Ajmalicine, tabersonine and catharanthine pathway

Figure 41. Pattern of the ajmalicine, tabersonine and catharanthine pathway.

Terpenoid indole alkaloid biosynthesis actually starts with the coupling of tryptamine and secologanin (Fig. 12). In the next step, a glucosidase splits off the sugar moiety and the reactive dialdehyde formed is further converted through different pathways to a cascade of products, including ajmalicine, catharanthine, tabersonine, and vindoline. 

L-Tryptophan is an indole ring containing aromatic amino acid derived via the shikimate pathway. The tryptophan-derived alkaloids are found in eight families, of which, Apocynaceae, Loganiaceae, Rubiaceae, and Nyssaceae are the best sources. The alkaloids under discussion are the Catharanthus alkaloids, namely, ajmalicine, tabersonine, catharanthine, vindoline, vinblastine, vincristine and vincamine as well as terpenoid alkaloids derived from other families, namely, yohimbine, reserpine, strychnine, brucine, and ellipticine. The above-mentioned alkaloids are pharmacologically very important and hence extremely valuable. This chapter describes various aspects of the tryptophan-derived alkaloids like occurrence, biological activity, phytochemistry, and commercial and biotechnological aspects. 

Co-overexpression of ORCA3 and SGD [53] Transcription activator and pathway enzyme Hairy root 0.5-fold increase in TIA including serpentine, ajmalicine, catharanthine, tabersonine, lochnericine, and horhammericine... 

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