeneration.

Dyslipidemia-induced neuropathy in mice: the role of oxLDL/LOX-1

OBJECTIVE

Neuropathy is a frequent and severe complication of diabetes. Multiple metabolic defects in type 2 diabetic patients result in oxidative injury of dorsal root ganglia (DRG) neurons. Our previous work focused on hyperglycemia clearly demonstrates induction of mitochondrial oxidative stress and acute injury in DRG neurons; however, this mechanism is not the only factor that produces neuropathy in vivo. Dyslipidemia also correlates with the development of neuropathy, even in pre-diabetic patients. This study was designed to explore the contribution of dyslipidemia in neuropathy.

RESEARCH DESIGN AND METHODS

Mice (n = 10) were fed a control (10% kcal %fat) or high-fat (45% kcal %fat) diet to explore the impact of plasma lipids on the development of neuropathy. We also examined oxidized lipid-mediated injury in cultured DRG neurons from adult rat using oxidized LDLs (oxLDLs).

RESULTS

Mice on a high-fat diet have increased oxLDLs and systemic and nerve oxidative stress. They develop nerve conduction velocity (NCV) and sensory deficits prior to impaired glucose tolerance. In vitro, oxLDLs lead to severe DRG neuron oxidative stress via interaction with the receptor lectin-like oxLDL receptor (LOX)-1 and subsequent NAD(P)H oxidase activity. Oxidative stress resulting from oxLDLs and high glucose is additive.

CONCLUSIONS

Multiple metabolic defects in type 2 diabetes directly injure DRG neurons through different mechanisms that all result in oxidative stress. Dyslipidemia leads to high levels of oxLDLs that may injure DRG neurons via LOX-1 and contribute to the development of diabetic neuropathy.

Activation of muscarinic M-1 cholinoceptors by curcumin to increase glucose uptake into skeletal muscle isolated from Wistar rats

Curcumin, an active principle contained in rhizome of Curcuma longa, has been mentioned to show merit for diabetes through its anti-oxidative and anti-inflammatory properties. In the present study, we found that curcumin caused a concentration-dependent increase of glucose uptake into skeletal muscle isolated from Wistar rats. This action was inhibited by pirenzepine at concentration enough to block muscarinic M-1 cholinoceptor (M(1)-mAChR). In radioligand binding assay, the binding of [(3)H]-pirenzepine was also displaced by curcumin in a concentration-dependent manner. In the presence of inhibitors for PLC-PI3K pathway, either U73122 (phospholipase C inhibitor) or LY294002 (phosphoinositide 3-kinase inhibitor), curcumin-stimulated glucose uptake into skeletal muscle was markedly reduced. In Western blotting analysis, the membrane protein level of glucose transporter 4 (GLUT4) increased by curcumin was also reversed by blockade of M(1)-mAChR or PLC-PI3K pathway in a same manner. In conclusion, the obtained results suggest that curcumin can activate M(1)-mAChR at concentrations lower than to scavenge free radicals for increase of glucose uptake into skeletal muscle through PLC-PI3-kinase pathway.

Assessment of genomic instability in normal and diabetic rats treated with metformin

To examine if a single or multiple oral administration of metformin, a member of the biguanide class of anti-diabetic agents, has any genotoxic and cytotoxic potential in normal and diabetic rats, a mammalian model, cytogenetic assays through several endpoints such as induction of micronuclei, chromosome aberrations, mitotic activity of bone marrow cells, sperm-head anomaly and assays of some oxidative stress markers have been conducted by the use of standard techniques. Diabetes was induced by streptozotocin injection. Metformin was administrated to both diabetic and non-diabetic rats in single doses of 100, 500 or 2500 mg/kg along with vehicle control groups for diabetic and non-diabetic rats. The animals were killed by cervical dislocation at 24h after treatment, and then bone marrow cells were sampled. Also, a multiple dose study has done in which diabetic and non-diabetic animals were treated with 100 or 500 mg/kg of metformin daily for 4 or 8 weeks after which the animals were killed by cervical dislocation, and then bone marrow and sperm cells were collected. Concurrent control groups were also included in each experiment. The obtained results revealed that metformin was neither genotoxic nor cytotoxic for the rats in all groups at all tested doses. Moreover, metformin significantly reduced the diabetes-induced genomic instability and cell proliferation changes in somatic and germinal cells in a dose-dependent manner (2500, 500, >100mg/kg). In addition, diabetes induced marked biochemical alterations characteristic of oxidative stress including, enhanced lipid peroxidation and reduction in the reduced glutathione level. Treatment with metformin ameliorated these biochemical markers. In conclusion, metformin is a non-genotoxic or cytotoxic compound and may protect from genomic instability induced by hyperglycemia. Apart from its well-known anti-diabetic effect, the antigenotoxic effect of metformin could be possibly ascribed to its radical scavenger effect that modulated the genomic instability responses and cell proliferation changes induced by hyperglycemia.

Therapeutic effects of Teucrium polium extract on oxidative stress in pancreas of streptozotocin-induced diabetic rats

Increased oxidative stress is a widely accepted factor in the development and progression of diabetes and its complications. In this study, we evaluated the antioxidative potential of Teucrium polium (Family Lamiaceae) aqueous extract for protecting rat pancreatic tissue against streptozotocin (STZ)-induced oxidative stress. Diabetes was induced in rats by intraperitoneal injections of at a single dose of STZ at 40 mg/kg. The crude extract (equivalent to 0.5 g of plant powder/kg of body weight) was administered orally (intragastrically) to a group of STZ diabetic rats for 30 consecutive days. Changes in antioxidant status were evaluated by determining catalase (CAT) and superoxide dismutase (SOD) activities and the level of reduced glutathione (GSH) in pancreatic tissue. In addition, serum nitric oxide (NO) concentration, pancreatic tissue malondialdehyde (MDA) (an index of lipid peroxidation) level, and reliable markers of protein oxidation such as protein carbonyl content (PCO) and advanced oxidation protein products (AOPP) were also determined. Under diabetic conditions, blood glucose level, serum NO concentration, and pancreatic MDA, PCO, and AOPP levels were all increased. The diabetic rats also exhibited pancreatic GSH depletion along with significant reductions in activities of CAT and SOD. Rats treated with T. polium extract had significantly higher GSH levels along with enhanced CAT and SOD activities in pancreatic tissue. In addition to suppressed blood glucose levels, serum NO, pancreatic MDA, PCO, and AOPP levels were all lower than in the diabetic group. Our results strongly support the proposal that antioxidative activity of T. polium occurs by quenching the extent of lipid and protein oxidation. Based on these observations, it is concluded that T. polium may have protective effect(s) on pancreatic tissue in STZ-induced oxidative stress due to its high antioxidative potential.

Produtos da glicação avançada dietéticos e as complicações crônicas do diabetes

A geração dos produtos de glicação avançada é um dos principais mecanismos desencadeadores das doenças associadas ao diabetes mellitus, que incluem cardiopatia, retinopatia, neuropatia e nefropatia. Esta revisão tem como objetivo analisar o papel dos produtos de glicação avançada presentes na alimentação como mediadores das complicações diabéticas e apresentar estratégias de redução de sua ingestão. Para tanto, foram realizados levantamentos em bancos de dados de publicações da área, dos últimos 15 anos, considerando-se artigos de revisão, estudos clínicos e experimentais. Os produtos de glicação avançada são um grupo heterogêneo de moléculas formadas a partir de reações não enzimáticas entre grupamentos amino e carbonilo, sendo a carboximetilisina e a pentosidina exemplos de produtos de glicação avançada identificados em alimentos e in vivo. Os produtos de glicação avançada ingeridos são absorvidos, somando-se aos endógenos no surgimento e na progressão das diversas complicações do diabetes, existindo uma correlação direta entre o consumo e a concentração sanguínea. Sua restrição na alimentação se correlaciona à supressão dos níveis séricos de marcadores de doença vascular e de mediadores inflamatórios diretamente envolvidos no desenvolvimento das degenerações diabéticas. As atuais orientações dietéticas centram-se na proporção em nutrientes e na restrição energética, sem considerar o risco da ingestão de produtos de glicação avançada formados durante o processamento dos alimentos. Recomendações simples, como a utilização de temperaturas baixas por períodos mais curtos, em presença de água, no preparo de alimentos, exercem efeitos importantes na prevenção das complicações do diabetes. O estudo dos mecanismos envolvidos na geração de produtos de glicação avançada e das propriedades anti-glicação de compostos presentes nos alimentos podem contribuir com a conduta terapêutica, concorrendo para a melhoria da qualidade de vida dos portadores dessa enfermidade.

Diabetic neuropathy: mechanisms to management

Neuropathy is the most common and debilitating complication of diabetes and results in pain, decreased motility, and amputation. Diabetic neuropathy encompasses a variety of forms whose impact ranges from discomfort to death. Hyperglycemia induces oxidative stress in diabetic neurons and results in activation of multiple biochemical pathways. These activated pathways are a major source of damage and are potential therapeutic targets in diabetic neuropathy. Though therapies are available to alleviate the symptoms of diabetic neuropathy, few options are available to eliminate the root causes. The immense physical, psychological, and economic cost of diabetic neuropathy underscore the need for causally targeted therapies. This review covers the pathology, epidemiology, biochemical pathways, and prevention of diabetic neuropathy, as well as discusses current symptomatic and causal therapies and novel approaches to identify therapeutic targets.

Antioxidant effect of thiamine on acutely alcoholized rats and lack of efficacy using thiamine or glucose to reduce blood alcohol content

Although there is no consensus about the use of glucose and thiamine for the treatment of acute ethanol intoxication, this is a routine practice in many countries. Our objective was to determine the efficacy of this treatment and the changes it causes in the antioxidant status of the liver. Male Wistar rats were intoxicated with an ethanol dose of 5 g/kg and divided into three groups: ethanol (EtOH; untreated), EtOH+G (treated with glucose), and EtOH+B1 (treated with thiamine). Blood and urinary ethanol as well as hepatic malondialdehyde, reduced glutathione and vitamin E were determined in all animals. Blood alcohol levels did not differ between groups, although urinary excretion was about four times higher in the group treated with thiamine (EtOH+B1). The malondialdehyde, reduced glutathione and vitamin E values used here as parameters of the antioxidant system of the liver showed improvement for the thiamine-treated group (EtOH+B1). Treatment with glucose or thiamine was ineffective in reducing blood alcohol levels in rats with acute ethanol intoxication. However, the beneficial effect of thiamine as an antioxidant for ethanol metabolism was demonstrated. Further investigations are necessary to clarify the urinary excretion of ethanol reported here for the first time and the possibility of using thiamine as an antioxidant in situations of chronic alcohol use.

O papel dos produtos finais da glicação avançada (AGEs) no desencadeamento das complicações vasculares do diabetes

Os produtos finais da glicação avançada (AGEs [do inglês, Advanced Glycation End-products]) constituem uma classe de moléculas heterogêneas formadas a partir de reações aminocarbonilo de natureza não-enzimática, que ocorrem aceleradamente no estado hiperglicêmico do diabetes. Considerados importantes mediadores patogênicos das complicações diabéticas, os AGEs são capazes de modificar, irreversivelmente, as propriedades químicas e funcionais das mais diversas estruturas biológicas. Na presente revisão, são apresentados os dados recentes da literatura que descrevem as vias de formação de AGEs, seu metabolismo, os principais mecanismos de ação dessas substâncias no desencadeamento dos processos patológicos, bem como os métodos de determinação de AGEs em amostras biológicas. Este artigo aponta, ainda, novas perspectivas de terapias anti-AGEs, a exemplo de estudos envolvendo a ação de compostos naturais dos alimentos, que podem oferecer potencial terapêutico para os portadores de diabetes ou de outras patologias associadas ao acúmulo degenerativo de AGEs.

Tetrahydrocurcumin inhibits HT1080 cell migration and invasion via downregulation of MMPs and uPA

AIM

Tetrahydrocurcumin (THC) is an active metabolite of curcumin. It has been reported to have similar pharmacological activity to curcumin. The proteases that participate in extracellular matrix (ECM) degradation are involved in cancer cell metastasis. The present study investigates the effect of an ultimate metabolite of curcumin, THC, on the invasion and motility of highly-metastatic HT1080 human fibrosarcoma cells.

METHODS

The effect of THC on HT1080 cell invasion and migration was determined using Boyden chamber assay. Cell-adhesion assay was used for examining the binding of cells to ECM molecules. Zymography assay was used to analyze the effect of THC on matrix metalloproteinase (MMP)-2, MMP-9, and urokinase plasminogen activator (uPA) secretion from HT1080 cells. Tissue inhibitor of metalloproteinase (TIMP)-2 and membrane-type 1 matrix metalloproteinase (MT1-MMP) proteins levels were analyzed by Western blotting.

RESULTS

Treatment with THC reduced HT1080 cell invasion and migration in a dose-dependent manner. THC also decreased the cell adhesion to Matrigel and laminin-coated plates. Analysis by zymography demonstrated that treatment with THC reduced the levels of MMP-2, MMP-9, and uPA. THC also inhibited the levels of MT1-MMP and TIMP-2 proteins detected by Western blot analysis.

CONCLUSION

Our findings revealed that THC reduced HT1080 cell invasion and migration. The inhibition of cancer cell invasion is associated with the downregulation of ECM degradation enzymes and the inhibition of cell adhesion to ECM proteins.

Combination of diabetes and cataract worsens the oxidative stress and micronutrient status in Indians

OBJECTIVES

We examined the synergism of cataract and diabetes in micronutrient and antioxidant statuses versus diabetes mellitus and cataract alone.

METHODS

Indian patients with type 2 diabetes mellitus (D; n = 76), those without diabetes and with cataract (NDC; n = 100), those with diabetes and cataract (DC; n = 53), and age- and sex-matched healthy controls (n = 90) 50-70 y were investigated. Plasma oxidative stress as thiobarbituric acid-reactive substances (TBARS) and the status of 11 micronutrients were studied as lens TBARS, opacity, and ratio of soluble to total proteins in patients with cataract with or without diabetes. Lipid profile, fasting glucose, and postprandial glucose were measured for all subjects.

RESULTS

A subnormal status of ascorbic acid, beta-carotene, thiamine, and ceruloplasmin was elicited for all four study groups. Plasma TBARS and fasting glucose were significantly higher in the DC group than in the NDC (P < 0.05), D, and control groups. Lens TBARS were comparable between the NDC and DC groups (5.5 and 5.08 nm/g of lens). Chi-square values for lens turbidity within the DC and NDC groups and for the ratio of soluble to total proteins and opacity within the NDC group were significant (P < 0.01). The prevalence of poor riboflavin status was 30-36% in all patients and 15-22.5% in controls. Men in the DC group showed a higher value of glycosylated hemoglobin than did men from the D group. Multivariate analysis of variance indicated significant interactions (P < 0.02) between HS and socioeconomic grades for fasting glucose and high-density lipoprotein levels, riboflavin status, plasma vitamin C, TBARS, and selenium. The DC group was found to be significantly different from the other groups with respect to beta-coefficients of a logistic regression equation for plasma levels of selenium, zinc, iron, thiamine, triacylglycerols, total cholesterol, ceruloplasmin, vitamin A, and superoxide dismutase.

CONCLUSION

The combination of diabetes and cataract coupled with gender bias and influence of socioeconomic factors seem to be associated with worsening of micronutrient status, oxidative stress, and lens opacity.

Endproducts and receptor of advanced glycation and lipoxidation (AGE, ALE, RAGE) and chronic diseases – a food perspective

Background: Chronic diseases as well as complications to acute and chronic disease are repeatedly associated with accumulation in the body of glycated and lipoxidated proteins and peptides. These molecules are strongly associated with activation of a specific receptor called RAGE and a long-lasting exaggerated level of inflammation in the body. Methods: PubMed reports in excess of 5000 papers plus about 14000 articles about the related HbA1c, most of them published in the last five years. Most of available abstracts have been read and circa 800 full papers studied in detail. Results: RAGE, a member of the immunoglobulin superfamily of cell surface molecules and receptor for advanced glycation endproducts, functions as a master switch, induces sustained activation of NF-κB, suppresses a series of endogenous autoregulatory functions and converts long-lasting pro-inflammatory signals into sustained cellular dysfunction and disease. Its activation is associated with high levels of dysfunctioning proteins in body fluids and tissues, and strongly associated with a series of diseases from allergy and Alzheimer to rheumatoid arthritis and urogenital disorders. Heat-treatment, irradiation and ionisation of foods increase the content in foods of AGE/ALE. Conclusions: Some processed foods are much like tobacco smoking great contributors to accumulation of glycated and lipoxidated molecules in the tissues. Change of life style: avoidance of foods rich in deranged proteins and peptides and increased consumption of antioxidants, especially polyphenols counteracts such a development.

Future strategies to prevent renal microvascular disease complications in diabetes

Nephropathy is one of the major chronic microvascular complications of diabetes. The epidemic of Type 2 diabetes and related incidence of end-stage renal disease is progressively increasing worldwide and represents a major public health concern that will seriously challenge any healthcare provider in the world. Despite a number of improvements in patient care, we are still unable to ameliorate or prevent the progression towards end-stage renal disease in the diabetic population. Hypertension and metabolic control appear to interact, resulting in the relentless decline in renal function observed in diabetic patients. Further understanding of the underlying mechanisms, and the development of new treatments against newly identified targets, is crucial for the prevention of this deadly microvascular diabetic complication.

Advanced glycation and lipoxidation end products--amplifiers of inflammation: the role of food

BACKGROUND

High levels of glycated and lipoxidated proteins and peptides in the body are repeatedly associated with chronic diseases. These molecules are strongly associated with activation of a specific receptor called RAGE and a long-lasting exaggerated level of inflammation in the body.

METHODS

PubMed reports over 5000 papers plus >13,500 articles about the related HbA(1c), most of them published in the past 5 years. Most of the available abstracts have been read and approximately 800 full papers have been studied.

RESULTS

RAGE, a member of the immunoglobulin superfamily of cell surface molecules and receptor for advanced glycation end products, known since 1992, functions as a master switch, induces sustained activation of nuclear factor kappaB (NFkappaB), suppresses a series of endogenous autoregulatory functions, and converts long-lasting proinflammatory signals into sustained cellular dysfunction and disease. Its activation is associated with high levels of dysfunctioning proteins in body fluids and tissues, and is strongly associated with a series of diseases from allergy and Alzheimers to rheumatoid arthritis and urogenital disorders. Heat treatment, irradiation, and ionization of foods increase the content of dysfunctioning molecules.

CONCLUSIONS

More than half of the studies are performed in diabetes and chronic renal diseases; there are few studies in other diseases. Most of our knowledge is based on animal studies and in vitro studies. These effects are worth further exploration both experimentally and clinically. An avoidance of foods rich in deranged proteins and peptides, and the consumption of antioxidants, especially polyphenols, seem to counteract such a development.

Tetrahydrocurcumin prevents brain lipid peroxidation in streptozotocin-induced diabetic rats

Oxidative damage has been suggested to be a contributory factor in the development and complication of diabetes. To investigate the effect of tetrahydrocurcumin (THC) on the occurrence of oxidative stress in the brain of rats during diabetes, we investigated the extent of oxidative damage as well as the status of the antioxidant defense system. Oral administration of THC at 80 mg/kg of body weight to diabetic rats for 45 days resulted in a significant reduction in blood glucose and significant increase in plasma insulin levels. In addition, THC caused significant increases in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, and reduced glutathione in the brains of diabetic rats with significant decrease in the lipid peroxidative markers thiobarbituric acid-reactive substances and hydroperoxides in brain, suggesting efficacy for protection against lipid peroxidation-induced membrane damage. The effect of THC was greater than that of curcumin. Results of the present study suggest that THC showed antioxidant effects in addition to its antidiabetic effect in type 2 diabetic rats.

Curcumin attenuates dimethylnitrosamine-induced liver injury in rats through Nrf2-mediated induction of heme oxygenase-1

Curcumin (diferuloymethane), a yellow colouring agent present in the rhizome of Curcuma longa Linn (Zingiberaceae), has been reported to possess anti-inflammatory, antioxidant, antimutagenic and anticarcinogenic activities. Curcumin exerts its chemoprotective and chemopreventive effects via multiple mechanisms. It has been reported to induce expression of the antioxidant enzymes in various cell lines. Heme oxygenase-1 (HO-1) is an important antioxidant enzyme that plays a pivotal role in cytoprotection against noxious stimuli of both endogenous and exogenous origin. In the present study, we found that oral administration of curcumin at 200mg/kg dose for four consecutive days not only protected against dimethylnitrosamine (DMN)-induced hepatic injury, but also resulted in more than three-fold induction of HO-1 protein expression as well as activity in rat liver. Inhibition of HO-1 activity by zinc protoporphyrin-IX abrogated the hepatoprotective effect of curcumin against DMN toxicity. NF-E2-related factor 2 (Nrf2) plays a role in the cellular protection against oxidative stress through antioxidant response element (ARE)-directed induction of several phase-2 detoxifying and antioxidant enzymes including HO-1. Curcumin administration resulted in enhanced nuclear translocation and ARE-binding of Nrf2. Taken together, these findings suggest that curcumin protects against DMN-induced hepatotoxicity, at least in part, through ARE-driven induction of HO-1 expression.

Effect of curcumin on chromium-induced oxidative damage in male reproductive system

Hexavalent chromium, an environmental contaminant, undergoes redox cycling with generation of free radicals inside the biological system. Curcumin, the yellow bioactive component of turmeric has established its antioxidant activities. The present study evaluates possible ameliorating effects of curcumin on potassium dichromate (K(2)Cr(2)O(7)) (hexavalent chromium) induced reproductive toxicity in adult male Sprague-Dawley rats. Three experimental groups, each consisting of eight rats, were treated with 0.4mg K(2)Cr(2)O(7)/kg bw/day, 0.4mg K(2)Cr(2)O(7)/kg bw/day+20mg curcumin/kg bw on every alternate day and 20mg curcumin/kg bw on every alternate day, respectively, for 26 days. Altered testicular histology, reduced sperm count, low testosterone level, decreased accessory sex organs weight, enhanced lipid peroxidation along with reduced SOD and catalase activities were observed following K(2)Cr(2)O(7) exposure while curcumin supplementation along with K(2)Cr(2)O(7) exposure had shown to prevent the altered parameters. The results thus suggest that curcumin may have a protective role against chromium(VI) induced oxidative damage in male reproductive system.

Respiratory protein–generated reactive oxygen species as an antimicrobial strategy

The evolution of the host-pathogen relationship comprises a series of invasive-defensive tactics elicited by both participants. The stereotype is that the antimicrobial immune response requires multistep processes. Little is known about the primordial immunosurveillance system, which probably has components that directly link sensors and effectors. Here we found that the respiratory proteins of both the horseshoe crab and human were directly activated by microbial proteases and were enhanced by pathogen-associated molecular patterns, resulting in the production of more reactive oxygen species. Hemolytic virulent pathogens, which produce proteases as invasive factors, are more susceptible to this killing mechanism. This 'shortcut' antimicrobial strategy represents a fundamental and universal mode of immunosurveillance, which has been in existence since before the split of protostomes and deuterostomes and still persists today.

BENEFICIAL ROLE OF CURCUMIN IN SKIN DISEASES

In recent years, considerable interest has been focused on curcumin a compound, isolated from turmeric. Curcumin is used as a coloring, flavoring agent and has been traditionally used in medicine and cuisine in India. The varied biological properties of curcumin and lack of toxicity even when administered at higher doses makes it attractive to explore its use in various disorders like tumors of skin, colon, duodenum, pancreas, breast and other skin diseases. This chapter reviews the data on the use of curcumin for the chemoprevention and treatment of various skin diseases like scleroderma, psoriasis and skin cancer. Curcumin protects skin by quenching free radicals and reducing inflammation through nuclear factor-KB inhibition. Curcumin treatment also reduced wound-healing time, improved collagen deposition and increased fibroblast and vascular density in wounds thereby enhancing both normal and impaired wound-healing. Curcumin has also been shown to have beneficial effect as a proangiogenic agent in wound-healing by inducing transforming growth factor-beta, which induces both angiogenesis and accumulation of extracellular matrix, which continues through the remodeling phase of wound repair. These studies suggest the beneficial effects of curcumin and the potential of this compound to be developed as a potent nontoxic agent for treating skin diseases.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

Experimental diabetes treated with Achillea santolina: effect on pancreatic oxidative parameters

Oxidative stress is produced under diabetic condition and is likely involved in progression of pancreatic damage found in diabetes. In the present study, we examined possible protective effect of Achillea santolina L. (Compositae) against pancreatic damage in streptozotocin (STZ)-treated diabetic rats. Achillea santolina extract (ASE) is used by the traditional healers in many part of Iraq, as a hypoglycaemic agent. We evaluated the effect of ASE on blood glucose level, serum nitric oxide (NO) concentration and the oxidative stress status in rat pancreatic tissue. STZ was injected intraperitonealy at a single dose of 40mgkg(-1) to induce diabetes. ASE (0.1g/kgday) was orally administered to a group of diabetic rats for 30 consecutive days. Results showed significant reduction in the activities of superoxide dismutase (SOD), catalase (CAT) and pancreatic glutathione (GSH) levels in the diabetic rats compared to the control subjects. On the other hand, blood glucose level, serum NO, malondialdehyde (MDA), a marker of lipid peroxidation, protein oxidation indices including protein carbonyl (PCO) and advanced oxidation protein products (AOPP) were significantly elevated in pancreas of the diabetic group. Treatment with ASE reduced blood glucose level, serum NO, pancreatic MDA, PCO and AOPP. In addition, the content of GSH was restored to the normal level of the control group. Furthermore, ASE significantly increased CAT and SOD activities in ASE-treated rats. Based on our data, it can be concluded that Achillea santolina have a high hypoglycaemic activity and this may be attributed to its antioxidative potential.

Effects of curcumin on retinal oxidative stress and inflammation in diabetes

BACKGROUND

Oxidative stress and inflammation are implicated in the pathogenesis of retinopathy in diabetes. The aim of this study is to examine the effect of curcumin, a polyphenol with antioxidant and anti-inflammatory properties, on diabetes-induced oxidative stress and inflammation in the retina of rats.

METHODS

A group of streptozotocin-induced diabetic rats received powdered diet supplemented with 0.05% curcumin (w/w), and another group received diet without curcumin. The diets were initiated soon after induction of diabetes, and the rats were sacrificed 6 weeks after induction of diabetes. The retina was used to quantify oxidative stress and pro-inflammatory markers.

RESULTS

Antioxidant capacity and the levels of intracellular antioxidant, GSH (reduced form of glutathione) levels were decreased by about 30-35%, and oxidatively modified DNA (8-OHdG) and nitrotyrosine were increased by 60-70% in the retina of diabetic rats. The levels of interleukin-1beta (IL-1beta) and vascular endothelial growth factor (VEGF) were elevated by 30% and 110% respectively, and the nuclear transcription factor (NF-kB) was activated by 2 fold. Curcumin administration prevented diabetes-induced decrease in the antioxidant capacity, and increase in 8-OHdG and nitrotyrosine; however, it had only partial beneficial effect on retinal GSH. Curcumin also inhibited diabetes-induced elevation in the levels of IL-1beta, VEGF and NF-kB. The effects of curcumin were achieved without amelioration of the severity of hyperglycemia.

CONCLUSION

Thus, the beneficial effects of curcumin on the metabolic abnormalities postulated to be important in the development of diabetic retinopathy suggest that curcumin could have potential benefits in inhibiting the development of retinopathy in diabetic patients.