Biosynthesis aromatic compounds

The predominant organic adds in commonly consumed fruit are citric and/or malic acids. Actinidia fruits are unusual in that quinic acid levels are similar to that of citric add as the predominant organic add. Although the nutritional importance of quinic add has not been established, it is an intensely interesting compound because it is a key intermediate for aromatic compound biosynthesis via the shikimic add pathway. Moreover, quinic add is a component of several potent free radical scavengers, including chlorogenic add. 

The Shikimate pathway is responsible for biosynthesis of aromatic amino acids in bacteria, fungi and plants [28], and the absence of this pathway in mammals makes it an interesting target for designing novel antibiotics, fungicides and herbicides. After the production of chorismate the pathway branches and, via specific internal pathways, the chorismate intermediate is converted to the three aromatic amino acids, in addition to a number of other aromatic compounds [29], The enzyme chorismate mutase (CM) is a key enzyme responsible for the Claisen rearrangement of chorismate to prephenate (Scheme 1-1), the first step in the branch that ultimately leads to production of tyrosine and phenylalanine. 

Malonyl-CoA is used as the nucleophilic species in the biosynthesis of fatty acids (see Section 15.5) and a whole host of other natural products, including the aromatic compounds seen in Box 10.14. 

U. Weiss and J. M. Edwards The Biosynthesis of Aromatic Compounds , Wiley,... 

Speck, John C., Jr., The Lobry de Bruyn-Alberda van Ekenstein Transformation, 13, 63-103 Spedding, H., Infrared Spectroscopy and Carbohydrate Chemistry, 19, 23-49 Sprinson, D. B., The Biosynthesis of Aromatic Compounds from d-G1u-cose, 16, 235-270... 

The biosynthesis of tryptophan from the branchpoint compound, chorismate in E. coli The first step involves the conversion of chorismate to the aromatic compound anthranilate. The anthranilate is transferred to a ribose phosphate chain. The product is cyclized to indoleglycerol phosphate by the removal of water and loss of the ring carboxyl by indoleglycerol phosphate synthase. Finally, in a... 

The first specific step in tryptophan biosynthesis is the glutamine-dependent conversion of chorismate to the simple aromatic compound anthranilate. Like most other glutamine-dependent reactions, the reaction can also occur with ammonia as the source of the amino group. However, high concentrations of ammonia are required. Thus far, almost all the anthranilate synthases examined have the glutamine amidotransferase activity (component II) and the choris-mate-to-anthranilate activity (component I) on separate proteins. 

The ester-substituted complex (34) has been used in synthesis of (+)- and (-)-shikimic acid, an important intermediate in the biosynthesis of aromatic compounds, as well as stereospecifically deuterium labeled shikimic acid.60 Addition of hydroxide anion to (+)-(34) gives the diene complex (+)-(182),... 

Natural and monocyclic annulated oxepines are not as numerous as their hydrogenated derivatives however, as mentioned in CHEC(1984) <1984CHEC(7)547> and CHEC-II(1996) <1996CHEC-II(9)45>, they play an important role in biosynthesis and metabolism of monocyclic and polycyclic aromatic compounds. Some new data concerning natural oxepines are presented. 

Weiss, V., and Edwards, J.M. 1980. The Biosynthesis of Aromatic Compounds. John Wiley Sons, Inc., New York. 

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