Doxorubicin (Dox) is a potent anthracycline antitumor drug whose clinical utility is significantly restricted by its dose-dependent, cumulative cardiotoxicity, driven by increased oxidative stress, impaired antioxidant defenses, and apoptosis-mediated cardiomyocyte loss. Methylene blue (MB), a phenothiazine derivative with well-documented redox-modulating properties, is being explored as a viable cardioprotective agent due to its antioxidant and anti-apoptotic effects. This study evaluated the protective role of MB against Dox-induced cardiotoxicity in rats by examining its impact on oxidative stress markers (Kelch-like ECH-associated protein 1; KEAP1, nuclear factor erythroid 2-related factor 2; NRF2, Glutathione peroxidase 4; GPX-4, 8-hydroxy-2′-deoxyguanosine; 8-OHdG), neurohormonal indicators (noradrenaline), cardiac injury biomarkers (troponin I), and apoptotic mediators (p53, Caspase-3). Forty male albino rats were divided equally into four groups: control, Dox (15 mg/kg, i.p.), MB alone (4 mg/kg/day, p.o. for 7 days), and Dox plus MB. Dox administration significantly increased serum troponin I and noradrenaline levels, elevated cardiac KEAP1 and 8-OHdG, and reduced NFE2L2, NRF2, and GPX-4 expression. It also upregulated p53 and Caspase-3 and caused marked myocardial degeneration, necrosis, and inflammatory infiltration. MB co-treatment significantly reduced troponin I and noradrenaline levels, restored KEAP1/NFE2L2 (NRF2)/GPX-4 pathway balance, decreased oxidative DNA damage, and attenuated p53 and Caspase-3 activation, preserving myocardial architecture with minimal inflammatory changes. These findings demonstrate that MB confers potent cardioprotection against Dox-induced cardiac injury by enhancing antioxidant defenses, limiting oxidative DNA damage, suppressing apoptosis, and normalizing neurohormonal imbalance, suggesting its promise as an adjunctive strategy to mitigate anthracycline-associated cardiotoxicity.

Background and Objectives: Doxorubicin (DOX) is a potential chemotherapeutic whose clinical application is limited by hepatotoxicity mediated through apoptosis, endoplasmic reticulum (ER) stress, and oxidative stress (OS). This study aimed to assess the hepatoprotective impact of methylene blue (MB) against DOX-induced liver injury. Methods: Forty rats were arbitrarily divided equally into four groups: control, DOX (15 mg/kg, i.p., single dose), MB (4 mg/kg, i.p., daily for 7 days), and DOX + MB (same regimen, MB initiated 1 h post DOX). Serum ALT, AST, and γ-GT were measured, along with hepatic TAC and HO-1. ELISA quantified PERK, GRP78, and CHOP. Immunohistochemistry assessed Caspase-3, p53, NF-κB, and Nrf2. Histopathological evaluation was performed using H&E staining. Results: DOX administration significantly elevated ALT, AST, γ-GT, HO-1, PERK, GRP78, and CHOP while reducing TAC and Nrf2 expression. Strong Caspase-3, p53, and NF-κB immunoreactivity and severe histopathological damage were observed. MB treatment markedly reversed these changes, restoring antioxidant status, downregulating ER stress markers, preserving Nrf2 expression, and improving hepatic architecture. Conclusions: MB exerts significant hepatoprotection against DOX-induced injury, likely via attenuation of OS, ER stress, apoptosis, and inflammation.

Background/Objectives: Doxorubicin (DOX) is a highly effective chemotherapeutic agent whose clinical use is limited by dose-dependent cardiotoxicity. This study aimed to investigate the potential protective effects of menthol against doxorubicin-induced cardiotoxicity (DIC) in a rat model. Methods: Forty rats were arbitrarily allocated into four groups: (1) normal control, (2) DOX-treated, (3) DOX + menthol treatment, and (4) menthol-only treatment. DOX (15 mg/kg) was applied intraperitoneally, and menthol (100 mg/kg) was applied orally for 7 days following the DOX injection. Cardiac tissue specimens and sera were collected for biochemical assays, histopathological analysis, and immunohistochemistry. Biomarkers of oxidative stress (MDA, GSH), inflammatory pathways (TLR4, MAPK, NF-κB, SREBP-1C), and apoptotic markers (P53, caspase-3) were assessed. Results: DOX employment caused remarkable rise in serum troponin levels (6.53 ± 0.98, p < 0.05), oxidative stress markers, and inflammatory proteins, alongside histopathological damage in cardiac tissues. Menthol treatment significantly suppressed oxidative stress (MDA, GSH), inflammation (TLR4, MAPK, NF-κB, SREBP-1C levels), and attenuated apoptosis (P53 and caspase-3 expression) (p < 0.05). Conclusions: Menthol may serve as a promising adjunctive therapy to reduce DOX cardiotoxicity without compromising DOX’s anticancer efficacy.