More than 70 bitter glycosides with cardiac activity, with five different aglyconees digitoxigenin, gitoxigenin, digoxigenin, diginatigenin and gitaloxigenin in the leaves act as a protection against herbivores. Yield and concentration of these cardiac glycosides are enhanced by greenhouse cultivation through enhanced temperature and enhanced carbon dioxide concentration.
In plants, over 70 bitter glycosides with cardiac activity are found in the leaves to deter herbivores. These glycosides include digitoxigenin, gitoxigenin, digoxigenin, diginatigenin, and gitaloxigenin. Greenhouse cultivation can increase both yield and concentration of these compounds by increasing temperature and carbon dioxide levels.