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Determination of the Minimum Exposure Time for Effecting Cytoprotection in Human Umbilical Vein Endothelial Cells (HUVEC) for Caffeic Acid Phenylethyl Ester (CAPE) and Amide (CAPA)

We have previously shown that CAPE and CAPA protect HUVEC from oxidant stress.1 This activity was correlated with the production of heme oxygenase‐1 (HO‐1). The objective of this study was to determine the minimum exposure time necessary to provide cytoprotection and HO‐1 production. HUVEC were exposed to cytoprotective doses of CAPE and CAPA for 0.5,1,2,3,4 and 6 hrs. The compounds were removed at the end of each time period and placed in fresh media. Levels of HO‐1 were then evaluated by gel electrophoresis and immunoblotting, and cytoprotection against H2O2 toxicity was measured. CAPE and CAPA both showed a significant increase in HO‐1 expression over vehicle control within 30 min of exposure. HO‐1 levels for both CAPE and CAPA peaked with a 4 h incubation time with no significant differences beyond 4 hours. Significant cytoprotective effects against hydrogen peroxide for both CAPE and CAPA were found with as little as a 1 h exposure time. CAPE and CAPA both showed significant effects on HUVEC HO‐1 expression and cytoprotection with only a brief exposure. It appears that the compounds do not need to be continually exposed to the cells in order for the beneficial properties to be expressed. Whether this is due to cell loading of the drug or that minimum exposure to drug triggers a switch that leads to the effect is under investigation. Funding provided by the US Army Medical and Material Command