Cellular and plasma antioxidant activity assay using tetramethoxy azobismethylene quinone

The kinetics of the reduction of enzymatically generated tetramethoxy azobismethylene quinone (TMAMQ), a newly developed antioxidant activity assay method, by pure cellular and plasma antioxidants was studied. Further, the potential application of TMAMQ to the estimation of the antioxidant activity of clinical serum samples was investigated. The highest reduction rate (k) was obtained with ascorbic acid (1.11x10(-2)microM(-1) s(-1)) and glutathione showed the lowest (2.94x10(-5)microM(-1) s(-1)). Comparing TMAMQ and the commercially available antioxidant method Total Antioxidant Capacity clearly shows a similar trend, although the values differ. This study also shows that TMAMQ is highly sensitive (only a minute plasma sample was required) and reproducible, and the reaction proceeds until steady state (until all antioxidants have reacted). TMAMQ is very stable in acetonitrile (>3months), making it a highly flexible method because it can be easily adapted for analysis of just a single sample or for high-throughput analysis. This has direct implications on reducing costs and experimental steps. TMAMQ is therefore a highly promising antioxidant activity assay method for cellular and plasma antioxidant activity assay.