Phenylpropanoid compounds

Using this system, (Z)-hinokiresinol isolated from cultured cells of A. officinalis was determined to be the optically pure (75 )-isomer, while ( )-hinokiresinol isolated from cultured cells of C. japonica had 83.3% e.e. in favor of the (7S)-enantiomer (Table 12.1). The enzymatically formed (Z)-hinokiresinol obtained following incubation of p-coumaryl p-coumarate with a mixture of equal amounts of recZHRSa and recZHRSf) was found to be the optically pure (75)-isomer, which is identical to that isolated from A. officinalis cells (Table 12.1). A similar result was obtained with the crude plant protein from A. officinalis cultured cells, where the formed (Z)-hinokiresinol was almost optically pure, 97.2% e.e. in favor of the (75)-isomer (Table 12.1). In sharp contrast, when each subunit protein, recZHRSa or recZHRSP, was individually incubated with p-coumaryl p-coumarate, ( )-hinokiresinol was formed (Table 12.1). The enantiomeric compositions of ( )-hinokiresinol thus formed were 20.6% e.e. (with recZHRSa) and 9.0% e.e. (with recZHRSP) in favor of the (7S)-enantiomer (Table 12.1). Taken together, these results clearly indicate that the subunit composition of ZHRS controls not only cis/trans selectivity but also enantioselectivity in hinokiresinol formation (Fig. 12.3). This provides a novel example of enantiomeric control in the biosynthesis of natural products. Although the mechanism for the cis/trans selective and enantioselective reaction remains to be elucidated, for example by x-ray crystallography, the enantioselective mechanism totally differs from the enantioselectivity in biosynthesis of lignans, another class of phenylpropanoid compounds closely related to norlignans in terms of structure and biosynthesis. 

Umezawa T (2001) Biosynthesis of hgnans and related phenylpropanoid compounds. Regul Plant Growth Dev 36 57-67... 

A four-year study of field-grown commercial carrot roots revealed that recently harvested, unprocessed carrot roots contained 24 ppm falcarinol and 65 ppm falcarindiol (8). 6-Methoxymellein (6-MM) had not been identified by Yates al (8) at that time, and was not measured in that study. Reexamination of data revealed that 6-MM was absent from most samples, but present in a few at concentrations of 2 to 8 ppm. Myristicin, 1 ppm, was detected in only one sample. Wulf et 1978, reported that myristicin was present in supermarket carrots. Other studies have shown that certain brands of supermarket carrots contain myristicin while others do not (Yates, unpub.). The presence of myristicin in some samples from the supermarket and its absence in unprocessed carrots analyzed as soon after harvest as possible suggests that myristicin formation is induced during some stage of processing. Since light is known to be an elicitor of a plant system that results in the synthesis of phenylpropanoid compounds, a study of the effect of light on harvested carrot roots was undertaken. 

Gauthier, A., Gulick, P.J., and Ibrahim, R.K., Characterization of two cDNA clones which encode 0-methyltransferases for the methylation of both fiavonoid and phenylpropanoid compounds. 

A number of volatile phenylpropanoid compounds have pronounced biological properties and are also found in essential... 

Several phenylpropanoid compounds have pronounced anti feeding activity. Isoasarone (from Piper futokadzura, Piperaceae) and piperenone were highly active against Spodoptera litura (54). 

Three groups of phenolic compounds are involved in defense responses (1) the signal molecule salicylic acid [42], (2) phenylpropanoid compounds (phenolics and phytoalexins) [43], and (3) lignin and related polyphenolics [44,45],... 

The similar spectrum of products isolated under similar conditions of reaction from hard and softwoods indicates a basic similarity in the structural features of the releasable fragment of each species. The liberation, as the major product, of either dihydroconiferyl alcohol or dihydro-coniferyl alcohol plus dihydrosinapyl alcohol (depending on the wood species) indicates that a fairly accessible portion of the lignin substance is of a polyphenylpropanoid structure. The other, more highly fragmented products are most likely secondary reaction products derived from the initially liberated phenylpropanoid compounds. As such they should not be considered as unique units of lignin structure. 

Tripathi, U., Rao, S.R. and Ravishankar, G.A. (2002) Biotransformation of phenylpropanoid compounds to vanilla flavor metabolites in cultures of FJaematococcus pluvialis. Process Biochemistry 38(3), 419 426. 

Type 2 MTs, also currently understood to function exclusively as OMTs, are found in all lignin-producing plants. This family is specific for coenzyme A derivatized phenylpropanoid compounds and appears to be less diverse in sequence and gene number than the type 1 family of MTs (Fig. 2.3). Based on database searches, type 2 OMTs consist of caffeoyl and feruloyl coenzyme-A specific OMTs (CCoAOMTs). The most closely related enzymes to plant CCoAOMTs are the mammalian small molecule methyltransferases, including catechol OMT and bacterial MTs involved in macrolide biosynthesis. 

Unlike most structurally characterized methyltransferases of non-plant origin that are monomeric, ChOMT forms a symmetric homodimer.21 Dimerization appears to be critical for activity in vitro as well as in vivo. The presence of a dimerization interface appears to be common to plant OMTs, and in this family of OMTs this homotypic protein-protein interface intimately contributes to substrate binding. Because of the broad structural diversity of phenylpropanoid compounds, ChOMT, like many plant OMTs, possesses highly selective substrate and positional specificity. Efficient substrate discrimination and binding is achieved through shape... 

Aroma-active molecules of natural origin are mainly formed via well-known biosynthetic pathways.17,27-29 The major class is the terpenoids followed by phenylpropanoid compounds (see Chapters 1.15, 1.16, and 1.24). Enzymatic and biosynthetic transformation and cleavage of fatty acid is another important source of aroma-active compounds (see Chapter 8.07). Transformation of amino acids and carbohydrates by fermentation is also... 

Matern, U. (1991) Coumarins and other phenylpropanoid compounds in the defense response of plant cells. Planta Med., 57, S15-20. 

Lignans, Phenolic, Quinone/Xanthone and Phenylpropanoid Compounds... 

Table 2 shows that the inhibitory effect of AOA is not specific for anthocyanin synthesis the synthesis of rather all phenylpropanoid compounds known to accumulate in buckwheat hypocotyls upon illumination (Scherf and Zenk, 1967) is blocked to more or less the same degree. AOA-mediated inhibition of anthocyanin synthesis in buckwheat is reversed by the simultaneous application only of compounds, which are known to be intermediates... 

Thus the pollen vail, particularly the exlne provides an Important. and In the case of higher plants a ubiquitously extensive accumulation area for secondary plant products, especially for phenylpropanoid compounds. It may be asked what physiological and biochemical principles form the basis of the accumulation process. 

Compounds derived from phenylalanine and/or tyrosine are among the most common of all secondary metabolites in plants, bacteria, and fungi. These include phenylpropanoid compounds as well as many C -Ci compounds (Fig. 8.1) (Gross, 1981). Relatively simple Ce-Cs compounds, such as cinnamic (1) and p-coumaric acids (2), are modified to produce more complex derivatives (Fig. 8.2) (Conn, 1981, 1986). The term phenylpropanoid is sometimes used to refer to any compound bearing a 3-carbon chain attached to 6-carbon aromatic ring (C6-C3 compounds). Most phenylpropanoids are formed from cinnamic or p-coumaric acids. 

A series of phenylpropanoid compounds fromPimpinella spp. (Apiaceae) that contained epoxide rings were powerful seed germination inhibitors (Cutler, 1992). 

The term phenylpropanoid also is used in a more restricted sense to indicate a number of relatively volatile compounds in which the carbonyl function has either been removed, reduced, or otherwise modified. A number of volatile phenylpropanoid compounds found in essential oils have pro-... 

The trunk woods of many species of Aniba (Lauraceae) contain phenylpropanoid compounds that serve as precursors to neolignans (see Chapters 8 and 11) oihQX Aniba species contain pyrones and benzophenones, whereas yet others possess benzylisoquinoline alkaloids and benzyl benzoates. It is possible to divide Aniba species into those that contain pyrones and those that contain neolignans (Gottlieb, 1980). 

The volatile fractions of many plants are isolated by steam distillation, distillation, or by solvent extraction (Banthorpe, 1991). The resulting volatile compounds that make up the essence or aroma of plants are called essential oils. Altiiough essential oils are comprised of many types of compounds, monoterpenes are major among them. These oils may also contain metabolically modified fatty acids, aldehydes, hydrocarbons, esters, phenylpropanoid compounds, acetylenic compounds, volatile alcohols, volatile alkaloids, phenylpro-panoids, and other shikimic acid derivatives. 

Several representatives of the genus Piper (Piperaceae) are of economic importance. Some of these plants [e.g.. Piper nigrum (black pepper)] include alkaloids that are partially responsible for the desirable pungent and preservative properties of the plant. Other species are P. hetle (widely used as a masticatory), P. methysticum (widely used in the South Pacific as a soporific drug), and P. guineense (ashanti pepper). Most of these plants contain compounds that combine phenylpropanoid compounds see Chapter 8) and pyr-... 

Chandra, P., G. Read, and L.C. Vining Studies on the Biosynthesis of Volucris-porin II. Metabolism of Some Phenylpropanoid Compounds by Volucrispora auran-tiaca Haskins. Canad. J. Biochem. 44, 403 (1966). 

Many of these aromatic compounds are phenylpropanoids, compounds based on a phenylpropane skeleton. Phenylpropanoids are related in structure to the common amino acids phenylalanine and tyrosine, and many are derived from a biochemical pathway called the shikimic acid pathway. 

The metabolic pathway responsible for biosynthesis of aromatic amino acids and for vitamin-like derivatives such as folic acid and ubiquinones is a major enzyme network in nature. In higher plants this pathway plays an even larger role since it is the source of precursors for numerous phenylpropanoid compounds, lignins, auxins, tannins, cyano-genic glycosides and an enormous variety of other secondary metabolites. Such secondary metabolites may originate from the amino acid end products or from intermediates in the pathway (Fig. 1). The aromatic pathway interfaces with carbohydrate metabolism at the reaction catalyzed by 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase, the condensation of erythrose-4-phosphate and PEP to form... 

While the results of the growth reversal experiments in the "supercomplex systems" described above had stimulated investigations at the level of "defined systems" (i.e. the examination of certain metabolic reactions in cell-free systems), no definitive answers as to the biochemical mode of action of glyphosate had been obtained. Based on our experience with inhibitors of phenylalanine ammonia-lyase (see below), we included the "complex system" level (i.e. the examination of a metabolic pathway jsi vivo) in our strategy in order to define the limits more closely. Hypocotyls from etiolated buckwheat seedlings provided a system in which the rapid synthesis of phenylalanine-derived products, such as anthocyanin and other phenylpropanoid compounds, can be very simply induced by illumination. Anthocyanins, in particular, can be conveniently extracted and quantified and, at least in buckwheat, are not subject to measurable turnover within... 

L-phenylalanine, L-a-aminooxy-g-phenylpropionic acid (AOPP, in Fig. 9) should have an increased inhibitory ability. This was confirmed beyond our expectations, as L-AOPP inhibited buckwheat PAL with a Ki of 1.4 nM (Table 2) and also inhibited the biosynthesis of phenylpropanoid compounds in vivo without deleterious effects on normal plant development. Selective accumulation of phenylalanine in... 

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