The Effects of Bergamot Polyphenolic Fraction, <i>Cynara cardunculus</i>, and <i>Olea europea</i> L. Extract on Doxorubicin-Induced Cardiotoxicity

Doxorubicin is an anthracycline that is commonly used as a chemotherapy drug due to its cytotoxic effects. The clinical use of doxorubicin is limited due to its known cardiotoxic effects. Treatment with anthracyclines causes heart failure in 15–17% of patients, resulting in mitochondrial dysfunction, the accumulation of reactive oxygen species, intracellular calcium dysregulation, the deterioration of the cardiomyocyte structure, and apoptotic cell death. Polyphenols have a wide range of beneficial properties, and particular importance is given to Bergamot Polyphenolic Fraction; Oleuropein, one of the main polyphenolic compounds of olive oil; and Cynara cardunculus extract. These natural compounds have particular beneficial characteristics, owing to their high polyphenol contents. Among these, their antioxidant and antoproliferative properties are the most important. The aim of this paper was to investigate the effects of these three plant derivatives using an in vitro model of cardiotoxicity induced by the treatment of rat embryonic cardiomyoblasts (H9c2) with doxorubicin. The biological mechanisms involved and the crosstalk existing between the mitochondria and the endoplasmic reticulum were examined. Bergamot Polyphenolic Fraction, Oleuropein, and Cynara cardunculus extract were able to decrease the damage induced by exposure to doxorubicin. In particular, these natural compounds were found to reduce cell mortality and oxidative damage, increase the lipid content, and decrease the concentration of calcium ions that escaped from the endoplasmic reticulum. In addition, the direct involvement of this cellular organelle was demonstrated by silencing the ATF6 arm of the Unfolded Protein Response, which was activated after treatment with doxorubicin