DERIVATIVES OF ALL-TRANS- AND 13-CIS RETINOIC ACID AND METHODS FOR PREPARING SAME

Abstract: New coenzyme A and N-hydroxysuccinimidyl esters of all-trans- and 13-cis-retinoic acid and to methods for preparing the same. A new method for preparing all-trans-retinoic acid anhydride is also disclosed.

Description: Description Derivatives of All-trans- and 13-cis Retinoic Acid and I-fethods for Preparing Same Field of the Inveτ-tion The present ircτention relates to novel derivatives of all-trans- and 13-cis-retinoic acid. Background of the Invention In 1967, 13-ci≤-retinoic acid was identified in rat tissue extracts and it was postulated to be a natural metabolite of all-trans-retinoic acid. The 13-cis-retinoic acid has been found to be at least as effective as all- trans-retinoic acid in prornoting vitamin A-dependent growth as well as in controlling epithelial cell differentiation. Recent work suggests that 13-cis-retinoic .acid is not solely produced as an artifact of isolation but that all trans- retinoic acid is isαrerized in mammals to some extent to 2 13-cis-retxnoic acid. The utlity of 13-cis-retinoic acid in treating derrsatological conditions, its tumor inhibitory properties, and its reduced toxicity relative to all-trans- retinoic acid are known. Disclosure of the Invention The present iiivention relates to novel derivatives of all-trans- and 13-cis-retinoic acid. More specifically, this invention relates to N-hydroxysuccinimidyl and coenzyme A esters of all-trans- and 13-cis-retinoic acid. The derivative of the present invention can be represented by the following formula: wherein R, and ?- are each selected from the group consisting of: (a) hydrogen, O (c) - C - S - C oλ where CoA represents coenzyme A, except that both of R. and R» cannot be (a) , bat one of R, and R~ must be (a) . The cc rpc n-is of the present invention can be prepared in accordance with the following schematic diagram and where 1_ = all Lrdiis-retinoic acid 2_ = all trans-retinoate 3_ = all trar-s-retinoic acid anhydride _4_ = all trH-r^-retincyl CoA where _5_ = 13-cis-retinoic acid 6_ = N-hydroxysuccinimidyl 13-cis-retinoate 7_ = 13-cis-retinoyl CoA Detailed Description of Processes Chemicals All trans-retinoic acid and the sodium salt of coenzyme A were purchased from Sigma Chemical Co. (St. Louis, MO) . -hydrσxysuccinimide and N,N'-^cyclchexylcarbodiimide were frcrα the Aldrich Chemical Co. CMilwaukee, WI). ' Disposable silica gel Sep-Pak cartridges (Platers Associates, Milford, MA) were used for purification of synthetic intermediates. All operations involving the use of retinoic acid analogs were performed under yellow light in a nitrogen atmosphere. Glassware silanized with dimerfe/ldiciilorosilane was used for the synthesis, handling and storage of retinoic acid CoA thioesters. All reactions were done using 1 and 5 ml Reacti-Vials (Pierce Chem. Corp., Rockford, IL) . Clιrc-τatographic Technique Analytical and preparative thin-layer c±romatography (TLC) was done using precoated alurrtinum silica gel sheets with UV indicator and glass pre-coated silica gel plates (20x20 cm, 2 π thick) without fluorescence indicator, respectively, obta ned from EM Science (Gibbstσwn, NJ) . Plates were developed using solvent systerrs: A; hexane-ethyl acetate 1:1 and B; n-butanol-acetic acid-water 5:2:3. Spectrometric Analyses Electron impact mass spectra (EI-MS) were recorded at 70 eV with an AEI I-S-9 spectrometer coupled to a DS-50 data system. Ultraviolet (UV) absorption spectra were recorded in absolute ethanol or dioxane with a Hitachi Model 100-60 UV-visible spectrσphotorreter. Infrared spectra (IR) were recorded on a Nicolet MX-1 FT-IR spectrometer in CC1 4 solution or using films of oily substances. Proton magnetic resonance spectra ( " Tϊ-NMR) were taken with a Bruker H-270 FT spectrometer in acetone-d fi solutions containing tetrarrβthylsilane (TMS) as internal standard. Beckman model 4500 pH meter equipped with Beckman COMB pH-electrode was used for pH adjustments. PREPARATIONS Preparation of N-hydroxysuccinirnidyl ester of all-trans-retinoic acid (2) All-trans-retinoic acid (1) (20 mg, 64 uM) in 0.8 ml of dioxane was treated with N-hydroxysuccinimide (7.6 mg, 64 uM) in 0.4 ml of dioxane and άicyclohexylcarbodiira.de (13.6 mg, 64 M) in 0.4 ml of dioxane. The resulting solution was ragnetically stirred at room temperature for 5 hours and then diluted with 10 ml of ethyl ether. The precipitated dicyclohexylurea was separated by filtration and the filtrate evaporated to dryness under reduced pressure. The oily residue was dissolved in warm methanol (10 ml) and the solution concentrated under reduced pressure until a slight precipitate became apparent. After standing overnight at -20°C, crystals were filtered off and washed with cold rethanol. Chromatographically pure product (2) showed TLC R- 0.47 (solvent system A) . ϋV (ethanol) λ 377 (36.400) ; IR 1758, 1734 cm -1 ; KMR (acetone-dg) 61.05 (s, 6,(CH 3 ) 2 C), 1.5 ( , 2, 2-CH 2 ) , 1.6 ( , 2, 3-σy , 1.72 (s, 3, 5-CH 3 ) , 2.01 (s, 3, 9-CH 3 ), 2.02 (2, 4-CH 2 ) , 2.37 (s, 3, 13-Ciy , 2.97 (s, 4, r-CH 2 2 » -CH 2 ); MS, n/e (relative intensity) (M) + 397 (65), 382 (5), 299 (12), 283 (40), 267 (19), 255 (10), 239 (17), 69 (100). Preparation of all-trans-retinoic acid anydride (3) All txans-retinoic acid (10 mg, 33 uM) in 0.2 ml of tatrahydrofuran was treated with dicyclohexylcarbcdiimide (7.2 eg, 34 uM) in 0.2 πl of acetonitrile. The solution was stirred at room temperature for 2 hours and then diluted with ethyl ether. Precipitated dicyclchexylurea was removed by filtration and solvent evaporated under reduced pressure. The residue was suspended in hexane and chromatographed on a Sep-Pak cartridge. Anhydride 3_ was eluted frc the cartridge with the mixture of 1.5% propanol-2 in hexane (20 ml) . Farther elution with, the same mixture afforded the unreacted substrate contaminated with the product of condensation of dicyclohexyicarbcdi.i.mide with all-trans-retinoic acid. The pure anhydride 3_ (solvent system A) was obtained as an ■ oily substance (from hexane) . TLC, R- 0.81 (solvent system A) . UV (ethanol) λ irsx 384 - j (e 76,000) [λ irictx 385, ε 68,300 (ethanol) ] ; IR 1701, 1767 cm ; ΪM (acetone-dg) 61.04 (s, 12, (CH 3 ) 2 C), 1.5 (m, 4, 2-CH2) , 1.6 (m, 4, -O , 1.74 (6, s, 5-OL , 2.1 fca, 10, 4-CH 2 , 9-CH 3 ), 2.44 (s, 6, 13-CHg) . MS, m/e (relative intensity) (M) + 582 (7), 444 (3.6), 404 (5.4), 381 (9.4), 366 (4.6), 243 (7), 177 (7), 159 (26), 145 (17), 44 (ICO). Preparation of all-trans-retinoic acid CoA ester (4) N-hydroxysucc-tnimidyl ester of all-trans-retinoic acid (2) (1.5 mg, 3.7 M) in 0.4 ml of tetrahydrofuran was added to a stirred solution of coenzyme A (2.5 mg, 2.8 uM) in 0.2 ml of water. The pH of the solution was adjusted to 8.0 - 8.5 with 1% NaKC0 3 . The reaction mixture was stirred under nitrogen arcsphere at 35°C for 20 hours until most of the CoA was ccT-surred as determined by TLC using the solvent system B. Ester _4_ was separated from the crude reaction mixture by preparative TLC using the solvent system B. Product was extracted frcm the TLC adsorbent using a mixture of acetic acid and water. Lyophilization of the extract, afforded pure ester 4_ as determined by TLC using the solvent system B (Rp 0.43, comparing with R, 0.40 and 0.41 for α-methylcrotσnyl and nyristoyl esters of CoA). UV (1^0) λ^^ 258 (ε 10,500 and λ 393 (ε 32,000) . rax Ester 4 was also obtained starting from anhydride 3_ using the same procedure and separation method as above. In this preparation, however, the formation of ester 4_ could not be completed even when cx>≥nzyme A was exposed to a 2-3-fold TTolar excess of anhydride 3 for double the time in above preparation. Preparation of N-hyαroxysuccinimidyl ester of 13-cis-retinoic acid (6) The compound 6_was prepared by the method essentially the same as for preparation of ester 2_ starting frcm 13-cis-retinoic acid 5_. TLC of chromatographically pure ccmpound 6_ showed R- 0.53 (solvent system A) . UV (ethanol) λ 380 (ε 35,000); IR 1760, 1747 ' cm "1 , NMR (acetone-dg) δ 1.05 (s, 6, (CH 3 ) 2 C), 1.5 (n, 2, 2-CH 2 ) , 1.65 (m, 2, 3-CH 2 ) , 1.76 (s, 3, 5-αy , 2.05 (m, 2, 4-αy , 2.1 (S, 3, -CB^) , 2.88 (s, 4, l'-CH j , 2'-CH 2 ); MS, m/e (relative intensity) (M) + 397 (36), 382 (2), 353 (7), 283 (17), 267 (10), 255 (8), 239 (19), 41 (100). Preparation of 13-cis-retinoic acid CoA ester (7) Ester 7_was prepared and purified by the method described for the preparation of ester 4_. TLC of chromatographically pure product showed R f 0.42 in solvent system B. The compounds of this invention find utility in the treatment of dermatological conditions such as acne and ichthyσsis, and as substitutes for all-trans-retinoic acid and 13-cis-retinoic acid in their various known applications. I ey may also be used as a substrate for biochemical reactions, such as, the transfer of retinoic acid to glycerol derivatives or diglycerides or in the β and omega oxidation of retinoic acid.

Claims: CLAIMS 1. (Compounds having the formula wherein R. and R-, are each selected from the group consisting of (a) hydrogen, o (c)_ .C-S-CoA except that both of R, and _ cannot be (a) , but one of R, and R~ ircst be (a) . 2. A corηpαund according to Claim 1 wherein R. is (a) and 3. A corrpσund according to Claim 1 wherein ΕL. is (a) and B j is (c). 4. A corrpound according to Claim 1 wherein R^ is (a) and R 1 is tb) . 5. A corrpound according to Claim 1 wherein R2 is (a) and R 1 is (c) . 6. A method for preparing all-trans-retinoic acid ar- ydriάe -which comprises condensing all-tran -retinoic acid with clicyclchexylcarbodiimide, separating formed dicyclchexylurea from the reaction mixture and recovering pure a 1 ~ -trar.s-retir.oic acid anhydride. 7. The r-Ec cc of Claim 6 where the recovered all-trans- retinoic acid ariiycride is further reacted with a solution of coenzyme A arc. all-trans-retinoyl CoA is recovered. 8. A rethod for preparing all-trans- and 13-cis-retincyl CoA which cαiurises treating, respectively, all-trans- or 13-cis-retinoic acid with N-hydrcxysucciniraide and dicyclohexyl carr d? imide , separating formed dicyclohexylurea front the reaction mixture, recovering the respective " Ssvxxinirtύάfl esters of all-trans- or 13-cis-retinoic acid, reacting said respective esters with a solution of coenzyme A and reccivering the desired al iHrraris-retinoyl CoA or 13-cάs-retinoyl CoA. 9. A method for preparing N-hydroxysuccinimidyl all—trans-or 13--cl3-retinoate which comprises treating, respectively, all -trans- or 13-cis-retinoic acid with and dicyclchexylcarbcdiind.de, separating formed dic^lchexylurea from the reaction πvixture and recovering the desired N-hydroxysu∞iriimidyl all-trans- qr 13-cis-retincate. References Zile, M., R. J. -Erjerick, H. F. DeLuca, "Identification of 13-cis-Retinoic Acid in Tissue Extracts in Its Biological Activity in Rats," Biochim. Bicphys. Acta, Vol. 141, pp. 639-641, 1967. Zile, M., R. C. Ii±orn, H. F. DeLuca, "Metabolites of All-trans Retinoic Acid in Bile: Identification of All- trans and 13-ci≤-riεtinoyl Glucuronides," J. Biol. Chem., Vol. 257, pp. 3537-3543, 1982.

Inventors: DELUCA HECTOR F, KUTNER ANDRZEJ, SCHNOES HEINRICH K, DELUCA, HECTOR, F., KUTNER, ANDRZEJ, SCHNOES, HEINRICH, K.
Applicants: WISCONSIN ALUMNI RES FOUND, WISCONSIN ALUMNI RESEARCH FOUNDATION
Application year: 1987
Main classification: C07D207
IPC codes: C07C51, C07D207, C07H19