Shikonin Attenuates Doxorubicin-Induced Cardiotoxicity

Oxidative stress was involved in the development of DOX-induced cardiotoxicity. Western blots showed that shikonin significantly reversed the up-regulation of NADPH oxidase subunit p67phox and down-regulation of SOD2 expression induced by dox treatment (Fig. 2A,B). In our study, we assessed several key oxidative stress indicators, including MDA level, 4-HNE level, GSH level, and total SOD activity, to comprehensively evaluate the oxidative status. Additionally, we measured NADPH oxidase activity as a crucial indicator of oxidative stress pathway activation. Consistent with the molecular changes, we observed that shikonin decreased the excessive MDA level, 4-HNE and NADPH oxidase activity caused by DOX, and increased the low GSH level and total SOD activity caused by DOX (Fig. 2C–G). In addition, the mRNA level of NADPH oxidase subunit (p67phox, p22phox and gp91phox) decreased significantly after shikonin administration (Fig. 2H).Figure 2

Shikonin attenuated DOX-induced oxidative stress in the hearts. (A,B) Western blot and quantitative analysis showing the protein levels of p67 phox and SOD2 in vehicle and shikonin treated mice (n = 8). Original blots/gels are presented in Supplementary Fig. S3. (C–E) Levels of 4-hydroxynonenal (4-HNE), endogenous antioxidants (GSH) content and malondialdehyde (MDA) in mice myocardium (n = 8). (F) NADPH oxidase activity (n = 8). (G) Total SOD activity in the myocardium (n = 8). H, NADPH oxidase subunits mRNA expression by real time RT-PCR (n = 8). ***p < 0.001, ****p < 0.0001, significantly different as indicated.