Mokko Lactone Alleviates Doxorubicin-Induced Cardiotoxicity in Rats via Antioxidant, Anti-Inflammatory, and Antiapoptotic Activities

Abstract

Doxorubicin (DOX), a commonly utilized anthracycline antibiotic, suffers deleterious side effects such as cardiotoxicity. Mokko lactone (ML) is a naturally occurring guainolide sesquiterpene with established antioxidant and anti-inflammatory actions. This study aimed at investigating the protective effects of ML in a DOX-induced cardiotoxicity model in rats. Our results indicated that ML exerted protection against cardiotoxicity induced by DOX as indicated by ameliorating the rise in serum troponin and creatine kinase-MB levels and lactate dehydrogenase activity. Histological assessment showed that ML provided protection against pathological alterations in heart architecture. Furthermore, treatment with ML significantly ameliorated DOX-induced accumulation of malondialdehyde and protein carbonyl, depletion of glutathione, and exhaustion of superoxide dismutase and catalase. ML's antioxidant effects were accompanied by increased nuclear translocation of NF-E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expression. Moreover, ML exhibited significant anti-inflammatory activities as evidenced by lowered nuclear factor κB, interleukin-6, and tumor necrosis factor-α expression. ML also caused significant antiapoptotic actions manifested by modulation in mRNA expression of Bax, Bcl-2, and caspase-3. This suggests that ML prevents heart injury induced by DOX via its antioxidant, anti-inflammatory, and antiapoptotic activities.

Keywords: doxorubicin; heart; mokko lactone.

Figure 1

Effect of ML on DOX-induced on ECG patterns: (A) control group; (B) DOX group; (C) DOX + ML (15 mg/kg); and (D) DOX + ML (30 mg/kg), DOX = Doxorubicin, ML = Mokko Lactone.

Figure 2

Effect of ML on DOX-induced histopathological changes on cardiac tissues: (A) control group demonstrating normal architecture of the heart tissues; (B) DOX group exhibiting mononuclear inflammatory cells infiltration and widespread necrosis of cardiac tissues (black arrow); (C) DOX + ML (15 mg/kg) treated group showing limited inflammatory areas and degenerated cardiomyocytes; (D) DOX + ML (30 mg/kg) treated group with restoration of a nearly normal cardiac histology. DOX = Doxorubicin, ML = Mokko Lactone.

Figure 3

Effect of ML on serum cardiac markers in DOX-treated rats: (A) serum troponin level; (B) serum CK-MB level; (C) serum LDH activity. Background dotted lines represent range of corresponding control values. Data are displayed as mean ± SD (n = 6). DOX = Doxorubicin, ML = Mokko Lactone. a, significantly different than control (p < 0.05); b, significantly different than DOX (p < 0.05); c, significantly different than DOX + ML (15 mg/kg) (p < 0.05).

Figure 4

Effect of ML on oxidative status of on DOX-induced cardiotoxicity in rats: (A) cardiac MDA content; (B) cardiac CAT activity; (C) cardiac SOD activity; (D) cardiac GSH; and (E) cardiac protein carbonyl content. Data are displayed as mean ± SD (n = 6). DOX = Doxorubicin, ML = Mokko Lactone. a, significantly different compared with control (p < 0.05); b, significantly different compared with DOX (p < 0.05); c, significantly different compared with DOX + ML (15 mg/kg) (p < 0.05).

Figure 5

Effect of ML on Nrf2 expression as determined immunohistochemically (A–E) and mRNA expression of Nrf2 (F) and HO-1 (G) in cardiac tissues of DOX-treated rats. Data shown as bar charts are mean ± SD (n = 6). DOX = Doxorubicin, ML = Mokko Lactone. a, b, or c: statistically different from control, DOX, or DOX + ML (15 mg/kg), respectively (p < 0.05).

Figure 6

Effect of ML on NFκB, IL-6, and TNF-α, as determined by immunohistochemistry (A) or ELISA (B) in cardiac tissues of DOX-treated rats. Data in bar charts are mean ± SD (n = 6). DOX = Doxorubicin, ML = Mokko Lactone. a, b or c: statistically significant compared with control, DOX, or DOX + ML (15 mg/kg), respectively (p < 0.05).

Figure 7

Effect of ML on cardiac mRNA expression of Bax (A), Bcl-2 (B), and caspase-3 (C) in DOX-treated rats. Data shown in bar charts are mean ± SD (n = 6). DOX = Doxorubicin, ML = Mokko Lactone. a, b or c: statistically significant compared with control, DOX, or DOX + ML (15 mg/kg), respectively (p < 0.05).