The cellular protective and antioxidant properties of phosphoenolpyruvate (PEP), a glycolytic metabolite with high-energy phosphate groups. PEP (0.1-10 mM) significantly attenuated the decrease in cell viability induced by hydrogen peroxide (H (2) O (2)) in HeLa cells in a dose-dependent manner. PEP also inhibited the reduction of cells stained with calcein acetylmethoxy group and the increase of cells stained with propidium iodide induced by H (2) O (2). The increase in intracellular reactive oxygen species stimulated by HEP (2) O (2) significantly decreased. PEP is a functional carbohydrate metabolite with cellular protection and antioxidant activity, and may serve as a therapeutic agent for diseases involving oxidative stress. However, no effect was observed at low doses (0.1, 1 mM). PEP (0.1-10 mM) also alleviated cell damage, but did not weaken the decrease in intracellular ATP content induced by the glycolytic inhibitor 2-deoxy-D-glucose. PEP can also alleviate the increase in leakage of aminotransferase and lactate dehydrogenase caused by organ preservation, histological changes, and changes in oxidative stress parameters (measured by thiobarbituric acid reactive substances and glutathione content) after 72 hours of liver preservation. Its effect can be comparable to the University of Wisconsin solution (a gold standard organ preservation agent). PEP treatment can alleviate the decrease in ATP content in the liver during refrigeration. PEP prevented cell damage in HepG2 cells and increased the content of intracellular reactive oxygen species. In addition, PEP cleared hydroxyl radicals but had no effect on superoxide anions, evaluated by electron paramagnetic resonance spin trapping technology.