Substrate Specificity of Vinorine Hydroxylase, a Novel Membrane-bound Key Enzyme of Rauwolfia Indole Alkaloid Biosynthesis

Enzymatic Biosynthesis of Vomilenine, a Key Intermediate of the Ajmaline Pathway, Catalyzed by a Novel Cytochrome P 450-Dependent Enzyme from Plant Cell Cultures of Rauwolfia serpentina

Abstract Microsomal preparations from Rauwolfia serpentina Benth. cell suspension cultures cata­lyze a key step in the biosynthesis of ajmaline -the enzymatic hydroxylation of the indole alkaloid vinorine at the allylic C-21 resulting in vomilenine. Vomilenine is an important branch-point intermediate, leading not only to ajmaline but also to several side reactions of the biosynthetic pathway to ajmaline. The investigation of the taxonomical distribution of the enzyme indicated that vinorine hydroxylase is exclusively present in ajmaline-producing plant cells. The novel enzyme is strictly dependent on NADPH2 and O2 and can be inhibited by typical cytochrome P450 inhibitors such as cytochrom…