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CAP-e (cell-based antioxidant protection in erythrocytes), is a novel in vitro bioassay for antioxidant activity developed by Alexander Schauss, Gitte Jensen, and associates at the American Institute for Biosocial and Medical Research (AIBMR), a private contract research organization (CRO) located in Puyallup, Washington, and Holger NIS, a private CRO located in Klamath Falls, Oregon.

The CAP-e assay is performed by first incubating red blood cells (erythrocytes) with a test sample at a range of concentrations. The cells are then combined with dichloro fluorescein diacetate (DCFDA), which is oxidized in the presence of free radicals to form a green fluorescent byproduct (DCF). In the next step of the assay, exogenous hydrogen peroxide is added at a concentration of 167 mM to artificially induce severe oxidative stress. The antioxidant activity of varying concentrations of the test compound is measured based on the degree of inhibition of DCF-fluorescence, which is an indirect and nonspecific measure of reactive oxygen species production.^[1] To date, the assay has been used in 2 published studies, both conducted by AIBMR and Holger NIS.^[2][3]

References

1. ^ "Fluorescence response of 3'-(p-aminophenyl) fluorescein (APF), 3'-(p-hydroxyphenyl) fluorescein (HPF) and dichlorodihydrofluorescein diacetate (H₂DCFDA) to various reactive oxygen species (ROS)". Invitrogen.com. http://www.invitrogen.com/site/us/en/home/References/Molecular-Probes-The-Handbook/tables/Fluorescence-response-of-3-p-aminophenyl-fluorescein-APF-3-p-hydroxyphenyl-fluorescein-HPF-and-dichlorodihydrofluorescein-diacetate-H2DCFDA-to-various-reactive-oxygen-species-ROS.html. Retrieved 2009-10-10.  
2. ^ Honzel D, Carter SG, Redman KA, Schauss AG, Endres JR, Jensen GS (2008). "Comparison of chemical and cell-based antioxidant methods for evaluation of foods and natural products: generating multifaceted data by parallel testing using erythrocytes and polymorphonuclear cells" (pdf). J Agric Food Chem 56 (18): 8319-25. http://pubs.acs.org/doi/pdfplus/10.1021/jf800401d.  
3. ^ Jensen GS, Wu X, Patterson KM, Barnes J, Carter SG, Scherwitz L, Beaman R, Endres JR, Schauss AG (2008). "In vitro and in vivo antioxidant and anti-inflammatory capacities of an antioxidant-rich fruit and berry juice blend. Results of a pilot and randomized, double-blinded, placebo-controlled, crossover study" (pdf). J Agric Food Chem 56 (18): 8326-33. http://pubs.acs.org/cgi-bin/sample.cgi/jafcau/2008/56/i18/pdf/jf8016157.pdf.