# Patent

## Title
Curcumin derivatives

## Abstract

The invention relates to novel curcumin derivatives in which one or two of the phenolic groups have been modified.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application is the U.S. National Phase of, and claims priority to, International Patent Application Number PCT/US2011/026308 filed 25 Feb. 2011, which claims the benefit of U.S. Provisional Application No. 61/308,362, filed Feb. 26, 2010, each of which is incorporated by reference.


BACKGROUND OF THE INVENTION
There is a vital need to find drugs that halt or reverse Alzheimer's disease (AD). AD presently affects 18 million people worldwide. The human and financial costs of AD in the US is expected to exceed $150 billion in 2005. FDA approved medications treat symptoms, but do not alter AD progression.
The hallmarks of AD are inter-neuronal plaques consisting of precipitates or aggregates of amyloid beta protein (Aβ), and intra-neuronal neurofibrillary tangles (NFTs) of tau protein. The major target for drug discovery for AD has been Aβ that forms insoluble senile plaques. Although the etiology of AD is not fully understood, the Aβ amyloid cascade hypothesis is the most common view of the pathological pathway of AD in which the generation of Aβ and accumulation of Aβ aggregates in the brain initiate the disease process. It is supported by genetic evidence that mutations leading to increased production of Aβ leads to familial AD. Agents that dissolve Amyloid plaque or reduce plaque burden via other mechanisms are considered potential Alzheimer's drugs.
Development of Water-Soluble Curcumin Derivatives for AD
Curcuma longa commonly referred to as “turmeric” is used as a spice in South Asian cooking, as a cosmetic and in the ancient Ayurvedic system of medicine2-4. There has recently been tremendous interest in curcumin, [(1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene 3,5-dione] the primary active ingredient in turmeric, because it has been shown to have antioxidant5, anticancer6, anti-inflammatory7, and potent anti-AD activity8. Encouraging results have been published regarding neuroprotective effects of curcumin and ongoing pilot clinical trials have been initiated9. Curcumin has been shown to reduce pathology in AD mouse models overproducing Aβ10-14 and bisdemethoxycurcumin was reported to improve the innate immune system by enhancing phagocytosis of Aβ15. Curcumin appears to have multiple neuroprotective mechanisms including inhibition of inflammation, suppression of Aβ production, reduction of reactive oxygen species by chelating metals, inhibition of stress pathways and induction of heat shock proteins8, 16-18. One of the major limitations of using curcumin as a drug is its poor water and plasma solubility; even doses as high as 8 g of curcumin per day administered to human subjects result in an average peak serum concentration of  ̃1.77 μM of curcumin19,20.
SUMMARY OF THE INVENTION
In one embodiment, the invention relates to a curcumin derivative having the formula I:




wherein:

    A is —CH2—CH2— or —CH═CH—;
    R1 represents H or L1m1-Y1;
    R2 represents H or L2m2-Y2;
    L1 and L2 are independently






    m1 and m2 are independently 0 or 1;
    n1 is independently 0 or an integer from 1 to 50;
    L3 is independently a saturated or unsaturated, branched or unbranched hydrocarbyl with 1 to 12 carbon atoms;
    Y1 and Y2 independently represent —OH; a saccharide with 1 to 51 monosaccharide units; —NH—(CH2CH2—O)n2—R3; —O—(CH2CH2—O)n2—R3; —CH═CH2; or —C≡CH;
    R3 independently represents a saturated, unbranched hydrocarbyl with 1 to 4 carbon atoms; and
    n2 independently represents an integer from 5 to 50;
    with the proviso that if R1═R2, then R1═R2≠H;
    with the proviso that if Y1 is OH, then L1 is






and R2 is not H;

    with the proviso that if Y2 is OH, then L2 is






and R1 is not H;

    with the proviso that if m1 is 0, then Y1 is not a saccharide;
    with the proviso that if m2 is 0, then Y2 is not a saccharide;
    with the proviso that if Y1 is —NH—(CH2CH2—O)n2—R3 or —O—(CH2CH2—O)n2—R3, then L1 is






and

    with the proviso that if Y2 is —NH—(CH2CH2—O)n2—R3 or —O—(CH2CH2—O)n2—R3, then L2 is






In another embodiment, the invention relates to a method of treating Ahzheimer's disease in a patient by administering a curcumin derivative having formula I.



BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 depicts anti-oxidant potentials of Curcumin 1, Curcumin mono-alkyne 1a, Curcumin mono-carboxylic acid 1b and sweet curry 1d in water. Compound 1d is a much better antioxidant than Curcumin 1 as well as other curcumin derivatives (1a,1b) in an aqueous medium which serves as a model for physiological conditions (plasma). Sweet curry 1d is also superiorly soluble in water compared to Curcumin and derivatives 1a and 1b.
FIG. 2 depicts AOP of sweet curry in water and ethanol.
FIG. 3 depicts a Cell Viability Chart of sweet curry at different concentrations.



DETAILED DESCRIPTION
The invention relates to novel curcumin derivatives in which one or two of the phenolic groups have been modified.
The curcumin derivative is represented by formula I below:




In formula I, A represents —CH2—CH2— or —CH═CH—. When A is —CH2—CH2—, the compound is a tetrahydrocurcumin derivative. When A is —CH═CH—, the compound is a curcumin derivative.
R1 represents H (hydrogen) or L1m1-Y1. R2 represents H (hydrogen) or L2m2-Y2. When only one of R1 and R2 represents H, then only one of the phenolic groups on the curcumin derivative is modified. When both R1 and R2 are not H, then both of the phenolic groups on the curcumin derivative are modified.
L1 and L2 are linkers that independently represent




In one embodiment, L1 and L2 both represent:





In another embodiment, L1 and L2 both represent:





In a third embodiment, L1 represents





and L2 represents





Conversely, in another embodiment, L2 represents





and L1 represents





The letters m1 and m2 are independently 0 or 1. Therefore, when m1 is 0, then there is no linker L1, so R1═Y1. Likewise, when m2 is 0, then there is no linker L2, so R2═Y2.
When m1 is 1 and L1 is




then L3 is independently a saturated or unsaturated, branched or unbranched hydrocarbyl with 1 to 12 carbon atoms. The carbon atoms of the hydrocarbyl can all be saturated, or can all be unsaturated. Alternatively, the chain can comprise a mixture of saturated and unsaturated carbon atoms. The unsaturated hydrocarbyl chains contain one or more double and/or triple bonds.

Some examples of suitable, saturated straight-chained hydrocarbyl chains include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, and dodecyl chains. Preferred straight chain alkyl groups include methyl and ethyl. Some examples of suitable, unsaturated straight-chained hydrocarbyl chains include 3-butenyl, 1,3-heptadienyl, and 2-dodecynyl chains.
Some examples of suitable saturated, branched alkyl groups include iso-propyl, iso-butyl, sec-butyl, t-butyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl(isopentyl), 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl(neopentyl), 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, and 4-methylpentyl. Preferred branched alkyl groups include isopropyl and t-butyl. Some suitable examples of unsaturated, branched alkyl groups include 1-methyl-4-pentenyl and 2-ethyl-1,8-decadienyl.
When, m2 is 1 and L2 is




then n1 is independently 0 or an integer from 1 to 50. All integers from 1 to 50 are contemplated, e.g., 1, 2, 3, 4, . . . , 46, 47, 48, 49, and 50. The preferred minimum value of n1 is 2, more preferably 3. The preferred maximum value of n1 is 20, more preferably 12.

Y1 and Y2 independently represent —OH; a saccharide with 1 to 51 monosaccharide units; —NH—(CH2CH2—O)n2—R3; —O—(CH2CH2—O)n2—R3; —CH═CH2 or —C≡CH. The preferred number of monosaccharide units are 1, 2, and 3. The most preferred saccharide is a monosaccharide.
Saccharides are well known in the art and include monosaccharides, disaccharides, trisaccharides, oligosaccharides, and polysaccharides with a maximum of 51 monosaccharide units. Therefore, saccharides such as dextran which contain over 51 monosaccharide units are excluded from the present invention.
Monosaccharide units include, but are not limited to, glucose (dextrose), fructose (levulose), galactose, allose, altrose, mannose, gulose, idose, talose, xylose, and ribose. The preferred monosaccharides units and monosaccharides are glucose and galactose.
Disaccharide units include, but are not limited to, sucrose, lactose, lactulose, maltose, trehalose, and cellobiose.
Saccharides of the invention must be connected to the phenolic group of the curcumin derivative through a linker. Therefore, if m1 is 0, then Y1 is not a saccharide. Likewise, if m2 is 0, then Y2 is not a saccharide.
The linker L1 or L2 can be attached to any —OH group on an end monosaccharide unit of the saccharide.
When Y1 or Y2 is a monosaccharide, the monosaccharide may or may not be a deoxy-aminosaccharide. When Y1 or Y2 is a deoxy-aminosaccharide, the monosaccharide may or may not be bonded to L1 or L2 through the amino group of the deoxy-aminosaccharide.
When Y1 or Y2 is a di-, tri-, or oligosaccharide (4-51), any one or more of the monosaccharide units may be a deoxy-aminosaccharide unit. If the proximal monosaccharide unit in a di-, tri-, or oligosaccharide is a deoxy-aminosaccharide and m1 or m2 is 1, the di-, tri-, or oligosaccharide may or may not be bonded to L1 or L2 through the amino group of the deoxy-aminosaccharide unit.
Monosaccharides that are deoxy-aminosaccharides are known in nature, and may also be synthesized by methods known in the art, such as those described in Du Bois at al., J. Am. Chem. Soc. 119, 3179-3180 (1977), and references cited therein. Di-, tri-, and oligosaccharides in which the proximal monosaccharide unit is a deoxy-aminosaccharide are also known in nature, and may also be synthesized by methods known in the art, such as those described by Nilsson, U.S. Pat. No. 5,936,075.
R3 independently represents a saturated, unbranched hydrocarbyl with 1 to 4 carbon atoms. Examples of saturated, unbranched hydrocarbyls are methyl, ethyl, propyl, and butyl.
The letter n2 independently represents an integer from 5 to 50. All integers from 5 to 50 are contemplated, e.g., 5, 6, 7, 8, . . . , 47, 48, 49, 50. The preferred minimum value of n2 is 6, more preferably 5. The preferred maximum value of n2 is 20, more preferably 12.
The main independent claim contains certain provisos. For example, if R1═R2, then R1 and R2 are not H. This excludes the possibility of the compound being unsubstituted curcumin or tetrahydrocurcumin.
In another proviso, if Y1 is OH, then L1 is




and R2 is not H. Likewise, if Y2 is OH, then L2 is





and R1 is not H.

If Y1 is —NH—(CH2CH2—O)n2—R3 or —O—(CH2CH2—O)n2—R3, then L1 is




Likewise, if Y2 is —NH—(CH2CH2—O)n2—R3 or —O—(CH2CH2—O)n2—R3, then L2 is





A list of preferred compounds of the invention is provided in Table I.
In this specification, groups of various parameters containing multiple members are described. Within a group of parameters, each member may be combined with any one or more of the other members to make additional sub-groups. For example, if the members of a group are a, b, c, d, and e, additional sub-groups specifically contemplated include any two, three, or four of the members, e.g., a and c; a, d, and e; b, c, d, and e; etc.
In some cases, the members of a First group of parameters, e.g., a, b, c, d, and e, may be combined with the members of a second group of parameters, e.g., A, B, C, D, and E. Any member of the first group or of a sub-group thereof may be combined with any member of the second group or of a sub-group thereof to form additional groups, i.e., b with C; a and c with B, D, and E, etc.
For example, in the present invention, groups of various parameters are defined (e.g. A, R1, R2, Y1, Y2, m1, m2, L1, and L2). Each group contains multiple members. For example, Y1 and Y2 independently represent —OH; a saccharide with 1 to 51 monosaccharide units;
—NH—(CH2CH2—O)n2—R3; —O—(CH2CH2—O)n2—R3; —CH═CH2; or —C≡CH. Each member may be combined with each other member to form additional sub-groups, e.g., —OH and a monosaccharide; —OH and —CH═CH2; or a monosaccharide, —NH—(CH2CH2—O)n2—R3, and —C≡CH.
The instant invention further contemplates embodiments in which each element listed under one group may be combined with each and every element listed under any other group unless specifically excluded by a proviso. For example, Y1 and Y2 are identified above as independently representing —OH; a saccharide with 1 to 51 monosaccharide units; —NH—(CH2CH2—O)n2—R3; —O—(CH2CH2—O)n2—R3; —CH═CH2, or —C≡CH. L1 and L2 are identified above as linkers independently representing




Each element of Y1 and Y2 (—OH; a saccharide with 1 to 51 monosaccharide units; —NH—(CH2CH2—O)n2—R3; —O—(CH2CH2—O)n2—R3; —CH═CH2; or —C≡CH) can be combined with each and every element of L1 and L2 





unless specifically excluded with proviso language.

For example, in one embodiment, Y1 may be —OH; L1 may be




Y2 may be —O—(CH2CH2—O)n2—R3; and L2 may be





Alternatively, Y1 may be a trisaccharide; L1 may be





Y2 may be —OH; and L2 may be





Similarly, a third group is A, in which the elements are defined as —CH2—CH2— or —CH═CH—. Each of the above embodiments may be combined with each and every element of A. For example, in the embodiment wherein Y1 may be —OH; L1 may be




Y2 may be —O—(CH2CH2—O)n2—R3; and L2 may be





A may be —CH2—CH2— (or any other chemical moiety within the element of A).

With each group, it is specifically contemplated that any one or more members can be excluded. For example, if Y1 is defined as —OH; a saccharide with 1 to 51 monosaccharide units; —NH—(CH2CH2—O)n2—R3; —O—(CH2CH2—O)n2—R3; —CH═CH2, or —C≡CH; it is also contemplated that Y1 is defined as a saccharide with 1 to 51 monosaccharide units; —O—(CH2CH2—O)n2—R3; or —C≡CH.
The compounds of this invention are limited to those that are chemically feasible and stable. Therefore, a combination of substituents or variables in the compounds described above is permissible only if such a combination results in a stable or chemically feasible compound. A stable compound or chemically feasible compound is one in which the chemical structure is not substantially altered when kept at a temperature of 40° C. or less, in the absence of moisture or other chemically reactive conditions, for at least a week.
All stereoisomers of the compounds of the instant invention are contemplated, either in admixture or in pure or substantially pure form. The definition of compounds according to the invention embraces all the possible stereoisomers and their mixtures; it also embraces the racemic forms and the isolated optical isomers having the specified activity. The racemic forms can be resolved by physical methods, such as, for example, fractional crystallization, separation, or crystallization of diastereomeric derivatives or separation by chiral column chromatography. The individual optical isomers can be obtained from the racemates from the conventional methods, such as, for example, salt formation with an optically active acid followed by crystallization.
A list following the word “comprising” is inclusive or open-ended, i.e., the list may or may not include additional unrecited elements. A list following the words “consisting of” is exclusive or closed ended, i.e., the list excludes any element not specified in the list.
All numbers in the specification are approximate unless indicated otherwise.
The method of treating a condition, disorder or disease with a chemical compound or a chemical composition includes the use of the chemical compound or chemical composition in the manufacture of a medicament for the treatment of the condition, disorder or disease. A compound or a group of compounds said to be effective in treating a condition, disorder or disease includes the compound or group of compounds for use in treating the condition, disorder or disease.
Synthesis of Compounds
The water/plasma solubility of curcumin is improved by selective covalent modification of one or both of its phenolic —OH groups by attaching water-soluble molecules such as polyethylene glycol (PEG) and sugar derivatives to produce covalent conjugates. The sugar/PEG component of the conjugate confers improved water/plasma solubility to the curcumin component. Several series of conjugates with varying hydrophilic-lipophilic balance (HLB) are synthesized to optimize the plasma solubility and the ability to cross the blood-brain barrier (BBB). Novel mono-functional curcumin derivatives have been synthesized in which one of the phenolic groups of curcumin has been chemically modified with reactive groups (e.g., azidyl, alkynyl and carboxyl groups)21.
Preferably, direct one/two step covalent modification of curcumin is utilized to produce the mono-functional and di-functional derivatives in good yields. The synthesis of mono-functional curcumin derivatives has two advantages; (1) the presence of at least one free phenolic group is necessary for the biological activity of many antioxidants like curcumin5 as mono-functional derivatives of curcumin retain their ability to bind and dissociate amyloid fibrils in vitro21, 22, and (2) high yields: conjugates produced using mono-functional derivatives result in soluble products in high yields.
Optionally, the carboxylate, azidyl, or alkynyl groups serve as covalent functional handles for attaching curcumin to biocompatible water-solubilizing molecules such as sugars and PEG. The glucuronidation of curcumin in vivo is another possible reason for the observation of very low plasma levels of the compound23. In the curcumin-glucuronide derivative, one of the phenolic groups of curcumin is enzymatically modified and the derivative is negatively charged. Therefore the derivative would not be likely to cross the blood brain barrier. Furthermore, the curcumin derivatives (in which one or both of the phenolic —OH groups of curcumin is covalently modified) will resist glucurodination because one or both of the phenolic —OH groups is blocked, it is also highly likely that they will not fit the active site of the glucuridination enzyme.
Three chemistries are employed: (a) Azide derivatives of carbohydrates/oligo-ethylene glycol (OEG) will be coupled with curcumin alkyne under the Sharpless “click” conditions to produce triazole derivatives of Curcumin, (b) OEG amines/carbohydrate amines will be condensed with a carboxylic acid derivatives of curcumin under amide coupling conditions to produce amide conjugates of Curcumin, (c) OEG/carbohydrates can also be coupled to Curcumin carboxylic acid via esterification. Well-defined efficient reactions such as amide couplings, esterifications or [3+2] azide-alkyne cycloaddition in preparing curcumin conjugates are used.
In the “clicked” derivatives of curcumin, curcumin is connected via an ether bond and a triazole linker to the sugar/OEG component. The ether and triazole links present in these conjugates are extremely stable to hydrolysis, it is anticipated that these derivatives can be administered orally and would survive acid in the gastrointestinal tract. It is also possible to administer these derivatives intravenously (injectible formulation). A “clicked” sugar curcumin conjugate with vastly improved water solubility has been synthesized. The amide and ester conjugates of curcumin and OEGs/sugars have ester links in their structures connecting the water solublizing component to curcumin. These links are labile and would undergo hydrolysis over time to produce curcumin, thus allowing us to explore a “prodrug” approach. The amide and ester conjugates may undergo acid hydrolysis in the gastrointestinal tract, and therefore may be administered either as an inhalable formulation or as an injectable. The triazole (sugar and OEG) conjugates (with improved water/plasma solubility) which are resistant to acid hydrolysis can be administered orally. The “clicked” sugar conjugate of curcumin has a direct water solubility of  ̃0.2 mmol, in a tau oligomer dissolution assay the mono-functional curcumin derivatives work at a micromolar concentrations, a therapeutically effective concentration can therefore be achieved in a facile fashion using this technology. It may also be possible to synthesize and screen a range of carbohydrate derivatives of curcumin to optimize brain uptake of the carbohydrate conjugates via the glucose transport mechanism24.



















TABLE 1







List of possible R groups attached via phenolic —OH groups








Entry



Number
Structures of the considerable groups











1
R1 = H R2 = —≡


2
R1 = R2 = —≡


 


3






 


4






 


5






 


6






 


7






 


8






 


9






 


10






 


11






 


12






 


13






 


14






 


15






 


16






 


17






 


18






 


19






 


20






 


21






 


22






 


23






 


24













EXAMPLES
1. Synthesis of Curcumin mono-alkyne (1a)




Curcumin (5 g, 13.57 mmol) and K2CO3 (1.88 g, 13.62 mmol) were added to 60 mL DMF followed by 1.62 g (13.61 mmol) of propargyl bromide. The mixture was stirred at room temperature under N2for 48 h, H2O was added to the mixture and the solvent was removed under vacuum. The product was purified by column chromatography, eluting with CHCl3:hexane90:10. Yield: 47%. 1H NMR (600 MHz, CDCl3), δ (ppm): 2.54 (s, 1H); 3.94 (d, 6H); 4.81 (d, 2H); 5.82 (d, 1H); 5.93 (d, 1H); 6.47-6.52 (t, 2H); 6.93-7.15 (m, 6H); 7.59-7.61 (d, 2H). 13CNMR (150 MHz, CDCl3), δ (ppm): 30.73; 30.77; 31.38; 31.40; 36.50; 55.70; 55.72; 55.76, 56.35; 101.44; 109.97; 110.01; 110.30; 113.39; 113.40; 115.14; 115.17; 121.22; 121.27; 121.94; 122.00; 122.25; 122.30; 122.85; 122.86; 127.13; 127.18; 128.93; 139.90; 139.92; 140.83; 140.86; 147.23; 148.33; 148.40; 148.46; 149.44; 162.74; 162.80; 182.57; 183.73. MS (ESI) calcd. for C24H22O6: 406.43; found: 407.2 [M+H]+, 445.2 [M+K]+.
2. Synthesis of Protected Curcumin-“Clicked”-mono-galactose




Curcumin mono-alkyne (1a) (500 mg, 1.23 mmol) was dissolved in 2 mL of THF and added to 2 mL of t-BuOH containing commercially available acetal protected Azido-Galactose derivative [2-[2-(2-Azidoethoxy)ethoxy]ethyl-2,3,4,6-Tetra-O-acetyl-D-galactopyranoside] (625 mg, 1.23 mmol) in a round bottom flask (r.b.). Fresh solutions of CuSO4.5H2O (76 mg, 0.3 mmol) and Sodium Ascorbate (90 mg, 0.45 mmol) were prepared separately in 1 mL of milipore water. Sodium Ascorbate solution was added to the r.b. followed by CuSO4 solution and stirred for 12 hours. The reaction was stopped and the solvent was removed by evaporation. The crude product was extracted from water-chloroform mixture. The organic layer was dried over anhydrous NaSO4 and solvent was evaporated. Finally the product was purified via column chromatography using Chloroform: Ethyl acetate (90:10) mixture to yield orange solid. Yield: 785 mg (70%). 1H NMR (CDCl3, 600 MHz): δ (ppm) 1.93 (s, 3H),1.97-1.99 (d, 6H), 2.08 (s, 3H), 3.52-3.56 (m, 7H), 3.64-3.66 (m, 1H), 3.81-3.90 (m, 10H), 4.04-4.11 (m, 3H), 4.46-4.50 (m, 3H), 4.95-4.97 (dd, 1H), 5.13-5.16 (m, 1H), 5.25-5.28 (m, 2H), 5.32 (m, 1H),5.76 (s, 1H), 6.41-6.45 (m, 2H), 6.86-6.88 (d, 1H), 6.99-7.07 (m, 4H), 7.51-7.54 (m, 2H), 7.80 (s, 1H); 13C NMR (CDCl3, 150 MHz): δ (ppm): 20.48, 20.54, 20.56, 20.65, 50.23, 55.82, 55.84, 61.09, 62.77, 66.92, 68.69, 69.04, 69.28, 70.07, 70.45, 70.47, 70.53, 70.75, 101.18, 101.23, 109.61, 110.30, 113.57, 114.84, 121.59, 122.15, 122.24, 122.84, 124.25, 139.99, 140.61, 143.39, 146.82, 147.93, 149.50, 149.51, 169.33, 170.04, 170.13, 170.28, 182.73, 183.52.; ESI-MS: for C44H53N3O18; calculated-911.33; observed-912.3 [M+H]+.
3. Synthesis of curcumin-“Clicked”-mono-galactose (Sweet Curry) 1d




Protected curcumin-“clicked”-galactose (90 mg, 0.098 mmol) was dissolved in 3 mL of 0.3 M NaOMe in anhydrous MeOH. The mixture was stirred at room temperature for 2 hours. The pH of the solution was neutralized to pH=7 using Amberlite15 ion exchange resin and the color of the solution became light yellow from dark orange. The solution was filtered and the solvent was removed. Finally the crude product was purified via column chromatography using CHCl3:MeOH (95:5) to yield 1d as a dark yellow solid. Yield: 55 mg (76%). NMR (CD3OD, 600 MHz): δ (ppm) 3.01 (s, 4H), 3.09-3.13 (m, 2H), 3.17-3.19 (m, 211), 3.25 (s, 4H), 3.27-3.29 (m, 2H), 3.32-3.42 (m, 3H), 3.47-3.52 (d, 2H), 3.54-3.57 (m, 6H), 3.62-3.64 (m, 1H), 3.86-3.87 (d, 1H), 4.25-4.27 (t, 2H), 4.91 (s, 211), 6.28-6.35 (m, 2H), 6.48-6.49 (d, 1H), 6.76-6.91 (m, 4H), 7.22-7.25 (dd, 2H), 7.80 (s, 1H); 13C NMR (CDCl3, 150 MHz): δ (ppm) 49.84, 51.48, 56.48, 56.53, 62.54, 62.79, 63.34, 69.59, 70.30, 71.09, 71.31, 71.37, 71.41, 72.50, 74.89, 76.66, 105.03, 111.79, 112.08, 115.35, 116.59, 123.55, 124.19, 126.57, 128.54, 130.50, 131.21, 141.30, 142.37, 144.47, 149.40, 150.50, 151.06, 151.37, 183.92, 185.37. ESI-MS: for C36H45N3O14; calculated-743.29; observed-744.3 [M+H]+.
4. Synthesis of Curcumin di-alkyne




Curcumin (2 g, 5.43 mmol) and K2CO3 (1.52 g, 11.0 mmol) were added to 50 mL DMF followed by 1.62 g (13.61 mmol) of propargyl bromide. The mixture was stirred at room temperature under N2 for 48 h, H2O was added to the mixture and the solvent was removed under vacuum. The product was purified by column chromatography, eluting with CHCl3:hexane 90:10. Yield: 1.78 g (74%). 1H NMR (600 MHz, CDCl3), δ (ppm): 2.47 (s, 2H); 3.84 (s, 6H); 4.71-4.74 (m, 4H); 6.42-6.44 (d, 2H); 6.95-7.07 (m, 6H); 7.51-7.53 (d, 2H). 13C NMR (150 MHz, CDCl3), δ (ppm): 55.91, 56.07, 56.58, 101.43, 110.37, 113.78, 122.05, 122.51, 129.17, 148.65, 149.60, 183.18. MS (ESI): calculated for C27H24O6: 444.16; found: 445.1 [M+H]+, 483.0 [M+K]+.
5. Synthesis of Curcumin ‘Clicked’ di-galactose (Protected)




Curcumin di-alkyne (2a) (500 mg, 1.12 mmol) was dissolved in 2 mL of THF and added to 2 mL of t-BuOH containing commercially available acetal-protected Azido-Galactose derivative [2-[2-(2-Azidoethoxy)ethoxy]ethyl-2,3,4,6-Tetra-O-acetyl-D-galactopyranoside] (1.14 g, 2.25 mmol) in a round bottom flask (r.b.). Fresh solutions of CuSO4.5H2O (100 mg, 0.4 mmol) and Sodium Ascorbate (90 mg, 0.45 mmol) were prepared separately in 1 mL of milipore water. Sodium Ascorbate solution was added to the r.b. followed by CuSO4 solution and stirred for 12 hours. The reaction was stopped and the solvent was removed by evaporation. The crude product was extracted from water-chloroform mixture. The organic layer was dried over anhydrous NaSO4 and solvent was evaporated. Finally the product was purified via column chromatography using Chloroform:Ethyl acetate (90:10) mixture to yield orange solid. Yield: 978 mg (60%). 1H NMR (CDCl3, 600 MHz): δ (ppm) 1.93 (s, 6H), 1.97-1.98 (d, 12H), 2.08 (s, 6H), 3.50-3.56 (m, 12H), 3.64-3.65 (m, 2H), 3.81-3.90 (m, 14H), 4.04-4.12 (m, 6H), 4.46-4.50 (m, 6H), 4.94-4.97 (dd, 2H), 5.12-5.15 (m, 2H), 5.25-5.28 (m, 4H), 5.32 (d, 2H), 5.77 (s, 1H), 6.43-6.46 (d, 2H), 7.02-7.06 (m, 4H), 7.52-7.54 (d, 2H), 7.80 (s, 2H); 13C NMR (CDCl3, 150 MHz): δ (ppm): 20.57, 20.63, 20.65, 20.73, 50.32, 55.92, 61.17, 62.89, 66.99, 68.77, 69.11, 69.37, 70.17, 70.54, 70.56, 70.62, 70.82, 101.31, 110.38, 113.66, 122.30, 122.34, 124.30, 128.70, 140.23, 143.49, 149.61, 149.62, 169.40, 170.12, 170.21, 170.36, 183.17; ESI-MS: for C67H86N6O30; calculated-1454.54; observed-1455.2 [M+H]+, 738.3 [M+Na]2+.
6. Synthesis of Curcumin ‘Clicked’ di-galactose




Protected curcumin-“clicked”-di-galactose (100 mg, 0.069 mmol) was dissolved in 3 mL of 0.3 M NaOMe in anhydrous MeOH. The mixture was stirred for 3 hours at room temperature. The pH of the solution was neutralized to pH=7 using Amberlite15 ion exchange resin and the color of the solution became light yellow from dark orange. The solution was filtered and the solvent was removed. Finally the crude product was purified via column chromatography using CHCl3:MeOH (95:5) to yield 1c as a dark yellow-orange solid. Yield: 66 mg (85%). 1H NMR (CD3OD, 600 MHz): δ (ppm) 3.52 (s, 4H), 2.65 (s, 4H), 3.01 (s, 1H), 3.09-3.13 (m, 4H), 3.17-3.22 (m, 2H), 3.25-3.29 (m, 12H), 3.26-3,41 (m, 6H), 3.46-3.51 (m, 2H), 3.53-3.56 (m, 6H), 3.62-3.63 (m, 2H), 3.85-3.87 (d, 2H), 4.26-4.50 (t, 4H), 4.91 (s, 2H), 6.33-6.36 (d, 2H), 6.78-6.91 (m, 4H), 7.57-7.59 (d, 2H), 7.64 (s, 1H), 7.80 (s, 2H); 13C NMR (CDCl3, 150 MHz): δ (ppm) 30.22, 35.52, 49.72, 55.12, 61.12, 61.93, 68.17, 68.86, 69.97, 71.08, 73.47, 75.25, 103.63, 110.66, 113.97, 114.52, 122.24, 125.16, 129.02, 140.23, 143.04, 149.72, 149.98, 163.43. ESI-MS: for C51H70N6O22; calculated-1118.45; observed-1119.4 [M+H]+, 560.4 [M+2H]2+.
7. Synthesis of Curcumin mono-carboxylic acid (1b)




To a solution of 2.01 g (5.46 mmol) of curcumin 1, and 112 mg (0.92 mmol) of DMAP in 100 ml THF was added 1.33 ml (9.55 mmol) of Et3N. 0.685 g (6 mmol) of glutaric anhydride (95%) in 5 mL THF was added slowly dropwise to the curcumin solution. The mixture was stirred and refluxed under argon overnight. THF was removed under vacuum, 55 mL EtOAc was added, followed by the addition of 15 mL of 1M HCL, the mixture was stirred for 10 minutes. The organic phase was separated and extracted with EtOAc three times; the solvent was removed and dried. The product was purified via column chromatography, eluting with CH2Cl2:MeOH, 95:5. Yield: 69%. 1HNMR (CDCl3), δ (ppm): 2.10-2.12 (t, 2H); 2.56-2.58 (t, 2H); 2.69-2.72 (t, 2H); 3.87 (s, 3H); 3.94 (s, 3H); 5.83 (s, 2H); 6.48-6.57 (t, 2H); 6.48-6.57 (m, 1H); 6.94-7.16 (m, 5H); 7.59-7.62 (d, 2H). 13C NMR (CDCl3), δ (ppm): 19.87; 32.65; 55.70; 101.48; 109.73; 111.23; 114.91; 120.83; 121.42; 123.02; 124.03; 127.22; 133.76; 133.90; 139.25; 141.06; 146.89; 148.09; 151.09; 170.85; 177.24; 181.59; 184.51. MS (ESI) calcd. for C26H26O9: 482.48; found: 483.2 [M+H]+.
8. Synthesis of curcumin mono-1,2:3,4-di-O-isopropylidene-D-galactopyranose ester




Curcumin mono-carboxylic acid (1 g, 2.07 mmol), 1,2:3,4-Di-O-isopropylidene-D-galactopyranose (97%) (535 mg, 2.05 mmol) and 4-Dimethylaminopyridine (12.5 mg, 0.10 mmol) were dissolved in 10 mL dry DCM and cooled to 0° C. 1,3-Dicyclohexylcarbodiimide (640 mg, 3.10 mmol) in 5 mL dry DCM was added drop-wise to the reaction mixture while stirring. Formed Dicyclohexyl urea was filtered off after stirring the reaction mixture at room temperature under N2 atmosphere for 12 hrs. The crude product was finally purified via column chromatography using CHCl3:EtOAc (95:5) as eluent. The product was isolated as orange powder. Yield: 1.195 g (80%). 1HNMR (600 MHz, CDCl3), δ (ppm): 1.17-1.33 (m); 1.45 (s); 1.50 (s); 1.52 (s); 1.54-1.57 (m); 1.67-1.74 (m); 1.90-1.91 (m); 2.20-2.24 (p); 2.51-2.54 (t); 2.66-2.68 (t); 2.76-2.79 (t); 3.17-3.20 (m); 3.46-3.48 (m); 3.71-3.76 (m); 3.83 (s); 3.84 (s); 3.87 (s); 3.92 (s), 4.26-4.27 (d); 4.32-4.33 (m); 4.60-4.61 (d); 5.55-5.56 (d); 5.82-5.85 (m); 6.54-6.57 (d); 6.90-6.91 (d); 7.03-7.14 (m); 7.59-7.62 (d). MS (ESI) calcd. for C38H44O14: 724.27; found: 725.25 [M+H]+.
9. Synthesis of Curcumin di-carboxylic acid (2b)




To a solution of 4 g (10.86 mmol) of curcumin, and 330 mg (2.71 mmol) of DMAP in 140 ml THF was added 3.78 ml (27.15 mmol) of Et3N. 2.73 g (23.88 mmol) of glutaric anhydride (95%) in 10 mL THF was added slowly dropwise to the curcumin solution. The mixture was stirred and refluxed under N2 atmosphere for 48 hrs. THF was removed under vacuum, redissolved in 100 mL CHCl3 and washed with 100 mL 0.1 N HCl followed by water (3×50 mL) and brine (3×50 mL). The organic layer was separated and dried over anhydrous Na2SO4. The product was purified via column chromatography, eluting with CHCl3:EtOAc (95:5) and isolated as dark yellow powder. Yield: 69%. 1HNMR (600 MHz, CDCl3), δ (ppm): 2.07-2.10 (t, 4H); 2.53-2.55 (t, 4H); 2.67-2.69 (t, 4H); 3.84 (s, 6H); 5.82 (s, 211); 6.51-6.54 (d, 2H); 7.02-7.13 (m, 6H); 7.57-7.59 (d, 2H). 13C NMR (150 MHz, CDCl3), δ (ppm): 19.87; 32.65; 55.70; 101.48; 109.73; 111.23; 114.91; 120.83; 121.42; 123.02; 124.03; 127.22; 133.76; 133.90; 139.25; 141.06; 146.89; 148.09; 151.09; 170.85; 177.24; 181.59; 184.51. MS (ESI) calcd. for C31H32O12: 596.19; found: 597.20 [M+H]+.
10. Synthesis of curcumin di-1,2:3,4-di-O-isopropylidene-D-galactopyranose ester




Curcumin mono-carboxylic acid (1 g, 1.67 mmol), 1,2:3,4-Di-O-isopropylidene-D-galactopyranose (97%) (690 mg, 2.65 mmol) and 4-Dimethylaminopyridine (12.5 mg, 0.10 mmol) were dissolved in 10 mL dry DCM and cooled to 0° C. 1,3-Dicyclohexylcarbodiimide (860 mg, 4.16 mmol) in 5 mL dry DCM was added drop-wise to the reaction mixture while stirring. Formed di-cyclohexyl urea was filtered off after stirring the reaction mixture at room temperature under N2 atmosphere for 12 hrs. The crude product was finally purified via column chromatography using CHCl3:EtOAc (95:5) as eluent. The product was isolated as dark orange powder. Yield: 1.31 g (72%). 1HNMR (600 MHz, CDCl3), δ (ppm): 1.15-1.34 (m); 1.43 (s); 1.48 (s); 1.50 (s); 1.52-1.55 (m); 1.69-1.71 (m); 1.88-1.89 (m); 2.04-2.09 (p); 2.18-2.23 (p); 2.38-2.40 (t); 2.49-2.52 (t); 2.64-2.66 (t); 2.75-2.77 (t); 3.14-3.19 (m); 3.84-3.85 (d); 4.17-4.32 (m); 4.57-4.60 (m); 5.11-5.12 (d); 5.83 (s); 5.52-6.55 (dd); 7.02-7.14 (m); 7.57-7.60 (dd). 13C NMR (150 MHz, CDCl3), δ (ppm): 14.22; 20.26; 24.49; 24.97; 25.98; 26.01; 33.01; 33.98; 34.94; 55.90; 60.40; 63.53; 65.98; 70.44; 70.72; 71.07; 96.32; 108.78; 109.67: 121.08: 122.15; 123.25; 124.24; 129.24; 133.92; 139.98; 141.33; 151.37; 170.82; 172.80; 183.10. MS (ESI) calcd. for C55H68O22: 1080.42; found: 1081.40 [M+H]+.
11. Solubility and Anti-Oxidant Activity Study of Curcumin mono-galactose (Sweet Curry) 1d
a. Solubility Study Via UV-Vis Spectroscopy.
The improved solubility of the curcumin sugar conjugate 1d was confirmed by UV spectroscopy via the following procedure: 5 mg of curcumin-sugar conjugate 1d was vortexed in 1 ml of deionized water in an eppendorfTM tube to create a stock solution of 5 mg/ml. A control sample was also prepared by adding 5 mg of curcumin in 1 ml of water in an eppendorfTM tube and vortexed. Both sample were centrifuged at 13,000 RPM for 2 min. 100 μL of the sugar conjugate solution was added to 900 μL of deionized water and thoroughly mixed. The UV-vis absorbance of the diluted sugar-curcumin conjugate and the stock curcumin solution were recorded. It is evident from the UV spectra that the conjugate 1d (6 mM in water, calculated from a previously determined molar extinction coefficient) has vastly improved solubility relative to curcumin (0.0 mM in water). It should be noted that the solubility study outlined above measures the direct solubility of the compounds in water and closely models “real life” conditions, in contrast to other experiments in which the compounds are first dissolved in other solvents followed by dilution in water. Sweet curry 1d thus has a far superior solubility compared to curcumin in water (plasma model).
b. Antioxidant Potentiality Assay by Linoleic Acid Peroxidation Method:
Using the Thiocyanide method, antioxdant potentiality assay was carried out with Curcumin 1, curcumin mono-alkyne 1a, curcumin mono-carboxylic acid 1b and sweet curry 1d (curcumin mono-galactose). 0.28 gm of linoleic acid, 0.28 gm of tween 40 as emulsifier and 50 ml of phosphate buffer (0.2 M, pH 7) were used to prepare a linoleic acid emulsion. The curcuminoids (5 mg per ml) were dissolved in water and 0.5 ml of each one of them was pipetted out into different test-tubes. Then 2.5 ml of linoleic acid emulsion was added to each one of them followed by the addition of 2.5 ml of phosphate buffer. All the tubes were incubated at 37° C. for 7 days. The mixture prepared as above without test sample was the control one. At the regular interval of 24 hours, 0.1 ml of the aliquots were drawn out of the incubation mixture and mixed with 5 ml of 75% ethanol, 0.1 ml of 30% ammonium thiocyanate and 0.1 ml of 20 mM ferrous chloride in 3.5% HCl. The tubes were allowed to stand in room temperature for 3 minutes. Spectrophotometric analysis was done at 500 nm. All the tests were carried out in duplicate and averaged.

Anoxidant activity=[1-increase in absorbance of the sample/increase in absorbance of control]*100.

12. Cell Viability Assay to Assess the Effect of Sweet Curry on Normal Brain Cells Using MTT
To assess the viability of the normal brain tissue in presence of the sweet curry MTT assay on cultured hippocampal slices were performed.
The results of the MTT assay show that at low concentrations (i.e. 8 nM and 8 μM) the viability of the cells is near the control samples but at a higher concentration (i.e., 80 μM) cell viability was a little higher than the control samples, which shows that the sweet curry has no harmful effect on the normal brain tissue as long as viability is concerned. Hence, the sweet curry has no harmful effect upon normal brain cells at low concentrations, and at higher concentrations the cell viability among the brain cells is even better.
a. Hippocampal Slice Culture25:
Mouse pups of specific ages were anesthetized with ketamine (100 mg/kg) and decapitated. Under sterile conditions, the brains were isolated and then cut at 60° from the longitudinal fissure at the top using a hippocampus-dissecting tool to expose the hippocampus. The hemispheres containing the hippocampi were then placed in modified Gey's balanced salt solution (mGBSS) at 4° C. for 30-40 minutes while bubbling a mixture of 95% O2 and 5% CO2. Individual hippocampi were isolated using dissection tool and then 400 μM thick transverse slices were prepared using a tissue chopper (Stoelting, Wood Dale, Ill., USA). The slices were placed in ice cold mGBSS and inspected using a dissection microscope for the presence of uninterrupted bright transparent neuronal layers characteristic of the hippocampal structure. Only such slices were placed on Millicell CM filters (Millipore, Bedford, Mass., USA). The filters were placed in a six well dish with 1 ml of medium in each well. The slices were kept on high K+ culture medium (25% horse serum, 50% Basal Essential Media-Eagles, 25% Eagle's Balanced Salt Solution (EBSS), 25 mM Na-HEPES, 1 mM Glutamine, 28 mM Glucose, pH 7.2) for the first two days. After incubation at 32° C. in a 5% CO2 atmosphere, the culture medium was changed to physiological K+ slice culture medium (20% dialyzed fetal bovine serum, 5% Basal Essential Media-Eagles, and EBSS modified to adjust the K+ concentration to 2.66 mM). After 20% dialyzed serum treatment for two days and the slices were placed in 5% serum medium (same medium as above but with 5% serum) for two days.
b. MTT Assay: MTT Assay Was Done According to the Protocol Described by Purkayastha et al26
Hippocampal slices from adult mice brain were cultured as described by Mehta et al (2007). After six days in vitro the slices were treated with different concentrations of the sweet curry (i.e., 8 nM, 8 μM and 80 μM respectively) overnight along with the slices treated with the carrier as control.
After the treatment with sweet curry, slices from each treatment group were placed in 400 μl PBS in one well of 48-well plate and then treated with 200 μl of MTT (5 mg/ml) per well with gentle mixing at 37° C. for 2 hours. The slices were triturated to homogenize with the help of a micropipette. After that 800 μl of lysis buffer (20% SDS, 50% dimethylformamide) was added to each well and the plate was sealed and incubated overnight at 37° C. with gentle mixing. Now 100 μl mix from each well was taken in respective wells of a 96 well plate in triplicates and absorbance was measured at 570 nm using a plate reader. Results obtained were normalized to the total protein content and then expressed as percent carrier-treated samples.
13. Dissolution of Amyloid βeta (Aβeta) Fragments
Amyloid βeta (Aβeta) fragment 25-35 (Sigma A-4559) was diluted in water to a stock of 1 mg/ml. 10 μM curcumin and sweet curry stocks were also prepared in distilled water. Samples were prepared so that an equal volume of Aβeta and the appropriate curcumin (sweet curry or curcumin) were added in a 1:1 ratio so that the final concentration of the Aβeta was 50 μg/ml and the curry was diluted to the desired molar concentration. Samples were incubated at 37° C. for 6 days. Aggregation of the protein fragment was determined using transmission electron microscopy. 200 mesh carbon coated grids (Electron Microscopy Sciences) were used and prepared for negative staining by adding 5 μl of incubation mixture to the grid surface for one minute, followed by drying the grid with filter paper and contrasting with 5 μl of freshly filtered 2% phosphotungstic acid (pH=7.2) for one minute. Once grids were dry, examination was done using the FEI Tecnai Spirit at the College of Staten Island's Advanced Imaging Facility. Micrographs were captured using an AMT CCD camera.
The electron micrographs demonstrate that sweet curry (1d) is significantly more effective than curcumin in dissolving amyloid aggregates. From the series of micrographs 1d works at 8 nmol compared to 8 micromolar for curcumin (1000 times more effective) This can correlated with its superior water solublity.
REFERENCES CITED


    
    
        1. Roberson, E. D.; Scearce-Levie, K.; Palop, J. J.; Yan, F.; Cheng, I. H.; Wu, T.; Gerstein, H.; Yu, G. Q.; Mucke, L., Reducing endogenous tau ameliorates amyloid beta-induced deficits in an Alzheimer's disease mouse model. Science 2007, 316 (5825), 750-4.
        2. Chattopadhyay, I.; Biswas, K.; Bandyopadhyay, U.; Banerjee, R. K., Turmeric and curcumin: Biological actions and medicinal applications. Current Science 2004, 87 (1), 44-53
        3. Goel, A.; Kunnumakkara, A. B.; Aggarwal, B. B., Curcumin as “Curecumin”: from kitchen to clinic. Biochem Pharmacol 2008, 75 (4), 787-809.
        4. Hatcher, H.; Planalp, R.; Cho, J.; Torti, F. M.; Torti, S. V., Curcumin: from ancient medicine to current clinical trials. Cell Mol Life Sci 2008, 65 (11), 1631-52.
        5. Aggarwal, B. B.; Shishodia, S., Molecular targets of dietary agents for prevention and therapy of cancer. Biochem Pharmacol 2006, 71 (10), 1397-421.
        6. Leyon, P. V.; Kuttan, G., Studies on the role of some synthetic curcuminoid derivatives in the inhibition of tumour specific angiogenesis. J Exp Clin Cancer Res 2003, 22 (1), 77-83.
        7. Nurfinal, A. N.; Reksohadiprodjo, M. S.; Timmerman, H.; Jenie, U. A.; Sugiyant, D.; van der Goot, H., Synthesis of some symmetrical curcumin derivatives and their anti inflammatory activity. European Journal of Medicinal Chemistry 1997, 32 (4), 321-328.
        8. Cole, G. M.; Teter, B.; Frautschy, S. A., Neuroprotective effects of curcumin. Adv Exp Med Biol 2007, 595, 197-212.
        9. Strimpakos, A. S.; Sharma, R. A., Curcumin: preventive and therapeutic properties in laboratory studies and clinical trials. Antioxid Redox Signal 2008, 10 (3), 511-45.
        10. Lim, G. P.; Chu, T.; Yang, F.; Beech, W.; Frautschy, S. A.; Cole, G. M., The curry spice curcumin reduces oxidative damage and amyloid pathology in an Alzheimer transgenic mouse. J Neurosci 2001, 21 (21), 8370-7.
        11. Yang, F.; Lim, G. P.; Begum, A. N.; Ubeda, O. J.; Simmons, M. R.; Ambegaokar, S. S.; Chen, P. P.; Kayed, R.; Glabe, C. G.; Frautschy, S. A.; Cole, G. M., Curcumin inhibits formation of amyloid beta oligomers and fibrils, binds plaques, and reduces amyloid in vivo. J Biol Chem 2005, 280 (7), 5892-901.
        12. Ringman, J. M.; Frautschy, S. A.; Cole, G. M.; Masterman, D. L.; Cummings, J. L., A potential role of the curry spice curcumin in Alzheimer's disease. Curr Alzheimer Res 2005, 2 (2), 131-6.
        13. Garcia-Alloza, M.; Borrelli, L. A.; Rozkalne, A.; Hyman, B. T.; Bacskai, B. J., Curcumin labels amyloid pathology in vivo, disrupts existing plaques, and partially restores distorted neurites in an Alzheimer mouse model. J Neurochem 2007, 102 (4), 1095-104.
        14. Ma, Q. L.; Yang, F.; Calon, F.; Ubeda, O. J.; Hansen, J. E.; Weisbart, R. H.; Beech, W.; Frautschy, S. A.; Cole, G. M., p21-activated kinase-aberrant activation and translocation in Alzheimer disease pathogenesis. J Biol Chem 2008, 283 (20), 14132-43.
        15. Fiala, M.; Liu, P. T.; Espinosa-Jeffrey, A.; Rosenthal, M. J.; Bernard, G.; Ringman, J. M.; Sayre, J.; Zhang, L.; Zaghi, J.; Dejbakhsh, S.; Chiang, B.; Hui, J.; Mahanian, M.; Baghaee, A.; Hong, P.; Cashman, J., Innate immunity and transcription of MGAT-III and Toll-like receptors in Alzheimer's disease patients are improved by bisdemethoxycurcumin. Proc Natl Acad Sci USA 2007, 104 (31), 12849-54.
        16. Yang, S.; Zhang, D.; Yang, Z.; Hu, X.; Qian, S.; Liu, J.; Wilson, B.; Block, M.; Hong, J. S., Curcumin protects dopaminergic neuron against LPS induced neurotoxicity in primary rat neuron/glia culture. Neurochem Res 2008, 33 (10), 2044-53.
        17. Kim, S. J.; Son, T. G.; Park, H. R.; Park, M.; Kim, M. S.; Kim, H. S.; Chung, H. Y.; Mattson, M. P.; Lee, J., Curcumin stimulates proliferation of embryonic neural progenitor cells and neurogenesis in the adult hippocampus. J Biol Chem 2008, 283 (21), 14497-505.
        18. Narlawar, R.; Pickhardt, M.; Leuchtenberger, S.; Baumann, K.; Krause, S.; Dyrks, T.; Weggen, S.; Mandelkow, E.; Schmidt, B., Curcumin-derived pyrazoles and isoxazoles: Swiss army knives or blunt tools for Alzheimer's disease? Chem Med Chem 2008, 3 (1), 165-72.
        19. 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., Phase I clinical trial of curcumin, a chemopreventive agent, in patients with high-risk or pre-malignant lesions. Anticancer Res 2001, 21 (4B), 2895-900.
        20. Anand, P.; Kunnumakkara, A. B.; Newman, R. A.; Aggarwal, B. B., Bioavailability of curcumin: problems and promises. Mol Pharm 2007, 4 (6), 807-18.
        21. Shi, W.; Dolai, S.; Rizk, S.; Hussain, A.; Tariq, H.; Averick, S.; L'Amoreaux, W.; El Idrissi, A.; Banerjee, P.; Raja, K., Synthesis of monofunctional curcumin derivatives, clicked curcumin dimer, and a PAMAM dendrimer curcumin conjugate for therapeutic applications. Org Lett 2007, 9 (26), 5461-4.
        22. Ryu, E. K.; Choe, Y. S.; Lee, K. H.; Choi, Y.; Kim, B. T., Curcumin and dehydrozingerone derivatives: synthesis, radiolabeling, and evaluation for beta-amyloid plaque imaging. J Med Chem 2006, 49 (20), 6111-9.
        23. Pfeiffer, E.; Hoehle, S. I.; Walch, S. G.; Riess, A.; Solyom, A. M.; Metzler, M., Curcuminoids form reactive glucuronides in vitro. J Agric Food Chem 2007, 55 (2), 538-44.
        24. Pardridge, W. M.; Boado, R. J.; Farrell, C. R., Brain-type glucose transporter (GLUT-1) is selectively localized to the blood-brain barrier. Studies with quantitative western blotting and in situ hybridization. J Biol Chem 1990, 265 (29), 18035-40.
        25. Mehta, M.; Ahmed, Z.; Fernando, S. S.; Cano-Sanchez, P.; Adayev, T.; Ziemnicka, D.; Wieraszko, A.; Banerjee, P., Plasticity of 5-HT 1A receptor-mediated signaling during early postnatal brain development. J Neurochem 2007, 101 (4), 918-28.
        26. Purkayastha, S.; Berliner, A.; Fernando, S. S.; Ranasinghe, B.; Ray, I.; Tariq, H.; Banerjee, P., Curcumin Blocks Brain Tumor Formation. Brain Res 2009.

## Claims

1. A curcumin derivative having the formula I:



wherein:
A is —CH2—CH2— or —CH═CH—;
R1 represents L1m1-Y1;
R2 represents L2m2-Y2;
L1 and L2 are




m1 and m2 are 1;
n1 is independently 0 or an integer from 1 to 50;
Y1 and Y2 independently represent a saccharide with 1 to 51 monosaccharide units; CH2—CH═CH2 or CH2—C═CH;
R3 independently represents a saturated, unbranched hydrocarbyl with 1 to 4 carbon atoms and n2 independently represents an integer from 5 and 50.

2. A curcumin derivative according to claim 1, wherein L1 is




and Y1 is a saccharide.

3. A curcumin derivative according to claim 2, wherein the saccharide is a monosaccharide.

4. A curcumin derivative according to claim 3, wherein the monosaccharide is glucose or galactose.

5. A curcumin derivative according to claim 1, wherein Y1 or Y2 is a saccharide.

6. A curcumin derivative according to claim 1, wherein Y1 or Y2 is a disaccharide or a trisaccharide.

7. A curcumin derivative according to claim 1, wherein the saccharide is a monosaccharide.

8. A curcumin derivative according to claim 1, wherein the monosaccharide is glucose or galactose.

9. A method of treating Alzheimer's disease in a patient comprising administering to the patient in need thereof a therapeutically effective amount of a curcumin derivative having the formula I:



wherein:
A is —CH2—CH2— or —CH═CH—;
R1 represents L1m1-Y1;
R2 represents L2m2-Y2;
L1 and L2 are




m1 and m2 are 1;
n1 is independently 0 or an integer from 1 to 50;
Y1 and Y2 independently represent a saccharide with 1 to 51 monosaccharide units; CH2—CH═CH2 or CH2—C═CH;
R3 independently represents a saturated, unbranched hydrocarbyl with 1 to 4 carbon atoms; and n2 independently represents an integer from 5 and 50.