Antioxidant mechanisms in human health
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Antioxidant Mechanisms and Reactive Species in Human Health
Antioxidants play a crucial role in maintaining human health by counteracting the harmful effects of reactive oxygen species (ROS) and reactive nitrogen species (RNS), which are generated during normal metabolism and in response to environmental stressors. These reactive species can damage DNA, proteins, and lipids, contributing to the development of diseases such as cancer, cardiovascular disorders, neurodegenerative diseases, and the aging process 12456910.
Types of Antioxidant Defenses: Enzymatic and Non-Enzymatic
The human body is equipped with a complex antioxidant defense system that includes both enzymatic and non-enzymatic components. Key antioxidant enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) are the first line of defense, neutralizing superoxide anions and hydrogen peroxide to prevent oxidative damage 24569. Non-enzymatic antioxidants include small molecules like glutathione (GSH), ascorbic acid (vitamin C), tocopherols (vitamin E), carotenoids, flavonoids, and other plant-derived compounds, many of which are obtained from the diet 256789.
Mechanisms of Antioxidant Action
Antioxidants protect cells through several mechanisms:
- Scavenging and Neutralizing Free Radicals: Antioxidants directly neutralize ROS and RNS before they can damage cellular components 256789.
- Repairing Oxidative Damage: Enzymes such as peroxidases and glycosylases repair oxidatively damaged lipids and DNA, respectively 24.
- Regulating Redox Signaling: Antioxidants modulate redox-sensitive signaling pathways, influencing gene expression, apoptosis, and cellular metabolism 23.
- Supporting Immune Function: The antioxidant system is vital for maintaining immune cell function and protecting against immune-related oxidative stress .
Dietary and Synthetic Antioxidants in Health
Diet-derived antioxidants, especially vitamins C and E, carotenoids, and flavonoids, are important for supplementing endogenous defenses, as the body’s own antioxidant systems are often insufficient to fully prevent oxidative damage 15678. There is growing interest in fortified foods and supplements containing these antioxidants to promote health and prevent disease 58.
Paradoxical and Context-Dependent Roles of Antioxidant Enzymes
While antioxidants are generally protective, their effects can be context-dependent. Overexpression or deletion of certain antioxidant enzymes can sometimes lead to unexpected outcomes, such as increased disease risk or improved fitness, depending on the physiological context. This highlights the complexity of redox biology and the need for careful consideration in antioxidant-based therapies .
Antioxidant Mechanisms in Disease Prevention and Therapy
Oxidative stress is implicated in the pathology of many diseases, including cancer, atherosclerosis, neurodegenerative disorders, diabetes, and age-related conditions. Antioxidant mechanisms help reduce inflammation, prevent cellular apoptosis and necrosis, and protect against DNA and lipid damage, thereby playing a role in disease prevention and potentially in therapeutic strategies 12456910.
Conclusion
Antioxidant mechanisms are essential for protecting human health by neutralizing harmful reactive species, repairing oxidative damage, and supporting immune and metabolic functions. Both endogenous and dietary antioxidants contribute to this defense, but their roles are complex and context-dependent. Understanding these mechanisms is key to optimizing health strategies and developing effective antioxidant-based therapies.
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