Curcumin

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Curcumin
Skeletal formula
Enol form
Skeletal formula
Keto form
Ball-and-stick model
Ball-and-stick model
Identifiers
CAS number 458-37-7 YesY
PubChem 969516
ChemSpider 839564 YesY
UNII IT942ZTH98 YesY
ChEBI CHEBI:3962 YesY
ChEMBL CHEMBL116438 N
Jmol-3D images Image 1
Properties
Molecular formula C21H20O6
Molar mass 368.38 g mol−1
Appearance Bright yellow-orange powder
Melting point 183 °C (361 °F; 456 K)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Curcumin (/ˈkərkjuːmən/) is a diarylheptanoid. It is the principal curcuminoid of turmeric, which is a member of the ginger family (Zingiberaceae). Turmeric's other two curcuminoids are desmethoxycurcumin and bis-desmethoxycurcumin. The curcuminoids are natural phenols that are responsible for the yellow color of turmeric. Curcumin can exist in several tautomeric forms, including a 1,3-diketo form and two equivalent enol forms. The enol form is more energetically stable in the solid phase and in solution.[1]

Curcumin can be used for boron quantification in the curcumin method. It reacts with boric acid to form a red-color compound, rosocyanine.

Curcumin is a bright-yellow color and may be used as a food coloring. As a food additive, its E number is E100.[2]

Curcumin

Chemistry[edit]

Curcumin incorporates several functional groups. 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. The structure was first identified in 1910 by J. Miłobędzka, Stanisław Kostanecki and Wiktor Lampe.[3]

Curcumin is used as an indicator for boron.[4]

Biosynthesis[edit]

The biosynthetic route of curcumin has proven to be very difficult for researchers to determine. In 1973, Roughly and Whiting proposed two mechanisms for curcumin biosynthesis. The first mechanism involved a chain extension reaction by cinnamic acid and 5 malonyl-CoA molecules that eventually arylized into a curcuminoid. The second mechanism involved two cinnamate units coupled together by malonyl-CoA. Both mechanisms use cinnamic acid as their starting point, which is derived from the amino acid phenylalanine. This is noteworthy because plant biosyntheses employing cinnamic acid as a starting point are rare compared to the more common use of p-coumaric acid.[5] Only a few identified compounds, such as anigorufone and pinosylvin, use cinnamic acid as their start molecule.[6][7] An experimentally backed route was not presented until 2008. This proposed biosynthetic route follows both the first and second mechanisms suggested by Roughley and Whiting. However, the labeling data supported the first mechanism model in which 5 malonyl-CoA molecules react with cinnamic acid to form curcumin. However, the sequencing in which the functional groups, the alcohol and the methoxy, introduce themselves onto the curcuminoid seems to support more strongly the second proposed mechanism.[5] Therefore, it was concluded the second pathway proposed by Roughly and Whiting was correct.

Biosynthetic pathway of curcumin in Curcuma longa.[5]

Preliminary research for potential health effects[edit]

A survey of the literature shows a number of potential effects under study and that daily doses over a 3-month period of up to 12 grams were safe.[8]

Clinical trials in humans are studying the effect of curcumin on various diseases, including multiple myeloma, pancreatic cancer, myelodysplastic syndromes, colon cancer, psoriasis, arthritis, major depressive disorder and Alzheimer's disease.[9][10][11][12][13][14]

A 2014 review of human clinical trials found no benefit to 5-8 weeks of curcumin consumption compared to placebo or no treatment for patients with major depressive disorder.[15]

A number of trials studying curcumin efficacy and safety revealed poor absorption and low bioavailability.[11]

Bioavailability[edit]

In Phase I clinical trials, dietary curcumin was shown to exhibit poor bioavailability (i.e., low levels in plasma and tissues).[16] Potential factors that limit the bioavailability of curcumin include insolubility in water (more soluble in alkaline solutions), poor absorption, rapid metabolism and systemic elimination. Numerous approaches to increasing curcumin bioavailability have been explored, including the use of absorption factors such as piperine.[16] Because of its stability and physical properties, pure curcumin can be vaporized or smoked, obviating the need for oral absorption factors. This ROA however carries higher risk of chelating iron from hemoglobin, and potentially higher risk of carcinogenicity.

The bioavailability of curcumin ingested in foods may be increased as a result of cooking or dissolution in oil.[17]

Potential risks and side-effects[edit]

Clinical studies in humans with high doses (2–12 grams) of curcumin have shown few side-effects,[18] with some subjects reporting mild nausea or diarrhea.[19] More recently, curcumin was found to alter iron metabolism by chelating iron and suppressing the protein hepcidin, potentially causing iron deficiency in susceptible patients.[20]

Possible diagnostic use[edit]

Preliminary research has found that curcuminoid binds to amyloid proteins associated with Alzheimer's disease.[21] Because curcumin increases fluorescent activity after it binds to amyloid protein, curcumin is being studied as a possible identifier. Tests have detected amyloid proteins in human eyes, offering the possibility that simple eye exams could provide early detection of the disease.[22][23]

References[edit]

Notes
  1. ^ Manolova, Yana; Deneva, Vera; Antonov, Liudmil; at al (2014). "The effect of the water on the curcumin tautomerism: A quantitative approach". Spectrochimica Acta 132A (1): 815–820. doi:10.1016/j.saa.2014.05.096. 
  2. ^ European Commission. "Food Additives". Retrieved 2014-02-15. 
  3. ^ Miłobȩdzka, J.; v. Kostanecki, St.; Lampe, V. (1910). "Zur Kenntnis des Curcumins". Berichte der deutschen chemischen Gesellschaft 43 (2): 2163–70. doi:10.1002/cber.191004302168. 
  4. ^ "EPA Method 212.3: Boron (Colorimetric, Curcumin)". 
  5. ^ a b c Kita, Tomoko; Imai, Shinsuke; Sawada, Hiroshi; Kumagai, Hidehiko; Seto, Haruo (2008). "The Biosynthetic Pathway of Curcuminoid in Turmeric (Curcuma longa) as Revealed by 13C-Labeled Precursors". Bioscience, Biotechnology, and Biochemistry 72 (7): 1789. doi:10.1271/bbb.80075. 
  6. ^ Schmitt, Bettina; Hölscher, Dirk; Schneider, Bernd (2000). "Variability of phenylpropanoid precursors in the biosynthesis of phenylphenalenones in Anigozanthos preissii". Phytochemistry 53 (3): 331–7. doi:10.1016/S0031-9422(99)00544-0. PMID 10703053. 
  7. ^ Gehlert, R.; Schoeppner, A.; Kindl, H. (1990). "Stilbene Synthase from Seedlings of Pinus sylvestris: Purification and Induction in Response to Fungal Infection" (pdf). Molecular Plant-Microbe Interactions 3 (6): 444–449. doi:10.1094/MPMI-3-444. 
  8. ^ Goel, Ajay; Kunnumakkara, Ajaikumar B.; Aggarwal, Bharat B. (2008). "Curcumin as "Curecumin": From kitchen to clinic". Biochemical Pharmacology 75 (4): 787–809. doi:10.1016/j.bcp.2007.08.016. PMID 17900536. Pilot phase I clinical trials have shown curcumin to be safe even when consumed at a daily dose of 12g for 3 months. 
  9. ^ Hatcher, H.; Planalp, R.; Cho, J.; Torti, F. M.; Torti, S. V. (2008). "Curcumin: From ancient medicine to current clinical trials". Cellular and Molecular Life Sciences 65 (11): 1631–52. doi:10.1007/s00018-008-7452-4. PMID 18324353. 
  10. ^ Yan, Jiao; Wilkinson, Di, Wang, Hatcher, Kock, D'Agostino, Jr, Knovich, Torti, Torti corresponding author (8 January 2009). "Red Cells, Iron, and Erythropoiesis Curcumin, a cancer chemopreventive and chemotherapeutic agent, is a biologically active iron chelator". Blood. 113(2): (Prepublished online 2008 September 24.): 462–469. doi:10.1182/blood-2008-05-155952. PMC 2615657. PMID 18815282. 
  11. ^ a b "ClinicalTrials.gov: Current clinical trials on curcumin". US National Institutes of Health, Clinical Trial Registry. 2013. 
  12. ^ Zhao, LN.; Chiu, SW.; Benoit, J.; Chew, LY.; Mu, Y. (Jun 2012). "The effect of curcumin on the stability of Aβ dimers". J Phys Chem B 116 (25): 7428–35. doi:10.1021/jp3034209. PMID 22690789. 
  13. ^ Sanmukhani, J; Satodia, V; Trivedi, J; Patel, T; Tiwari, D; Panchal, B; Goel, A; Tripathi, C. B. (2014). "Efficacy and safety of curcumin in major depressive disorder: A randomized controlled trial". Phytotherapy Research 28 (4): 579–85. doi:10.1002/ptr.5025. PMID 23832433.  edit
  14. ^ Mancuso, C.; Barone, E. (2009). "Curcumin in clinical practice: myth or reality?". Trends in Pharmacological Science 30 (7): 333–334. doi:10.1016/j.tips.2009.04.004. PMID 19523696. 
  15. ^ Andrade, Chittaranjan (2014). "A critical examination of studies on curcumin for depression". The Journal of Clinical Psychiatry 75 (10): e1110–1112. PMID 25373119. 
  16. ^ a b Anand, P.; Kunnumakkara, A. B.; Newman, R. A.; Aggarwal, B. B. (2007). "Bioavailability of curcumin: problems and promises". Molecular Pharmaceutics 4 (6): 807–818. doi:10.1021/mp700113r. PMID 17999464. 
  17. ^ Marczylo, T. H.; Verschoyle, R. D.; Cooke, D. N.; Morazzoni, P.; Steward, W. P.; Gescher, A. J. (2007). "Comparison of systemic availability of curcumin with that of curcumin formulated with phosphatidylcholine". Cancer Chemotherapy and Pharmacology 60 (2): 171–177. doi:10.1007/s00280-006-0355-x. PMID 17051370. 
  18. ^ Cheng, A. L.; Hsu, C. H.; Lin, J. K.; Hsu, M. M.; Ho, Y. F.; Shen, T. S.; Ko, J. Y.; Lin, J. T.; Lin, B. R.; Ming-Shiang, W; Yu, H. S.; Jee, S. H.; Chen, G. S.; Chen, T. M.; Chen, C. A.; Lai, M. K.; Pu, Y. S.; Pan, M. H.; Wang, Y. J.; Tsai, C. C.; Hsieh, C. Y. (2001). "Phase I clinical trial of curcumin, a chemopreventive agent, in patients with high-risk or pre-malignant lesions". Anticancer research 21 (4B): 2895–900. PMID 11712783.  edit
  19. ^ Hsu, C. H.; Cheng, A. L. (2007). "Clinical studies with curcumin". Advances in Experimental Medicine and Biology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 595: 471–480. doi:10.1007/978-0-387-46401-5_21. ISBN 978-0-387-46400-8. PMID 17569225. 
  20. ^ Jiao Y et al. (January 2009). "Curcumin, a cancer chemopreventive and chemotherapeutic agent, is a biologically active iron chelator". Blood 113 (2): 462–469. doi:10.1182/blood-2008-05-155952. PMC 2615657. PMID 18815282. 
  21. ^ Yanagisawa, D.; Taguchi H; Yamamoto A; Shirai N; Hirao K; Tooyama I. (2011). "Curcuminoid binds to amyloid-β1-42 oligomer and fibril". Journal of Alzheimer's Disease. 24 Suppl 2: 33–42. doi:10.3233/JAD-2011-102100 (inactive 2014-10-25). PMID 21335654. Retrieved July 13, 2014. 
  22. ^ Smell And Eye Tests Might Detect Alzheimer's Early, retrieved July 13, 2014 
  23. ^ "Eye tests could detect early Alzheimer's: Researchers say Alzheimer's marker can be detected in retina and lens of eye". The Guardian. July 13, 2014. Retrieved July 13, 2014. 

External links[edit]