Biosynthesis, monoterpene alkaloids

Asymmelric kydroboradon. A key step in an asymmetric synthesis of loganin (I), a key intermediate in the biosynthesis of indole and monoterpene alkaloids, involved... 

The intent of this chapter is to provide an update of pyridine and piperidine alkaloid literature since this topic was last covered in Volume 3 of this series [1], The approximate time period covered by this review is 1984-1994. Due to the wealth of information available, this review had to be somewhat selective. For example, with the exception of a few selected pyridine monoterpenes, alkaloids containing a pyridine or piperidine ring fused to another ring system were excluded. The focus of this review is placed on describing new compounds isolated, biosynthesis, and biological properties. Synthesis has not been emphasized in most cases reference is made to only the most recent syntheses. 

CioH.jN, Mr 147.22, oil, bp. 100-103 °C(1 kPa),[a]i, -7.2° (CHCI3), a monoterpene alkaloid ( iridoids) from the east Asian creeper Actinidia polygama and other Actinidiaceae, Bignoniaceae, and Valerianaceae. It is a component of the defensive secretion of black beetles, ants, grasshoppers, and flies. Only the (5) enantiomer occurs in nature. A. exhibits antimicrobial properties and a deterrent effect against birds and arthropods , while cats are strongly attracted Synthesis There are various syntheses of the racemate and the unnatural (/I) enantiomer, but only three for the (5) enantiomer. The biosynthesis presumably proceeds from iridodial. 

Loganin is an iridoid glucoside which occupies a central position in the biosynthesis of Corynanthe, Aspidosperma, Iboga, Ipecacuanha, Cinchona, and structurally simpler monoterpene alkaloids. For a review of the extensive researches that led to confirmation of the key role of loganin in alkaloid biosynthesis, see A. R. Battersby, Biochem. Soc. Symp., 29, 157 (1970) A. R. Battersby, Chem. Soc. Spec. Period. Rep., 1, 31 (1971) A. I. Scott, Accts. Chem. Res., 3, 151 (1970). For a useful account of the chemistry of iridoid glucosides see, J. M. Bobbitt and K. -P. Segebarth in Cyclopentanoid terpene Derivatives, Eds., W. I. Taylor and A. R. Battersby, Marcel Dekker, New York, 1969, p 1. 

Davis EM, Croteau R, Leeper FJ, Vederas JC (2000) Cyclization enzymes in the biosynthesis of monoterpenes, sesquiterpenes, and diterpenes. In Topics in current chemistry biosynthesis-aromatic polyketides, isoprenoids, alkaloids. Springer, Heidelberg, pp 53-95... 

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. 

Sites of biosynthesis are compartmentalized in the plant cell. While most biosynthetic pathways proceed (as least partially) in the cytoplasm, there is evidence that some alkaloids (such as coniine, quinolizidines and caffeine), furanocoumarins and some terpenes (such as monoterpenes, diterpenes. 

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

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. 

Biosynthesis A. is formed from tryptamine and the monoterpene secologanin (see secoiridoids) via stric-tosidine, catalysed by ca. 10 known enzymes (see also figure under monoterpenoid indole alkaloids). 

Biosynthesis In plants the quinoline system can be formed by several different biogenetic routes (biochemical convergence). In the Cinchona alkaloids tryptophan acts as the precursor while simple quinolines, furoquinolines, and acridines originate from an-thranilic acid. The second biosynthetic parmer is often a hemiterpene (for furoquinolines) or an iridoid monoterpene (secologanin, see secoiridoids) for Cinchona alkaloids. 

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