Biosynthesis terpene indole alkaloids

Fig. 3 Primary precnrsor-end product relationships in alkaloid biosynthesis. Color codes blue, terpene indole alkaloids green, benzophenanthridine alkaloids gray, benzylisoquinoline alkaloids red, quinolizi-dine alkaloids yellow, pyridine alkaloids pink, tropane alkaloids...

Biosynthesis of some classes of terpene indole alkaloids is well understood. In certain cases, many of the enzymes that are responsible for biosynthesis have been cloned and mechanistically studied. In other cases, biosynthesis pathway is only proposed based on the results of feeding studies with isotopically labeled substtates and from the structures of isolated biosynthetic intermediates. All terpene indole alkaloids are derived from tryptophan and the iridoid terpene secologanin (Fig. 14.11). Tryptophan decarboxylase, a pyridoxal-dependent enzyme [29], converts tryptophan to tryptamine [30]. The following strictosidine synthase-catalyzed Mannich reaction connects ttyptamine and secologanin to yield strictosidine [31]. The Apocynaceae, Loganiaceae, Rubiaceae, and Nyssaceae families of plants each produce terpene indole alkaloids with dramatically diverse structures [32-34]. The mechanisms and control of... 

O Connor SE, Maresh JJ. Chemistry and biology of mono-terpene indole alkaloid biosynthesis. Nat. Prod. Rep. 2006 23 532-547. 

Monoterpenoid indole alkaloids (MIAs) are derived from tryptophan metabolism. MIAs are one of the most structurally diverse class of compounds with over 2,000 structures. They are mostly found in the Apocynaceae, Loganiaceae, and Rubiaceae family of plants [12]. Similar to BIA biosynthesis, the committed step of MIA biosynthesis begins with the condensation of tryptamine (derived from tryptophan) and secologanin (derived from terpene biosynthesis) to form strictosidine... 

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