Phenylpropanoid wood

The use of nitrogen fertilization results in higher content of N-containing compounds, including free amino acids, and also increases in terpene content in wood plants, whilst starch, total carbohydrates, phenylpropanoids and total carbon-based phytochemicals decreased (Koricheva et al., 1998). Higher levels of nitrogen favoured its uptake and increased the nitrate content of the crop, which is critical for salad vegetables and baby foods. 

Van der Klashorst, G. H. The Modification of Lignin at the 2- and 6-Positions of the Phenylpropanoid Nuclei. Part III. Hydroxymethylation of Industrial Alkali Lignin. J. Wood Chem. Technol., in press. 

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. 

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. 

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). 

Jiang HX, Wood KV, Morgan JA (2005) Metabolic engineering of the phenylpropanoid pathway in Saccharomyces cerevisiae. Appl Environ Microbiol 71 2962-2969. doi 10.1128/ AEM.71.6.2962-2969.2005... 

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