Biological actions of green tea catechins on cardiac troponin C

Background and purpose: Catechins, biologically active polyphenols in green tea, are known to have a protective effect against cardiovascular diseases. In this study, we investigated direct actions of green tea catechins on cardiac muscle function to explore their uses as potential drugs for cardiac muscle disease.

Experimental approach: The effects of catechins were systematically investigated on the force‐pCa relationship in skinned cardiac muscle fibers to determine their direct effects on cardiac myofilament contractility. Mechanisms of action of effective catechins were investigated using troponin exchange techniques, quartz crystal microbalance, NMR, and a transgenic mouse model.

Key results: (‐)‐Epicatechin‐3‐ gallate (ECg) and (‐)‐epigallocatechin‐3‐gallate (EGCg), but not their stereoismers (‐)‐catechin‐3‐gallate (Cg) and (‐)‐gallocatechin‐3‐gallate (GCg), decreased cardiac myofilament Ca²⁺ sensitivity probably through its interaction with cardiac troponin C. EGCg restored cardiac output in isolated working hearts by improving diastolic dysfunction caused by increased myofilament Ca²⁺ sensitivity in a mouse model of hypertrophic cardiomyopathy.

Conclusions and implications: The green tea catechins, ECg and EGCg, are Ca²⁺desensitizers acting through binding to cardiac troponin C. These compounds might be useful compounds for development of therapeutic agents to treat the hypertrophic cardiomyopathy caused by increased Ca²⁺ sensitivity of cardiac myofilaments.