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Flavonoids are synthesized by the phenylpropanoid metabolic pathway in which the amino acid phenylalanine is used to produce 4-coumaroyl-CoA. [1] This can be combined with malonyl-CoA to yield the true backbone of flavonoids, a group of compounds called chalcones , which contain two phenyl rings.
4-Coumaroyl-CoA is the central biosynthetic precursor to phenylpropanoids (shown in protonated state) Phenylalanine Tyrosine. The phenylpropanoids are a diverse family of organic compounds that are biosynthesized by plants from the amino acids phenylalanine and tyrosine in the shikimic acid pathway. [1]
In plants, all phenylpropanoids are derived from the amino acids phenylalanine and tyrosine. Phenylalanine ammonia-lyase (PAL, a.k.a. phenylalanine/tyrosine ammonia-lyase) is an enzyme that transforms L-phenylalanine and tyrosine into trans-cinnamic acid and p-coumaric acid, respectively.
Flavonoids are widely distributed in plants, fulfilling many functions. [1] They are the most important plant pigments for flower coloration, producing yellow or red/blue pigmentation in petals designed to attract pollinator animals. In higher plants, they are involved in UV filtration, symbiotic nitrogen fixation, and floral pigmentation.
Phenolics are formed by three different biosynthetic pathways: (i) the shikimate/chorizmate or succinylbenzoate pathway, which produces the phenyl propanoid derivatives (C6–C3); (ii) the acetate/malonate or polyketide pathway, which produces the side-chain-elongated phenyl propanoids, including the large group of flavonoids (C6–C3–C6) and ...
In plants it is a key biosynthetic enzyme that catalyzes the first step in the synthesis of a variety of polyphenyl compounds [2] [3] and is mainly involved in defense mechanisms. PAL is involved in 5 metabolic pathways: tyrosine metabolism, phenylalanine metabolism, nitrogen metabolism, phenylpropanoid biosynthesis, and alkaloid biosynthesis.
They are packed with potent antioxidants called flavonoids, including anthocyanins (the plant compound that gives berries and other colorful produce their rich pigments) that help combat ...
The biosynthesis of flavones proceeds from the phenylpropanoid pathway, which uses L-phenylalanine as a starting point. [6] Phenylalanine ammonia lyase facilitates the deamination of L-phenylalanine to (E)-cinnamate , [ 6 ] which is then oxidized by cinnamate 4-hydroxylase to yield p-Coumaric acid . [ 7 ]