Editing Curcumin (section)

== Chemistry ==
[[File:Curcumin thin lipid film.jpg|alt=A bright red substance in a small glass flask, held by gloved fingers|thumb|Curcumin becomes bright red when it interacts [[electrostatics|electrostatically]] with a [[phospholipid]] film]]

Curcumin incorporates a seven carbon linker and three major functional groups: an α,β-unsaturated β-diketone moiety and an aromatic O-methoxy-phenolic group.<ref name=pubchem/><ref name=History /> The aromatic ring systems, which are [[phenols]], are connected by two α,β-unsaturated [[carbonyl]] groups.<ref name=pubchem/><ref>{{cite journal |doi=10.1002/cber.191004302168 |title=Zur Kenntnis des Curcumins |trans-title=Knowing about curcumin |language=de |year=1910 | vauthors = Miłobȩdzka J, van Kostanecki S, Lampe V |journal= Berichte der Deutschen Chemischen Gesellschaft |volume= 43 |issue= 2 |pages= 2163–2170 |url=https://zenodo.org/record/1426403 }}</ref> It is a [[diketone]] [[tautomer]], existing in [[enol]]ic form in [[organic solvent]]s and in [[ketone|keto]] form in water.<ref>{{cite journal | vauthors = Manolova Y, Deneva V, Antonov L, Drakalska E, Momekova D, Lambov N | title = The effect of the water on the curcumin tautomerism: a quantitative approach | journal = Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | volume = 132 | pages = 815–820 | date = November 2014 | pmid = 24973669 | doi = 10.1016/j.saa.2014.05.096 | url = http://eprints.ugd.edu.mk/10453/1/The%20effect%20of%20the%20water%20on%20the%20curcumin%20tautomerism.pdf | bibcode = 2014AcSpA.132..815M }}</ref> The diketones form stable enols and are readily deprotonated to form [[enolate]]s; the α,β-unsaturated carbonyl group is a good [[Michael acceptor]] and undergoes [[nucleophilic addition]].{{citation needed|date=September 2021}} Because of its hydrophobic nature, curcumin is poorly soluble in water<ref name=pubchem/> but is easily soluble in organic solvents.<ref name=History />

===Biosynthesis===
The biosynthetic route of curcumin is uncertain. In 1973, Peter J. Roughley and Donald A. Whiting proposed two mechanisms for curcumin biosynthesis. The first mechanism involves a chain extension reaction by [[cinnamic acid]] and 5 [[malonyl-CoA]] molecules that eventually arylize into a curcuminoid. The second mechanism involves two cinnamate units coupled together by malonyl-CoA. Both use cinnamic acid as their starting point, which is derived from the amino acid [[phenylalanine]].<ref name="Kita, T. 2008" />

Plant biosynthesis starting with cinnamic acid is rare compared to the more common [[p-Coumaric acid|''p''-coumaric acid]].<ref name="Kita, T. 2008">{{cite journal | vauthors = Kita T, Imai S, Sawada H, Kumagai H, Seto H | title = The biosynthetic pathway of curcuminoid in turmeric (Curcuma longa) as revealed by 13C-labeled precursors | journal = Bioscience, Biotechnology, and Biochemistry | volume = 72 | issue = 7 | pages = 1789–1798 | date = July 2008 | pmid = 18603793 | doi = 10.1271/bbb.80075 | doi-access = free }}</ref> Only a few identified compounds, such as [[anigorufone]] and [[pinosylvin]], build from cinnamic acid.<ref>{{cite journal | vauthors = Schmitt B, Hölscher D, Schneider B | title = Variability of phenylpropanoid precursors in the biosynthesis of phenylphenalenones in Anigozanthos preissii | journal = Phytochemistry | volume = 53 | issue = 3 | pages = 331–337 | date = February 2000 | pmid = 10703053 | doi = 10.1016/S0031-9422(99)00544-0 | bibcode = 2000PChem..53..331S }}</ref><ref>{{cite journal | vauthors =  Gehlert R, Schoeppner A, Kindl H |title= Stilbene Synthase from Seedlings of ''Pinus sylvestris'': Purification and Induction in Response to Fungal Infection |journal= Molecular Plant-Microbe Interactions |year= 1990 |volume= 3 |issue= 6 |pages= 444–449 |doi= 10.1094/MPMI-3-444 |url= http://www.apsnet.org/publications/mpmi/backissues/Documents/1990Articles/Microbe03_444.pdf }}</ref>

[[File:Curcumin biosynthesis.svg|500px|center|thumb|class=skin-invert-image|alt= Curcumin biosynthesis diagram|Biosynthetic pathway of curcumin in ''[[Curcuma longa]]''.<ref name="Kita, T. 2008"/>]]