Repletion of antioxidant status by EGCG and retardation of oxidative damage induced macromolecular anomalies in aged rats

Current Nutritional and Pharmacological Approaches for Attenuating Sarcopenia

Sarcopenia is characterized by a gradual slowing of movement due to loss of muscle mass and quality, decreased power and strength, increased risk of injury from falls, and often weakness. This review will focus on recent research trends in nutritional and pharmacological approaches to controlling sarcopenia. Because nutritional studies in humans are fairly limited, this paper includes many results from nutritional studies in mammals. The combination of resistance training with supplements containing amino acids is the gold standard for preventing sarcopenia. Amino acid (HMB) supplementation alone has no significant effect on muscle strength or muscle mass in sarcopenia, but the combination of HMB and exercise (whole body vibration stimulation) is likely to be effective. Tea catechins, soy isoflavones, and ursolic acid are interesting candidates for reducing sarcopenia, but both more detailed basic research on this treatment and clinical studies in humans are needed. Vitamin D supplementation has been shown not to improve sarcopenia in elderly individuals who are not vitamin D-deficient. Myostatin inhibitory drugs have been tried in many neuromuscular diseases, but increases in muscle mass and strength are less likely to be expected. Validation of myostatin inhibitory antibodies in patients with sarcopenia has been positive, but excessive expectations are not warranted.

Polyphenols Mediate Neuroprotection in Cerebral Ischemic Stroke-An Update

Stroke is one of the main causes of mortality and disability, and it is due to be included in monetary implications on wellbeing frameworks around the world. Ischemic stroke is caused by interference in cerebral blood flow, leading to a deficit in the supply of oxygen to the affected region. It accounts for nearly 80-85% of all cases of stroke. Oxidative stress has a significant impact on the pathophysiologic cascade in brain damage leading to stroke. In the acute phase, oxidative stress mediates severe toxicity, and it initiates and contributes to late-stage apoptosis and inflammation. Oxidative stress conditions occur when the antioxidant defense in the body is unable to counteract the production and aggregation of reactive oxygen species (ROS). The previous literature has shown that phytochemicals and other natural products not only scavenge oxygen free radicals but also improve the expressions of cellular antioxidant enzymes and molecules. Consequently, these products protect against ROS-mediated cellular injury. This review aims to give an overview of the most relevant data reported in the literature on polyphenolic compounds, namely, gallic acid, resveratrol, quercetin, kaempferol, mangiferin, epigallocatechin, and pinocembrin, in terms of their antioxidant effects and potential protective activity against ischemic stroke.

Physiologically-obtainable polyphenol exposures modulate reactive oxygen and nitrogen species signaling in the C2C12 model of skeletal muscle ageing

Age-related frailty is a significant health and social care burden, with limited treatment options. There is a lack of suitable cell culture model for screening large numbers of test compounds to identify those which promote healthy skeletal muscle function. This paper describes the characterization of reactive oxygen and nitrogen species (RONS) signalling changes in young and aged myoblasts and myotubes using C₂C₁₂ cells, and the application of aged cultures to assess the effect of dietary polyphenols on RONS signalling. Aged myoblasts and myotubes showed significantly increased reactive oxygen species (p < 0.01 and p < 0.001 respectively), nitric oxide (p < 0.05 for myoblasts and myotubes), and lipid peroxidation (p < 0.05 for myoblasts and myotubes). Nine polyphenols were assessed in aged myoblasts and myotubes using concentrations and incubation times consistent with known pharmacokinetic parameters for these compounds. Although several polyphenols were seen to reduce single markers of RONS signalling, only kaempferol and resveratrol significantly reduced multiple markers in both cell models. Modulation of enzymatic antioxidant activities was assessed as a possible mechanism of action, although superoxide dismutase and catalase activities were significantly reduced in aged (versus young) myotubes (p < 0.01 and p < 0.05 respectively), no effect of polyphenol treatment on these enzyme activities were observed. Overall, this research has shown the utility of the C₂C₁₂ model (myoblasts and myotubes) for screening compounds in aged muscle, and that resveratrol and kaempferol (using pharmacokinetically-informed exposures) can modulate RONS signalling in skeletal muscle cells after an acute exposure.

Melatonin and multiple sclerosis: antioxidant, anti-inflammatory and immunomodulator mechanism of action

BACKGROUND

Melatonin is an indole hormone secreted primarily by the pineal gland that showing anti-oxidant, anti-inflammatory and anti-apoptotic capacity. It can play an important role in the pathophysiological mechanisms of various diseases. In this regard, different studies have shown that there is a relationship between Melatonin and Multiple Sclerosis (MS). MS is a chronic immune-mediated disease of the Central Nervous System.

AIM

The objective of this review was to evaluate the mechanisms of action of melatonin on oxidative stress, inflammation and intestinal dysbiosis caused by MS, as well as its interaction with different hormones and factors that can influence the pathophysiology of the disease.

RESULTS

Melatonin causes a significant increase in the levels of catalase, superoxide dismutase, glutathione peroxidase, glutathione and can counteract and inhibit the effects of the NLRP3 inflammasome, which would also be beneficial during SARS-CoV-2 infection. In addition, melatonin increases antimicrobial peptides, especially Reg3β, which could be useful in controlling the microbiota.

CONCLUSION

Melatonin could exert a beneficial effect in people suffering from MS, running as a promising candidate for the treatment of this disease. However, more research in human is needed to help understand the possible interaction between melatonin and certain sex hormones, such as estrogens, to know the potential therapeutic efficacy in both men and women.

Beneficial Effects of Flavonoids on Skeletal Muscle Health: A Systematic Review and Meta-Analysis

Skeletal muscle (SkM) is a highly dynamic tissue that responds to physiological adaptations or pathological conditions, and SkM mitochondria play a major role in bioenergetics, regulation of intracellular calcium homeostasis, pro-oxidant/antioxidant balance, and apoptosis. Flavonoids are polyphenolic compounds with the ability to modulate molecular pathways implicated in the development of mitochondrial myopathy. Therefore, it is pertinent to explore its potential application in conditions such as aging, disuse, denervation, diabetes, obesity, and cancer. To evaluate preclinical and clinical effects of flavonoids on SkM structure and function. We performed a systematic review of published studies, with no date restrictions applied, using PubMed and Scopus. The following search terms were used: "flavonoids" OR "flavanols" OR "flavones" OR "anthocyanidins" OR "flavanones" OR "flavan-3-ols" OR "catechins" OR "epicatechin" OR "(-)-epicatechin" AND "skeletal muscle." The studies included in this review were preclinical studies, clinical trials, controlled clinical trials, and randomized-controlled trials that investigated the influence of flavonoids on SkM health. Three authors, independently, assessed trials for the review. Any disagreement was resolved by consensus. The use of flavonoids could be a potential tool for the prevention of muscle loss. Their effects on metabolism and on mitochondria function suggest their use as muscle regulators.

Senescence-Mediated Redox Imbalance in Liver and Kidney: Antioxidant Rejuvenating Potential of Green Tea Extract

This study investigates the catechin composition and protective effect of green tea extract on senescence-mediated redox imbalance in the livers and kidneys of aged mice. The results showed that the seven catechins in the green tea extract analyzed in this study could be completely separated within 30 min and the main components of catechins in green tea extract were EGCG, EGC and ECG. In terms of the anti-senescence effects of green tea extract, green tea extract supplementation at doses of 125, 625 and 1250 mg/kg for 4 weeks significantly alleviated the senescence-mediated redox imbalance, as exhibited from significantly (p < 0.05) reduced thiobarbituric acid-reactive substances (TBARS) and protein carbonyls levels in the serum, and increased glutathione (GSH) and total thiols contents in the plasma. Additionally, hepatic and renal protein carbonyls levels were significantly diminished (p < 0.05) and the activities of superoxide dismutase (SOD), catalase, glucose-6-phosphate dehydrogenase (G6PD), glutathione peroxidase (GSH-Px) and glutathione reductase (GSH-Rd) in the liver and kidney were remarkably elevated (p < 0.05). Overall, these results clearly show that green tea extract exhibits extremely potent protective effects against senescence-mediated redox imbalance in the livers and kidneys of mice by inhibiting oxidative damage of lipids and proteins and increasing the activities of antioxidant enzymes in organs.

Identification of regulated proteins by epigallocatechin gallate treatment in an ischemic cerebral cortex animal model: a proteomics approach

Ischemic stroke is a fatal disease that has long-term disability. It induces excessive oxidative stress generation and cellular metabolic disorders, result in tissue damage. Epigallocatechin gallate (EGCG) is a naturally derived flavonoid with strong antioxidant property. We previously reported the neuroprotective effect of EGCG in ischemic stroke. The defensive mechanisms of stroke are very diverse and complex. This study investigated specific proteins that are regulated by EGCG treatment in the ischemic brain damage. Middle cerebral artery occlusion (MCAO) was performed to induce focal cerebral ischemia. EGCG (50 mg/kg) or vehicle was intraperitoneally administered just prior to MCAO. MCAO induced severe neurological deficits and disorders. EGCG treatment alleviated these neurological disorder and damage. Cerebral cortex was used for this study. Two-dimensional gel electrophoresis and mass spectrometry were performed to detect the proteins altered by EGCG. We identified various proteins that were changed between vehicle- and EGCG-treated animals. Among these proteins, isocitrate dehydrogenase, dynamin-like protein 1, and γ-enolase were decreased in vehicle-treated animals, while EGCG treatment prevented these decreases. However, pyridoxal-5'-phosphate phosphatase and 60 kDa heat shock protein were increased in vehicle-treated animals with MCAO injury. EGCG treatment attenuated these increases. The changes in these proteins were confirmed by Western blot and reverse transcription-PCR analyses. These proteins were associated with cellular metabolism and neuronal regeneration. Thus, these findings can suggest that EGCG performs a defensive mechanism in ischemic damage by regulating specific proteins related to energy metabolism and neuronal protection.

Impacts of Green Tea on Joint and Skeletal Muscle Health: Prospects of Translational Nutrition

Osteoarthritis and sarcopenia are two major joint and skeletal muscle diseases prevalent during aging. Osteoarthritis is a multifactorial progressive degenerative and inflammatory disorder of articular cartilage. Cartilage protection and pain management are the two most important strategies in the management of osteoarthritis. Sarcopenia, a condition of loss of muscle mass and strength, is associated with impaired neuromuscular innervation, the transition of skeletal muscle fiber type, and reduced muscle regenerative capacity. Management of sarcopenia requires addressing both skeletal muscle quantity and quality. Emerging evidence suggests that green tea catechins play an important role in maintaining healthy joints and skeletal muscle. This review covers (i) the prevalence and etiology of osteoarthritis and sarcopenia, such as excessive inflammation and oxidative stress, mitochondrial dysfunction, and reduced autophagy; (ii) the effects of green tea catechins on joint health by downregulating inflammatory signaling mediators, upregulating anabolic mediators, and modulating miRNAs expression, resulting in reduced chondrocyte death, collagen degradation, and cartilage protection; (iii) the effects of green tea catechins on skeletal muscle health via maintaining a dynamic balance between protein synthesis and degradation and boosting the synthesis of mitochondrial energy metabolism, resulting in favorable muscle homeostasis and mitigation of muscle atrophy with aging; and (iv) the current study limitations and future research directions.

EGCG exerts its protective effect by mitigating the release of lysosomal enzymes in aged rat liver on exposure to high cholesterol diet

The aim is to test the hypothesis whether the cholesterol loaded lysosomes are capable of mediating lysosomal membrane permeabilization (LMP) during aging and to study the efficacy of epigallocatechin-3-gallate (EGCG) in preserving the lysosomal membrane stability. Aged rats were fed with high cholesterol diet (HCD) and treated with EGCG orally. Serum and tissue lipid status, cholesterol levels in lysosomal fraction, activities of lysosomal enzymes in lysosomal, and cytosolic fractions were measured. Transmission electron microscopic studies (TEM), oil red "O" (ORO) staining, and immunohistochemical analysis of oxidized low density lipoprotein (OxLDL) were carried out. Significant increase in serum, tissue lipid profile, and lysosomal cholesterol levels were observed in aged HCD-fed rats with a concomitant decrease in high density lipoprotein (HDL) levels. We also observed a significant increase in lipid accumulation in hepatocytes of aged HCD-fed rats by TEM, ORO, and immunohistochemical staining. Upon treatment with EGCG to aged HCD-fed animals, we found augmented levels of HDL with a concomitant decrease in lysosomal cholesterol levels and other lipoproteins. TEM studies and immunohistochemistry of OxLDL also showed a marked reduction in lipid deposition of hepatocytes. Thus, EGCG has preserved the lysosomal membrane stability in HCD stressed aged rats. SIGNIFICANCE OF THE STUDY: The research article is focused mainly on the effect of EGCG and its capability on mitigating the release of lysosomal enzymes in aged animals fed with HCD. The study signifies the cellular function of the organelle lysosome following administration of aged rats with HCD, which would make the readers to understand the action of EGCG and the interrelationship of both cholesterol and activity of lysosomes when cholesterol is loaded.

Long-term supplementation with EGCG and beta-alanine decreases mortality but does not affect cognitive or muscle function in aged mice

We have previously shown that 6weeks of a diet containing epigallocatechin gallate (EGCG) and beta-alanine (B-ALA) was not effective in improving either cognitive or muscle function in aged (18month) mice (Gibbons et al. Behav Brain Res 2014). However, diet reduced oxidative stress in the brain, and previous studies using longer-term interventions have documented beneficial effects in cognitive, but not muscle, function. Therefore, we investigated the effect of 6months of feeding on measures of cognitive and muscle function in mice. Mice (12months, N=15/group) were fed AIN-93M containing 0.15% EGCG and 0.34% B-ALA or standard AIN-93M for 6months, then underwent a battery of tests for cognitive and muscle function at 18months. Interestingly, a higher percentage of mice receiving EGCG and B-ALA (E+B, 80%) survived to study end compared to control (Ctrl, 40%) mice (p=0.02). E+B did not affect arm preference in the Y-maze test (p=0.74, novel arm) and did not alter performance in an active avoidance test (p=0.16, avoidances per 50 trials). E+B increased rotarod performance (p=0.03), did not affect grip strength (p=0.91), and decreased time to exhaustion in a treadmill fatigue test (p=0.02) compared to Ctrl. In conclusion, E+B reduced mortality, had no effect on cognitive function and variable effects on muscle function.

Dose-dependent decrease in mortality with no cognitive or muscle function improvements due to dietary EGCG supplementation in aged mice

We have previously shown that a diet containing epigallocatechin gallate (EGCG) and beta-alanine is not effective in improving either cognitive or muscle function in aged (18 month) mice (Gibbons et al., Behav. Brain Res., 2014, 272:131–140; Pence et al., Appl. Physiol. Nutr. Metab., 2016, 41(2): 181–190). However, this diet reduced oxidative stress in the brain, and previous studies using longer term interventions and other doses have documented beneficial effects in cognitive and muscle function, especially with EGCG. Here we hypothesized that a different dose of EGCG or longer feeding period would be more efficacious in improving cognition. Aged (21–25 mo) Balb/cByJ male mice underwent 63 days of feeding with EGCG at 0, 0.091, or 3.67 mg/g AIN-93M diet and were then subjected to a battery of cognitive and muscle function tests. EGCG feeding at either of the 2 doses did not alter preference for novel versus familiar arm in the Y-maze test (p = 0.29) and did not affect learning in the active avoidance test (p = 0.76). Similarly, EGCG did not affect preference for novel versus familiar mice in a social discrimination test (p = 0.17). Likewise, there was no effect of EGCG on muscle function by grip strength (p = 0.16), rotarod (p = 0.18), or treadmill test to exhaustion (p = 0.25). EGCG reduced mortality in a dose-dependent fashion (p = 0.05, log-rank test for trend), with 91% of high EGCG, 72% of low EGCG, and 55% of control mice surviving to the end of the study. In conclusion, EGCG improves survival in aged mice but does not affect cognitive or muscle function.

Polyphenols in Health and Disease

Deadly diseases, such as cardiovascular diseases and cancer, remain the major health problems worldwide. Research in cardiovascular diseases and genome-wide association studies were successful in indentifying the gene loci associated with these threatening diseases. Yet, a substantial number of casual factors remain unexplained. Over the last decade, a better understanding of molecular and biochemical mechanisms of cardiac diseases led to developing a rationale for combining various protective agents, such as polyphenols, to target multiple signaling pathways. The present review article summarizes recent advances of the use of polyphenols against diseases, such as cardiac diseases.

The effects of 30 mT electromagnetic fields on hippocampus cells of rats

BACKGROUND

Despite the use of electromagnetic waves in the treatment of some acute and chronic diseases, application of these waves in everyday life has created several problems for humans, especially the nerve system. In this study, the effects of 30mT electromagnetic fields (EMFs) on the hippocampus is investigated.

METHODS

Twenty-four 5-month Wistar rats weighing 150-200 g were divided into two groups. The experimental group rats were under the influence of an EMF at an intensity of 3 mT for approximately 4 hours a day (from 8 AM to 12 PM) during 10 weeks. After the hippocampus was removed, thin slides were prepared for transmission electron microscope (TEM) to study the ultrastructural tissue. Cell death detection POD kits were used to determine the apoptosis rate.

RESULTS

The results of the TEM showed that, in the hippocampus of the experimental group, in comparison to the control group, there was a substantial shift; even intracellular organelles such as the mitochondria were morphologically abnormal and uncertain. The number of apoptotic cells in the exposed group compared to the control group showed significant changes.

CONCLUSIONS

Similar to numerous studies that have reported the effects of EMFs on nerves system, it was also confirmed in this lecture. Hence, the hippocampus which is important in regulating emotions, behavior, motivation, and memory functions, may be impaired by the negative impacts of EMFs.

Effects of exercise and dietary epigallocatechin gallate and β-alanine on skeletal muscle in aged mice

Aging leads to sarcopenia and loss of physical function. We examined whether voluntary wheel running, when combined with dietary supplementation with (-)-epigallocatechin-3-gallate (EGCG) and β-alanine (β-ALA), could improve muscle function and alter gene expression in the gastrocnemius of aged mice. Seventeen-month-old BALB/cByJ mice were given access to a running wheel or remained sedentary for 41 days while receiving either AIN-93M (standard feed) or AIN-93M containing 1.5 mg·kg(-1) EGCG and 3.43 mg·kg(-1) β-ALA. Mice underwent tests over 11 days from day 29 to day 39 of the study period, including muscle function testing (grip strength, treadmill exhaustive fatigue, rotarod). Following a rest day, mice were euthanized and gastrocnemii were collected for analysis of gene expression by quantitative PCR. Voluntary wheel running (VWR) improved rotarod and treadmill exhaustive fatigue performance and maintained grip strength in aged mice, while dietary intervention had no effect. VWR increased gastrocnemius expression of several genes, including those encoding interleukin-6 (Il6, p = 0.001), superoxide dismutase 1 (Sod1, p = 0.046), peroxisome proliferator-activated receptor gamma coactivator 1-α (Ppargc1a, p = 0.013), forkhead box protein O3 (Foxo3, p = 0.005), and brain-derived neurotrophic factor (Bdnf, p = 0.008), while reducing gastrocnemius levels of the lipid peroxidation marker 4-hydroxynonenal (p = 0.019). Dietary intervention alone increased gastrocnemius expression of Ppargc1a (p = 0.033) and genes encoding NAD-dependent protein deacetylase sirtuin-1 (Sirt1, p = 0.039), insulin-like growth factor I (Igf1, p = 0.003), and macrophage marker CD11b (Itgam, p = 0.016). Exercise and a diet containing β-ALA and EGCG differentially regulated gene expression in the gastrocnemius of aged mice, while VWR but not dietary intervention improved muscle function. We found no synergistic effects between dietary intervention and VWR.

Green tea in dermatology--myths and facts

Green tea consumption has a long tradition in Asian countries--especially China. The epidemiologically and experimentally observed anticarcinogenic and antiinflammatory effects of green tea have led to the implementation of green tea extracts in multiple therapeutic applications - both in dermatological and cosmeceutical preparations. The most abundant evidence exists for the anticarcinogenic and chemopreventive effect of green tea or its major constituent epigallocatechin-3-gallate. Almost equally evident is the effect in infectious diseases such as cutaneous viral infections. For external genital warts, a topical ointment with green tea extracts was licensed in the USA in 2010, and recently also in Europe. Experimental evidence pinpointing the block of central signal transduction factors in inflammatory mechanisms has led to the evaluation of catechins in inflammatory disorders such as atopic dermatitis. The belief of green tea as a "wonder weapon" against diseases dates back thousands of years. According to a Chinese legend, ancient Emperor Shen Nung noted a delightful aroma after some leaves of a nearby tree had fallen into boiling water. He immediately proclaimed the new "drink" as "heaven-sent", starting the belief - persisting until today - of green tea as a medication from nature against many different diseases. This review summarizes biological effects and clinical implications of green tea.

Antioxidant supplementation can reduce the survival costs of excess amino acid intake in honeybees

Over-consuming amino acids is associated with reduced survival in many species, including honeybees. The mechanisms responsible for this are unclear but one possibility is that excessive intake of amino acids increases oxidative damage. If this is the case, antioxidant supplementation may help reduce the survival costs of high amino acid intake. We tested this hypothesis in African honeybees (Apis mellifera scutellata) using the major antioxidant in green tea, epigallocatechin-3-gallate (EGCG). We first determined the dose-range of EGCG that improved survival of caged honeybees fed sucrose solution. We then provided bees with eight diets that differed in their ratio of essential amino acids (EAA) to carbohydrate (C) (0:1, 1:250, 1:100, 1:75, 1:50, 1:25, 1:10, 1:5 EAA:C) and also in their EGCG dose (0.0 or 0.4 mM). We found that bees fed sucrose only solution survived better than bees fed EAA diets. Despite this, bees preferred a diet that contained intermediate ratios of EAA:C (ca. 1:25), which may represent the high demands for nitrogen of developing nurse bees. EGCG supplementation improved honeybee survival but only at an intermediate dose (0.3-0.5 mM) and in bees fed low EAA diets (1:250, 1:100 EAA:C). That EGCG counteracted the lifespan reducing effects of eating low EAA diets suggests that oxidative damage may be involved in the association between EAAs and lifespan in honeybees. However, that EGCG had no effect on survival in bees fed high EAA diets suggests that there are other physiological costs of over-consuming EAAs in honeybees.

Effects of a green tea extract, Polyphenon E, on systemic biomarkers of growth factor signalling in women with hormone receptor-negative breast cancer

BACKGROUND

Observational and experimental data support a potential breast cancer chemopreventive effect of green tea.

METHODS

We conducted an ancillary study using archived blood/urine from a phase IB randomised, placebo-controlled dose escalation trial of an oral green tea extract, Polyphenon E (Poly E), in breast cancer patients. Using an adaptive trial design, women with stage I-III breast cancer who completed adjuvant treatment were randomised to Poly E 400 mg (n = 16), 600 mg (n = 11) and 800 mg (n = 3) twice daily or matching placebo (n = 10) for 6 months. Blood and urine collection occurred at baseline, and at 2, 4 and 6 months. Biological endpoints included growth factor [serum hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF)], lipid (serum cholesterol, triglycerides), oxidative damage and inflammatory biomarkers.

RESULTS

From July 2007-August 2009, 40 women were enrolled and 34 (26 Poly E, eight placebo) were evaluable for biomarker endpoints. At 2 months, the Poly E group (all dose levels combined) compared to placebo had a significant decrease in mean serum HGF levels (-12.7% versus +6.3%, P = 0.04). This trend persisted at 4 and 6 months but was no longer statistically significant. For the Poly E group, serum VEGF decreased by 11.5% at 2 months (P = 0.02) and 13.9% at 4 months (P = 0.05) but did not differ compared to placebo. At 2 months, there was a trend toward a decrease in serum cholesterol with Poly E (P = 0.08). No significant differences were observed for other biomarkers.

CONCLUSIONS

Our findings suggest potential mechanistic actions of tea polyphenols in growth factor signalling, angiogenesis and lipid metabolism.

Regulation of nodularin-induced apoptosis by epigallocatechin-3-gallate on fish lymphocytes in vitro

Nodularin is one of the most conspicuous and widespread pollutants that elicit water ecological hazards to fish, causing serious damage on the immune system and physiological functions. Nodularin can cause oxidative stress-induced apoptosis on fish lymphocytes. The regulatory effects of epigallocatechin-3-gallate (EGCG) at 10, 100, and 1000 μg/L levels on the antioxidant defense system and apoptosis of Carassius auratus lymphocytes exposed to a high dose of nodularin (100 μg/L) were quantified in vitro. EGCG reduced nodularin-induced oxidative damage on fish immune cells. This compound significantly increased the activities of superoxide dismutase and catalase and the level of glutathione but decreased the levels of intracellular reactive oxygen species and malondialdehyde. Flow cytometry results showed that the percentages of apoptotic cells after treatment with 10, 100, and 1000 μg/L EGCG for 12 h reached 27.9%, 19.1%, and 13.7%, respectively. By contrast, the nodularin alone-induced group showed a high percentage of apoptosis (44.2%). Western blot analysis showed the increased expression of bcl-2 and the decreased expression of bax and caspase-3 in EGCG-treated fish lymphocytes. EGCG also inhibited the potential collapse of the mitochondrial membrane. Overall, EGCG can inhibit nodularin-induced apoptosis and protect the normal immunity of fish by regulating bax/bcl-2 and blocking the downstream of mitochondrial apoptosis pathway with increased intracellular antioxidant enzyme activity.

Panax ginseng reduces oxidative stress and restores antioxidant capacity in aged rats

Nutritional antioxidants interact with cells in an active mode, including retrieving and sparing one another, to diminish oxidative stress. However, the intracellular balance of prooxidants and antioxidants becomes unbalanced, favoring prooxidants during the aging process. One hypothesis is that an aging-associated increase in oxidative stress is the primary cause of aging. Hence, the research hypothesis for this study is that Korean red ginseng reduces oxidative stress in vivo. Therefore, we investigated the efficacy of Korean red ginseng water extract (GWE) in reducing aging-associated oxidative stress by measuring lipid peroxidation and antioxidant levels in older rats compared with young rats. We observed a significant increase in the markers for oxidative damage (eg, lipid peroxidation) and markers for vital organ damage (eg, aspartate aminotransferase, alanine aminotransferase, urea, and creatinine levels) in aged rats. The oxidative damage was accompanied by a significant decrease in enzymatic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase, and nonenzymatic antioxidants such as reduced glutathione, vitamin E, and vitamin C. Aged rats fed a diet supplemented with Korean red ginseng water extract had significantly less oxidative damage, possibly by enhancing the enzymatic and nonenzymatic antioxidants status. Our data suggest that consumption of Korean red ginseng reduces lipid peroxidation and restores antioxidant capacity by suppressing oxidative stress in rats.

Cordycepin (3'-deoxyadenosine) attenuates age-related oxidative stress and ameliorates antioxidant capacity in rats

Free radical-induced oxidative damage is considered to be the most important consequence of the aging process. The activities and capacities of antioxidant systems of cells decline with increased age, leading to the gradual loss of pro-oxidant/antioxidant balance and resulting in increased oxidative stress. Our investigation was focused on the effects of cordycepin (3'-deoxyadenosine) on lipid peroxidation and antioxidation in aged rats. Age-associated decline in the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), reduced glutathione (GSH), vitamin C and vitamin E, and elevated levels of malondialdehyde (MDA) were observed in the liver, kidneys, heart and lungs of aged rats, when compared to young rats. Furthermore, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, and creatinine were found to be significantly elevated in aged rats compared to young rats. Aged rats receiving cordycepin treatment show increased activity of SOD, CAT, GPx, GR and GST, and elevated levels of GSH, and vitamins C and E such that the values of most of these parameters did not differ significantly from those found in young rats. In addition, the levels of MDA, AST, ALT, urea and creatinine became reduced upon administration of cordycepin to aged rats. These results suggest that cordycepin is effective for restoring antioxidant status and decreasing lipid peroxidation in aged rats.

Effect of fermented Panax ginseng extract (GINST) on oxidative stress and antioxidant activities in major organs of aged rats

The intracellular levels of oxidant and antioxidant balances are gradually distorted during the aging process. An age associated elevation of oxidative stress occurring throughout the lifetime is hypothesized to be the major cause of aging. The present study was undertaken to evaluate the putative antioxidant activity of the fermented Panax ginseng extract (GINST) on lipid peroxidation and antioxidant status of major organs of aged rats compared to young rats. Increased levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea and creatinine were observed in the serum of aged rats. Increased levels of malondialdehyde (MDA) and significantly lowered activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) were observed in the liver, kidneys, heart and lungs of aged rats, when compared with those in young rats. Quantitative analysis of the non-enzymatic antioxidants such as reduced glutathione (GSH), ascorbic acid and α-tocopherol levels showed significantly lower values in the liver, kidneys, heart and lungs of aged rats. On the other hand, administration of the fermented Panax ginseng extract (GINST) to aged rats resulted in increased activities of SOD, CAT, GPx, GR and GST as well as elevation in GSH, ascorbic acid and α-tocopherol levels. Besides, the level of MDA, AST, ALT, urea and creatinine were reduced on administration of GINST to aged rats. These results suggested that treatment of GINST can improve the antioxidant status during aging, thereby minimizing the oxidative stress and occurrence of age-related disorders associated with free radicals.

Green tea and prevention of esophageal and lung cancers

Green tea contains high concentrations of tea polyphenols that have shown inhibitory effects against the development, progress, and growth of carcinogen-induced tumors in animal models at different organ sites, including the esophagus and lung. Green tea polyphenols also have shown to suppress cell proliferation and induce apoptosis. Besides antioxidative property, green tea polyphenols have pro-oxidative activities under certain conditions and modulate phase II metabolic enzymes that can enhance the detoxification pathway of environmental toxicants and carcinogens. Although epidemiological studies have provided inconclusive results on the effect of green tea consumption against the development of esophageal and lung cancers in humans overall, the inverse association between green tea intake and risk of esophageal cancer risk is more consistently observed in studies with adequate control for potential confounders. Epidemiological studies also have demonstrated an inverse, albeit moderate, association between green tea consumption and lung cancer, especially in non-smokers. This article reviews data on the cancer-preventive activities of green tea extract and green tea polyphenols and possible mechanisms against the esophageal and lung carcinogenesis in experimental animals, and summarizes the current knowledge from epidemiological studies on the relationship between green tea consumption and esophageal and lung cancer risk in humans.

Mechanistic issues concerning cancer prevention by tea catechins

The cancer preventive activities of tea (Camellia sinensis, Theaceae) have been demonstrated in animal models for cancers at different organ sites and suggested by some epidemiological studies. Many mechanisms for cancer prevention have been proposed based on studies in cell lines, which demonstrated the modulation of signal transduction and metabolic pathways by (-)-epigallocatechin-3-gallate (EGCG), the most abundant and active polyphenol in green tea. These molecular events may result in cellular changes, such as enhancement of apoptosis, suppression of cell proliferation, and inhibition of angiogenesis. Nevertheless, it is not known whether these are the molecular mechanisms of inhibition of carcinogenesis in animals and humans. This article discusses the key issues involved in extrapolating results from cell line studies to mechanistic information in vivo and in translating animal studies to human cancer prevention.

Cancer prevention by tea: Evidence from laboratory studies

The cancer preventive activities of tea (Camellia sinensis Theaceae) have been studied extensively. Inhibition of tumorigenesis by green tea extracts and tea polyphenols has been demonstrated in different animal models, including those for cancers of the skin, lung, oral cavity, esophagus, stomach, small intestine, colon, bladder, liver, pancreas, prostate, and mammary glands. Many studies in cell lines have demonstrated the modulation of signal transduction and metabolic pathways by (-)-epigallocatechin-3-gallate (EGCG), the most abundant and active polyphenol in green tea. These molecular events can result in cellular changes, such as enhancement of apoptosis, suppression of cell proliferation, and inhibition of angiogenesis. Nevertheless, the molecular mechanisms of inhibition of carcinogenesis in animals and humans remain to be further investigated. Future research directions in this area are discussed.

Alcohol-induced deterioration in primary antioxidant and glutathione family enzymes reversed by exercise training in the liver of old rats

Chronic alcohol consumption causes severe hepatic oxidative damage, particularly to old subjects by decreasing various antioxidant enzymes. In this study, we test the hypothesis that exercise training can protect the aging liver against alcohol-induced oxidative damage. Two different age groups of Wistar albino rats (3 months young, n=24; 18 months old, n=24) were evenly divided into four groups: control (Con), exercise trained (Tr, 23 m/min 30 min/day, 5 days/week for 2 months), ethanol drinking/treated (Et, 2.0 g/kg b.w. orally), and exercise training plus ethanol drinking/treated (Tr+Et). We found significantly (P<.001) lowered hepatic antioxidant enzymes including superoxide dismutase, catalase, selenium (Se)-dependent glutathione peroxidase (Se-GSH-Px), Se-non-dependent glutathione peroxidase (non-Se-GSH-Px), glutathione reductase, and glutathione S-transferase activities in aged rats compared with young. Age-related decrease in antioxidant enzyme status was further exacerbated with ethanol drinking, which indicates liver in aged rats is more susceptible to oxidative damage because of decreased free radical scavenging system in aged/old ethanol-drinking rats. However, the decrease in liver antioxidant enzymes status with ethanol consumption was ameliorated by 2 months exercise training in old and young rats. These results demonstrate that age-associated decrease in hepatic free radical scavenging system exacerbated by ethanol drinking. For the first time, we found that this deterioration was significantly reversed by exercise training in aging liver, thus protects against alcohol-induced oxidative damage.

The antioxidant and pro-oxidant activities of green tea polyphenols: a role in cancer prevention

Green tea (Camellia sinensis) is rich in catechins, of which (-)-epigallocatechin-3-gallate (EGCG) is the most abundant. Studies in animal models of carcinogenesis have shown that green tea and EGCG can inhibit tumorigenesis during the initiation, promotion and progression stages. Many potential mechanisms have been proposed including both antioxidant and pro-oxidant effects, but questions remain regarding the relevance of these mechanisms to cancer prevention. In the present review, we will discuss the redox chemistry of the tea catechins and the current literature on the antioxidant and pro-oxidative effects of the green tea polyphenols as they relate to cancer prevention. We report that although the catechins are chemical antioxidants which can quench free radical species and chelate transition metals, there is evidence that some of the effects of these compounds may be related to induction of oxidative stress. Such pro-oxidant effects appear to be responsible for the induction of apoptosis in tumor cells. These pro-oxidant effects may also induce endogenous antioxidant systems in normal tissues that offer protection against carcinogenic insult. This review is meant point out understudied areas and stimulate research on the topic with the hope that insights into the mechanisms of cancer preventive activity of tea polyphenols will result.

Aging of different avian cultured cells: lack of ROS-induced damage and quality control mechanisms

Elevated reactive oxygen species (ROS) levels have been observed in mammals during aging, implying an important role of ROS in the aging process. Most bird species are known to live longer and to contain lower ROS levels than mammals of the same body weight. The influence of ROS on the aging process of birds has been investigated using pigeon embryonic fibroblasts (PEF) and chicken embryonic fibroblasts (CEF). ROS levels in young avian cells were much lower than in human cells. When cultivated till replicative senescence, PEF proliferated about one-third longer compared to CEF. However, both senescent avian cell populations showed no increased ROS levels or accumulation of ROS-induced damage on the mtDNA or protein level. The investigation for quality control (QC) mechanisms revealed that the autophagosomal/lysosomal pathway was not downregulated in old avian cells and stable overexpression of the autophagy protein ATG5 improved mitochondrial fitness, enhanced the resistance against oxidative stress and prolonged the life span of CEF. Oxidative stress-mediated apoptosis induced a dose-dependent cell proliferation in CEF as well as in PEF. Taken together, our data indicate that autophagy and compensatory proliferation act as QC mechanisms, while ROS did not influence the aging process in avian cells.

Green tea polyphenols ameliorate pancreatic injury in cerulein-induced murine acute pancreatitis

OBJECTIVE

Green tea polyphenols (GTPs) are naturally occurring antioxidants acting through pathways that include reactive oxygen species and nuclear factor kappa B (NF-kappaB). This study investigates the effect of GTPs in a cerulein-induced murine model of acute pancreatitis (AP).

METHODS

Male CD mice (median weight, 37.7 g) were divided into 4 groups: mice administered with cerulein alone, cerulein and GTP, saline alone (sham), and GTP alone. Acute pancreatitis was induced by serial intraperitoneal administration of cerulein (50 microg/kg, x6). Green tea polyphenol was administered intraperitoneally at 25 mg/kg on the first, third, and sixth hours after pancreatitis induction.We analyzed histologic and biochemical features of AP, NF-kappaB pathway activity, leukocyte-mediated damage, cytokine levels, oxidative stress injury, lipid peroxidation, expression of poly-(adenosine diphosphate-ribose) synthetase, and presence of apoptosis.

RESULTS

Treatment with GTP reduced the histologic and biochemical features of AP. Western blot revealed significant NF-kappaB inactivation. Immunostaining for P selectin and intercellular adhesion molecule 1, tumor necrosis factor alpha, transforming growth factor beta, vascular endothelial growth factor, nitrotirosine, poly-(adenosine diphosphate ribose) synthetase, and malondialdheide levels were significantly reduced. There was a significant down-regulation of apoptotic markers.

CONCLUSIONS

Our results demonstrated that GTP significantly ameliorated the effects of cerulein-induced AP in mice. These effects of GTP are mediated by actions at the NF-kappaB/IkB (inhibitor kB) proteins and oxidative stress pathways.

Cancer prevention by tea: animal studies, molecular mechanisms and human relevance

Extracts of tea, especially green tea, and tea polyphenols have been shown to inhibit the formation and development of tumours at different organ sites in animal models. There is considerable evidence that tea polyphenols, in particular (-)-epigallocatechin-3-gallate, inhibit enzyme activities and signal transduction pathways, resulting in the suppression of cell proliferation and enhancement of apoptosis, as well as the inhibition of cell invasion,angiogenesis and metastasis. Here, we review these biological activities and existing data relating tea consumption to human cancer risk in an attempt to understand the potential use of tea for cancer prevention.

Antioxidative and anti-carcinogenic activities of tea polyphenols

Tea (Camellia sinensis, Theaceace), a popular beverage consumed world-wide, has been studied for its preventive effects against cancer as well as cardiovascular, neurodegenerative, and other diseases. Most of the proposed beneficial effects have been attributed to the polyphenolic compounds in tea, but the nature of these activities and the molecular mechanisms of their actions remain unclear. Tea polyphenols are known to be strong antioxidants. Prevention of oxidative stress, modulation of carcinogen metabolism, and prevention of DNA damage have been suggested as possible cancer preventive mechanisms for tea and tea polyphenols. In this chapter, we discuss these topics in the light of biotransformation and bioavailability of tea polyphenols. We also review the preventive effects of tea polyphenols in animal models of carcinogenesis and some of the possible post-initiation mechanisms of action. Finally, we discuss the effects of tea consumption on cancer risk in humans. It is our aim to raise some of the unanswered questions regarding cancer prevention by tea and to stimulate further research in this area.