Iridoids biosynthesis

There was proposed a detailed account of iridoid biosynthesis in rove beetles which resembles the biosynthesis in leaf beetle larvae but exhibits distinct stereochemical differences [134], see also the chapter by Laurent et al., this volume. 

The study of the last stages of the iridoid biosynthesis in Oleaceae, can be observed that oleoside and 10-hydroxy derivatives are common to the tribes Jasmineae and Oleae. 

Other insects and pathogenic microorganisms, can induce an iridoids biosynthesis increase, helping to the plants, even more, to protect themselves against hervibores [14, 15],... 

WEIBEL, D.B., OLDHAM, N.J., FELD, B., GLOMBITZA, G., DETTNER, K., BOLAND, W., Iridoid biosynthesis in staphylinid rove beetles (Coleoptera Staphylinidae, Philonthinae), Insect Biochem. Mol. Biol, 2001,31, 583-591. 

Geu-Flores, F., et al.. An alternative route to cyclic terpenes by reductive cyclization in iridoid biosynthesis. Nature, 2012. 492(7427) 138-142. 

Jensen, S.R., Plant iridoids, their biosynthesis and distribution in angiosperms, in Ecological Chemistry and Biochemistry of Plant Terpenoids, Harbome, J.B. et al., Eds., Clarendon Press, Oxford, 1991, 133. 

Fig. 17 Iridoid derivatives from rove beetles and divergent biosynthesis in chrysomelids and in rove beetles...

Since the biosynthesis of iridoid monoterpenes in insects has been shown to... 

Sampaio-Santos MI, Kaplan MAC. Biosynthesis Significance of Iridoids in Chemo-systematics. Journal of the Brazilian Chemical Society 2001 12(2) 144-153. 

Oudin A, Courtois M, Rideau M, Clastre M. The Iridoid Pathway in Catharanthus roseus Alkaloid Biosynthesis. Phytochemical Reviews 2007 6 259-276. 

Of biochemical interest is the presence of quite significant amounts (up to 5%) of the iridoid glycoside loganin (see page 188) in the fruit pulp of Strychnos nux-vomica. This compound is, of course, an intermediate in the biosynthesis of strychnine and other terpenoid indole alkaloids. 

Kunert, M S0e, A., Bartram, S Discher, S., Tolzin-Banasch, K., Nie, L., David, A., Pasteels, J. and Boland. W. (2008). De novo biosynthesis versus sequestration A network of transport systems supports in iridoid producing leaf beetle larvae both modes of defense. Insect. Biochem. Mol. Biol., 38, 895-904. 

Cyclopentanes, Iridoids.—A very useful review of the biosynthesis of the known sweroside-, morroniside-, and oleuropein-type secoiridoid glucosides, together with the biosynthesis of alkaloidal glucosides which can be regarded as secoiridoid... 

In structural terms these fungal metabolites are analogous to the iridoid monoterpenoids cf. Chapter 1). Recent studies on the biosynthesis of cyclonerodiol,cyclonerotriol, and abscisic acid (25) are described in Chapter 6. 

Only a few examples for alkaloids of terpenoid origin have been identified from arthropods. The ant Mommorium fiddi was shown to contain (2 ) and (2 2)-farnesylamine (148), which, surprisingly, constitutes the first identification of farnesylamine or any ofits derivatives in nature. The defensive agent actinidine (16) has been found in a number of insect species and probably derives from an iridoid precursor, although the details of actinidine biosynthesis in insects have not yet been fully clarified." ... 

ABSTRACT This paper attempts to present a review on the study of phytochemical and pharmacological activities of plants from the genus Hedyotis (Rubiaceae) in the last seven decades, which include our work on Malaysian Hedyotis species. The structure-activity relationships of compounds isolated from this genus are compiled and discussed. Finally, there is also a brief discussion on the biosynthesis of anthraquinones, iridoid glycosides and alkaloids, which are the common constituents of Hedyotis species. 

Loganin is the intermediate that undergoes the ring opening reaction which leads to the formation of secoiridoids. This step occurs by a mechanism that remains to be elucidated and affords secologanin (31) as the precursor of all of the secoiridoids and consequently, of the indole alkaloids that incorporate this pattern [1, 2, 3]. General biosynthesis of iridoids is given in fig. 1. 

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