Background: Doxorubicin (DOX), although widely employed in cancer therapy, induces significant cardiotoxicity primarily via oxidative stress and DNA damage. Pachymic acid (PA), a natural triterpenoid with established antioxidative and anti-inflammatory properties, has not yet been fully investigated for its protective actions against DOX-induced injury. This study aimed to explore the cardioprotective role of PA in mitigating DOX-induced cardiotoxicity, focusing on oxidative stress, inflammatory responses, DNA damage, and apoptosis.

Methods: H9c2 cardiomyocytes were treated with various concentrations of DOX and PA, either individually or in combination. The experimental groups consisted of control, DOX alone, PA alone, and PA plus DOX. A range of assays (CCK-8, TUNEL, ELISA, comet assay, Western blot) were performed to evaluate cell viability, apoptosis, inflammatory cytokine production, oxidative stress, and DNA damage. In vivo, the cardioprotective potential of PA was further evaluated in a rat model using histopathological analysis and serum biomarker evaluation.

Results: In vitro, PA pretreatment significantly improved cell viability and inhibited apoptosis in DOX-exposed H9c2 cells (p < 0.01), as demonstrated by modulation of Bcl-2, cleaved-PARP, Bax, and cleaved-caspase-3 expression (p < 0.01). PA suppressed oxidative stress by reducing reactive oxygen species (ROS) and Malondialdehyde (MDA) levels while enhancing Superoxide dismutase (SOD) and Glutathione (GSH) activities (p < 0.01). Additionally, PA mitigated DNA damage and downregulated DNA damage response proteins (p-ATR, γH2AX, P53, and P21) (p < 0.01). Proinflammatory cytokines tumor necrosis factor α (TNF-α), interleukin (IL)-6, and IL-1β were significantly decreased following PA treatment (p < 0.01). In vivo, serum concentrations of lactate dehydrogenase (LDH), cardiac troponin I (cTnI), brain natriuretic peptide (BNP), and creatine kinase-MB (CK-MB) were markedly reduced, and myocardial histopathology revealed alleviated structural damage (p < 0.01). These protective effects were accompanied by decreased oxidative damage, inflammatory responses, and cardiomyocyte loss in cardiac tissue (p < 0.01).

Conclusion: PA attenuated DOX-induced cardiotoxicity through the inhibition of oxidative stress, inflammatory responses, DNA damage, and apoptosis, highlighting its potential as a novel cardioprotective agent.