A Comprehensive Review of Biochemical and Molecular Evidences from Animal and Human Studies on the Role of Oxidative Stress in Aging: An Epiphenomenon or the Cause

Eriodictyol attenuates Furan induced testicular toxicity in Rats: Role of oxidative stress, steroidogenic enzymes and apoptosis

Furan (C₄H₄O) is a naturally occurring organic compound. It develops as a result of the thermal processing of food and stimulates critical impairments in male reproductive tract. Eriodictyol (Etyol) is a natural dietary flavonoid possessing diverse pharmacological potentials. The recent investigation was proposed to ascertain the ameliorative potential of eriodictyol against furan-instigated reproductive dysfunctions. Male rats (n = 48) were classified into 4 groups: untreated/control, furan (10 mg/kg), furan+ eriodictyol (10 mg/kg + 20 mg/kg) and eriodictyol (20 mg/kg). At the 56th day of the trial, the protective effects of eriodictyol were evaluated by assessing various parameters. Results of the study revealed that eriodictyol attenuated furan-induced testicular toxicity in the biochemical profile by increasing catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD) along with glutathione reductase (GSR) activities, whereas reduced the reactive oxygen species (ROS) along with malondialdehyde (MDA) levels. It also restored the normal state of sperm motility, viability, the count of hypo-osmotic tail swelled sperm as well as epididymal sperm number along with reduced sperm anomalies (morphological) tail, mid-piece and head. Furthermore, it elevated the decreased levels of luteinizing hormone (LH), plasma testosterone and follicle-stimulating hormone (FSH) as well steroidogenic enzymes (17β-HSD, StAR protein & 3β-HSD) and testicular anti-apoptotic marker (Bcl-2) expression, whereas, down-regulating apoptotic markers (Bax & Caspase-3) expression. Eriodictyol treatment also effectively mitigated the histopathological damages. The outcomes of the current study provide fundamental insights into the ameliorative potential of eriodictyol against furan-instigated testicular toxicity.

Creatine and Nicotinamide Prevent Oxidant-Induced Senescence in Human Fibroblasts

Dermal fibroblasts provide structural support by producing collagen and other structural/support proteins beneath the epidermis. Fibroblasts also produce insulin-like growth factor-1 (IGF-1), which binds to the IGF-1 receptors (IGF-1Rs) on keratinocytes to activate signaling pathways that regulate cell proliferation and cellular responses to genotoxic stressors like ultraviolet B radiation. Our group has determined that the lack of IGF-1 expression due to fibroblast senescence in the dermis of geriatric individuals is correlated with an increased incidence of skin cancer. The present studies tested the hypothesis that pro-energetics creatine monohydrate (Cr) and nicotinamide (NAM) can protect normal dermal human fibroblasts (DHF) against experimentally induced senescence. To that end, we used an experimental model of senescence in which primary DHF are treated with hydrogen peroxide (H2O2) in vitro, with senescence measured by staining for beta-galactosidase activity, p21 protein expression, and senescence associated secretory phenotype cytokine mRNA levels. We also determined the effect of H2O2 on IGF-1 mRNA and protein expression. Our studies indicate that pretreatment with Cr or NAM protects DHF from the H2O2-induced cell senescence. Treatment with pro-energetics post-H2O2 had no effect. Moreover, these agents also inhibited reactive oxygen species generation from H2O2 treatment. These studies suggest a potential strategy for protecting fibroblasts in geriatric skin from undergoing stress-induced senescence, which may maintain IGF-1 levels and therefore limit carcinogenesis in epidermal keratinocytes.

α-Lipoic acid prevents senescence, cell cycle arrest, and inflammatory cues in fibroblasts by inhibiting oxidative stress

Senescence is a process characterized by an irreversible growth arrest in cells and induced by oxidative stress. In the current study, anti-aging potential of a well-known antioxidant, α-lipoic acid (α-LA), in rat embryonic fibroblast (REF) cells was assessed. In this regard, oxidative stress, inflammation, and apoptosis pathways were investigated on REF cells exposed to H2O2 as a senescence inducer and α-LA as a protective compound. In cells treated with α-LA and H2O2, level of β-galactosidase, as an aging marker, and oxidative stress biomarkers, were significantly lower than those exposed to H2O2 only. Furthermore, flow cytometry assay showed that α-LA caused a significant reduction in the number of apoptotic cells via the caspase-dependent pathway. In addition, it could neutralize the inflammatory effects of H2O2 and attenuated the concentration of inflammatory cytokines. In comparison to H2O2 group, a significant increase in G0/G1 arrest was observed during cell cycle analysis in cells exposed to H2O2 and α-LA. The results of this study show that α-LA has beneficial effects on H2O2-induced cellular senescence. α-LA works by attenuating the reactive oxygen species, subsiding inflammation, and affecting cell division.

Effects of exogenous vitamins A, C, and E and NADH supplementation on proliferation, cytokines release, and cell redox status of lymphocytes from healthy aged subjects

Aging is an inevitable biological event that is associated with immune alterations. These alterations are related to increased cellular oxidative stress and micronutrient deficiency. Antioxidant supplementation could improve these age-related abnormalities. The aim of this study was to determine in vitro effects of vitamin A, vitamin C, vitamin E, and nicotinamide adenine dinucleotide (NADH) on T cell proliferation, cytokine release, and cell redox status in the elderly compared with young adults. Peripheral blood lymphocytes were isolated using a density gradient of Histopaque. They were cultured in vitro and stimulated with concanavalin A in the presence or absence of vitamins. Cell proliferation was determined by conducting MTT assays, and based on interleukin-2 and interleukin-4 secretions. Cell oxidant/antioxidant balance was assessed by assaying reduced glutathione (GSH), malondialdehyde, carbonyl protein levels, and catalase activity. The present study demonstrated that T-lymphocyte proliferation was decreased with aging and was associated with cytokine secretion alterations, GSH depletion, and intracellular oxidative stress. In the elderly, vitamin C, vitamin E, and NADH significantly improved lymphocyte proliferation and mitigated cellular oxidative stress, whereas vitamin A did not affect cell proliferation or cell redox status. In conclusion, vitamin C, vitamin E, and NADH supplementation improved T-lymphocytes response in the elderly, and could contribute to the prevention of age-related immune alterations. Consumption of food items containing these vitamins is recommended, and further investigation is necessary to evaluate the effect of vitamin supplementation in vivo.

Establishment of a ternary network system for evaluating the antioxidant fraction of Danhong injection

Oxidative stress plays a crucial role in numerous cardiovascular diseases. As an effective therapy, Danhong injection (DHI) is considered to act through an antioxidant mechanism for the treatment of cardiovascular disease. In our study, we focused on the potential contribution of the antioxidant capacity of DHI fractions (Frs) and established an innovative screening method based on a 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity assay. A ternary network evaluation system, which was constructed based on the radical scavenging activity, the area under the activity-concentration curve and the solid content of the fractions, was implemented to select the fractions that posed the greatest antioxidant effect. As a result, Frs 5-7 and Frs 17-19 were shown to exhibit superior antioxidant activity according to the regression area of the ternary network, which was >0.5. Furthermore, the active fractions were characterized by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry combined with nuclear magnetic resonance. This study provided an effective method for the comprehensive evaluation of the antioxidant effect of DHI fractions. Copyright © 2016 John Wiley & Sons, Ltd.

Methods for the discovery of new anti-aging products--targeted approaches

INTRODUCTION

Aging is considered to be one of the most complicated and heterogeneous phenomena and is the main risk factor for most chronic diseases, disabilities and declining health. Aging cells cease to divide and drive the progression of illness through various pathways. Over the years, a number of anti-aging medicines of natural and synthetic origin have been introduced. Indeed, some studies have identified senescent cells as potential therapeutic targets in the treatment of aging and age-related diseases.

AREAS COVERED

In this review, the authors highlight and critically review the possible mechanisms of the aging process and related illnesses. The authors give particular attention to illnesses, including Alzheimer's disease, Parkinson's disease, skin aging and cardiovascular diseases.

EXPERT OPINION

Several reports have highlighted that mitochondria are a key factor in the progression of aging and neurodegenerative illnesses. This is due to their production of extra amounts of reactive oxygen species, which leads into progressive caspase-dependent apoptosis and cell death. Therefore, strategies to prevent/reduce oxidative stress-mediated aging, whether environmental, nutritional and pharmacological, need to be taken into account. Presently, Drosophila melanogaster and Caenorhabditis elegans, which focus on the evolutionary and genetic foundations of aging, have helped to establish the screening of several synthetic and natural compounds with large cohorts in a quick manner. However, there is yet to be any efficient experimental evidence to prove the exact role of senescent cells in age-related dysfunction and further studies are required to better understand these processes.

Toxicological and pharmacological concerns on oxidative stress and related diseases

Although reactive oxygen species (ROS) such as superoxide, hydrogen peroxide and hydroxyl radical are generated as the natural byproduct of normal oxygen metabolism, they can create oxidative damage via interaction with bio-molecules. The role of oxidative stress as a remarkable upstream part is frequently reported in the signaling cascade of inflammation as well as chemo attractant production. Even though hydrogen peroxide can control cell signaling and stimulate cell proliferation at low levels, in higher concentrations it can initiate apoptosis and in very high levels may create necrosis. So far, the role of ROS in cellular damage and death is well documented with implicating in a broad range of degenerative alterations e.g. carcinogenesis, aging and other oxidative stress related diseases (OSRDs). Reversely, it is cleared that antioxidants are potentially able to suppress (at least in part) the immune system and to enhance the normal cellular protective responses to tissue damage. In this review, we aimed to provide insights on diverse OSRDs, which are correlated with the concept of oxidative stress as well as its cellular effects that can be inhibited by antioxidants. Resveratrol, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, statins, nebivolol and carvedilol, pentaerythritol tetranitrate, mitochondria-targeted antioxidants, and plant-derived drugs (alone or combined) are the potential medicines that can be used to control OSRD.

Sublethal oxidative stress induces the premature senescence of human mesenchymal stem cells derived from endometrium

The specific responses of mesenchymal stem cells to oxidative stress may play a crucial role in regulation of tissue homeostasis as well as regeneration of organs after oxidative injury. The responses of human endometrium-derived mesenchymal stem cells (hMESCs) to oxidative stress remain still unknown. Herein, we examined the impact of H2O2 on cell viability, induction of premature senescence, and apoptosis. hMESCs were highly resistant to H2O2 compared with human diploid fibroblasts. To test a hypothesis whether hMESCs may undergo oxidative stress-induced premature senescence, cells were briefly exposed to the sublethal H2O2 doses. H2O2-treated cells were permanently arrested, lost Ki67 proliferation marker, and exhibited a senescent phenotype including cell hypertrophy and increased SA- β -Gal activity. Additionally, in stressed cells the expression levels of p21Cip1, SOD1, SOD2, and GPX1 were elevated. hMESCs survived under stress were not able to resume proliferation, indicating the irreversible loss of proliferative potential. While the low H2O2 doses promoted senescence in hMESCs, the higher H2O2 doses induced also apoptosis in a part of the cell population. Of note, senescent hMESCs exhibited high resistance to apoptosis. Thus, we have demonstrated for the first time that hMESCs may enter a state of premature senescence in response to sublethal oxidative stress.

Effects of IMOD™ and Angipars™ on mouse D-galactose-induced model of aging

The aim of this study was to evaluate the effects of two registered herbal drugs called IMOD and Angipars on mouse model. Aging was induced by D-galactose (500 mg/kg) administered to animals for 6 weeks through drinking water. Male BALB/c mice were randomly divided into 5 groups receiving D-galactose (D-galactose, 500 mg/kg) for 6 weeks; positive control (D-galactose [500 mg/kg] for 6 weeks + Vitamin E [200 mg/kg/day] intraperitoneally for 4 weeks); IMOD (D-galactose [500 mg/kg] for 6 weeks + IMOD [20 mg/kg/day] intraperitoneally for 4 weeks), Angipars (D-galactose [500 mg/kg] for 6 weeks + Angipars [2.1 mg/kg/day] by gavage for 4 weeks); and the fifth group that was sham and not given D-galactose. At the end of treatment, pro-inflammatory markers including tumor necrosis factor-α (TNF-α), interlukine-1β (IL-β), interlukine-6 (IL-6), Nuclear Factor-kappaB (NF-κb), total antioxidant power (TAP), lipid peroxides (LPO) and male sex hormones i.e. testosterone and dehydroepiandrosterone-sulfate (DHEA-S) were measured in the blood.

Results showed that D-Galactose induces a significant oxidative stress and proinflammatory cascade of aging while both IMOD and Angipars recovered all of them. Interestingly, IMOD and Angipars were better than Vitamin E in improving male sex hormones in aged mice. This effect is so important and should be considered as an advantage although it cannot be explained with current knowledge. The conclusion is that IMOD and Angipars have marked anti-aging effect on D-galactose-induced model of aging.

ADMET considerations for phosphodiesterase-5 inhibitors

INTRODUCTION

ADMET (absorption, distribution, metabolism, excretion, and toxicity) profiling is an important aspect of all drug developments. The pharmaceutical industry must always consider ADMET properties in order to optimize drug candidates and to introduce new formulations against existing marketed drugs. Consequently, candidate drug development may be halted early in the discovery phase or during the more costly drug development process because of their poor ADMET properties.

AREAS COVERED

The main focus of this article is ADMET profiling, pharmacokinetic (PK) drug interactions, mechanisms and possible adverse drug reactions (ADRs) for approved phosphodiesterase-5 inhibitors (PDE5Is). The authors also look at the efficacy and non-erectogenic benefits of current PDE5Is, which are widely used by patients with erectile dysfunction (ED). The authors also discuss other unapproved PDE5Is such as aildenafil and udenafil, which are currently in use in clinical trials.

EXPERT OPINION

The authors believe that the enhancing effect of PDE5Is on the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway means that PDE5Is could be used to treat various conditions. An important issue in their development is 'cross-talk' between PDE5 and other PDEs and thus their specificity for other PDEs. But while it might be difficult to achieve the ideal ADMET profile, it should not necessarily prevent further development of a lead PDE5I. The risk assessment of PDE5Is, with respect to their ADMET properties, is therefore very important for predicting drug-drug interactions, possible side effects, ADRs and its future clinical applications.