Preventive Effect of Protocatechuic Acid Ethyl Ester against Doxorubicin-Induced Toxicity in Cardiomyocytes

Administration of doxorubicin (DOX), an effective anticancer drug, is associated with cardiotoxicity. Protocatechuic acid ethyl ester (PCAE) is a natural phenolic acid derivative with antioxidant, iron-chelating capability and prolyl hydroxylase inhibitory effects. This in vitro investigation tested whether PCAE could protect against toxicity induced by doxorubicin in cardiomyocytes and compared its effects with those of protocatechuic acid (PCA).

After evaluation of the cytotoxicity of PCAE (1-100 µM) and DOX (0.125-8 µM) on H9C2 cardiomyocytes, the cells were exposed to DOX (2 μM) following 24 h pretreatment with PCAE (1-100 µM). MTT assay was done to estimate the cytotoxicity or cell viability. The level of intracellular reactive oxygen species (ROS) was examined by fluorescence assay. The ferric reducing antioxidant power (FRAP) assay was performed as a measure of antioxidant capacity. Glutathione depletion assay was performed using 5,5-dithiobis-2-nitrobenzoic acid.

PCAE (1-100 µM) had no inhibitory effect on the survival rate of cardiomyocytes after 24-hour incubation. Pretreatment with PCAE at 10-100 μM significantly prevented cytotoxicity of DOX using MTT test. PCAE declined the ROS level (at 1-100 µM) and glutathione depletion (at 80 and 100 μM) and raised the FRAP level (at 20-100 μM). These protective and antioxidant effects were significantly more potent than those of PCA activities.

PCAE showed antioxidant and cytoprotective activities against toxicities caused by DOX in cardiomyocytes more potent than those of PCA. PCAE may be a potential candidate for prevention and treatment of DOX-induced cardiotoxicity, which requires further in vivo and clinical researches.