efficacy of protective effects of tannic acid, gallic acid, ellagic acid, and propyl gallate against hydrogen peroxide-induced oxidative stress and DNA damages in IMR-90 cells

There is increasing evidence that reactive oxygen species (ROS) are intimately involved in the oxidative damage of tissues for a wide variety of pulmonary diseases. Thus, it is desirable to search for chemopreventive agents that can counteract ROS-mediated injury to the pulmonary tissues. Using a human lung fibroblast IMR-90 cells as the experimental model, we first demonstrated that nearly 90% of intracellular ROS could be removed when H₂O₂-treated cells (200 μM) simultaneously incubated with 10 μg/mL of tannic acid (TA), gallic acid (GA), ellagic acid (EA), and propyl gallate (PA). Using C₁₁-BODIPY⁵⁸¹/⁵⁹¹ as a lipid peroxidation probe, we also attested that all these compounds examined (10 μg/mL) could alleviate H₂O₂-evoked lipid peroxidation phenomena. Next, we examined the protective effects of these compounds on the depletion of intracellular glutathione (iGSH) in H₂O₂-treated cells using CMF-DA probe. Interestingly, PA was demonstrated to be the only compound that could effectively protect the integrity of iGSH from being depleted by this system. Finally, the protective effects of these compounds against oxidative DNA damage were evaluated using 8-oxoguanine formation as a marker. Our data indicated that all four compounds suppressed the formation of 8-oxoguanine effectively. Taken together, our data suggested that TA, GA, EA, and PA can protect cells from oxidative stress.