Redox- and non-redox-metal-induced formation of free radicals and their role in human disease.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing biochemical and mechanistic concepts without systematic search criteria or primary empirical human data.
PubMed 26343967 · doi:10.1007/s00204-015-1579-5
What was done
This narrative review synthesizes biochemical mechanisms through which redox-active metals (iron, copper) and redox-inactive metals or metalloids (arsenic, cadmium, zinc) induce reactive oxygen species (ROS) and reactive nitrogen species (RNS). It examines the resulting oxidative damage to lipids, proteins, and DNA, as well as downstream links to chronic human pathologies.
What was found
The abstract provides no quantitative data or effect sizes. It details qualitative pathways: redox-active iron and copper undergo redox-cycling via the Fenton reaction to generate hydroxyl radicals, whereas redox-inactive arsenic and cadmium primarily exert toxicity by binding protein sulfhydryl groups and depleting glutathione. Zinc depletion impairs DNA repair mechanisms. These mechanisms cause lipid peroxidation (yielding malondialdehyde and 4-hydroxynonenal), compromise cellular antioxidant defenses (including SOD, catalase, and glutathione peroxidase), and impair signal transduction and tumor suppressor functions.
Why it matters
It provides a conceptual overview of the molecular pathways linking environmental or metabolic metal dysregulation to oxidative stress and major diseases, including cancer, cardiovascular disease, Alzheimer's disease, and Parkinson's disease.
Limits
The abstract reports no primary clinical data, quantitative risk estimates, exposure thresholds, or systematic literature search methodology. Causal links to human diseases are described at a conceptual and mechanistic level without evaluating confounding variables or clinical trial outcomes.
Cited by
- supports Copper generates free radicals because it possesses an unpaired d-orbital electron, a characteristic zinc lacks.