The biosynthesis of monoterpenoid indole alkaloids from strictosidine

Abstract

The differential incorporation of doubly labelled strictosidine and vincoside into several indole alkaloids belonging to the Corynanthe (3a and 3p series), Aspidosperma, and lboga types in three plant families has been studied, and it has been demonstrated that only strictosidine is incorporated while vincoside is metabolically inert in these plants with regard to alkaloid formation. During the conversion of strictosidine into the 3P-indole alkaloids, the hydrogen atom at the 3-position is lost, while it is retained during the biosynthesis of the 32 alkaloids. The chemical synthesis of [7-3H]secologanin, an important intermediate for further work in the biosynthesis of monoterpenoid alkaloids, is also described. as a variety of other species in cell cultures by in vivo and in vitro t e c h n i q u e~.~J~ The crucial enzyme catalysing the condensation of (1) with (2) to yield exclusively the a-epimer strictosidine (3) has been discovered and which was shown to be biologically rearranged to the diverse structures of the indole alkaloids found in nature.2 Chemical condensation of (1) and (2) yields a mixture of the two epimers strictosidine (3) and vincoside

Indole monoterpene alkaloids from Chimarrhis turbinata DC Prodr.: a contribution to the chemotaxonomic studies of the Rubiaceae family

“…Ixoroideae subfamily). However, in Cinchonoideae, seco-iridoids are involved in the biosynthesis of indole terpene alkaloids and thus establishing two distinct chemotaxonomic branches (Nagakura et al, 1979).…”

Secondary Metabolites from Rubiaceae Species

“…Thus, if there are morphological similarities, they can either be due to a common ancestry or convergent evolution [54]. Furthermore, the seco-iridoids are iridoids precursors and also participate in the biosynthesis of monoterpene indole alkaloids, so they may be involved in two distinct chemotaxonomic subdivisions [57,58]. Thus, different species may exhibit different chemical substance classes, but having the same precursor, which may indicates a phylogenetic relationship [59][60][61][62][63][64].…”

Purification and Properties of Strictosidine Synthase, the Key Enzyme in Indole Alkaloid Formation

“…To prove the position of the label in the tryptamine thus formed, it was transformed into tetrahydroharman under physiologically mild conditions [16]. [8].…”

“…Recently the key enzyme, catalyzing the stereospecific condensation of tryptamine with secologanin to yield the alkaloidal glucoside strictosidine with 3 -4 9 configuration, was discovered [3 -51 and some properties of the enzyme from crude extracts of cell cultures of alkaloid-producing Apocynaceae plants were preliminarily reported for the first time [6]. Strictosidine is the universal precursor for the multitude of monoterpenoid indole alkaloids both of the 3-c( as well as of the 3-1) series [7,8]. This enzyme catalyzes a PictetSpengler-type reaction between the aldehyde function of secologanin and the amino group of tryptamin as shown in Fig.…”