Cymarin is primarily used in medical research for its cardiotonic properties. It works by inhibiting the sodium-potassium ATPase pump in heart muscle cells, which increases intracellular calcium levels and enhances cardiac contractility. This makes it useful in the study of heart function and in the development of treatments for certain cardiovascular conditions, particularly congestive heart failure. Due to its potent biological activity, it is also used as a reference compound in pharmacological assays involving cardiac glycosides. Additionally, cymarin has been investigated for its potential cytotoxic effects on cancer cells, showing promise in preliminary studies as an anti-tumor agent. Its natural origin and specific mechanism of action make it valuable in both therapeutic research and toxicological studies.