Potential Candidates of Natural Antioxidants From Herbs for Treating Lung Disorders: Focus on Redox Balance and Natural Products

Oxidative stress (OS) refers to an imbalance between oxidation and antioxidation processes. Reactive oxygen species (ROS) are normal byproducts of redox reactions occurring in vivo. When there is an overproduction of ROS or an insufficient antioxidant capacity, ROS accumulate in airway tissues and alveolar cells, potentially inducing OS. This condition can cause the migration and accumulation of activated inflammatory cells in the pulmonary microcirculation, airways, and alveoli, further enhancing lung inflammatory responses and triggering an inflammatory cascade. Inflammation inevitably results in pulmonary tissue damage and remodeling, leading to pulmonary diseases. Since the discovery of artemisinin, a malaria inhibitor, by Nobel laureate Youyou Tu, the effects of natural antioxidants on pulmonary diseases have been extensively evaluated. Recently, many active components of natural antioxidants have been shown to be effective in modulating redox imbalances in alveolar, endothelial, and tumor cells. Therefore, the supplementation of natural antioxidants may be an effective strategy to mitigate asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, and lung cancer. This paper reviews the advances in natural antioxidants for protecting against various pulmonary diseases by regulating redox imbalance. Antioxidants offer unique advantages and substantial potential.