Context-Dependent Toxicity of Antioxidants: When Protective Molecules Become Harmful

Mpora Kakwanzi Evelyn

Department of Pharmacognosy Kampala International University Uganda

Email: evelyne.mpora@studwc.kiu.ac.ug

                                                                  ABSTRACT
Antioxidants are traditionally viewed as beneficial agents that defend cells against oxidative damage by neutralizing reactive oxygen species (ROS) and reactive nitrogen species (RNS). However, accumulating evidence demonstrates that their impact is highly context-dependent: under specific biochemical conditions, physiological states, and dosages, antioxidants can shift from protective to harmful roles. This review synthesizes current research showing that antioxidants may act as pro-oxidants, disrupt redox signaling, contribute to disease progression, and interfere with therapeutic outcomes. We explore the molecular mechanisms underlying this duality, including redox potential, concentration-dependent effects, presence of transition metals, and interactions with endogenous antioxidant networks. Clinical and toxicological implications are discussed, with examples from cancer biology, pharmacology, and environmental exposure scenarios. Understanding the nuanced behavior of antioxidants is critical for optimizing their application in diet, supplementation, and therapeutic settings, and for avoiding unintended adverse effects.

Keywords: Antioxidants, Context-dependent toxicity, Pro-oxidant effects, Redox biology, Therapeutic implications.

CITE AS: Mpora Kakwanzi Evelyn (2026). Context-Dependent Toxicity of Antioxidants: When Protective Molecules Become Harmful. NEWPORT INTERNATIONAL JOURNAL OF BIOLOGICAL AND APPLIED SCIENCES 7(2):48-53. https://doi.org/10.59298/NIJBAS/2026/7.2.4853