Monoterpene indole alkaloids monoterpenes

During the past two decades a great number of papers have been published on the isolation, structure elucidation, synthesis and transformation, biogenesis, chemotaxonomy, and pharmacology of indole alkaloids. In this chapter we summarize the new results that appeared from 1968 to mid 1984 for the cory-nantheine-yohimbine group of monoterpene indole alkaloids with greater emphasis on their chemistry, excluding the related oxindoles and heteroyohimbines. 

Geissoschizine (30) (7) is one of the most widely investigated monoterpene indole alkaloids. Since the first structure elucidation, carried out by Rapoport... 

This review of the biosynthesis of the bisindole alkaloids of C. roseus is organized along a developing biosynthetic pathway, as far as possible, and relies on the notion that the most sophisticated studies are those utilizing the purified enzyme systems. Biosynthetic studies on the other monoterpene indole alkaloids are not reviewed here. 

The incorporation of acetate into the monoterpene unit of the indole alkaloids has recently been reexamined (176). Using [l,2- C2]acetate it was established that no intact incorporation occurred, and a similar labeling pattern to that from [2- C2]acetate was observed, i.e., C-3, C-4, C-20, C-22, and C-23. Extensive scrambling of the acetate occurred via the Krebs cycle to label the 1 and 2 positions of acetate prior to incorporation. [2- C]Mevalonate was incorporated equally into C-17 and C-22 of ajmalicine (39), indicating that an equilibration occurs at some point in the pathway, as had been established previously with radiolabeled precursors 176). 

This is the latest volume in the series "The Alkaloids Chemistry and Biology and covers a group of alkaloids comprising the carbazole nucleus. Single-topic volumes in this series have been rare, and the last one discussed antitumor alkaloids and was published as Volume 25 in 1985. This is the first volume dedicated to a single alkaloid structure type since Volume 8, which dealt with the monoterpene indole alkaloids over 40 years ago. 

Within the natural products field, the investigation of complete biosynthetic pathways at the enzyme level has been especially successful for plant alkaloids of the monoterpenoid indole alkaloid family generated from the monoterpene gluco-side secologanin and decarboxylation product of tryptophan, tryptamine [3-5]. The most comprehensive enzymatic data are now available for the alkaloids ajmalicine (raubasine) from Catharanthus roseus, and for ajmaline from Indian Rauvolfia serpentina [6] the latter alkaloid with a six-membered ring system bearing nine chiral carbon atoms. Entymatic data exsist also for vindoline, the vincaleucoblastin (VLB) precursor for which some studies on enzymatic coupling of vindoline and catharanthine exist in order to get the so-called dimeric Catharanthus indole-alkaloids VLB or vincristine [7-9] with pronounced anti-cancer activity [10, 11]. 

Thomas (23) predicted that the non-tryptamine moiety of the indole alkaloids is derived from a cyclopentanoid monoterpene precursor. Wenkert (2k) independently reached to the same conclusion. 

Keywords alkaloid biosynthesis alkaloid genes nicotine tropane alkaloids pyrrolizidine alkaloids benzylisoquinoline alkaloids monoterpene indole alkaloids ergot alkaloids acridone alkaloids purine alkaloids taxol betalains... 

Stereospecific condensation between tiyptamine and seco-loganin in a Mannich-like reaction is carried out by the enz)une (S)-strictosidine s)m-thase and results in the formation of the glucoalkaloid, (S)-strictosidine, from which most monoterpene indole alkaloids are derived (Figs. 2.1 and 2.9). 

Figure 2.13 Putative localization and intercellular trafficking of monoterpene indole alkaloids in Catharanthus roseus. (After Facchini and De Luca, 2008 Murata et a ., 2008.)...

Buriat, V., Oudin, A., Courtois, M., Rideau, M. and St. Pierre, B. (2004) Co-expression of three MEP pathway genes and geraniol-lO-hydroxylase in internal phloem parenchyma of Catharanthus roseus implicates multicellular location of intermediates during the biosynthesis of monoterpene indole alkaloids and isoprenoid-derived primary metabolites. Plant., 38,131 1. 

Schiel, O., Witte, L. and Berlin, J. (1987) Geraniol-lO-hydroxylase activity and its relation to monoterpene indole alkaloid accumulation in cell suspension cultures of Catharanthus roseus. Z. Naturforsch., 42c, 1075-81. 

Strictosidine synthase has a wide distribution among plants, although it is functionally expressed in a small group of taxa producing monoterpene indole alkaloids (see arrow in Fig. 7.17b). Related genes occur in animals and... 

The largest group of alkaloids is the monoterpene indole alkaloids, distributed in the Apocynaceae (mutual exclusion with cardenolides) and in the... 

Strictosidine is produced, stereospecifically, from tryptamine and secologanin by strictosidine synthase, isolated from several species producing monoterpene indole alkaloids. The enzyme was cloned and can be expressed in large quantity (Fig. 37). 

No article was found reporting anxiolytic activity of phenolic acids. However, the anxiolytic activity of the alkaloids is known. Anxiolytic properties may be a crucial feature of newer antipsychotics associated with the improvement of negative symptoms in schizophrenic patients. The indole alkaloid alstonine acts as an atypical antipsychotic in behavioral models, but differs in its dopamine and serotonin binding profile [310]. Behavioral effects of psychollatine, a glycoside indole monoterpene alkaloid isolated from Psychotria umbellate Thoim., was investigated in models of anxiety, depression, memory, tremor, and... 

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