DIGITALIS (3 G)

Biological Functions

Lanatoside A is composed of the aglycone digitoxigenin (genin indicates no sugar) connected to three digitoxose sugar molecules, the third of which carries a 3-acetyl group, and a terminal glucose molecule. In other words, the structure sequence is glucose4-3-acetyldigitoxose3-digitoxose2- digitoxose1-digitoxigenin.
Lanatoside B has the identical sugar portion to lanatoside A, except that the aglycone has extra hydroxyl group at C-16 and is given the name gitoxigenin. The structural sequence is glucose4-3- acetyldigitoxose3-digitoxose2-digitoxose1-gitoxigenin.
Lanatoside C also has the same sugars found in both lanatosides A and B; however, the aglycone has the nucleus of lanatoside A plus an additional hydroxyl group at C-12. This cardenolide is named digoxigenin. The structural sequence is glucose4-3-acetyldigitoxose3-digitoxose2-digitoxose1- digoxigenin.
Partial hydrolysis of the glucose molecule and the acetate group from lanatoside A and C produces, respectively, two new and most important cardiac glycosides, digitoxin and digoxin, with the following sequences: digitoxin, (digitoxose)3-digitoxigenin; and digoxin, (digitoxose)3-digoxigenin.