Forsythiaside B inhibits myocardial fibrosis via down regulating TGF-β1/Smad signaling pathway.

Forsythiaside B is the major ingredient of Callicarpa kwangtungensis Chun, and has been proven to protect myocardium from ischemia-reperfusion injury to achieve myocardial protection. However, the effect of forsythiaside B on adverse myocardial fibrosis remains unclear. In the present study, the myocardial fibrosis animal models were established induced by isoproterenol (ISO) to investigate whether forsythiaside B exhibited antifibrotic actions. Forsythiaside B was found to significantly improve the cardiac ejection fraction and fractional shortening rate of myocardial fibrosis mice compared with the normal saline group. In addition, forsythiaside B could lower the level of TGF-β1, the expression of α-SMA and collagen III. Forsythiaside B down-regulated the expression of Smad4 and the phosphorylation level of Smad3, which indicates that forsythiaside B could suppress myocardial fibrosis by inhibiting the TGF-β1/Smad signaling pathway. These results demonstrated that forsythiaside B could prevent myocardial fibrosis in ISO-induced mice, and may be a potentially rational therapeutic approach for the treatment of myocardial fibrosis.