Solanaceous plants are the main source of the tropane class of alkaloids, notably
the anticholinergic hyoscyamine and scopolamine. These plants have traditionally
been used for their medicinal, hallucinogenic, and poisonous properties. Biosynthetically
related to tropane alkaloids, nicotine is also found in the Solanaceae.
The biosynthesis of nicotine and tropane alkaloids has not yet been completely
elucidated. Our biochemical and molecular genetic understanding of nicotine/
tropane alkaloid biosynthesis is as follows.