The preclinical experiment used 28 rats divided equally into four groups, with seven animals in each group. The control animals received neither doxorubicin nor hydroxytyrosol. A second group received hydroxytyrosol orally at 100 mg/kg/day for four weeks. The third group received a single 10 mg/kg dose of doxorubicin by intraperitoneal injection on day 1. The fourth group received the same doxorubicin dose followed by oral hydroxytyrosol at 100 mg/kg/day, beginning 24 hours after the injection. Researchers examined serum 8-OHdG levels, cardiac expression of ISM-1, PODXL, p-mTOR and p-AKT, and histopathological changes in heart tissue. The analysis focused on biochemical, molecular and microscopic outcomes in an animal model rather than the protective effects of hydroxytyrosol in patients receiving cancer chemotherapy.

Doxorubicin is an effective chemotherapeutic agent used for various malignancies, but its clinical use is limited by cardiotoxicity. In the doxorubicin-only group, investigators found significantly elevated cardiac expression of ISM-1, PODXL, p-mTOR and p-AKT compared with controls, with each comparison reported at p < 0.001. These animals also showed marked histopathological damage. Vacuolization, mononuclear cell infiltration, necrosis and fibrosis scores were all significantly higher than in the control group, again at p < 0.001. Serum 8-OHdG concentrations also increased in the doxorubicin group. The authors interpreted this pattern as evidence of oxidative stress, DNA damage and deterioration in cardiac tissue under the experimental conditions.

When hydroxytyrosol was administered after doxorubicin, p-mTOR and p-AKT expression in cardiac tissue was significantly lower than in the doxorubicin-only group. The combination also produced significant reductions in intracytoplasmic vacuolization, mononuclear cell infiltration and necrosis. Serum 8-OHdG levels fell significantly in the combined-treatment group relative to the doxorubicin group, indicating less oxidative DNA damage according to the study’s measurement. The researchers characterized the overall findings as modulation of ISM-1, PODXL, p-mTOR and p-AKT expression, together with attenuation of tissue injury. The reduction in fibrosis did not reach statistical significance, with p = 0.590, so the results do not support a claim that hydroxytyrosol definitively reversed this component of cardiac injury.

These results indicate that hydroxytyrosol may influence molecular and biochemical pathways associated with doxorubicin toxicity in rat heart tissue. The treatment was associated with lower 8-OHdG concentrations, reduced p-mTOR and p-AKT expression, and improvement in several—but not all—measures of microscopic cardiac injury after a single doxorubicin dose. The experiment does not establish that hydroxytyrosol prevents cardiotoxicity in patients, preserves heart function, improves cancer-treatment outcomes or offers a substitute for established monitoring and treatment practices. The authors identified the limited sample size, the absence of cardiac functional assessment and the need for further studies as key limitations. Accordingly, the findings represent controlled laboratory evidence from 28 rats: hydroxytyrosol mitigated several measured indicators of doxorubicin-associated cardiac injury, while the reduction in fibrosis remained statistically uncertain.

Subject of Research: Effects of hydroxytyrosol on biochemical, molecular and histopathological markers of doxorubicin-associated cardiac injury in a rat model

Article Title: Effects of hydroxytyrosol on ISM-1, PODXL, p-mTOR, and p-AKT protein expression and 8-OHdG levels in doxorubicin-associated cardiac injury

Article References: Erdoğan, M. M., Kocaman, N., Onat, E., Erdoğdu, H., & Özdem, B. (2026). Effects of hydroxytyrosol on ISM-1, PODXL, p-mTOR, and p-AKT protein expression and 8-OHdG levels in doxorubicin-associated cardiac injury. BMC Complementary Medicine and Therapies. https://doi.org/10.1186/s12906-026-05646-2

Image Credits: AI Generated

DOI: 10.1186/s12906-026-05646-2

Keywords: hydroxytyrosol, doxorubicin, cardiotoxicity, cardiac injury, oxidative DNA damage, 8-OHdG, p-mTOR, p-AKT, rat model, olive oil polyphenol, Effects, ISM-1