Curcumin purification

Abstract

The present invention relates to a process for the purification of curcumin comprising provision of a curcuminoid composition, contacting said curcuminoid composition with basic amino acid or amino acid ester in order to form an amino acid salt of curcumin, separating the salt of curcumin, and recovering curcumin at increased purity levels. Curcumin may be obtained at purity levels beyond 90 wt. %.

Claims

1. A process for purification of curcumin comprising: (i) providing a curcuminoid composition; (ii) contacting said curcuminoid composition with a basic amino acid or an amino acid derivative to form an amino acid salt of curcumin; (iii) separating the salt of curcumin; and (iv) recovering purified curcumin.

2. The process of claim 1, wherein the basic amino acid is selected from the group consisting of lysine, arginine and histidine.

3. The process of claim 1, wherein the amino acid salt of curcumin is formed in a polar alcoholic solvent in which the curcumin, the basic amino acid, or the amino acid derivative and the amino acid salt of curcumin are soluble.

4. The process of claim 1, wherein separating the curcumin salt occurs by concentrating the solution containing said salt, thereby precipitating the salt.

5. The process of claim 1, wherein separating the curcumin salt includes adding a solvent in which the curcumin salt is not soluble.

6. The process of claim 4, wherein the precipitate is filtered.

7. The process of claim 1, further comprising drying the recovered curcumin salt.

8. The process of claim 1, wherein recovering purified curcumin further comprises redissolving the salt in solution and acidifying the solution.

9. The process of claim 8, wherein said salt is redissolved in water.

10. The process of claim 8, wherein curcumin is recovered by filtration, washed and possibly dried.

11. The process of claim 1, wherein steps (ii), (iii) and (iv) are repeated.

12. The process of claim 1, wherein the amino acid derivative is an ester or carboxamide.

13. The process of claim 2, wherein the basic amino acid is lysine or arginine.

14. The process of claim 13, wherein the basic amino acid is lysine.

Description

EXAMPLE

(1) An aliquot of 3.5 g of standardized curcuminoid extract (CAS N 458-37-7) containing 75-80 wt. % curcumin in its enol and ketone form, together with demethoxycurcumine and bisdemethoxycurcumine and other impurities (Sigma Aldrich) is solubilized in 400 ml methanol under stirring and heated at 35 C. during 5 minutes. A yellow solution is obtained. The insoluble residue (a brownish resin) is filtered and eliminated.

(2) A fraction of 1.388 g of lysine base is added to the filtrate under agitation. The solution becomes bordeaux red. After 5 additional minutes of stirring, the solution is concentrated under vacuum at 25 C. such as to reduce its volume to approx. 50 ml. 250 ml of ethanol are added under stirring. The obtained curcumin lysinate salt is recovered by filtration and dried. Approx 4 g of salt are obtained.

(3) A 2 g aliquot of the curcumin lysinate salt obtained above are dissolved in 200 ml of water at 25 C., under stirring. The solution is acidified to pH=1 by addition of concentrated hydrochloric acid. A yellow curcumine precipitate settles and is recovered by filtration and washed with water. The purity is higher than 95%. Yield has been computed to be higher than 90%.

(4) In order to further increase purity level of curcumin, the steps described above may be repeated. The product obtained may be used to form a salt with lysine base again; the salt may be recovered as described above and redissolved it in water, followed by addition of hydrochloric acid.