Tropane number system

Applying the uniform numbering system presented in Fig. 1, most disubstituted tropane alkaloids that in the literature have been designated as C-3,C-6 disubstituted become C-3,C-7 disubstituted. The same principle, where applicable, is applied to the C-3,C-6,C-7 trisubstituted tropane alkaloids. 

There are considerable literatures on the production of tropane alkaloids in tissue and cell cultures derived firom various parts of intact plants [4]. In a number of cases, root differentiation is required for enhanced tropane alkaloid biosynthesis [3, 5]. The production of the economically valuable tropane alkaloids, scopolamine and hyoscyamine, by these cultures has not been commercially successful, however, root cultures are so far the best system to investigate the production and biosynthesis of tropane alkaloids. 

Tropane alkaloids are compounds known as muscarinic receptor antagonists. Atropine, its best-known member, and a number of other compounds, block the action of the neurotransmitter acetylcholine on post-ganglionic cholinergic nerves of the parasympathetic nervous system, essentially by blocking its binding to muscarinic cholinergic receptors, whereas they are much less potent at nicotinic receptor sites. 

Plant roots have a very active metabolism and can biosynthesize a high number of secondary compounds in an exclusive way (Table 89.2). Some of these compounds, including shikonin or triterpenoid saponins of Panax ginseng (ginsenosides), can also be biosynthesized in undifferentiated systems such as cell cultures, but in some cases, cell differentiation and organ formation is necessary for producing the bioactive compounds, which is the case of tropane alkaloids, bomyl esters, ajmalicine, and other compounds. 

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