Of terpenoid alkaloids

Perhaps the most important examples of terpenoid alkaloids from a pharmacological point of view are those found in aconite or wolfsbane (Aconitum species Ranunculaceae) and species of Delphinium (Ranunculaceae). Whilst Aconitum... 

The biosynthesis of the isoprenoid moiety of terpenoid alkaloids has been reviewed. It has been found ° that catharanthine (which accumulates in Vinca rosea) inhibited a membrane-bound monoxygenase that oxidized geraniol at C-10. The inhibition was reversible and non-competitive in solubilized preparations of the enzyme and hence was probably not due to disruption of membranes. Other alkaloids that were produced as end-products were less inhibitory and catharanthine may mediate feed-back control of alkaloid biosynthesis in vivo. 

Battersby A R 1970 Biosynthesis of terpenoid alkaloids. In Goodwin T W (ed) Natural substances formed biologically from mevalonic acid. Academic Press New York, 157-168... 

A variety of chemicals may be leached from the aerial portions of plants by rainwater or by fog-drip (16) including organic acids, sugars, amino acids, pectic substances, gibberellic acids, terpenoids, alkaloids, and phenolic compounds. Colton and Einhellig (17) suggested that leaf leachates of velvetleaf (Abutilon theophrasti) may be inhibitory to soybean (Glycine maxT We have recently discovered specialized hairs on the stems of velvetleaf plants which exude toxic chemicals. 

From the hair-pencils of butterflies in Danainae and Ithomiinae (Papilion-oidea Nymphalidae), a wider variety of pyrrolizines (la-d, and 6a-d) have been identified than from Arctiidae moths. These compounds are biosynthesized from pyrrolizidine alkaloids, which are included in host plants fed by the larvae and protect them from the attacks of other herbivores [122]. In addition to novel lactones (7, 8a, and 8b) derived from an acid part of the alkaloids, many volatiles of more than 100 compounds (aromatics, terpenoids, hydrocarbons, and others) constitute scent bouquets of the male butterflies [123]. For example, the hair-pencil of Idea leuconoe (Danainae) which is distributed in South-East Asia contained 16 compounds (6b, 8a, 8b, 9, and others), and a mixture of the major volatiles applied to a butterfly dummy elicited an abdomen-curling acceptance posture in the females as a crude extract of the male hair-pencils did [ 124]. A chiral GC analysis revealed the absolute config-... 

The interaction between Drosophila, yeasts and columnar cacti of the Sonoran Desert has been the subject of much recent interest (37) As a coevolved system, perhaps more is known about this interaction than any other. The chemistry of the cacti (70 spp.) has been postulated to play a significant role in the establishment of this system (38 ), but this was based upon reports of a relatively small number of relatively simple alkaloids, and a small number of terpenoid compounds. Only recently, the diversification of plant compounds has been discovered to be much greater (5). In their section on alkaloids in the above work, BajaJ and McLaughlin report the presence of some thirty-five structures. In addition, I have been able to isolate some sixty triterpenoid glycosides (structures were not determined) and more were detected but not Isolated. 

Catharanthus roseus, biosynthesis of terpenoid indole alkaloids in, 49, 222 (1997) Celastraceae alkaloids, 16, 215 (1977)... 

This structural group of indole alkaloids covers simple indole alkaloids (e.g., tryptamine, serotonin, psilocin and psilocybin), /3-carboline alkaloids (e.g., harmine), terpenoid indole (e.g., ajmalicine, catharanthine and tabersonine), quinoline alkaloids (e.g., quinine, quinidine and cinchonidine), pyrroloindole... 

The chemistry of the Daphniphyllum alkaloids has been reviewed. Terpenoid alkaloids are also reviewed in the Specialist Periodical Report The Alkaloids . Two new alkaloids, deoxyyuzurimine (13) and isodaphnilactone B (14), have been isolated from the leaves of Daphniphyllum gracile ... 

One current estimate of NP diversity totals ryo.ooo different structures, yet this huge chemical diversity is generated from only a few biochemical pathways that branch from the metabolism shared by most organisms. About 60% of the known NP diversity comes from one ancient pathway (the isoprenoids or terpenoids), another 30% comes from some other ancient pathways related to each other (the polyphenols, phenylpropanoids or polyketides) and less than 10% of NPs (alkaloids) comes from a more diverse family of pathways. There seems to be a rough correlation between the number of species possessing one pathway and the total diversity of NPs made by that route. Consequently, the minor groups of NPs that comprise less than 1% of the total NP diversity (e.g., the glucosinolates) tend to be restricted to a small number of species. 

Occasional reports of alkaloids and amino acids have appeared with respect to species of Abies and Pinus, but the family is best known for its assortment of terpenoids. 

Alkaloids like preakuammicine (Figure 6.79) and akuammicine (Figure 6.75) contain the C10 and C9 Corynanthe type terpenoid units respectively. They are, however, representatives of a subgroup of Corynanthe alkaloids termed the Strychnos type because of their structural similarity to many of the alkaloids found in Strychnos... 

Some of the most remarkable examples of terpenoid indole alkaloid modifications are to be found in the genus Cinchona (Rubiaceae), in the alkaloids quinine, quinidine, cinchonidine,... 

Verpoorte R, van der Heijden R and Moreno PRH (1997) Biosynthesis of terpenoid indole alkaloids in Catharanthus roseus cells. The Alkaloids, Chemistry and Pharmacology (ed Cordell GA) Vol 49. Academic, San Diego, pp 221-299. 

Terpenoid Indole Alkaloids.—Important recent work has defined strictosidine (97) as a key intermediate in the biosynthesis of terpenoid indole alkaloids with both 3a- and 3/3-configurations. Some of this work, published earlier in preliminary form (cf. Vol. 9, p. 18), is now available in a full paper.26 In addition to those alkaloids examined earlier, strychnine, gelsemine, vincadifformine, isoreserpiline, aricine, isoreserpinine, and ajmaline have been shown to derive from strictosidine (data are also included for ajmalicine, for catharanthine, and for vindoline which had been reported earlier). 

The biosynthesis of terpenoid indole alkaloids from tryptophan has long been known.1,2 In new experiments with DL-[2-14C,2, 3 - 3C2]tryptophan [as (94)], this has been confirmed for vindoline (106).35 Incorporation measured by assay for radioactivity and by n.m.r. spectroscopy was the same, thus indicating an intact incorporation (with loss, of course, of the carboxy-group) (for discussion of the particular application of 13C labelling used here, see pp. 1-2). 

Synthesis of the anti-arrhythmic drug ajmaline from Rauvolfia plants, an efficient source of several alkaloid types used in therapy, represents an even more advanced study of the total enzymatic synthesis of terpenoid indole alkaloids. Ajmaline is a class I anti-arrhythmic alkaloid because of its activity as heart muscle sodium channels antagonist [35],... 

Anwer, F., Kapil, R.S. and Popli, S.P. (1 972) Terpenoid alkaloids from Murraya koenigiiVW. Synthesis of DL-O-methylmahanine and related carbazoles. Experientia 28, 769. 

---