Curcumin

Curcumin is the principal curcuminoid of the Indian curry spice turmeric, the other two curcuminoids being demethoxycurcumin and Bis-demethoxycurcumin.The curcuminoids are polyphenols and are responsible for the yellow color of turmeric. Curcumin can exist in at least two tautomeric forms, keto and enol. The enol form is more energetically stable in the solid phase and in solution.^[1] It is also hepatoprotective.^[2]

Curcumin can be used for boron quantification in the so-called curcumin method. It reacts with boric acid forming a red colored compound, known as rosocyanine.

Since curcumin is brightly colored, it may be used as a food coloring. As a food additive, its E number is E100.

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Potential medical uses

Curcumin is known for its antitumor,[4] antioxidant, antiarthritic, anti-amyloid and anti-inflammatory properties.[5] Anti-inflammatory properties may be due to inhibition of eicosanoid biosynthesis.^[3] In addition it may be effective in treating malaria, prevention of cervical cancer, and may interefere with the replication of the HIV virus.^[4] In HIV, it appears to act by interfering with P300/CREB-binding protein (CBP) of its reverse transcriptase.

Curcumin acts as a free radical scavenger and antioxidant, inhibiting lipid peroxidation and oxidative DNA damage. Curcuminoids induce glutathione S-transferase and are potent inhibitors of cytochrome P450.

For the last few decades, extensive work has been done to establish the biological activities and pharmacological actions of curcumin. Its anticancer effects stem from its ability to induce apoptosis in cancer cells without cytotoxic effects on healthy cells. Curcumin can interfere with the activity of the transcription factor NF-κB, which has been linked to a number of inflammatory diseases such as cancer.^[5] Indeed, when 0.2% curcumin is added to diet given to rats or mice previously given a carcinogen, it significantly reduces colon carcinogenesis (Data from sixteen scientific articles reported in the Chemoprevention Database). A 2007 report indicates that curcumin may suppress MDM2, an oncogene involved in mechanisms of malignant tumor formation[6].

A 2004 UCLA-Veterans Affairs study involving genetically altered mice suggests that curcumin might inhibit the accumulation of destructive beta-amyloid in the brains of Alzheimer's disease patients and also break up existing plaques associated with the disease.^[6]

There is also circumstantial evidence that curcumin improves mental functions; a survey of 1010 Asian people who ate yellow curry and were between the ages of 60 and 93 showed that those who ate the sauce "once every six months" or more had higher MMSE results than those who did not.^[7] From a scientific standpoint, though, this does not show whether the curry caused it, or people who had healthy habits also tended to eat the curry, or some completely different relationship.

Little curcumin, when eaten, is absorbed — 2 grams of curcumin alone resulted in undetectable to very low serum levels.^[8] Much of it is excreted through glucuronidation. Co-supplementation with 20 mg of piperine (extracted from black pepper) significantly increased the absorption of curcumin by 2000%^[8]. However, due to its effects on drug metabolism, piperine should be taken cautiously (if at all) by individuals taking other medications. Some benefits of curcumin, such as the potential protection from colon cancer, may not require systemic absorption. Alternatively, dissolving curcumin in hot water prior to ingestion, or in warm oily liquids, appears to increase bioavailability.

Recently, a polymeric nanoparticle encapsulated formulation of curcumin ("nanocurcumin"[7]) has been synthesized which has the potential to bypass many of the shortcomings associated with free curcumin, such as poor solubility and poor systemic bioavailability. Nanocurcumin particles have a size of less than 100 nanometers on average, and demonstrate comparable to superior efficacy compared to free curcumin in human cancer cell line models.^[9] Other researchers have developed a number of other curcumin analogs that appear to have greater bioavailability, but these analogs have not been tested broadly, either in vitro or in vivo, for medicinal purposes.

Risks

Kawanishi et al. (2005) remarked that curcumin is a "double-edged sword" having both anti-cancer and carcinogenic effects.^[10] Carcinogenic effects are inferred from interference with the p53 tumor suppressor pathway, an important factor in human colon cancer.^[11] Carcinogenic and LD50 tests in mice and rats, however, have failed to establish a relationship between tumorogenesis and administration of curcumin in turmeric oleoresin at >98% concentrations.^[12] This may prove curcumin medicinally useful as it helps activate p53^{[citation needed]}. When a cell is inhibited by cancer the concentrations of p53 increase, helping cells defend against cancer mechanisms^{[citation needed]}. But it may also suppress p53 levels, preventing cells from initiating defensive mechanisms, a response seen only in certain diseases^{[citation needed]}.

References

Notes

1. ^ Kolev T.M., et at, DFT and Experimental Studies of the Structure and Vibrational Spectra of Curcumin, International Journal of Quantum Chemistry, 102, 6, (2005)
2. ^ [1]
3. ^ Srivastava KC, Bordia A, Verma SK. Curcumin, a major component of the food spice turmeric (Curcuma longa), inhibits aggregation and alters eicosanoid metabolism in human blood platelets. Prostaglandins Leukot Essent Fatty Acids. 1995 Apr;52(4):223-7. PMID 7784468.
4. ^ [2]
5. ^ Aggarwal BB, Shishodia S. Suppression of the nuclear factor-kappaB activation pathway by spice-derived phytochemicals: reasoning for seasoning. Ann N Y Acad Sci. 2004 Dec;1030:434-41. PMID 15659827.
6. ^ Yang F, Lim GP, Begum AN, Ubeda OJ, Simmons MR, Ambegaokar SS, Chen PP, Kayed R, Glabe CG, Frautschy SA, Cole GM. Curcumin inhibits formation of amyloid beta oligomers and fibrils, binds plaques, and reduces amyloid in vivo. J Biol Chem. 2005 Feb 18;280(7):5892-901. Epub 2004 Dec 7. PMID 15590663.
7. ^ Ng TP, Chiam PC, Lee T, Chua HC, Lim L, Kua EH. Curry consumption and cognitive function in the elderly. Am J Epidemiol. 2006 Nov 1;164(9):898-906. Epub 2006 Jul 26. PMID 16870699.
8. ^ ^{a b} Shoba G, Joy D, Joseph T, Majeed M, Rajendran R, Srinivas PS. Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta Med. 1998 May;64(4):353-6. PMID 9619120.
9. ^ "Bisht S, Feldmann G, Soni S, Ravi R, Karikari C, Maitra A, Maitra A. Polymeric nanoparticle encapsulated curcumin ("nanocurcumin"): a novel strategy for human cancer therapy. J Nanobiotechnol 2007 Apr 17;5:3. PMID 17439648.
10. ^ Kawanishi, S. Oikawa, S. Murata, M. 2005. "Evaluation for safety of antioxidant chemopreventive agents." Antioxidants & Redox Signaling 7(11-12), 1728-1739. (PMID 16356133)
11. ^ Moos PJ, Edes K, Mullally JE, Fitzpatrick FA. 2004 "Curcumin impairs tumor suppressor p53 function in colon cancer cells". Carcinogenesis, 25(9):1611-7. PMID 15090465.
12. ^ Lois Swirsky Gold. Turmeric (>98% curcurmin). Carcinogenic Potency Database Project. Last updated 3 Apr 2006. Last accessed 4 Jan 2007. [3]

General references

• Aggarwal, Bharat B.; Kumar, Anushree; Aggarwal, Manoj S.; Shishodia, Shishir. 2005. "Curcumin derived from turmeric (Curcuma longa): A spice for all seasons." Phytopharmaceuticals in Cancer Chemoprevention, 349-387.

• Aggarwal, Bharat et al; December 2006; "Curcumin: The Indian Solid Gold" [8]

• Aggarwal BB, Kumar A, Bharti AC; "Anticancer potential of curcumin: preclinical and clinical studies." Anticancer Res.' 2003 Jan-Feb;23(1A):363-98. (PMID 12680238)

• Ahmed M. Zahran. Influence of Curcumin on the Redox ‎System and Lipid Peroxidation in Gamma Irradiated Rats. ‎Egypt. J. Rad. Sci. Applic., 20(2): 385-404 (2007).‎

• Campbell, Frederick C.; Collett, Gavin P. 2005. "Chemopreventive properties of curcumin." Future Oncology, 1(3), 405-414. (PMID 16556014)

• Chattopadhyay, Ishita; Biswas, Kaushik; Bandyopadhyay, Uday; Banerjee, Ranajit K. 2004. "Turmeric and curcumin: biological actions and medicinal applications." Current Science', 87(1), 44-53.

• Goel A, Kunnumakkara AB, Aggarwal BB; "Curcumin as 'Curecumin': From kitchen to clinic." Biochem Pharmacol', 2007 Aug 19; (PMID 17900536)

• Ringman, John M.; Frautschy, Sally A.; Cole, Gregory M.; Masterman, Donna L.; Cummings, Jeffrey L. "A potential role of the curry spice curcumin in Alzheimer's disease." Current Alzheimer Research, 2(2), 131-136. (PMID 15974909)