Highly potent Na+/K+-ATPase inhibitor, blocking the active efflux of Na+ and reuptake of K+. Water soluble cardiotonic glycoside from the class of bufadienolides (with 2-pyrone ring). Inhibits cancer cell growth in vitro. Shown to induce caspase-dependent apoptosis, reducing MDR resistance and the rate of mitochondrial oxidative phosphorylation in cancer cells. Inotropic by increasing the intracellular Ca2+ concentration. Immunosuppressive and anti-inflammatory agent that inhibits allogeneic T cell activation with much higher potency than cortisol or cyclosporin A.