Design and synthesis of novel SCM-198 analogs as cardioprotective agents: Structure-activity relationship studies and biological evaluations

SCM-198 (Leonurine) has attracted great attention due to its cardioprotective effects in myocardial infarction (MI). However, no systematic modifications and structure-activity relationship (SAR) studies could be traced so far. In this study, 35 analogs of SCM-198 were designed, synthesized and their cardioprotective effects were evaluated. The cell viability assay on cardiomyocyte cell line H9c2 challenged with H2O2 showed that several analogs exhibited more potent cytoprotective effects than SCM-198 at 1 μM and 10 μM concentrations. LDH release level in cells treated with 1 μM 14o was comparable with cells treated with 10 μM SCM-198. Results of Bcl-2 expression and caspase-3 activation accordingly indicated higher protective activity of 14o than SCM-198. Moreover, in a mouse model of MI, the mice pretreated with 14o had much lower infarct size compared with that of SCM-198. The mechanism study suggested that 14o improved cardiac morphology and reduced apoptosis of cardiomyocytes in the border zone of infarction, as proved by H&E and TUNEL staining.