Compounds of Mixed Biosynthetic Origin

Adult chrysomeline beetles, when disturbed, release from their elytra (the hardened fore-wings of beetles) and from their thorax curious 

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Alkaloids and Compounds of Mixed Biosynthetic Origin BACKGROUND AND FURTHER READING... 

The majority of natural products from tropical macroalgae are terpenoids (mainly sesqui- and diterpenoids), followed by acetogenins (acetate-derived compounds), and metabolites of mixed biosynthetic origin (such as meroditerpenes), frequently composed of terpenoid and aromatic portions (Blunt et al. 2007 and previous reviews see Chap. 1). 

Isocochlioquinones, xanthone isomers of the cochlioquinone-type food crop-associated mycotoxins (649), are of mixed biosynthetic origin, with the addition of a famesyl unit and methionine-derived methyl groups (650). Isocochlioquinones A and C (981 and 982) (Fig. 13.17) were isolated from Bipolaris cynodontis cynA (657) and the culture broth of Bipolaris bicolor El-1 (652), and also from Bipolaris oryzae (649). These compounds were also purified from Drechslera dematioidea, a... 

Polyketides occuring in plants are not always exclusively synthesized from acetate units, but often are of mixed biosynthetic origin. Phenylpropanoid or terpenoid building blocks or sometimes both can be connected with the acetate-derived backbone. In addition, parts of the carbon skeleton can be derived from fatty acids or amino acids. This mixed assembly principle results in a plethora of structurally diverse compounds. Polyketide alkaloids obtained when nitrogen or nitrogen-containing precursors are incorporated into the polyketide backbone will also be discussed. 

Figure 9.17 Humulone, an example of mixed biosynthetic origin, is made of a triketide with three isoprene units grafted onto it (shown with thick black lines). The phenyl-Cs unit of p-coumaric acid is extended with a triketide to give at least four series of important plant compounds. Flavones, isoflavones and anthocyanins have been found in insects. 3-Methoxykaempferol and quercetin 3, 4 -diglucoside are from the Common Blue butterfly.

From a biogenetic point of view, these compounds are thought to be of mixed shikimate and acetate biosynthetic origin in which the acetate... 

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