The steroid part of the pathway is as in other plants. The sterols of the plants and the alkaloids are often similar structurally. Cycloartenol and cholesterol are frequent precursors. The glycoalkaloids appear to be synthesized in the above-ground part of the plants, not in the roots as is the case for tropane alkaloids. Compounds such as tomatidine and solasodine have the basic nitrogen included into an oxaazaspirane unit that includes the original steroidal side chain.
Solanidine biosynthesis involves the intermediates verazine and etioline.
These alkaloids also are usually glycosides. The 3-amino group is probably introduced late in the biosynthesis by transamination. As mentioned above, alkaloids of this series are toxic and occur in many common plants. Many of them have antifeeding effects against insects. This alkaloid also disrupts membranes.