A New Biosynthetic Pathway to Alkaloids in Plants: Acetogenic Isoquinolines We thank Dr. D. Marek and Dr. D. Moskau (Bruker AG, Fällanden, Switzerland), who made the cryoprobe technique available to us, Prof. L. Aké Assi (Centre National de Floristique, Abidjan Ivory Coast) for a long and fruitful collaboration on Dioncophyllaceae and Ancistrocladaceae plants, and Dr. D. Scheutzow (Universität Würzburg) for valuable advice. This work was supported by the Deutsche Forschungsgemeinschaft (SFB 251 and Graduiertenkolleg "NMR in vivo und in vitro"), by the Fonds der Chemischen Industrie, and by the Max-Buchner-Stiftung

CYP96T1 of Narcissus sp. aff. pseudonarcissus Catalyzes Formation of the Para-Para' C-C Phenol Couple in the Amaryllidaceae Alkaloids

The Amaryllidaceae alkaloids are a family of amino acid derived alkaloids with many biological activities; examples include haemanthamine, haemanthidine, galanthamine, lycorine, and maritidine. Central to the biosynthesis of the majority of these alkaloids is a C-C phenol-coupling reaction that can have para-para', para-ortho', or ortho-para' regiospecificity. Through comparative transcriptomics of Narcissus sp. aff. pseudonarcissus, Galanthus sp., and Galanthus elwesii we have identified a para-para' C-C phenol coupling cytochrome P450, CYP96T1, capable of forming the products (10bR,4aS)-noroxomaritidine and (10bS,4aR)-noroxomaritidine from 4'-O-methylnorbelladine. CYP96T1 was also shown to catalyzed formation of the para-ortho' phenol coupled product, N-demethylnarwedine, as less than 1% of the total product. CYP96T1 co-expresses with the previously characterized norbelladine 4'-O-methyltransferase. The discovery of CYP96T1 is of special interest because it catalyzes the first major branch in Amaryllidaceae alkaloid biosynthesis. CYP96T1 is also the first phenol-coupling enzyme characterized from a monocot.