Antioxidant vitamins and mineral supplementation, life span expansion and cancer incidence: a critical commentary

Meal timing of dietary total antioxidant capacity and its association with all-cause, CVD and cancer mortality: the US national health and nutrition examination survey, 1999-2018

BACKGROUND

The association of the meal timing of dietary total antioxidant capacity (DAC) with mortality is unclear. We aimed to investigate the association between the meal timing of DAC and all-cause, cardiovascular disease (CVD), and cancer mortality in general adult populations.

METHODS

A total of 56,066 adults who participated in the US National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018 were recruited for this study. Dietary intake (quantity and timing) was evaluated by nonconsecutive 24-h dietary recalls. The main exposure variables were the DAC across three meals (total, breakfast, lunch, and dinner; without coffee) and the difference between dinner and breakfast DAC (Δ = dinner-breakfast; without coffee). The outcomes were all-cause, CVD, and cancer mortality. The adjusted hazard ratios [aHRs] and 95% confidence intervals [CI] were imputed by Cox proportional hazards regression.

RESULTS

Among the 56,066 participants, there were 8566 deaths from any cause, including 2196 from CVD and 1984 from cancer causes. Compared to participants in the lowest quintiles of the total DAC, those in the highest quintiles had 34% and 27% decreased risks of all-cause and CVD mortality, respectively (all-cause mortality: aHRs 0.66 [95% CI 0.57-0.76]; CVD mortality: aHRs 0.73 [95% CI 0.57-0.94]). More importantly, participants in the highest quintiles of the dinner DAC, but not those in that of breakfast or lunch, had a 24% decrease in all-cause mortality (aHRs 0.76 [95% CI 0.67-0.87]) compared with those in the lowest quintiles. Inverse associations were further confirmed for Δ DAC (aHRs 0.84 [95% CI 0.74-0.96]). Above associations did not change when including DAC from snacks or tea. Mediation analysis showed that the total associations of total, dinner or Δ DACs with reduced all-cause mortality were 24%, 13% and 6%, respectively, mediated by serum CRP. Additionally, all-cause mortality was decreased by 7% in models replacing 10% breakfast DAC (aHRs 0.93 [95% CI 0.9-0.97]) with an equivalent proportion of dinner DAC. For cancer mortality, no statistical significance was detected in the adjusted models.

CONCLUSIONS

The findings emphasize the putative beneficial relationship of a diet rich in antioxidants and meal timing on serum CRP and all-cause mortality.

Association of Dietary Fiber, Composite Dietary Antioxidant Index and Risk of Death in Tumor Survivors: National Health and Nutrition Examination Survey 2001-2018

BACKGROUND

Dietary fiber is a functional substance with strong antioxidant activity that plays an important role in human health. Dietary fiber has been shown to reduce the risks of many types of cancers, but whether it can reduce the risk of death in cancer survivors remains undetermined.

METHODS

This study included the dietary data of cancer survivors who participated in the National Health and Nutrition Examination Surveys from 2001 to 2018. Firstly, the relationship between fiber intake and composite dietary antioxidant index (CDAI) was explored by weighted multiple regression and smooth curve. Subsequently, multivariable Cox proportional hazards regression models were used to explore the effects of dietary fiber intake and CDAI level on the risks of all-cause, tumor, and cardiovascular death among cancer survivors.

RESULTS

A total of 2077 participants were included in the study, representing approximately 11,854,509 cancer survivors in the United States. The dietary fiber intake of tumor survivors had a nonlinear positive relationship with CDAI levels (β = 0.24, 95% CI: 0.08-0.40, p = 0.004). Multivariable Cox proportional hazards regression models showed that high dietary fiber intake and CDAI levels were associated with reduced risks of all-cause and tumor death in tumor survivors, but were not associated with the risk of cardiovascular death.

CONCLUSION

An increased dietary fiber intake can enhance the body's antioxidant capacity. A higher dietary fiber intake and CDAI level may reduce the risk of all-cause and tumor death in tumor survivors.

Novel Insights into the Role of the Antioxidants in Prostate Pathology

To date, it is known that antioxidants protect cells from damage caused by oxidative stress and associated with pathological conditions. Several studies have established that inflammation is a state that anticipates the neoplastic transformation of the prostate. Although many experimental and clinical data have indicated the efficacy of antioxidants in preventing this form of cancer, the discrepant results, especially from recent large-scale randomized clinical trials, make it difficult to establish a real role for antioxidants in prostate tumor. Despite these concerns, clinical efficacy and safety data show that some antioxidants still hold promise for prostate cancer chemoprevention. Although more studies are needed, in this review, we briefly describe the most common antioxidants that have shown benefits in preclinical and clinical settings, focusing our attention on synthesizing the advances made so far in prostate cancer chemoprevention using antioxidants as interesting molecules for the challenges of future therapies.

Roles of Reactive Oxygen Species in Biological Behaviors of Prostate Cancer

Prostate cancer (PCa), known as a heterogenous disease, has a high incidence and mortality rate around the world and seriously threatens public health. As an inevitable by-product of cellular metabolism, reactive oxygen species (ROS) exhibit beneficial effects by regulating signaling cascades and homeostasis. More and more evidence highlights that PCa is closely associated with age, and high levels of ROS are driven through activation of several signaling pathways with age, which facilitate the initiation, development, and progression of PCa. Nevertheless, excessive amounts of ROS result in harmful effects, such as genotoxicity and cell death. On the other hand, PCa cells adaptively upregulate antioxidant genes to detoxify from ROS, suggesting that a subtle balance of intracellular ROS levels is required for cancer cell functions. The current review discusses the generation and biological roles of ROS in PCa and provides new strategies based on the regulation of ROS for the treatment of PCa.

Terpenoids as Potential Geroprotectors

Terpenes and terpenoids are the largest groups of plant secondary metabolites. However, unlike polyphenols, they are rarely associated with geroprotective properties. Here we evaluated the conformity of the biological effects of terpenoids with the criteria of geroprotectors, including primary criteria (lifespan-extending effects in model organisms, improvement of aging biomarkers, low toxicity, minimal adverse effects, improvement of the quality of life) and secondary criteria (evolutionarily conserved mechanisms of action, reproducibility of the effects on different models, prevention of age-associated diseases, increasing of stress-resistance). The number of substances that demonstrate the greatest compliance with both primary and secondary criteria of geroprotectors were found among different classes of terpenoids. Thus, terpenoids are an underestimated source of potential geroprotectors that can effectively influence the mechanisms of aging and age-related diseases.

Selenium, aging and aging-related diseases

Selenium is an essential trace element in the human body and plays an important role in the body via selenoprotein, which contains selenium. Selenoproteins (glutathione peroxidase, thioredoxin reductase, methionine sulfoxide reductase1 and endoplasmic reticulum-selenoproteins, etc.) have antioxidant effects and are involved in regulating antioxidant activities. Aging is an inevitable process and is always accompanied by aging-related diseases. Reactive oxygen species are important initial factors in aging and aging-related diseases. Selenium contributes to the alleviation of reduced reactive oxygen species-mediated inflammation, reduced DNA damage and prolonged telomere length and thereby plays roles in fighting aging and preventing aging-related diseases. In the elderly, aging-related diseases include neuropsychiatric diseases, tumors, cardiovascular diseases, and skin aging, among others. Selenium supplementation is an important strategy for anti-aging and the prevention of aging-related diseases and is of great significance for the elderly. However, with the accumulation of related research, selenium supplementation does not necessarily contribute to the prevention of aging and aging-related diseases. It is believed that a low level of selenium is beneficial to the human body. Thus, the effect of selenium on human aging and aging-related diseases is still controversial. This paper reviews the research progress and objective role of selenium in aging and aging-related diseases.

The aging heart

As the elderly segment of the world population increases, it is critical to understand the changes in cardiac structure and function during the normal aging process. In this review, we outline the key molecular pathways and cellular processes that underlie the phenotypic changes in the heart and vasculature that accompany aging. Reduced autophagy, increased mitochondrial oxidative stress, telomere attrition, altered signaling in insulin-like growth factor, growth differentiation factor 11, and 5'- AMP-activated protein kinase pathways are among the key molecular mechanisms underlying cardiac aging. Aging promotes structural and functional changes in the atria, ventricles, valves, myocardium, pericardium, the cardiac conduction system, and the vasculature. We highlight the factors known to accelerate and attenuate the intrinsic aging of the heart and vessels in addition to potential preventive and therapeutic avenues. A greater understanding of the processes involved in cardiac aging may facilitate our ability to mitigate the escalating burden of CVD in older individuals and promote healthy cardiac aging.

Protective effect of Rhus coriaria fruit extracts against hydrogen peroxide-induced oxidative stress in muscle progenitors and zebrafish embryos

Background and Purpose

Oxidative stress is involved in normal and pathological functioning of skeletal muscle. Protection of myoblasts from oxidative stress may improve muscle contraction and delay aging. Here we studied the effect of R. coriaria sumac fruit extract on human myoblasts and zebrafish embryos in conditions of hydrogen peroxide-induced oxidative stress.

Study Design and Methods

Crude ethanolic 70% extract (CE) and its fractions was obtained from sumac fruits. The composition of sumac ethyl acetate EtOAc fraction was studied by ¹H NMR. The viability of human myoblasts treated with CE and the EtOAc fraction was determined by trypan blue exclusion test. Oxidative stress, cell cycle and adhesion were analyzed by flow cytometry and microscopy. Gene expression was analyzed by qPCR.

Results

The EtOAc fraction (IC₅₀ 2.57 µg/mL) had the highest antioxidant activity and exhibited the best protective effect against hydrogen peroxide-induced oxidative stress. It also restored cell adhesion. This effect was mediated by superoxide dismutase 2 and catalase. Pre-treatment of zebrafish embryos with low concentrations of the EtOAc fraction protected them from hydrogen peroxide-induced death in vivo. ¹H NMR analysis revealed the presence of gallic acid in this fraction.

Conclusion

Rhus coriaria extracts inhibited or slowed down the progress of skeletal muscle atrophy by decreasing oxidative stress via superoxide dismutase 2 and catalase-dependent mechanisms.

Polyphenolic drug composition based on benzenepolycarboxylic acids (BP-C3) increases life span and inhibits spontaneous tumorigenesis in female SHR mice

Effects of long-term application of novel polyphenolic composition BP-C3, containing polyphenolic benzenepolycarboxylic acids, vitamins and minerals on some biomarkers of aging, life span and spontaneous tumorigenesis has been studied in female SHR mice. Administration of BP-C3 with drinking water (0.005%) did not exert any toxic effect (did not have effect on general condition of animals, weight dynamics and consumption of food), postponed age-related switch-off of estrous function, caused slight reduction of body temperature. An increased survival was observed in mice treated with BP-C3 (p=0.00164, log rank test). BP-C3 increased mean lifespan – by 8.4%, lifespan of the last 10% of animals – by 12.4%, and life span of tumor-free mice – by 11.6%. A tendency in ability of BP-C3 to inhibit development of spontaneous tumors in mice was detected, though it did not reach the level of statistical significance (p=0.166, log rank test). The number of malignant mammary tumors was 1.5 times less and total number of tumors of various localizations was 1.6 times less in BP-C3 treated animals. Multiple tumors were registered in 8% of mice in the control group and no cases – in BP-C3 treated group. Thus, BP-C3 demonstrated some anti-carcinogenic and a pronounced geroprotective activity.

Mitochondrial thioredoxin reductase 2 is elevated in long-lived primate as well as rodent species and extends fly mean lifespan

In a survey of enzymes related to protein oxidation and cellular redox state, we found activity of the redox enzyme thioredoxin reductase (TXNRD) to be elevated in cells from long‐lived species of rodents, primates, and birds. Elevated TXNRD activity in long‐lived species reflected increases in the mitochondrial form, TXNRD2, rather than the cytosolic forms TXNRD1 and TXNRD3. Analysis of published RNA‐Seq data showed elevated TXNRD2 mRNA in multiple organs of longer‐lived primates, suggesting that the phenomenon is not limited to skin‐derived fibroblasts. Elevation of TXNRD2 activity and protein levels was also noted in liver of three different long‐lived mutant mice, and in normal male mice treated with a drug that extends lifespan in males. Overexpression of mitochondrial TXNRD2 in Drosophila melanogaster extended median (but not maximum) lifespan in female flies with a small lifespan extension in males; in contrast, overexpression of the cytosolic form, TXNRD1, did not produce a lifespan extension.

Anti-aging pharmacology: Promises and pitfalls

Life expectancy has grown dramatically in modern times. This increase, however, is not accompanied by the same increase in healthspan. Efforts to extend healthspan through pharmacological agents targeting aging-related pathological changes are now in the spotlight of geroscience, the main idea of which is that delaying of aging is far more effective than preventing the particular chronic disorders. Currently, anti-aging pharmacology is a rapidly developing discipline. It is a preventive field of health care, as opposed to conventional medicine which focuses on treating symptoms rather than root causes of illness. A number of pharmacological agents targeting basic aging pathways (i.e., calorie restriction mimetics, autophagy inducers, senolytics etc.) are now under investigation. This review summarizes the literature related to advances, perspectives and challenges in the field of anti-aging pharmacology.

Can diet and lifestyle prevent breast cancer: what is the evidence?

Breast cancer is the most common cancer among women in both developed and less-developed countries. Rates of breast cancer are increasing worldwide, with a particular increase in postmenopausal and estrogen receptor-positive cases. The World Cancer Research Fund (WCRF) and American Cancer Society (ACS) cancer prevention guidelines recommend maintaining a healthy weight, undertaking at least 150 minutes of moderate intensity exercise per week, limiting alcohol consumption, and eating a plant-based diet. Observational data link adherence to physical activity and alcohol guidelines throughout life to a reduced risk of developing pre- and postmenopausal breast cancer. Weight control throughout life appears to prevent cases after menopause. Adherence to a healthy dietary pattern does not have specific effects on breast cancer risk but remains important as it reduces the risk for other common diseases, such as cardiovascular disease (CVD), diabetes, and dementia. Emerging data suggest that smoking during adolescence or early adulthood increases later risk of breast cancer. Lifestyle factors appear to modify risk among high-risk women with a family history and those with typical risk of the general population, although their effects among carriers of BRCA mutations are not well defined. Recent expert reports estimate that successful lifestyle changes could prevent 25% to 30% of cases of breast cancer. These reductions will only be achieved if we can implement targeted prevention programs for high-risk women and women in population-based breast screening programs during childhood, adolescence, and early adulthood when the rapidly developing breast is particularly susceptible to carcinogenesis.

Folic acid supplementation at lower doses increases oxidative stress resistance and longevity in Caenorhabditis elegans

Folic acid (FA) is an essential nutrient that the human body needs but cannot be synthesized on its own. Fortified foods and plant food sources such as green leafy vegetables, beans, fruits, and juices are good sources of FA to meet the daily requirements of the body. The aim was to evaluate the effect of dietary FA levels on the longevity of well-known experimental aging model Caenorhabditis elegans. Here, we show for first time that FA extends organism life span and causes a delay in aging. We observed that FA inhibits mechanistic target of rapamycin (mTOR) and insulin/insulin growth factor 1 (IGF-1) signaling pathways to control both oxidative stress levels and life span. The expression levels of stress- and life span-relevant gerontogenes, viz. daf-16, skn-1, and sir. 2.1, and oxidative enzymes, such as glutathione S-transferase 4 (GST-4) and superoxide dismutase 3 (SOD-3), were also found to be highly enhanced to attenuate the intracellular reactive oxygen species (ROS) damage and to delay the aging process. Our study promotes the use of FA to mitigate abiotic stresses and other aging-related ailments.

Serum Biomarkers of (Anti)Oxidant Status for Epidemiological Studies

In this review, we disclose a selection of serum/plasma biomarkers of (anti)oxidant status related to nutrition, which can be used for measurements in large-scale epidemiological studies. From personal experience, we have come to the following proposal of a set of biomarkers for nutritional intake, (anti)oxidant status, and redox status. We have selected the individual antioxidant vitamins E and A, and the carotenoids which can be measured in large series by HPLC. In addition, vitamin C was selected, which can be measured by an auto-analyzer or HPLC. As a biomarker for oxidative stress, the ROM assay (reactive oxygen metabolites) was selected; for the redox status, the total thiol assay; and for the total antioxidant status the BAP assay (biological antioxidant potential). All of these biomarkers can be measured in large quantities by an auto-analyzer. Critical points in biomarker validation with respect to blood sampling, storage conditions, and measurements are discussed. With the selected biomarkers, a good set is presented for use in the risk assessment between nutrition and (chronic) diseases in large-scale epidemiological studies. Examples of the successful application of these biomarkers in large international studies are presented.

Nutritional supplements and cancer: potential benefits and proven harms

Nutritional supplements are widely used among patients with cancer who perceive them to be anticancer and antitoxicity agents. Large-scale, randomized cancer prevention trials have mainly been negative, with some notable adverse and beneficial effects. For example, these trials showed that beta-carotene increases the risk of lung and stomach cancer, vitamin E increases prostate cancer and colorectal adenoma, and selenium reduces gastric and lung cancer in populations with low selenium levels but increase rates in those with higher levels. Both beta-carotene and vitamin E supplementation increase overall mortality. This article reviews phase II and III trials that examine the effects of multivitamins, antioxidants, vitamin D, and n-3 supplements on outcome and toxicity from cancer treatments. Although vitamin E and beta-carotene reduce toxicity from radiotherapy among patients with head and neck cancer, it has been found to increase recurrence, especially among smokers. Antioxidants have mixed effects on chemotherapy toxicity, but there are no data on outcome. Vitamin D deficiency is relatively common among patients with cancer, and ongoing phase III trials are studying the effect of vitamin D on outcome as well as optimum vitamin D and calcium intakes for bone health. Docosahexanoic and eicosopentanoic acid supplements have mixed effects on cachexia and are currently being tested as potential adjuncts to maximize response to chemotherapy. Nutritional supplementation tailored to an individual's background diet, genetics, tumor histology, and treatments may yield benefits in subsets of patients. Clinicians should have an open dialogue with patients about nutritional supplements. Supplement advice needs to be individualized and come from a credible source, and it is best communicated by the physician.

Coffee consumption and the risk of lung cancer: an updated meta-analysis of epidemiological studies

BACKGROUND/OBJECTIVES

Coffee is one of the most popularly consumed beverages worldwide. Many epidemiological studies have investigated the association between coffee consumption and lung cancer risk, but the results are inconsistent. Hence, we conducted a systematic analysis of relevant population-based studies to examine this association and derive a more precise estimation.

SUBJECTS/METHODS

The Cochrane library, PubMed and Embase databases were searched to identify studies published through Mar 2015 that met the predetermined inclusion criterion. Seventeen studies (5 cohort and 12 case-control studies) involving 12 276 cases and 102 516 controls were included.

RESULTS

The summary odds ratio (OR) of lung cancer was 1.17 (95% confidence interval (CI): 1.03-1.33) for coffee drinkers compared with nondrinkers and 1.31 (95% CI: 1.11-1.55) for the highest category of coffee consumption compared with the lowest category. Compared with nondrinkers, the pooled ORs for lung cancer were 1.10 (95% CI: 0.92-1.31) for ⩽1 cup per day, 1.10 (95% CI: 0.93-1.30) for 2-3 cups per day and 1.20 (95% CI: 1.02-1.39) for ⩾3 cups per day. Further analysis showed that the ORs for hospital-based case-control studies, population-based case-control studies and prospective cohort studies were 1.36 (95% CI: 1.10-1.69), 0.99 (95% CI: 0.77-1.28) and 1.59 (95% CI: 1.26-2.00), respectively. Significant associations for high coffee intake with increased risk of lung cancer were observed in men (OR=1.41 95% CI: 1.21-1.63), but not in women (OR=1.16, 95% CI: 0.86-1.56), in American (OR=1.34 95% CI: 1.08-1.65) and Asian populations (OR=1.49 95% CI: 1.28-1.74), but not in European populations (OR=1.12, 95% CI: 0.74-1.67), and in smokers (OR=1.24, 95% CI: 1.00-1.54), but not in nonsmokers (OR=0.85, 95% CI: 0.64-1.11). Particularly over the last 5 years, studies have consistently indicated that lung cancer risk is significantly increased by 47% in the population with the highest category intake of coffee compared with that with the lowest category intake (OR=1.47, 95% CI: 1.21-1.79).

CONCLUSION

The present study suggested that coffee intake was associated with an increased risk of lung cancer.

Trolox and ascorbic acid reduce direct and indirect oxidative stress in the IPEC-J2 cells, an in vitro model for the porcine gastrointestinal tract

Oxidative stress in the small intestinal epithelium is a major cause of barrier malfunction and failure to regenerate. This study presents a functional in vitro model using the porcine small intestinal epithelial cell line IPEC-J2 to examine the effects of oxidative stress and to estimate the antioxidant and regenerative potential of Trolox, ascorbic acid and glutathione monoethyl ester. Hydrogen peroxide and diethyl maleate affected the tight junction (zona occludens-1) distribution, significantly increased intracellular oxidative stress (CM-H₂DCFDA) and decreased the monolayer integrity (transepithelial electrical resistance and FD-4 permeability), viability (neutral red) and wound healing capacity (scratch assay). Trolox (2 mM) and 1 mM ascorbic acid pre-treatment significantly reduced intracellular oxidative stress, increased wound healing capacity and reduced FD-4 permeability in oxidatively stressed IPEC-J2 cell monolayers. All antioxidant pre-treatments increased transepithelial electrical resistance and viability only in diethyl maleate-treated cells. Glutathione monoethyl ester (10 mM) pre-treatment significantly decreased intracellular oxidative stress and monolayer permeability only in diethyl maleate-treated cells. These data demonstrate that the IPEC-J2 oxidative stress model is a valuable tool to screen antioxidants before validation in piglets.

Use of Vitamins and Minerals in the Treatment of Hair Loss: A Cross-Sectional Survey among Dermatologists in Saudi Arabia

Background:

Several controversies exist regarding the use of vitamin and mineral supplements in treating hair loss.

Objectives:

To explore practices, knowledge, and attitudes for using vitamins and minerals in treating hair loss among dermatologists in Saudi Arabia.

Methods:

A self-administrated questionnaire containing 33 questions was distributed to 177 dermatologists attending a national dermatology conference in Riyadh, Saudi Arabia, in 2012.

Results:

Of the 177 attending dermatologists, 144 responded to the questionnaire (81% response rate). Vitamins and minerals were recommended for treating at least one type of hair loss by 60%. Vitamins and minerals were most commonly used for acute telogen effluvium (62%). The majority (72%) reported a good knowledge of vitamins and minerals toxicity.

Conclusion:

Although dermatologists in Saudi Arabia displayed positive believes in the usefulness of vitamins and minerals in treating hair loss, further research is needed to prove their role in the management of different hair loss disorders.

Structural re-arrangement and peroxidase activation of cytochrome c by anionic analogues of vitamin E, tocopherol succinate and tocopherol phosphate

Cytochrome c is a multifunctional hemoprotein in the mitochondrial intermembrane space whereby its participation in electron shuttling between respiratory complexes III and IV is alternative to its role in apoptosis as a peroxidase activated by interaction with cardiolipin (CL), and resulting in selective CL peroxidation. The switch from electron transfer to peroxidase function requires partial unfolding of the protein upon binding of CL, whose specific features combine negative charges of the two phosphate groups with four hydrophobic fatty acid residues. Assuming that other endogenous small molecule ligands with a hydrophobic chain and a negatively charged functionality may activate cytochrome c into a peroxidase, we investigated two hydrophobic anionic analogues of vitamin E, α-tocopherol succinate (α-TOS) and α-tocopherol phosphate (α-TOP), as potential inducers of peroxidase activity of cytochrome c. NMR studies and computational modeling indicate that they interact with cytochrome c at similar sites previously proposed for CL. Absorption spectroscopy showed that both analogues effectively disrupt the Fe-S(Met(80)) bond associated with unfolding of cytochrome c. We found that α-TOS and α-TOP stimulate peroxidase activity of cytochrome c. Enhanced peroxidase activity was also observed in isolated rat liver mitochondria incubated with α-TOS and tBOOH. A mitochondria-targeted derivative of TOS, triphenylphosphonium-TOS (mito-VES), was more efficient in inducing H2O2-dependent apoptosis in mouse embryonic cytochrome c(+/+) cells than in cytochrome c(-/-) cells. Essential for execution of the apoptotic program peroxidase activation of cytochrome c by α-TOS may contribute to its known anti-cancer pharmacological activity.

Natural forms of vitamin E: metabolism, antioxidant, and anti-inflammatory activities and their role in disease prevention and therapy

The vitamin E family consists of four tocopherols and four tocotrienols. α-Tocopherol (αT) is the predominant form of vitamin E in tissues and its deficiency leads to ataxia in humans. However, results from many clinical studies do not support a protective role of αT in disease prevention in people with adequate nutrient status. On the other hand, recent mechanistic studies indicate that other forms of vitamin E, such as γ-tocopherol (γT), δ-tocopherol, and γ-tocotrienol, have unique antioxidant and anti-inflammatory properties that are superior to those of αT in prevention and therapy against chronic diseases. These vitamin E forms scavenge reactive nitrogen species, inhibit cyclooxygenase- and 5-lipoxygenase-catalyzed eicosanoids, and suppress proinflammatory signaling such as NF-κB and STAT3/6. Unlike αT, other vitamin E forms are significantly metabolized to carboxychromanols via cytochrome P450-initiated side-chain ω-oxidation. Long-chain carboxychromanols, especially 13'-carboxychromanols, are shown to have stronger anti-inflammatory effects than unmetabolized vitamins and may therefore contribute to the beneficial effects of vitamin E forms in vivo. Consistent with mechanistic findings, animal and human studies show that γT and tocotrienols may be useful against inflammation-associated diseases. This review focuses on non-αT forms of vitamin E with respect to their metabolism, anti-inflammatory effects and mechanisms, and in vivo efficacy in preclinical models as well as human clinical intervention studies.

PMC, a potent hydrophilic α-tocopherol derivative, inhibits NF-κB activation via PP2A but not IκBα-dependent signals in vascular smooth muscle cells

The hydrophilic α-tocopherol derivative, 2,2,5,7,8-pentamethyl-6-hydroxychromane (PMC), is a promising alternative to vitamin E in clinical applications. Critical vascular inflammation leads to vascular dysfunction and vascular diseases, including atherosclerosis, hypertension and abdominal aortic aneurysms. In this study, we investigated the mechanisms of the inhibitory effects of PMC in vascular smooth muscle cells (VSMCs) exposed to pro-inflammatory stimuli, lipopolysaccharide (LPS) combined with interferon (IFN)-γ. Treatment of LPS/IFN-γ-stimulated VSMCs with PMC suppressed the expression of inducible nitric oxide synthase (iNOS) and matrix metalloproteinase-9 in a concentration-dependent manner. A reduction in LPS/IFN-γ-induced nuclear factor (NF)-κB activation was also observed in PMC-treated VSMCs. The translocation and phosphorylation of p65, protein phosphatase 2A (PP2A) inactivation and the formation of reactive oxygen species (ROS) were significantly inhibited by PMC in LPS/IFN-γ-activated VSMCs. However, neither IκBα degradation nor IκB kinase (IKK) or ribosomal s6 kinase-1 phosphorylation was affected by PMC under these conditions. Both treatments with okadaic acid, a PP2A-selective inhibitor, and transfection with PP2A siRNA markedly reversed the PMC-mediated inhibition of iNOS expression, NF-κB-promoter activity and p65 phosphorylation. Immunoprecipitation analysis of the cellular extracts of LPS/IFN-γ-stimulated VSMCs revealed that p65 colocalizes with PP2A. In addition, p65 phosphorylation and PP2A inactivation were induced in VSMCs by treatment with H₂O₂, but neither IκBα degradation nor IKK phosphorylation was observed. These results collectively indicate that the PMC-mediated inhibition of NF-κB activity in LPS/IFN-γ-stimulated VSMCs occurs through the ROS-PP2A-p65 signalling cascade, an IKK-IκBα-independent mechanism. Therapeutic interventions using PMC may therefore be beneficial for the treatment of vascular inflammatory diseases.

Sepsis-induced Cardiac Mitochondrial Damage and Potential Therapeutic Interventions in the Elderly

The incidence of sepsis and its attendant mortality risk are significantly increased with aging. Thus, severe sepsis in the elderly is likely to become an emerging concern in critical care units. Cardiac dysfunction is an important component of multi-organ failure after sepsis. In our laboratory, utilizing a pneumonia-related sepsis animal model, our research has been focused on the mechanisms underlying sepsis-induced cardiac failure. In this review, based on findings from others and ours, we discussed age-dependent decay in mitochondria and the role of mitochondrial reactive oxygen species (mtROS) in sepsis-induced cardiac inflammation and autophagy. Our recent discovery of a potential signal transduction pathway that triggers myocardial mitochondrial damage is also discussed. Because of the significance of mitochondria damage in the aging process and in sepsis pathogenesis, we hypothesize that specific enhancing mitochondrial antioxidant defense by mitochondria-targeted antioxidants (MTAs) may provide important therapeutic potential in treating elder sepsis patients. In this review, we summarized the categories of currently published MTA molecules and the results of preclinical evaluation of MTAs in sepsis and aging models.

Induction of apoptosis by a hexane extract of aged black garlic in the human leukemic U937 cells

BACKGROUND/OBJECTIVES

In this study, the apoptogenic activity and mechanisms of cell death induced by hexane extract of aged black garlic (HEABG) were investigated in human leukemic U937 cells.

MATERIALS/METHODS

Cytotoxicity was evaluated by MTT (3-(4, 5-dimethyl-thiazol-2-yl)-2, 5-diphenyl tetrazoliumbromide) assay. Apoptosis was detected using 4,6-diamidino-2-phenyllindile (DAPI) staining, agarose gel electrophoresis and flow cytometry. The protein levels were determined by Western blot analysis. Caspase activity was measured using a colorimetric assay.

RESULTS

Exposure to HEABG was found to result in a concentration- and time-dependent growth inhibition by induction of apoptosis, which was associated with an up-regulation of death receptor 4 and Fas legend, and an increase in the ratio of Bax/Bcl-2 protein expression. Apoptosis-inducing concentrations of HEABG induced the activation of caspase-9, an initiator caspase of the mitochodrial mediated intrinsic pathway, and caspase-3, accompanied by proteolytic degradation of poly(ADP-ribose)-polymerase. HEABG also induced apoptosis via a death receptor mediated extrinsic pathway by caspase-8 activation, resulting in the truncation of Bid, and suggesting the existence of cross-talk between the extrinsic and intrinsic pathways. However, pre-treatment of U937 cells with the caspase-3 inhibitor, z-DEVD-fmk, significantly blocked the HEABG-induced apoptosis of these cells, and increased the survival rate of HEABG-treated cells, confirming that HEABG-induced apoptosis is mediated through activation of caspase cascade.

CONCLUSIONS

Based on the overall results, we suggest that HEABG reduces leukemic cell growth by inducing caspase-dependent apoptosis through both intrinsic and extrinsic pathways, implying its potential therapeutic value in the treatment of leukemia.

A lycopene-enriched virgin olive oil enhances antioxidant status in humans

BACKGROUND

Lycopene, a bioactive red pigment, represents the most potent in vitro antioxidant among carotenoids. Virgin olive oil contains trace amounts of a wide variety of phytochemicals, which have proven to exert beneficial effects on oxidative stress. Since the ingestion of lycopene together with oil reportedly increases its bioavailability, we evaluated urinary antioxidant capacity after the consumption of a lycopene-enriched virgin olive oil (7 mg lycopene day(-1)) compared with the antioxidant effect produced after the ingestion of a virgin olive oil and a sunflower oil during 5 days, in young (25-30 years of age), middle-aged (35-55 years of age) and elderly (65-85 years of age) subjects.

RESULTS

The results showed that the consumption of virgin olive oil increased urinary antioxidant capacity in middle-aged and elderly volunteers, whereas the administration of a lycopene-enriched virgin olive oil produced higher antioxidant effects in all of the three age groups assayed.

CONCLUSION

The incorporation of the lycopene-enriched virgin olive oil into the diet may enhance the health-promoting effects of the virgin olive oil, contributing as a functional tool against several disorders where oxidative stress plays an important role.

Dimovski A. Natural antioxidants in cancer prevention

It is well known that oxidative stress is an inevitable event in aerobic life. When our cells use oxygen to create energy, a variety of reactive oxygen (ROS) and nitrogen species (RNS) are generated. These species could attack DNA directly and form mutagenic lesions afterwards. According to the oxidative stress hypothesis of aging, the oxidative damage to critical molecules accumulates over the life period and could ultimately impair the body’s function. Moreover, severe oxidative stress causes mutations of tumor suppressor genes, known as one of the initial events in carcinogenesis. Furthermore, it could also play a crucial role in the promotion of the multi-step carcinogenesis. On the other hand, the human body possesses a number of mechanisms that counteract oxidative stress by producing antioxidants in situ, or externally supplied them through foods and/or supplements. Indeed, a considerable amount of laboratory evidence from chemical, cell culture, and animal studies indicates that antioxidants may slow down or possibly prevent the cancer development. Yet, the information from recent cohort, case-control and/or ecological studies is less clear. Therefore, the objectives of this review are to compile a compendium of studies, and to identify effective and promising natural antioxidant interventions.