Curcumin, a phytochemical with antioxidant and other cytoprotective properties, has been reported to reduce nitrite formation during nitric oxide (NO) oxidation in solution. This decrease in nitrite production was attributed to the direct sequestration of NO by curcumin. In this report, we confirm that curcumin inhibits nitrite formation from DEA/NO-derived NO in a concentration-dependent manner. However, curcumin over a concentration range of 3-50μM had no effect on the concentration of free NO (0.5μM) in solution at 37°C as assessed using an NO electrode. We conclude that the inhibitory effect of curcumin on the oxidation of NO to nitrite is due to its known sequestration of the reaction intermediate nitrogen dioxide (NO2). The ability of curcumin to sequester NO2, but not NO, suggests that curcumin may be useful for separating the actions of NO2 from those of NO in various biological systems.
Bibliographical noteFunding Information:
This work was supported by the Department of Veterans Affairs and by the National Institute of Alcohol Abuse and Alcoholism Grant AA12730.
- Nitric oxide
- Nitrogen dioxide