p-Coumaric acid, a novel and effective biomarker for quantifying hypoxic stress by HILIC-ESI-MS.

In this study, we report p-coumaric acid as novel and effective response marker for indirectly measuring the levels of hypoxia in normal primary bronchial epithelial cells. We developed a simple and rapid technique based on hydrophilic interaction chromatography-electrospray ionization-mass spectrometry (HILIC-ESI-MS). During 168h of hypoxia without induction of reactive oxygen species (ROS), an almost linear increase of p-coumaric acid levels was observed. We interpret the increasing p-coumaric acid concentrations during hypoxia as a result of cell damage, triggered by reduced co-enzyme Q10 levels, because the oxidative cascade was not able to supply sufficient energy. The HILIC-ESI-MS assay within p-coumaric acid exhibited a linear dynamic range from 60 to 610 ng/µL with correlation coefficient of 0.9998. The precision of the assay was ≤15% RSD and method accuracies between 97 and 108%.