Background: 

Ca²⁺ signalling is very sensitive to oxidants or reducing agents; changes in the redox state result in relevant changes in Ca²⁺ homeostasis, either altering Ca²⁺ mobilization from the internal stores and Ca²⁺ entry from the extracellular medium or modulating the activity of Ca^{2+ "}off"mechanisms, including Ca²⁺ pumps and exchangers. In cardiac, smooth, and skeletal muscles ROS induce Ca²⁺ release via modifications in D-myo-inositol 1,4,5-trisphosphate (IP3)-induced Ca²⁺ release. it has been reported that stimulates IP3-induced Ca²⁺ release from the SR of vascular smooth muscle.

Aim: 

Of this study was to investigate whether four flavanoids: quercetin, kaempferol, (+) catechin and (-) epicatechin are able to increase the superoxide anion production modulating the activity of MnSOD. In order to underline a role of these molecules in Ca²⁺ homeostasis.

Method: 

The SOD modulation activity was monitored with a spectrophotometric assay using the xantina/xantina oxidase(XO)-XTT system. The molecule concentrations ranged from 1 to 100 mM for each.

Results: 

Quercetin and kaempferol increase the rate of superoxide generation at lower concentrations (<10mM). Instead, they become inhibitors of the enzyme when increasing in concentration (100-150mM). Catechin and epicatechin are activators of SOD or radical scavengers at lower concentrations (<= 25mM).

Conclusion: 

We hypothesize that flavonoids could induce relevant changes in Ca⁺² homeostasis by increasing the superoxide production.