Protective Effects of Oroxylin A against Doxorubicin‐Induced Cardiotoxicity via the Activation of Sirt1 in Mice

Figure 1. OA treatment attenuated cardiac dysfunction in DOX-treated mice. (a) Bodyweight in the indicated group (n = 10). (b) The ratio of heart weight to tibial length (n = 10). (c, d) Serum and cardiac CK-MB (n = 6). (e, f) Serum and cardiac LDH (n = 6). (g) Heart rate in the indicated groups (n = 6). (h) EF in the indicated groups (n = 6). (i, j) ±dP/dt in DOX-treated mice (n = 6). (k, l) LVSP and LVEDP in DOX-treated mice (n = 6). Differences between multiple groups were determined by one-way ANOVA followed by Tukey's test. ∗P < 0.05 vs. control group, #P < 0.05 vs. DOX group.

Figure 2. OA treatment improved contractile function in cardiomyocytes. (a) Resting cell length (n = 6). (b) Peak shortening (n = 6). (c, d) ±dL/dt (n = 6). Differences between multiple groups were determined by one-way ANOVA followed by Tukey's test. ∗P < 0.05 vs. control group, #P < 0.05 vs. DOX group.

Figure 3. OA treatment prevented oxidative damage induced by DOX in cardiac tissue. (a, b) Myocardial 4-HNE and nitrotyrosine (n = 6). (c) GSH levels (n = 6). (c, d) Gpx and SOD activity (n = 6). (f–i) The mRNA levels of gp91phox, Nox4, p47phox, and p67phox (n = 6). (j) The protein expression of Nrf2 and downstream targets (n = 6). Differences between multiple groups were determined by one-way ANOVA followed by Tukey's test. ∗P < 0.05 vs. control group, #P < 0.05 vs. DOX group.

Figure 4. OA treatment attenuated inflammatory response and myocardial apoptosis in DOX-treated hearts. (a–d) Relative mRNA levels of inflammatory factors (n = 6). (e, f) The mRNA levels of MMP-2 and MMP-9 (n = 6). (g) The protein expression of p-IκBα and nuclear p65 (n = 6). (h) The protein expression of Bcl-2 (n = 6). (i) TUNEL staining and apoptotic rate (n = 6). (j, k) Caspase3/7 and PARP activities (n = 6). Differences between multiple groups were determined by one-way ANOVA followed by Tukey's test. ∗P < 0.05 vs. control group, #P < 0.05 vs. DOX group.

Figure 5. OA treatment exerted protection via Sirt1. (a, b) The Sirt1 protein expression and activity in vivo (n = 6). (c, d) The Sirt1 protein expression and activity in vitro (n = 6). (e, f) The production of ROS and superoxide (n = 5). (g) Nrf2 DNA binding activity (n = 5). (h, i) The mRNA levels of HO-1 and NQO1 (n = 6). (j) NF-κB binding activity (n = 5). (k) The mRNA level of TNF-α (n = 5). (l) Cell viability (n = 5). Differences between multiple groups were determined by one-way ANOVA followed by Tukey's test. For (a–i), ∗P < 0.05 vs. matched control; for (j, k), ∗P < 0.05 vs. control group, #P < 0.05 vs. DOX group, †P < 0.05 vs. DOX+OA group.

Figure 6. Sirt1 depletion abolished the protection provided by OA. (a, b) The cardiac CK-MB and LDH in DOX-treated mice (n = 6). (c) EF in the indicated groups (n = 10). (d, e) Myocardial 4-HNE and nitrotyrosine (n = 6). (f) The protein expression of nuclear Nrf2 and NF-κB (n = 6). (g, h) Caspase3/7 and PARP activities (n = 6). Differences between multiple groups were determined by one-way ANOVA followed by Tukey's test. ∗P < 0.05 vs. matched control.

Figure 7. OA treatment activated Sirt1 via cAMP/PKA signaling axis. (a, b) Relative NAD+ levels (n = 6). (c, d) Relative cAMP levels (n = 6). (e) Relative PKA activity in cells (n = 6). (f) Relative PKA activity in the hearts (n = 6). (g) Relative Sirt1 activity in cells (n = 6). (h) Cell viability of cells (n = 6). Differences between multiple groups were determined by one-way ANOVA followed by Tukey's test. For (a–e), ∗P < 0.05 vs. control/PBS group, #P < 0.05 vs. DOX group. For others, ∗P < 0.05 versus the matched group.

Figure 8. OA treatment did not increase tumor growth. (a) Schedule of the experiment. (b, c) Tumor size and tumor tissue mass (n = 6). (d–f) DOX concentrations in vivo in tissue (n = 6). Differences between multiple groups were determined by one-way ANOVA followed by Tukey's test. ∗P < 0.05 vs. matched control.