Phenylpropanoid

<h2 id="hydroxycinnamic-acids">Hydroxycinnamic acids</h2>

<p>Phenylalanine is first converted to <a href="/facts/Cinnamic_acid/2oBQIQIw">cinnamic acid</a> by the action of the <a href="/facts/Enzyme/DSI1Fh7y">enzyme</a> <a href="/facts/Phenylalanine_ammonia-lyase/qaAokxQA">phenylalanine ammonia-lyase</a>  (PAL). Some plants, mainly <a href="/facts/Monocotyledonous/mXCuuCYo">monocotyledonous</a>, use <a href="/facts/Tyrosine/RJhEgE4C">tyrosine</a> to synthesize <a href="/facts/P-Coumaric_acid/oAIjVxRC"><i>p</i>-coumaric acid</a> by the action of the bifunctional enzyme <a href="/facts/Phenylalanine/tyrosine_ammonia-lyase/pmAt3fpx">phenylalanine/tyrosine ammonia-lyase</a> (PTAL). A series of enzymatic <a href="/facts/Hydroxylation/AevYpR6L">hydroxylations</a> and <a href="/facts/Methylation/EvDMWVW5">methylations</a> leads to <a href="/facts/Coumaric_acid/zkwyy60y">coumaric acid</a>, <a href="/facts/Caffeic_acid/QrdjMYzV">caffeic acid</a>, <a href="/facts/Ferulic_acid/zkuT33jj">ferulic acid</a>, <a href="/facts/5-hydroxyferulic_acid/uqKNUlI1">5-hydroxyferulic acid</a>, and <a href="/facts/Sinapic_acid/qmdXu3SP">sinapic acid</a>. Conversion of these acids to their corresponding <a href="/facts/Ester/FoUAIIw4">esters</a> produces some of the volatile components of herb and flower <a href="/facts/Fragrance/h3MF95yb">fragrances</a>, which serve many functions such as attracting <a href="/facts/Pollinator/DBJNeDtv">pollinators</a>.  <a href="/facts/Ethyl_cinnamate/HEUW8N78">Ethyl cinnamate</a> is a common example.
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<h2 id="cinnamic-aldehydes-and-monolignols">Cinnamic aldehydes and monolignols</h2>

<p>Reduction of the <a href="/facts/Carboxylic_acid/U4xuMosy">carboxylic acid</a> functional groups in the cinnamic acids provides the corresponding aldehydes, such as <a href="/facts/Cinnamaldehyde/nQEeRBqV">cinnamaldehyde</a>. Further reduction provides <a href="/facts/Monolignol/SXBaXhNp">monolignols</a> including <a href="/facts/Coumaryl_alcohol/TmTUetcC">coumaryl alcohol</a>, <a href="/facts/Coniferyl_alcohol/P6AkT2PA">coniferyl alcohol</a>, and <a href="/facts/Sinapyl_alcohol/pe7wlnzR">sinapyl alcohol</a>, which vary only in their degree of <a href="/facts/Methoxy/KbrAmwQc">methoxylation</a>.  The monolignols are monomers that are <a href="/facts/Polymer/eF32E50K">polymerized</a> to generate various forms of <a href="/facts/Lignin/CdaxpB3b">lignin</a> and <a href="/facts/Suberin/gK5mHsmu">suberin</a>, which are used as a structural component of plant cell walls.
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<p>The phenylpropenes, phenylpropanoids with <a href="/facts/Allylbenzene/sLPbVJ2E">allylbenzene</a> (3-phenylpropene) as the <a href="/facts/Parent_compound/32I6krIn">parent compound</a>, are also derived from the monolignols. Examples include <a href="/facts/Eugenol/3WqJ0xko">eugenol</a>, <a href="/facts/Chavicol/vwGN7FwB">chavicol</a>, <a href="/facts/Safrole/Xp2qz89H">safrole</a>, and <a href="/facts/Estragole/yAlzUmWx">estragole</a>. These compounds are the primary constituents of various <a href="/facts/Essential_oil/cq8V5ocP">essential oils</a>.
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<h2 id="coumarins-and-flavonoids">Coumarins and flavonoids</h2>

<p>Hydroxylation of <a href="/facts/Cinnamic_acid/2oBQIQIw">cinnamic acid</a> in the 4-position by <a href="/facts/Trans-cinnamate_4-monooxygenase/QX5ukWau">trans-cinnamate 4-monooxygenase</a> leads to <a href="/facts/Coumaric_acid/zkwyy60y"><i>p</i>-coumaric acid</a>, which can be further modified into hydroxylated derivatives such as <a href="/facts/Umbelliferone/h0QovlRx">umbelliferone</a>. Another use of <i>p</i>-coumaric acid via its <a href="/facts/Thioester/UwfKqs1F">thioester</a> with <a href="/facts/Coenzyme_A/loAfeGpx">coenzyme A</a>, i.e. <a href="/facts/4-coumaroyl-CoA/8xHnJDoM">4-coumaroyl-CoA</a>, is the production of <a href="/facts/Chalconoid/UGo4KFQU">chalcones</a>. This is achieved with the addition of three <a href="/facts/Malonyl-CoA/n1eNlSYs">malonyl-CoA</a> molecules and their cyclization into a second <a href="/facts/Phenyl/Ql9Yx5uu">phenyl</a> group. <a href="/facts/Chalcones/UGo4KFQU">Chalcones</a> are the precursors of all <a href="/facts/Flavonoid/J7FEAtLE">flavonoids</a>, a diverse class of <a href="/facts/Phytochemical/Txrr3QVx">phytochemicals</a>.
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<h2 id="stilbenoids">Stilbenoids</h2>

<p><a href="/facts/Stilbenoid/tTqUnyL2">Stilbenoids</a>, such as <a href="/facts/Resveratrol/5sF3fvl7">resveratrol</a>, are hydroxylated derivatives of <a href="/facts/Stilbene/RT7dCGhr">stilbene</a>. They are formed through an alternative cyclization of <a href="/facts/Cinnamoyl-CoA/2CxHGncw">cinnamoyl-CoA</a> or <a href="/facts/4-coumaroyl-CoA/8xHnJDoM">4-coumaroyl-CoA</a>.
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<h2 id="sporopollenin">Sporopollenin</h2>
<p>Phenylpropanoids and other <a href="/facts/Natural_phenol/sMCro6sW">phenolics</a> are part of the chemical composition of <a href="/facts/Sporopollenin/BQtQKBqz">sporopollenin</a>.  It is related to <a href="/facts/Cutin/trhkVT3m">cutin</a> and <a href="/facts/Suberin/gK5mHsmu">suberin</a>.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> This ill-defined substance found in pollen is unusually resistant to degradation. Analyses have revealed a mixture of <a href="/facts/Biopolymer/GaCwr4EY">biopolymers</a>, containing mainly hydroxylated <a href="/facts/Fatty_acid/JGg3erIu">fatty acids</a>, phenylpropanoids, phenolics and traces of <a href="/facts/Carotenoid/Jm2eHYwW">carotenoids</a>. Tracer experiments have shown that <a href="/facts/Phenylalanine/eyojfW7t">phenylalanine</a> is a major precursor, but other carbon sources also contribute. It is likely that sporopollenin is derived from several precursors that are chemically cross-linked to form a rigid structure.
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<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Apiole/Cfj8dRCL">Apiole</a></li>
<li><a href="/facts/Asarone/HSv3fTbB">Asarone</a></li>
<li><a href="/facts/Chavicol/vwGN7FwB">Chavicol</a></li>
<li><a href="/facts/Dillapiole/UUMN0yds">Dillapiole</a></li>
<li><a href="/facts/Elemicin/DqVPh1rP">Elemicin</a></li>
<li><a href="/facts/Estragole/yAlzUmWx">Estragole</a></li>
<li><a href="/facts/Eugenol/3WqJ0xko">Eugenol</a></li>
<li><a href="/facts/Methyl_eugenol/zT1Qb5Xq">Methyl eugenol</a></li>
<li><a href="/facts/Myristicin/N51fu9Ap">Myristicin</a></li></ul>
<ul><li><a href="/facts/Eleutheroside/4u3R9W3V">Eleutherosides</a></li></ul>

<h2 id="external-links">External links</h2>
<ul><li>K Hahlbrock, D Scheel (1989). "Physiology and Molecular Biology of Phenylpropanoid Metabolism". <i>Annual Review of Plant Physiology and Plant Molecular Biology</i>. 40: 347–69. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1146%2Fannurev.pp.40.060189.002023">10.1146/annurev.pp.40.060189.002023</a>.</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Barros J, Serrani-Yarce JC, Chen F, Baxter D, Venables BJ, Dixon RA (2016). "Role of bifunctional ammonia-lyase in grass cell wall biosynthesis". Nat. Plants. 2 (6): 16050. doi:10.1038/nplants.2016.50. PMID 27255834. S2CID 3462127.{{cite journal}}:  CS1 maint: multiple names: authors list (link) <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Vogt, T. (2010). "Phenylpropanoid Biosynthesis". Molecular Plant. 3: 2–20. doi:10.1093/mp/ssp106. PMID 20035037. <a href="https://doi.org/10.1093%2Fmp%2Fssp106" target="_blank">https://doi.org/10.1093%2Fmp%2Fssp106</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Vogt, T. (2010). "Phenylpropanoid Biosynthesis". Molecular Plant. 3: 2–20. doi:10.1093/mp/ssp106. PMID 20035037. <a href="https://doi.org/10.1093%2Fmp%2Fssp106" target="_blank">https://doi.org/10.1093%2Fmp%2Fssp106</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
</ol>

Phenylpropanoid open-in-new

Phenylpropanoid