Manganese Porphyrin-Based Antioxidant Therapeutics in Oncology

Manganese porphyrins represent a class of redox-active compounds designed to mimic the catalytic activity of superoxide dismutase (SOD) and to modulate cellular oxidative stress. These complexes harbour a central Mn(III) core within a meso-substituted porphyrin scaffold, enabling them to dismute superoxide, react with hydrogen peroxide, peroxynitrite and other reactive species, and to influence redox-sensitive signalling pathways. In cancer cells, manganese porphyrins frequently act as pro-oxidants, amplifying intracellular oxidative stress and triggering apoptosis, cell-cycle arrest and inhibition of migratory and invasive phenotypes. By contrast, in normal tissues they often behave as antioxidants, scavenging harmful reactive oxygen species and protecting against collateral damage during radiotherapy or chemotherapy. Mechanisms of action extend beyond simple radical scavenging to include post-translational oxidative modification of transcription factors such as NF-κB and Nrf2, regulation of mitogen-activated protein kinases and modulation of antiapoptotic proteins. Early-generation compounds focused primarily on SOD-like activity, while newer derivatives have been optimised for lipophilicity, redox potential and tissue distribution, facilitating improved central nervous system penetration and enhanced tumour selectivity. Clinical translation is underway, with lead molecules now entering phase II studies in glioma, head and neck cancers and metastatic settings. The global significance of this approach lies in its potential to increase therapeutic index, overcoming radio- and chemoresistance in solid tumours while preserving healthy tissue integrity.

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Manganese Porphyrin-Based Antioxidant Therapeutics in Oncology publication trend

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Technical terms

Superoxide dismutase mimic: A synthetic compound that catalyses the dismutation of superoxide radicals to hydrogen peroxide and oxygen, emulating the activity of the native enzyme.

Reactive oxygen species (ROS): Chemically reactive molecules derived from oxygen, including superoxide, hydrogen peroxide and hydroxyl radical, which can damage cellular components or act as signalling mediators.

Pro-oxidant: An agent that increases the concentration of ROS within cells, often inducing oxidative stress and downstream cytotoxic effects.

Antioxidant: A molecule capable of scavenging or neutralising ROS, thereby preventing oxidative damage to lipids, proteins and nucleic acids.

Epithelial–mesenchymal transition (EMT): A cellular programme by which epithelial cells acquire mesenchymal traits, enhancing motility and invasiveness, commonly implicated in metastasis.

References

1. The Redox-Active Manganese(III) Porphyrin, MnTnBuOE-2-PyP5+, Impairs the Migration and Invasion of Non-Small Cell Lung Cancer Cells, Either Alone or Combined with Cisplatin. Cancers (2023).
2. The Addition of Manganese Porphyrins during Radiation Inhibits Prostate Cancer Growth and Simultaneously Protects Normal Prostate Tissue from Radiation Damage. Antioxidants (2018).
3. MnTnHex-2-PyP5+, Coupled to Radiation, Suppresses Metastasis of 4T1 and MDA-MB-231 Breast Cancer via AKT/Snail/EMT Pathways. Antioxidants (2021).