The inventors of the present application found that a compound represented by formula (I) exhibits a protective effect on myocardial cells. Therefore, the present invention provides a pharmaceutical composition for protecting myocardial cells, the composition containing a compound represented by formula (I) or an ester thereof, an oxide thereof, or a pharmaceutically acceptable salt or solvate thereof. Said pharmaceutical composition can be used for preventing or treating heart diseases associated with myocardial cell death, such as myocardial infarction, chronic heart failure, hypertensive heart failure, and dilated cardiomyopathy, in particular, myocardial infarction.本案發明人發現式(I)的化合物具有保護心肌細胞的效果。因此，本發明提供一種用於保護心肌細胞的醫藥組成物，其包含式(I)的化合物或其酯、氧化物、藥學上可容許的鹽、或是溶劑化物。該醫藥組成物，能夠用來處置或預防心肌梗塞、慢性心臟衰竭、高血壓性心臟衰竭或擴張型心肌症等伴隨心肌細胞死亡的心臟疾病，尤其能夠用來處置心肌梗塞。
