Phenylpropanoids organisms

Hall R, Holden M, Yeoman M (1987) The accumulation of phenylpropanoid and capsaicinoid compounds in cell cultures and whole fruit of the chili pepper, Capsicum frutescens MiU. Plant Cell Tissue Organ Cult 8 163-176... 

The functions of phenylpropanoid derivatives are as diverse as their structural variations. Phenylpropanoids serve as phytoalexins, UV protectants, insect repellents, flower pigments, and signal molecules for plant-microbe interactions. They also function as polymeric constituents of support and surface structures such as lignins and suberins [1]. Therefore, biosynthesis of phenylpropanoids has received much interest in relation to these functions. In addition, the biosynthesis of these compounds has been intensively studied because they are often chiral, and naturally occurring samples of these compounds are usually optically active. Elucidation of these enantioselective mechanisms may contribute to the development of novel biomimetic systems for enantioselective organic synthesis. 

Phenylalanine Ammonia-Lyase. The building units of lignin are formed from carbohydrate via the shikimic acid pathway to give aromatic amino acids. Once the aromatic amino acids are formed, a key enzyme for the control of lignin precursor synthesis is phenylalanine ammonia-lyase (PAL) (1). This enzyme catalyzes the production of cinnamic acid from phenylalanine. It is very active in those tissues of the plant that become lignified and it is also a central enzyme for the production of other phenylpropanoid-derived compounds such as flavonoids and coumarins, which can occur in many parts of the plant and in many different organs (35). Radioactive phenylalanine and cinnamic acid are directly incorporated into lignin in vascular tissue (36). 

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. 

Costa MA, Collins RE, Anterola AM, Cochrane FC, Davin LB. 2003. An in silico assessment of gene function and organization of the phenylpropanoid pathway metabolic networks in Arabidopsis thaliana and limitations thereof. Phytochemistry 64 1097-112... 

BIOLOGICAL ROLE OF PHENYLPROPANOIDS IN MEDIATING PLANT INTERACTIONS WITH OTHER ORGANISMS... 

Type 1 MTs, currently exclusive for oxygen atoms (OMTs), methylate hydroxyl moieties of phenylpropanoid-based compounds (Fig. 2.3). The phenylpropanoid scaffold is used as a building block for many other types of compounds in the plant. Modification of this basic unit by multiple condensation reactions yields chalcone, flavonoid, isoflavonoid, and pterocarpan skeletons, for example. Flavonoids are ubiquitous in higher plants, where they function as UV protectants,5 defense compounds,6 and stimulators of beneficial mutualistic interactions with microorganisms, insects, and other organisms.7 Isoflavonoid natural products are limited primarily to leguminous plants, where they function as pre-... 

Methods based on classical organic chemistry led to the conclusion, already by 1940, that lignin is built up of phenylpropane units. Examples of typical reactions used in these studies are illustrated in Fig. 4-1. However, the concept of a phenylpropanoid structure failed to win unanimous acceptance, and as late as 30 years ago, some scientists were not convinced that lignin in its native state was an aromatic substance. Finally, the problem was solved by Lange in 1954, who applied UV microscopy at various wavelengths directly on thin wood sections, obtaining spectra typical of aromatic compounds. 

Amino acids, organic acids, carbohydrates, phenylpropanoids Bacterially infected Brassica rapa 1H NMR and 2D NMR 44... 

PAL and TAL are apparently represented to a very limited extent in bacteria, this presumably accounting for the general paucity of phenylpropanoids in such organisms. Isolation and characterization of PALs have, however, been described for R. toruloides Streptomyces maritimus Photorhabdus luminescens Sorangium cdlulosum, and Streptomyces verticillatus with the -cinnamic acid (3) so-formed being considered, for... 

Several simple phenylpropanoids (C6-C3) are produced from cinnamate via a series of hydroxylation, methylation, and dehydration reactions these include p-coumaric, caffeic, ferulic and sinapic acids and simple coumarins. The free acids rarely accumulate to any great extent within plant cells but are usually conjugated to sugars, cell wall carbohydrates, or organic acids (quinic, malic, tartaric, etc.). Lignin and suberin are complex polymers formed from a mixture of simple phenylpropanoids, and will not be considered in the present review. 

From a quantitative point of view, the main phenolics are phenylpropanoid derivatives which accumulate as esters, flavonoids, or are polymerized as lignins (Ref. l). All these products may be synthesized in the same organ from cinnamic acids via their cinnamoyl-coenzyme A thioesters (Ref. 23). Consequently, the following reactions may indeed occur simultaneously ... 

A number of phenylpropanoids are perceived as pungent by humans and presumably by other organisms. Among these are capsaicin (20), the pungent principle of peppers Capsicum species, Solanaceae) and piperine (21), the pungent principle of black pepper Piper nigrum, Piperaceae) (Fig. 8.9) (Harbome, 1982). 

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