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Updated: May 10, 2026
11:56
A Rapid and Specific Microplate Assay for the Determination of Intra- and Extracellular Ascorbate in Cultured Cells
Published on: April 11, 2014
Manganoporphyrins increase ascorbate-induced cytotoxicity by enhancing H2O2 generation
Malvika Rawal1, Samuel R Schroeder, Brett A Wagner
1Department of Radiation Oncology, The University of Iowa Carver College of Medicine, Iowa City, IA, USA.
Cancer Research
|June 15, 2013
Summary
Catalytic manganoporphyrins (MnPs) enhance the cancer-fighting effects of pharmacological ascorbate (AscH-) by increasing hydrogen peroxide (H2O2) production. This combination therapy shows promise in reducing tumor growth and cancer cell survival.
Area of Science:
- Biochemistry
- Pharmacology
- Oncology
Background:
- Pharmacological ascorbate (AscH-) is being re-evaluated for cancer treatment due to its cytotoxic properties.
- AscH- generates hydrogen peroxide (H2O2) by donating electrons to oxygen, a key mechanism in cancer cells.
Purpose of the Study:
- To investigate if catalytic manganoporphyrins (MnPs) can enhance AscH- oxidation rates.
- To determine if increased H2O2 flux mediated by MnPs and AscH- synergy boosts cytotoxicity.
Main Methods:
- Tested three MnPs (MnTBAP, MnT2EPyP, MnT4MPyP) with varying properties.
- Assessed AscH- oxidation rates, oxygen consumption, and ascorbate radical [Asc•-] concentrations.
- Evaluated synergistic cytotoxicity in human pancreatic cancer cells and tumor growth in vivo.
Main Results:
- MnT4MPyP most effectively increased AscH- oxidation, ascorbate radical formation, and oxygen consumption.
- Combined MnPs and AscH- showed synergistic cytotoxicity, reversed by catalase, confirming H2O2 mediation.
- MnPs increased Asc•- concentrations in whole blood ex vivo.
- Combined MnT4MPyP and AscH- significantly inhibited tumor growth in vivo.
Conclusions:
- MnPs accelerate AscH- oxidation, enhancing H2O2 flux and ascorbate-induced cytotoxicity.
- This synergistic approach offers a potential strategy for improving cancer therapy.
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