Backgrounds and Objective: Recent study suggests that all active Magnolia constituents including magnolol, honokiol and CH-6784 decrease the reactive oxygen species in mammalian cell, which are essential for the biologic and physiologic cell function. In the cardiomyocytes (CMCs), the role of CH-6784 was not known. We assessed the hypothesis that CH-6784 reduces the hydrogen peroxide-induced apoptosis of neonatal rat CMCs by upregulation of redox-regulating thioredoxin(Trx) system. Design and Methods: Under the concentration of 100關g/ml of hydrogen peroxide, neonatal rat CMCs (3��10⁵ cells) were incubated with different concentrations of CH-6784 (0.1, 1, 10 關g/ml) for 24 hours. We measured the extent of CMCs��� apoptosis by Annexin-V-FLUOS staining, the amount of oxidative stress by oxyblot, the redox regulating Trx system and the anti-apoptotic Bcl-2 signals by Western blot analysis. Results: In CH-6784 treatment, hydrogen peroxide-induced CMCs��� apoptosis was more decreased than control (0.1關M; 32.6, 1關M; 29.4, 10關M; 28.8 vs control; 46.2%). And, nonspecific oxidation by oxyblot was also decreased. Whereas redox regulating Trx was slightly decreased, Trx-interacting protein (Txnip) known as endogenous Trx inhibitor was significantly increased by Western blot analysis. Functional Trx activity (Trx/Txnip) was increased (Optical density(OD) ratio: 0.1關M; 1.3, 1關M; 1.9, 10關M; 2.3 vs control; 1AU) with it���s downstream NF-kB (OD ratio: 0.1關M; 0.86, 1關M; 0.81, 10關M; 0.23 vs control; 1AU). Bcl-2/Bax-慣 was also increased at dose-dependent manner (OD ratio: 0.1關M; 4.3, 1關M; 7.1, 10關M; 13.5 vs control; 1AU). Caspase-3, the final executor of apoptosis signal, was also decreased at CH-6784 treatment. Conclusion: CH-6784, new active Magnolol compound, reduces hydrogen peroxide-induced CMCs��� apoptosis by upregulation of Bcl-2/Bax-慣 and functional Trx activity (Trx/Txnip). These findings suggest CH-6784 is one of the candidates for myocardial ischemic protection