Curcumin
Enol form
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Keto form
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Preferred IUPAC name
(1E,6E)-1,7-Bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione
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Other names
(1E,6E)-1,7-Bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione
Diferuloylmethane
Curcumin I
C.I. 75300
Natural Yellow 3
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| E number | E100 (colours) |
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| Properties |
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| C21H20O6 |
| Molar mass | 368.39 g·mol−1 |
| Appearance | Bright yellow-orange powder |
| Melting point | 183 °C (361 °F; 456 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 verify (what is   ?) |
| Infobox references |
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It was first isolated in 1815 when Vogel and
Pierre Joseph Pelletier reported the isolation of a "yellow coloring-matter" from the
rhizomes of turmeric and named it curcumin.
[3] Although curcumin has been used historically in
Ayurvedic medicine,
[4] its potential for medicinal properties remains unproven and is questionable as a therapy when used orally.
[5][6][7]
Chemically, curcumin is a
diarylheptanoid, belonging to the group of curcuminoids, which are
natural phenols responsible for turmeric's yellow color. It is a tautomeric compound existing in enolic form in organic solvents and as a keto form in water.
[8]
Applications[edit]
Annual sales of curcumin have increased since 2012, largely due to an increase in its popularity as a dietary supplement.
[1] It is increasingly popular in
skincare products that are marketed as containing natural ingredients or dyes, especially in Asia.
[1] The largest market is in North America, where sales exceeded US$20 million in 2014.
[1]
Chemistry[edit]
Curcumin incorporates several functional groups whose structure was first identified in 1910.
[9] The aromatic ring systems, which are
phenols, are connected by two α,β-unsaturated
carbonyl groups. The diketones form stable
enols and are readily deprotonated to form
enolates; the α,β-unsaturated carbonyl group is a good
Michael acceptor and undergoes
nucleophilic addition.
Biosynthesis[edit]
The biosynthetic route of curcumin is uncertain. In 1973, Roughly and 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 arylized 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.
[11]
Research[edit]
In vitro, curcumin exhibits numerous interference properties which may lead to misinterpretation of results.
[5][6]
Although curcumin has been assessed in numerous laboratory and
clinical studies, it has no medical uses established by well-designed
clinical research.
[14] According to a 2017 review of over 120 studies, curcumin has not been successful in any
clinical trial, leading the authors to conclude that "curcumin is an unstable, reactive, non-bioavailable compound and, therefore, a highly improbable lead".
[5]
Pharmacology[edit]
In Phase I
clinical trials, curcumin had poor
bioavailability, was rapidly
metabolized, retained low levels in plasma and tissues, and was extensively and rapidly
excreted, factors that make its
in vivo bioactivity unlikely and difficult to accurately assess.
[5][21] Curcumin appears to reduce circulating
C-reactive protein in human subjects, although no
dose-response relationship was established.
[22] Factors that limit the bioactivity of curcumin or its analogs include chemical instability, water insolubility, absence of potent and selective target activity, low bioavailability, limited tissue distribution, extensive metabolism, and potential for toxicity.
[5]
Toxicity[edit]
Two preliminary clinical studies in cancer patients consuming high doses of curcumin (up to 8 grams per day for 3–4 months) showed no toxicity, though some subjects reported mild
nausea or
diarrhea.
[23]
Alternative medicine[edit]
Some
alternative medicine practitioners give curcumin (as turmeric) intravenously as a treatment for a wide range of health problems, leading to a death in California in 2017
[24] despite the absence of reliable clinical research and concerns about safety or efficacy.
[5][6]
