Abstract
Reactive oxygen and nitrogen species (RONS) are generated through various endogenous and exogenous processes; however, they are neutralized by enzymatic and non-enzymatic antioxidants. An imbalance between the generation and neutralization of oxidants results in the progression to oxidative stress (OS), which in turn gives rise to various diseases, disorders and aging. The characteristics of aging include the progressive loss of function in tissues and organs. The theory of aging explains that age-related functional losses are due to accumulation of reactive oxygen species (ROS), their subsequent damages and tissue deformities. Moreover, the diseases and disorders caused by OS include cardiovascular diseases [CVDs], chronic obstructive pulmonary disease, chronic kidney disease, neurodegenerative diseases and cancer. OS, induced by ROS, is neutralized by different enzymatic and non-enzymatic antioxidants and prevents cells, tissues and organs from damage. However, prolonged OS decreases the content of antioxidant status of cells by reducing the activities of reductants and antioxidative enzymes and gives rise to different pathological conditions. Therefore, the aim of the present review is to discuss the mechanism of ROS-induced OS signaling and their age-associated complications mediated through their toxic manifestations in order to devise effective preventive and curative natural therapeutic remedies.
Highlights
The foremost evolutionary outcome following various metabolic changes is the ability to bind energy in the form of adenosine triphosphate (ATP)
The imbalance between the production and the elimination of free radicals leads to oxidative stress (OS) inside the human body, which indicates that the level of oxidants overpowers the antioxidant system and these oxidants negatively affect the various cellular structures, including membranes, proteins, lipids and deoxyribonucleic acid (DNA) [1,86–90]
It has been reported that OS-induced DNA damage leads to the increased production of mutagenic base8-oxo-2 -deoxyguanosine levels in a tissue which acts as a biomarker for OS [93]
Summary
The foremost evolutionary outcome following various metabolic changes is the ability to bind energy in the form of adenosine triphosphate (ATP). Enzymes involved in various metabolic pathways produce energy through different biochemical reactions that prompt the final reduction in molecular oxygen (O2). Different processes of amphibolic metabolic pathways such as the tricarboxylic acid (TCA) cycle and the respiratory chain are linked to the inner mitochondrial membrane, which produces reactive oxygen species (ROS) and generates free radicals. The generation of free radicals is a basic and useful incident for the proper functioning, protection and survival of cells within physiological limits [1–3]. An imbalance in the generation and neutralization of ROS may lead to the accumulation of ROS intermediate products which are thought to be detrimental and may induce oxidative stress (OS) [1,4,5]. Oxidative stress may be increased in the cell or tissue if there will be elevation in the rate of production and alleviation in the rate of neutralization of ROS [11]. Elucidating the underlying mechanisms of OS-induced pathogenesis of numerous clinical conditions and aging will help in the development of therapeutic agents against such diseases and disorders for the overall well-being of humans
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