Secologanin tryptamine condensation with

Secologanin undergoes condensation with tryptamine in some groups of plants to yield strictosidine (isovincoside)... 

Strictosidine (97) is formed by condensation of tryptamine (95) with secologanin (96), as shown in Scheme 9. The enzyme which catalyses the condensation has been isolated, purified, and characterized.27 Subsequent transformation of strictosidine (97) involves first the loss of the glucose moiety. Two strictosidine-specific glucosidases have been isolated and characterized.28... 

Terpenoid Indole Alkaloids.—Experiments in intact plants have in the past given results from which a fairly clear picture of the biosynthesis of terpenoid indole alkaloids has emerged.114 An important stage in the biosynthesis of these alkaloids is reached when tryptamine (128) condenses with secologanin (129) to give... 

Condensation of tryptamine with secologanin opened the way to studies of the later stages of the biosynthesis. Two basic glucosides, vincoside and... 

The general biosynthetic pathway of indole alkaloids involves condensation of tryptamine with secologanin to afford strictosidine... 

In principle there appears no reason why a condensation product of secologanin with tryptophan instead of tryptamine should not occur in nature to give a new series of carboxy terpenoid indole alkaloids parallel to the known tryptamine derivatives. A few representatives have been isolated in recent years, and probably more will follow with the adoption of isolation techniques suited to amino acids. 

In analogy with the synthesis of strictosidine and vincoside from tryptamine, a mixture of 5a-carboxystrictosidine (33a) (major) and 5a-carboxyvincoside (33d) could be obtained by condensation of L-tryptophan with secologanin. Again in... 

Condensation of tryptamine with secologanin in the presence of jS-glucosidase and sodium cyanoborohydride affords a tetracyclic product (Scheme 17), which is 2,3-secoakuammigine (135), since a mixture of tetrahydroalstonine (120) and akuammigine (136) is obtained on oxidation [Hg(OAc)2] followed by reduction presumably no pentacyclic products are obtained in the initial condensation since the imine formed from tryptamine and secologanin suffers reduction before it can cyclise to a tetrahydro-j8-carboline i.e. vincoside or strictosidine). 

Biosynthesis The biosynthesis of these alkaloids begins with the key reaction, the condensation of tryptamine with secologanin to give strictosidine catalyzed by the enzyme strictosidine synthase. The biosynthesis was elucidated mainly by the use of plant cell suspension cultures. Cell cultures of Catharanthus and Rauvolfia species have been the subject of intense phytochemical studies. 

As shown in Scheme 13.61, a Pictet-Spengler-type condensation and cyclization between tryptamine and secologanin forms the first committed step with the generation of strictosidine. The process is effected by the enzyme strictosidine synthase (EC 4.3.3.2), and, interestingly, strictosidine synthase (the complementary DNA) is... 

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... 

All monoterpenoid indole alkaloids are synthesized from strictosidine 44, which is a general biosynthetic intermediate formed by enzymatic condensation of trypt-amine with secologanin [162]. Recently, cDNA coding strictosidine synthase (E.C. 4.3.3.2) was isolated from 0. pumila and expressed further in E. coli. The enzyme has been characterized regarding its substrate specificity toward a number of tryptamines and activity regulation [163]. In another work distribution of strictosidine activity in O. pumila, tissues were shown to correlate with the pattern of respective mRNA expression [164]. 

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