Leonurine possesses cardioprotective effects in myocardial ischemia due to its anti-apoptotic properties. However, the process to isolate and purify leonurine is difficult, because of its low content in the Herb Leonuri and its impurity. Moreover, the high dosage used indicates low potency of leonurine. To overcome these defects, we had synthesized a novel twin drug of leonurine, 3,5-dimethoxy-4-(3-(2-carbonyl-ethyldisulfanyl)-propionyl)-benzoic acid 4-guanidino-butyl ester (compound 2). In this paper, we focused on investigating the cardioprotective effect and underlying mechanisms of compound 2. Our data showed that cell viability was significantly increased in a dose-dependent manner and the levels of lactate dehydrogenase (LDH) and creatine kinase (CK) were also significantly attenuated in the compound 2-treated group. In addition, we observed the cardioprotective effects by Hoechst 33258 nucleus staining, JC-1 staining, Annexin V-FITC/PI staining and transmission electron microscopy. Compound 2 inhibited apoptosis by reducing the ratio of Bcl-2/Bax, decreasing cleaved-caspase-3 expression and enhancing the phosphorylation of Akt. Furthermore, the phosphorylation effect of compound 2 was reversed by LY294002 the phosphatidylinositol-3-kinase (PI3K) inhibitor from happening. We concluded that compound 2 played a cardioprotective role in hypoxia-induced primary cardiac myocytes apoptosis partly via modulating the PI3K/Akt pathway at a 10-fold lower concentration than leonurine.