The terms 'antioxidant', 'oxidative stress' and 'oxidative damage' are widely used but rarely defined. This brief review attempts to define them and to examine the ways in which oxidative stress and oxidative damage can affect cell behaviour both in vivo and in cell culture, using cancer as an example.

Biochemistry of oxidative stress

Aging is characterized by a progressive deterioration of physiological integrity, leading to impaired functional ability and ultimately increased susceptibility to death. It is a major risk factor for chronic human diseases, including cardiovascular disease, diabetes, neurological degeneration, and cancer. Therefore, the growing emphasis on "healthy aging" raises a series of important questions in life and social sciences. In recent years, there has been unprecedented progress in aging research, particularly the discovery that the rate of aging is at least partly controlled by evolutionarily conserved genetic pathways and biological processes. In an attempt to bring full-fledged understanding to both the aging process and age-associated diseases, we review the descriptive, conceptual, and interventive aspects of the landscape of aging composed of a number of layers at the cellular, tissue, organ, organ system, and organismal levels. 

The landscape of aging

Synthesized titanium oxide nanoparticles (TiO2-NPs) nanotubes were used for the disinfection of new emerging corona virus-19 (SARS-CoV-2) in this study. The newly synthesized TiO2-NPs (nanotubes) were characterized by chemical spectroscopic analysis Fourier-transform infrared spectroscopy and ultraviolet FT-IR and UV. The chemical purity and Zeta potential distribution of the TiO2-NPs (nanotubes) were evaluated to confirm their nano-range, and their surface morphology was determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and energy dispersive X-ray analysis (EDX). The antiviral activity of the TiO2-NPs (nanotubes) against SARS-CoV-2 was evaluated using 10% (Dimethyl sulfoxide) DMSO and dist.H2O using a cytotoxicity assay and inhibitory concentration assay (to determine the cytotoxic half concentration CC50 and half maximal inhibitory concentration IC50). The current results confirmed that TiO2-NPs exhibit strong anti-SARS-CoV-2 activity at very low cytotoxic concentrations in vitro with a non-significant selectivity index (CC50/IC50 ≤ 1). The obtained results indicate that TiO2-NPs and nanotubes have potent antiviral activity at a very low concentrations (IC50 = 568.6 ng/mL), with a weak cytotoxic effect on the cellular host (CC50 = 399.1 ng/mL). Thus, we highly recommend the use of TiO2-NPs (nanotubes) in vitro and in wall coatings as a potent disinfectant to combat SARS-CoV-2 with little irritation of the cellular hosts. Furthermore, we also recommend more and excessive prospective studies on the complexation of natural active or natural compounds with TiO2-NPs (nanotubes) to minimize their cytotoxicity, enhance their antiviral activity, and increase their inhibition of SARS-CoV-2.

https://www.mdpi.com/2079-6412/11/6/680/pdf

A New Sterilization Strategy Using TiO2 Nanotubes for Production of Free Radicals that Eliminate Viruses and Application of a Treatment Strategy to Combat Infections Caused by Emerging SARS-CoV-2 during the COVID-19 Pandemic

Cadmium (Cd) is widely used in some industries and emitted from fossil fuels. It is a heavy metal with a number of side effects, including hepatotoxicity. Resveratrol (Rs) is considered an important polyphenol, which is a secondary plant metabolite and has the ability to scavenge free radicals. The study was designed to evaluate the effects of resveratrol on Cd, which induced hepatotoxicity, by the assessment of some histopathological and biochemical alterations. Forty male albino rats were divided into four groups: the 1st group was the control group, the 2nd group was treated with Cd (5 mg/kg), the 3rd group was given Rs (20 mg/kg), and the 4th group was treated with Cd in combination with Rs intraperitoneally for 30 successive days. The results indicate that Cd increased liver enzymes alanine aminotransferase and aspartate aminotransferase (AST and ALT), alkaline phosphatase ALP and gamma-glutamyl transferase (γ-GT) while reducing the total protein level; Cd increased the malondialdhyde (MDA) level while decreasing the levels of other antioxidant enzymes super oxide dismutase, catalase and glutathione peroxidase (SOD, CAT and GPx). Serious congestion and hemorrhage related to the hepatic tissues were noticed in the Cd group, and Rs plays a major role in alleviating histopathological injuries and hepatic oxidative damage. It is clear that Rs has the ability to minimize the hepatotoxicity induced by Cd in male rats.

Protective Effect of Resveratrol against Hepatotoxicity of Cadmium in Male Rats: Antioxidant and Histopathological Approaches

The evolutionary theory of aging supports a trade-off relationship between reproduction and aging. Aging of the male reproductive system primarily affects the testes, leading to a decrease in the levels of sexual hormones, alterations in sperm quality and production, and a decline in fertility that does not necessarily involve a complete cessation of spermatogenesis. Inflammation, oxidation, and apoptosis are events considered as predictors of pathogenesis and the development of age-related diseases that are frequently observed in aged testes. Although the molecular mechanisms are still poorly understood, accumulating evidence points toward pro-inflammatory molecules and reactive oxygen species as primary contributing factors for testicular aging. However, the real impact of aging-related testicular alterations on fertility, reproductive health, and life span is far from being fully revealed. This work discusses the current knowledge on the impact of aging in the testis, particularly of aging-related dysregulated inflammation and oxidative damage on the functioning of its different cell populations. More interestingly, this review covers the potential benefits of anti-aging interventions and therapies using either pharmacological compounds (such as non-selective non-steroidal anti-inflammatory medication) or more natural alternatives (such as various nutraceuticals or even probiotics) that exhibit anti-inflammatory, antioxidant, and anti-apoptotic properties. Some of these are currently being investigated or are already in clinical use to delay or prevent testicular aging.

Hallmarks of Testicular Aging: The Challenge of Anti-Inflammatory and Antioxidant Therapies Using Natural and/or Pharmacological Compounds to Improve the Physiopathological Status of the Aged Male Gonad

Aging is a neurological disease that is afforded by incidence of oxidative stress. Chitosan has received global interests due to its wide medical uses. Quercetin (Q) is a bioflavonoid and widely distributed in vegetables and fruits. Resveratrol is considered as a potent antioxidant and is a component of a wide range of foods. The using of either chitosan nanopartciles (CH-NPs), querectin (Q), and resveratrol (RV) to reduce the oxidative stress and biochemical alterations on brain and testicular tissues induced by D-galactose (DG) (100 mg/Kg) were the aim of the present study. This study investigated the probable protective effects of CH-NPs in two doses (140,280 mg/Kg), Q (20 mg/Kg) and RV (20 mg/Kg), against DG induced aging and neurological alterations. Brain antioxidant capacity as malonaldehyde (MDA), catalase (CAT), and glutathione reductase (GRx), as well as histopathological damages of the brain and testicular tissues were measured. The DG treated group had significantly elevated the oxidative stress markers by 96% and 91.4% in brain and testicular tissues respectively and lower significantly the antioxidant enzyme activities of both brain and testicular tissues than those of the control group by 86.95%, 69.27%, 83.07%, and 69.43%. Groups of DG that treated with a combination of CH-NPs in two doses, Q and RV, the levels of oxidative stress marker declined significantly by 68.70%, 76.64% in brain tissues and by 74.07% and 76.61% in testicular tissues, and the enzymatic antioxidants increased significantly by 75.55%, 79.24%, 62.32%, and 61.97% as compared to the DG group. The present results indicate that CH-NPs, Q, and RV have protective effects against DG-induced brain and testis tissue damage at the biochemical and histopathological levels. Mechanisms of this protective effect of used compounds against neurological and testicular toxicity may be due to the enhanced brain and testis antioxidant capacities.

https://www.mdpi.com/2079-6412/11/4/435/pdf

Neurological Alterations and Testicular Damages in Aging Induced by D-Galactose and Neuro and Testicular Protective Effects of Combinations of Chitosan Nanoparticles, Resveratrol and Quercetin in Male Mice

The journal retracts the article “Neurological Alterations and Testicular Damages in Aging Induced by D-Galactose and Neuro and Testicular Protective Effects of Combinations of Chitosan Nanoparticles, Resveratrol and Quercetin in Male Mice [...]

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Retraction: Hamza et al. Neurological Alterations and Testicular Damages in Aging Induced by D-Galactose and Neuro and Testicular Protective Effects of Combinations of Chitosan Nanoparticles, Resveratrol and Quercetin in Male Mice. Coatings 2021, 11, 435

Munirah A. Al-Hazaa

Papers

Neurological Alterations and Testicular Damages in Aging Induced by D-Galactose and Neuro and Testicular Protective Effects of Combinations of Chitosan Nanoparticles, Resveratrol and Quercetin in Male Mice

Retraction: Hamza et al. Neurological Alterations and Testicular Damages in Aging Induced by D-Galactose and Neuro and Testicular Protective Effects of Combinations of Chitosan Nanoparticles, Resveratrol and Quercetin in Male Mice. Coatings 2021, 11, 435