The biosynthesis of plant alkaloids and nitrogenous microbial metabolites

The biosynthesis of plant alkaloids and nitrogenous microbial metabolites

“…Tropane alkaloids, e.g. hyoscyamine (6), nicotine (9), and cocaine (8) are biosynthesized from the amino acid ornithine (4).8-10 Long ago it was established that in Datura strarnoniurn ornithine is incorporated into (6) in an unsymmetrical manner, that is to say C-2 and C-5 of the amino acid became C-1 and C-5 respectively of the alkaloid. This was confirmed for other Datura species (reviewed in ref.…”

The biosynthesis of plant alkaloids and nitrogenous microbial metabolites

“…that ornithine ( 4) is incorporated into tropane alkaloids, e.g. hyoscyamine (6) in Datura species, in an unsymmetrical fashion (distinction between C-2 and C-5 in the amino acid is maintained in the derived alkaloid). It has now been found16 that ornithine (4) is incorporated symmetrically (label at C-5 appears equally at C-1 and C-5) into hyoscyamine (6) in root cultures of Hyoscyamus albus.…”

“…hyoscyamine (6) in Datura species, in an unsymmetrical fashion (distinction between C-2 and C-5 in the amino acid is maintained in the derived alkaloid). It has now been found16 that ornithine (4) is incorporated symmetrically (label at C-5 appears equally at C-1 and C-5) into hyoscyamine (6) in root cultures of Hyoscyamus albus. In definitive work, arginine decarboxylase, ornithine decarboxylase, and putrescine N-methyltransferase activities in cultures of H .…”

“…tropane alkaloids such as hyoscyamine (6) are biosynthesized from ornithine (4)/arginine through the symmetrical compound putrescine ( 5 ) and N-methylputrescine. The evidence for an unsymmetrical pathway from ornithine in Datura species still stands, however, and will repay similar close scrutiny at the enzyme level.…”

“…Scopolamine (8) is biosynthesized from hyoscyamine (6). The first step is a 6p hydroxylation to give (7), which is catalysed by a 2-oxoglutarate-dependent dioxygenase.…”