Free radicals and their impact on health and antioxidant defenses: a review

Abstract

Free radicals, characterized by the presence of unpaired electrons, are highly reactive species that play a significant role in human health. These molecules can be generated through various endogenous processes, such as mitochondrial respiration and immune cell activation, as well as exogenous sources, including radiation, pollution, and smoking. While free radicals are essential for certain physiological processes, such as cell signaling and immune defense, their overproduction can disrupt the delicate balance between oxidants and antioxidants, leading to oxidative stress. Oxidative stress results in the damage of critical biomolecules like DNA, proteins, and lipids, contributing to the pathogenesis of various diseases. Chronic conditions such as cancer, cardiovascular diseases, neurodegenerative disorders, and inflammatory diseases have been strongly associated with the harmful effects of free radicals. This review provides a comprehensive overview of the characteristics and types of free radicals, their mechanisms of formation, and biological impacts. Additionally, we explore natural compounds and extracts studied for their antioxidant properties, offering potential therapeutic avenues for managing free radical-induced damage. Future research directions are also discussed to advance our understanding and treatment of free radical-associated diseases.

Fig. 1. Overview of free radicals and their characteristics.

Characteristics, sources, types, mechanisms of action, and antioxidant defenses related to free radicals. Free radicals, characterized by unpaired electrons, are highly reactive species generated endogenously through processes like mitochondrial respiration and enzymatic reactions, and exogenously from environmental factors such as UV radiation and pollution. The primary types include reactive oxygen species (ROS) and reactive nitrogen species (RNS). Free radicals induce cellular damage through lipid peroxidation, protein oxidation, and DNA damage, contributing to various diseases.

Fig. 2. Future research directions in oxidative stress management.

key research areas for advancing the management of oxidative stress. The central focus is on understanding and improving oxidative stress management through ten key avenues: elucidating mechanisms of free radical action, developing novel antioxidant therapies, personalizing antioxidant interventions, investigating antioxidants in preventive medicine, exploring synergies with other therapies, assessing long-term safety of supplements, understanding lifestyle and environmental impacts, advancing biomarker discovery, expanding non-pharmacological interventions, and enhancing public awareness and education. These areas collectively aim to deepen insights into oxidative stress and refine therapeutic strategies for better health outcomes.