Ouabain (1a), a cardioactive glycoside isolated from the bark of the African ouabio tree (Acokanthera ouabio) by Arnaud in 1888),[1] has received considerable attention since it was discovered that an ouabain-like compound occurs naturally in mammals and acts as an endogenous digitalis as proposed by Szent–Gyorgyi.[2] After some debate, it was established that the endogenous and plant derived ouabain are in fact identical.[3] ...