Oxidative stress and antioxidant mechanisms in human body

Abstract

The present review aims to high light on the oxidative stress, and prevention by internal antioxidants and external antioxidants by some natural products possessing antioxidant properties. Oxidative stress occurs when the balance between reactive oxygen species (ROS) formation and detoxification favors an increase in ROS levels, leading to disturbed cellular function. ROS causes damage to cellular macromolecules causing lipid peroxidation, nucleic acid, and protein alterations. Their formation is considered as a pathobiochemical mechanism involved in the initiation or progression phase of various diseases such as atherosclerosis, ischemic heart diseases, diabetes, and initiation of carcinogenesis or liver diseases. In order to maintain proper cell signaling, it is likely that a number of radical scavenging enzymes maintain a threshold level of ROS inside the cell. However, when the level of ROS exceeds this threshold, an increase in ROS production may lead to excessive signals to the cell, in addition to direct damage to key components in signaling pathways. ROS can also irreversibly damage essential macromolecules. Protein-bound thiol and non-protein-thiol are the major cytosolic low molecular weight sulfhydryl compound that acts as a cellular reducing and a protective reagent against numerous toxic substances including most inorganic pollutants, through the –SH group. Hence, thiol is often the first line of defense against oxidative stress. Flavonoids have been found to play important roles in the non-enzymatic protection against oxidative stress, especially in the case of cancer. Flavonoids have occurred widely in tea, fruit, red wine, vegetables, and cocoas. Flavonoids, including flavones, flavanone, flavonols, and isoflavones, are polyphenolic compounds which are widespread in foods and beverages, and possess a wide range of biological activities, of which anti-oxidation has been extensively explored. It can be concluded that oxidative stress causes irreversible damage in cellular macromolecules that leads to initiation of various diseases such as atherosclerosis, ischemic heart diseases, liver diseases, diabetes, and initiation of carcinogenesis. Antioxidants inhibit reactive oxygen species production and scavenging of free radicals. Therefore, the review recommends that high consumption of natural foods that are rich in antioxidants will provide more protection against toxic agents and related diseases.

Fate of β-Carotene within Loaded Delivery Systems in Food: State of Knowledge

“…In addition to the aforesaid molecules, several exogenous antioxidants molecules from animal or plant origins are deliberately incorporated, i.e. fortified, into the diet [5].…”

“…Oxidative stress can be defined as a phenomenon triggered by an imbalance between the generation and accumulation of ROS. In general, ROS, including organic hydro peroxides, hydrogen peroxide, nitric oxide, hydroxyl radicals and superoxide, are generated as by-products of oxygen metabolism; in addition, these environmental stimuli (UV, pollutants, heavy metals, and xenobiotics (including antiblastic drugs, antiallergic drugs, immunosuppressant drugs) equally contribute to ROS production, thus causing oxidative stress [5]. Accruing scientific evidence is accumulating on the involvement of oxidative stress in the occurrence of several health complications, which are attributed to inactivation of metabolic enzymes and damage vital cellular components, oxidization the nucleic acids, resulting in eye disorders, atherosclerosis, cardiovascular diseases, joint and bone disorders, neurological diseases (amyotrophic lateral sclerosis, Parkinson's disease and Alzheimer's disease) and misfunctioning of different organ including lung, kidney, liver and reproductive system [6].…”

Fate of β-Carotene within Loaded Delivery Systems in Food: State of Knowledge

“…Human body adopt several strategies to combat the negative effect generated due to oxidative stress depending upon enzymatic (superoxide dismutase, glutathione peroxidase and catalase) or nonenzymatic (L-arginine, glutathione, coenzyme Q10 and lipoic acid) antioxidant molecules. In addition to aforesaid molecules several exogenous antioxidants molecules from animal or plant origin are deliberately incorporated in diet [5].…”

“…Oxidative stress can be defined as a phenomenon triggered by an imbalance between generation and accumulation of ROS. In general, ROS including organic hydro peroxides, hydrogen peroxide, nitric oxide, hydroxyl radicals and superoxide are generated as by-product of oxygen metabolism, despite this, environmental stimuli (UV, pollutants, heavy metals, and xenobiotics (including antiblastic drugs, antiallergic drugs, immunosuppressant drugs) equally contributes ROS production, thus causing oxidative stress [5]. Accruing scientific evidences are accumulating on involvement of oxidative stress in the occurrence of several health complications which are attributed to inactivation of metabolic enzymes and damage vital cellular components, oxidization the nucleic acids, resulting in eye disorders, atherosclerosis, cardiovascular diseases, joint and bone disorders, neurological diseases (amyotrophic lateral sclerosis, Parkinson's disease and Alzheimer's disease) and different organ misfunctioning including lung, kidney, liver and reproductive system [6].…”

Pharmacological Benefits of Triphala: A Perspective for Allergic Rhinitis

“…For example, 1) urban pollutants aggravate nasal inflammation and AR-related symptoms, 2) pollen grains that contain endogenous reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase damage airway epithelial cells and trigger granulocyte recruitment (Boldogh et al, 2005). However, our bodies have sophisticated antioxidant defense mechanisms, for example, enzymatic mechanisms, including glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), as well as non-enzymatic mechanisms involving glutathione, ascorbate, urate, a-tocopherol, bilirubin, lipoic acid, transferrin, and albumin, in order to prevent overwhelming by and accumulation of oxidative stress (Frei et al, 1988;Adwas et al, 2019). The imbalance between ROS production and endogenous antioxidant defense leads to an exhaustion of oxidative stress markers such as NO, MDA, and nitrite/nitrate (Birben et al, 2012;Ayala et al, 2014;Nadif et al, 2014).…”