Gitoxin is isolated from leaves of Digitalis purpurea L. genus Scrofphulariaceae.
10.0 g pure gitoxin are boiled under reflux with 1 L pure acetic anhydride. Gitoxin thereby goes into solution in the course of 1 h. The boiling is discontinued after 1 h and the acetic anhydride distilled off in a vacuum as completely as possible. After taking up the oily residue with 500 ml chloroform, the solution is successively washed with 200 ml of 2 N potassium bicarbonate solution, 0.1 N hydrochloric acid and water. After drying the chloroform solution with anhydrous sodium sulfate, the chloroform is first distilled off over an open flame and then on a water bath at 40°C in a vacuum, a substantially crystalline residue thereby being obtained. The 12.8 g of crude product obtained are recrystallized from 12 times the amount of a mixture of pyridine, methanol and water (25:10:65) to give rhombic crystals, melting point 151°-155°C.
