RU2340597C1 - Nitroxyalkylamino acids - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: claimed are novel biologically active compounds - derivatives of natural hydroxyamino acids of general formula

where R=H or CH₃, and X represents anion residue of inorganic acid. Said derivatives represent O-nitroesters of said amino acids and are donors of nitrogen oxide, belonging to group of organic nitrates. Characteristic feature of claimed compounds is that release of nitrogen oxide leads to formation of natural amino acids, harmless for organism, without any by-products. Compounds can be obtained by direct nitrating of hydroxyamino acids in organic solvent and isolated in crystalline state in form of salts with inorganic or organic acids.

EFFECT: improvement of compound obtaining method.

1 cl, 5 ex

Description

The invention relates to organic chemistry, specifically to new biologically active compounds - nitroxy derivatives of natural hydroxy amino acids of the general formula

where R = H or CH ₃ , and X ^- represents the anionic residue of an inorganic acid.

The inventive compounds belong to the class of nitroxyalkylamines and are O-nitrates of natural hydroxy amino acids.

Hydroxy amino acids are not only common components of proteins and peptides, but also have their own biological activity. Thus, D-serine is a natural agonist of the glutamate receptor of the NMDA type (D. Bohning and SHSnyder Annu. Rev. Neurosci. 2003. 26, 105-31) and acts as a neuronal modulator (M. J. Schell et al., Proc Nat. Acad. Sci. USA 1995, 92, 3948-52). L-Serine along with glycine acts as the main astroglial trophic factor for cerebellar Purkinje neurons (S. Furuya, T. Tabata, et al. Proc. Nat. Acad. Sci. USA 2000, 97, 11528-11533). Threonine is an essential amino acid and is used as a dietary supplement to maintain the correct protein balance in the body.

Known nitroksialkilaminy non-amino acid derivatives, for example N- [2- (nitroxyethyl)] - 3-piridinkarbamid, which is the active principle of a medicament nicorandil (Merck Index, 13 ^th ed 2001, Monograph Number: 6548.). Nitroesters of protected dipeptides containing serine are also described (A. Gavrila, L. Andersen, T. Skrydstrup. Tetrahedron Letters 2005, 46, 6205-6207). However, O-nitro derivatives of natural hydroxy amino acids were not known.

It should be noted that nitro derivatives of serine-containing dipeptides cannot be obtained from their derivatives with protective groups, since the conditions for their removal do not allow preserving the nitro ester function. For the same reasons, it is impossible to obtain free amino acid nitroesters by hydrolysis of dipeptide nitroesters.

To date, methods for the preparation and physicochemical properties of the claimed compounds, which are new chemical compounds, have not been described.

Various methods are known for producing nitroesters, including treating alcohol with fuming nitric acid in the presence of sulfuric acid or acetic anhydride, a mixture of boron trifluoride hydrate and potassium nitrate, and lithium nitrate in the presence of trifluoroacetic acid and sodium carbonate. An indirect method for the synthesis of nitrates by the exchange of halogen to nitrate is also used. These methods can be applied to the synthesis of the claimed compounds, however, they have disadvantages that reduce the yield of the target products. Since the use of nitric acid in a mixture with sulfuric leads to insoluble sulfates, the use of acetic anhydride gives acetates as a by-product. The reaction of the exchange of halogen to nitrate is usually accompanied by an inversion of configuration and cannot be used to obtain nitroesters of natural amino acids.

The inventive compounds can be obtained in high yield by direct nitration of both the hydroxy amino acids themselves and by nitration of their silyl derivatives in a mixture of concentrated nitric acid with methylene chloride. In both cases, the target compounds are isolated in the form of nitric salts, which can then be converted to hydrochlorides or other salts with an acid inert to the nitro group using standard ion exchange methods using available ion exchange resins, for example Amberlyte A26 (Peers AM 1958. J Appl. Chem. 8, 106; Yu.A. Kokotov, Ionites and Ion Exchange, 1980, 150 pp. Chemistry, Leningrad Branch).

The inventive compounds can be used for the synthesis of peptide analogues (examples 4-5), in which serine or threonine are replaced by the corresponding nitro derivatives, as well as independent compounds. Since they are derivatives of natural amino acids, similar biological properties can be expected in them. In mammals, organic nitrates are known to undergo biochemical transformations to form nitric oxide (Feelisch M, Kelm M. 1991. Biochem Biophys Res Commun. 180, 286). Therefore, the claimed compounds, presumably, can act as donors of nitric oxide, the release of which will not be accompanied by the formation of additional non-natural molecular fragments. It is known that the release of nitric oxide by organic nitrates is an enzymatic thiol-dependent process (Thatcher GRJ, Nicolescu AC, et al. 2004, Free Radical Biology & Medicine, 37, 1122), therefore, spontaneous release of NO by the claimed compounds in solutions does not occur, which ensures their safety in pharmacologically acceptable solvents.

Nitroxyalkyl amino acids are non-toxic, LD ₅₀ > 100 mg / kg.

The following examples illustrate but do not limit the application of the present invention.

Example 1. Nitric acid salt of 2-amino-3-nitroxypropionic acid (L).

1680 mg of L-serine (16 mmol) was added in portions over 10 minutes to a solution of 3 ml of HNO ₃ (100%) in 20 ml of methylene chloride at 0 ° C and stirred at that temperature for 50 minutes. Then, 2 ml of Ac ₂ O are added dropwise and stirred for 40 minutes at 25 ° C. The precipitate formed is filtered off and recrystallized from ethanol-chloroform. Obtain 2.14 g of nitric acid salt of 2-amino-3-nitroxypropionic acid (63%), white crystals, mp = 111-113 ° C. 1 H-NMR spectrum (trifluoroacetic acid), δ, ppm: 4.93 (1H, br.s, CH). 5.25 (2H, m, CH ₂ ), 7.87 (3H, br s, NH ₂ , CO ₂ H). IR spectrum (ν, cm ^-1 ): 1285 (NO ₂ , sim), 1382, 1482, 1644 (NO ₂ , asym), 1733 (СО), 2905.

Example 2. The nitric acid salt of 2-amino-3-nitroxypropionic acid (D).

840 mg of D-serine (8 mmol) was added in portions over 10 minutes to a solution of 1.5 ml of HNO ₃ (~ 96%) in 10 ml of methylene chloride at 0 ° C and stirred at this temperature for 50 minutes. Then, 1 ml of Ac ₂ O is added dropwise and stirred for 40 minutes at 25 ° C. The precipitate formed is filtered off and recrystallized from ethanol-chloroform. Obtain 1.3 g of nitric acid salt of 2-amino-3-nitroxypropionic acid (75%), white crystals, mp = 113-115 ° C. 1 H-NMR spectrum (trifluoroacetic acid), δ, ppm: 4.93 (1H, br s, CH), 5.25 (2H, m, CH ₂ ), 7.87 (3H, br.s, NH ₂ , CO ₂ H ) IR spectrum (ν, cm ^-1 ): 1285 (NO ₂ , sim), 1382, 1482, 1644 (NO ₂ , asym), 1733 (СО), 2905.

Example 3. The nitric acid salt of 2-amino-3-nitroxybutanoic acid.

1904 mg of L-threonine (16 mmol) was added in portions over 10 minutes to a solution of 3 ml of HNO ₃ (100%) in 20 ml of methylene chloride at 0 ° C and stirred at this temperature for 50 minutes. Then 3 ml of Ac ₂ O are added dropwise and stirred for 1 hour at 25 ° C. The precipitate formed is filtered off and recrystallized from ethanol-chloroform. Obtain 2.27 g of nitric acid salt of 2-amino-3-nitroxybutanoic acid (63%), white crystals, mp = 121.5-122.5 ° C (decomp.). 1 H-NMR spectrum (trifluoroacetic acid), δ, ppm: 1.79 (3H, d, CH ₃ ), 4.7 (1H, m, NH ₂ CH), 5.88 (1H, br s, MeCH), 7.80 (3H, br s, NH ₂ , CO ₂ H).

IR spectrum (ν, cm ^-1 ): 1283 (NO ₂ , sim), 1382, 1482.1642 (NO ₂ , asymme), 1720 (СО), 2905.

Example 4. Obtaining 2 - {[1- (2,2-dimethylpropionyl) pyrrolidine-2-carbonyl] amino} -3-nitroxypropionic acid. (Boc-Pro-NO ₂ -Ser).

215 mg of N-Boc-Proline (1 mM) was dissolved in 2 ml of acetone, 155 μl of triethylamine (1.1 mmol) and 145 μl of isobutyl chloroformate (1.1 mmol) were added. The reaction mixture was stirred for 40 minutes at room temperature and a solution of 216 mg of (D) -nitroserine (1 mM) in 1 ml of water and 300 μl of triethylamine was added. The reaction mixture was stirred for 2 hours, acidified with an aqueous solution of 1 M hydrochloric acid to pH 3-4 and extracted with ethyl acetate (3 × 5 ml). The combined organic extract was washed with water, saturated sodium chloride solution, dried with anhydrous Na ₂ SO ₄ . The desiccant is filtered off, the filtrate is evaporated. The remaining oil is triturated in ether. The resulting crystals are filtered off. Receive 181 mg of the dipeptide (62%), white crystals. PMR spectrum (DMSO-d ₆ ), δ, ppm: 8.13 (1Н, m, NH), 4.85 (1Н, m, CHNH), 4.63 (2Н, m, CH ₂ ONO ₂ ), 4.12 (1Н, m, NCH), 3.35 (2H, m, NCH ₂ ), 1.94 (4H, m, CH ₂ CH ₂ ), 1.37 (9H, s, C (CH ₃ ) ₃ ).

Example 5. Obtaining 2- [3- (2,2-dimethylpropionylamino) -2-oxopropylamino] -3-nitroxybutanoic acid (Boc-Gly-NO ₂ -Tre).

175 mg of N-Boc-glycine (1 mM) are dissolved in 2 ml of acetone, 155 μl of triethylamine (1.1 mmol) and 145 μl of isobutyl chloroformate (1.1 mmol) are added. The reaction mixture was stirred for 40 minutes at room temperature and a solution of 230 mg of (L) -nitrotreonine (1 mM) in 1 ml of water and 300 μl of triethylamine was added. The reaction mixture was stirred for 2 hours, acidified with an aqueous solution of 1 M hydrochloric acid to pH 3-4 and extracted with ethyl acetate (3 × 5 ml). The combined organic extract was washed with water, saturated sodium chloride solution, dried with anhydrous Na ₂ SO ₄ . The desiccant is filtered off, the filtrate is evaporated. A vitreous mass is obtained. After recrystallization from a mixture of benzene-acetone (1: 1), 196 mg of dipeptide (61%) are obtained, white crystals, mp = 96-97 ° C. 1 H-NMR spectrum (DMSO-d ₆ ), δ, ppm: 7.48 (1Н, d, J = 9 Hz, CHNH), 7.39 (1Н, s, ОН), 5.98 (1Н, m, CH ₂ NH), 5.63 (1H, dm, J = 2.8 Hz, CHONO ₂ ), 4.88 (1H, dd, J = 9 Hz, J = 2.8 Hz, CHNH), 3.82 (2H, dm, J = 5 Hz, CH ₂ ), 1.45 (9H, s, C (CH ₃ ) ₃ ), 1.41 (3H, d, J = 6.4 Hz, CHCH ₃ ).

Claims (1)

Derivatives of natural hydroxy amino acids of the general formula

where R is H or CH ₃ and X ^is the anionic residue of an inorganic acid.