Patent Application
20090042271
Long-chain alcohols have a number of uses in cosmetics and personal care. Long chain alcohols such as behenyl alcohol are useful as emollients to make skin smoother and prevent moisture loss. Other alcohols are useful as active ingredients. One such example is idebenone, which is a potent anti-oxidant which has been shown to reduce skin roughness and fine lines and wrinkles, and also to improve photodamaged skin (McDaniel, D. H.; Neudecker, B. A.; Dinardo, J. C.; Lewis II, J. A.; Maibach, H. I. Journal of Cosmetic Dermatology 2005, 4, 167-173). This material has also been claimed to induce protective and regenerative effects (U.S. Pat. No. 6,756,045), reduce skin hyperpigmentation (US Patent Publication 2005/0175559), and to reduce irritation and/or inflammatory reaction in human skin (US Patent Application Publication 2005/0197407). Ester derivatives of idebenone may improve the physical properties of this orange solid. In addition, esters of idebenone with fatty acids will hydrolyze in the skin to afford idebenone along with the fatty acid derivative which may also have positive benefits.
The classical chemical preparation of esters such as idebenone involves either the reaction of the alcohol with an acid, acid chloride, or acid anhydride. These methods often use either harsh reagents or high temperatures, which can cause difficulties if either the alcohol or the acid derivative is unstable.
There have been reports of short-chain esters of idebenone and similar molecules. U.S. Pat. No. 4,271,083 reports alkyl esters of idebenone and similar molecules where the alkyl ester has 1-4 carbon atoms. U.S. Pat. No. 4,407,757 describes acetate esters of idebenone and similar molecules. U.S. Pat. No. 6,756,045 describes hydrophilic esters of idebenone, particularly sulfonic acid esters. None of these references prepared these materials by enzymatic means.
None of the references describe a derivative of idebenone with a long-chain fatty acid, which may be more physiologically compatible and less irritating to skin than a shorter chain fatty acid (Schurer, 2002, Contact Dermatitis 47: 199; Kojima et al., 1998, Altern Animal Test. Exper. 5: 201).
A first embodiment according to the present invention concerns a composition, comprising an ester represented by the general formula 1:
R and R1 are independently a C1-C4 alkyl, R2 is selected from the group consisting of a C5-C22 alkyl, a C5-C22 alkenyl, a C5-C20 dienyl, a C6-C22 trienyl, a C8-C22 tetraenyl and mixtures thereof, and n is 2-12.
Another embodiment of the present invention concerns a process for the preparation of an ester represented by formula 1:
comprising reacting an alcohol represented by formula 2:
with a long-chain acid R2COOH or long-chain ester R2COOR4 in the presence of an inert solvent and an enzyme. R and R1 are independently a C1-C4 alkyl, R2 is selected from the group consisting of a C5-C22 alkyl, a C5-C22 alkenyl, a C5-C20 dienyl, a C6-C22 trienyl, a C8-C22 tetraenyl and mixtures thereof, n is 2-12, and R4 is a C1-C4 alkane or alkene.
The present invention concerns a series of novel esters of long-chain alcohols represented by the general formula 1:
wherein
R and R1 are selected from branched- and straight-chain C1-C4 alkyl, R2 is selected from substituted and unsubstituted, branched- and straight-chain saturated C5-C22 alkyl, substituted and unsubstituted, branched- and straight-chain C5-C22 alkenyl, substituted and unsubstituted, branched- and straight-chain C5-C20 dienyl, substituted and unsubstituted, branched- and straight-chain C6-C22 trienyl, and substituted and unsubstituted, branched- and straight-chain C8-C22 tetraenyl or mixtures thereof, and n is 2-12.
The alkyl, alkenyl, dienyl, trienyl, and tetraenyl groups which may be represented by R2 may be straight- or branched-chain aliphatic hydrocarbon radicals containing up to about 20 carbon atoms and may be substituted, for example, with one to three groups selected from C1-C6-alkoxy, cyano, C2-C6-alkoxycarbonyl, C2-C6-alkanoyloxy, hydroxy, aryl, heteroaryl, thiol, thioether, and halogen. The terms “C1-C6-alkoxy”, “C2-C6-alkoxycarbonyl”, and “C2-C6-alkanoyloxy” are used to denote radicals corresponding to the structures —OR3, —CO2 R3, and —OCOR3, respectively, wherein R3 is C1-C6-alkyl or substituted C1-C6-alkyl.
Examples of the compounds of the invention include those represented by formula 1 wherein acyl group R2—CO is linoleoyl, stearoyl, linolenoyl, conjugated linoleoyl, palmoyl, and oleoyl or mixtures thereof.
Another embodiment of the present invention concerns a process for the preparation of esters 1:
comprising the reaction of alcohol 2
with a long-chain acid R2COOH or long-chain ester R2COOR4 in the presence of an inert solvent and an enzyme with or without methods for the removal of water wherein R, R1, and R2 are as defined above and R4 is a straight or branched C1-C4 alkane or alkene. For the purposes of the present invention, a long-chain acid or a long-chain ester would include those acids or esters having chains of 5 carbon atoms or more.
The straight or branched C1-C4 alkyl or alkenyl group represented by R4 may be chosen from methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, vinyl, 1-propenyl, 2-propenyl, 2-butenyl and the like.
The process is carried out in an inert solvent chosen from cyclic or acyclic ether solvents such as diethyl ether, diisopropyl ether, tert-butyl methyl ether, or tetrahydrofuran, aromatic hydrocarbons such as benzene, toluene, or xylene, aliphatic or alicyclic saturated or unsaturated hydrocarbons such as hexane, heptane, cyclohexane, or limonene, halogenated hydrocarbons such as dichloromethane, dichloroethane, dibromoethane, tetrachloroethylene, or chlorobenzene, polar aprotic solvents such as acetonitrile, dimethyl formamide, or dimethyl sulfoxide, or mixtures thereof. Examples of acceptable solvents include toluene, limonene, and acetonitrile. The process may be carried out at a temperature between about −100° C. and the boiling point of the solvent, or between about 0-60° C., or even between about 20-50° C. The amount of long-chain acid or long-chain ester may be between 0.85 and 20 equivalents based on the amount of the alcohol represented by 2, or between 1 and 10 equivalents based on the amount of alcohol. The enzyme used in the process is chosen from a protease, a lipase, or an esterase. For example, lipases may be used and may be in the form of whole cells, isolated native enzymes, or immobilized on supports. Examples of these lipases include but are not limited to Lipase PS “Amano” (from Pseudomonas sp), Lipase PS-C “Amano” (from Psuedomonas sp immobilized on ceramic), Lipase PS-D “Amano” (from Pseudomonas sp immobilized on diatomaceous earth), LipoPrime® 50T, Lipozyme® TL IM, or Novozym® 435 (from Candida antarctica immobilized on acrylic resin).
The process may optionally be carried out in the presence of various addenda chosen from molecular sieves or ion exchange resins. For example, 3A, 4A, or 5A molecular sieves can be used.
The product of the process may be isolated using methods known to those of skill in the art, e.g., extraction, filtration, or crystallization. The product 1 may be purified if necessary using methods known to those of skill in the art, e.g., extraction, chromatography, distillation, or crystallization.
This invention can be further illustrated by the following examples, although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise specifically indicated.
Idebenone (2a, R=R1=Me, n=9; 547 mg; 1.6 mmol) was dissolved in 10 mL of toluene. Linoleic acid (2.18 g; 4.9 equiv) was added followed by 641 mg of 4A molecular sieves and 309 mg of Novozym® 435. The reaction mixture was stirred at ambient temperature for 2 days, at which point tlc analysis (1:1 ethyl acetate:heptane eluant) indicated no remaining idebenone. The solids were removed by filtration and the precipitate washed with toluene. The combined filtrate and washes were concentrated at reduced pressure. The residue was dissolved in heptane (22 mL) and washed with a mixture of 11 mL of methanol and 11 mL of 10% aqueous potassium carbonate. The organic layer was further washed with a mixture of 11 mL of methanol, 4 mL of saturated sodium bicarbonate, and 7 mL of water. The organic layer was then dried with sodium sulfate and concentrated to afford 0.84 g (87%) of 1a (R=R1=Me, n=9).
1H NMR (CDCl3) δ5.40-5.30 (m, 4H); 4.049 (t, 2H, J=6.87 Hz); 3.988 (s, 6H); 2.768 (t, 2H, J=5.77 Hz); 2.45 (m, 2H); 2.288 (t, 2H, J=7.42 Hz); 2.08-2.01 (m, 3H); 2.009 (s, 3H); 1.64-1.57 (m, 3H); 1.40-1.29 (m, 30H); 0.89 (t, 3H, J=6.60 Hz).
Idebenone (2a; 499 mg; 1.48 mmol) was dissolved in 10 mL of toluene. Conjugated linoleic acid (Tonalin® FFA; 2.07 g; 5 equiv) was added followed by 500 mg of 4A molecular sieves and 300 mg of Novozym® 435. The reaction mixture was stirred at ambient temperature for 2 days, at which point tlc analysis (1:1 ethyl acetate:heptane eluant) indicated a small amount of idebenone. Additional 4A molecular sieves were added and the mixture was stirred for an additional 2 days, at which point tlc analysis indicated no remaining idebenone. The solids were removed by filtration and the precipitate washed with toluene. The combined filtrate and washes were concentrated at reduced pressure. The residue was dissolved in heptane (50 mL) and washed twice with a 1:1 mixture of methanol and 10% aqueous potassium carbonate (50 mL, then 20 mL). The organic layer was further washed with a mixture of 15 mL of methanol, 5 mL of saturated sodium bicarbonate, and 10 mL of water. The organic layer was then dried with sodium sulfate and concentrated to afford 850 mg (96%) of 1b.
1H NMR (CDCl3) δ6.33-6.24 (m,1H); 5.935 (t,1H, J=11.0 Hz); 5.60-5.60 (m,1H); 5.35-5.26 (m,1H); 4.049 (t, 2H, J=6.60 Hz); 3.988 (s, 3H); 3.986 (s, 3H); 2.445 (t, 2H, J=6.87 Hz); 2.285 (t, 2H, J=7.42 Hz); 2.18-2.05 (m, 3H); 2.009 (s, 3H); 1.62-1.56 (m, 5H); 1.30-1.23 (m, 30H); 0.91-0.86 (m, 3H).
Idebenone (2a; 501 mg; 1.48 mmol) was dissolved in 10 mL of toluene. Pamolyn 200® linoleic acid (2.07 g; 5 equiv) was added followed by 500 mg of 4A molecular sieves and 300 mg of Novozym® 435. The reaction mixture was stirred at ambient temperature for 2 days, at which point tlc analysis (1:1 ethyl acetate:heptane eluant) indicated a small amount of idebenone. Additional 4A molecular sieves were added but no change was observed by tlc. The solids were removed by filtration and the precipitate washed with toluene. The combined filtrate and washes were concentrated at reduced pressure. The residue was dissolved in heptane (50 mL) and washed with a 1:1 mixture of methanol and 10% aqueous potassium carbonate (50 mL). The organic layer was further washed with a mixture of 15 mL of methanol, 5 mL of saturated sodium bicarbonate, and 10 mL of water. The organic layer was then dried with sodium sulfate and concentrated to afford 798 mg (90%) of 1b.
Idebenone (2a; 500 mg; 1.48 mmol) was dissolved in 10 mL of toluene. Octanoic acid (1.07 g; 5 equiv) was added followed by 500 mg of 4A molecular sieves and 300 mg of Novozym® 435. The reaction mixture was stirred at ambient temperature for 2 days, at which point tlc analysis (1:1 ethyl acetate:heptane eluant) indicated no idebenone. The solids were removed by filtration and the precipitate washed with toluene. The combined filtrate and washes were concentrated at reduced pressure. Concentration in vacuo afforded 630 mg (92%) of 1d.
1H NMR (CDCl3) δ4.051 (t, 2H, J=6.87 Hz); 3.990 (s, 3H); 3.987 (s, 3H); 2.446 (t, 2H, J=7.15 Hz); 2.289 (t, 2H, J=7.42 Hz); 2.010 (s, 3H); 1.61-1.57 (m, 5H); 1.33-1.28 (m, 30H); 0.878 (t, 3H, J=6.60 Hz).
The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
