NOVEL AMINO ACID DERIVATIVE

Abstract: A novel amino acid derivative represented by general formula (I) and a salt thereof have been synthesized and it has been found that they promote the growth and physiological action of the T cells of mammals and have an immunomodulator effect and either an antitumor or a carcinostatic effect, and that they also have the effect of promoting the growth of hematopoietic stem cells wherein Y represents 0 or 1; R¹ represents unsusbstituted C₁-C₈ alkyl, etc.; R² represents hydrogen, C₁-C₅ alkyl, etc.; R³ represents hydrogen, C₁-C₈ alkyl, etc.; R⁴ represents hydrogen, C₁-C₃ alkyl, etc.; and R⁵ represents -OR⁴², -NR⁴³R⁴⁴, etc.

Description: This invention relates to novel amino acid derivatives which have immunomodulating activity, antitumor activity and/or hematopoietic stem cell-amplifying activity and are represented by the general formulae (I-1) to (I-5) shown hereinafter, and also it relates to salts of salt-formable ones of said amino acid derivatives. Further, this invention relates to an immunomodulator comprising as active ingredient a novel amino acid derivative represented by the general formulae (I-1) to (I-5) or a salt thereof, and an antitumor agent comprising as active ingredient a novel amino acid derivative represented by the general formulae (I-1) to (I-5) or a salt thereof, as well as a hematopoietic stem cell amplifier comprising as active ingredient a novel amino acid derivative represented by the general formulae (I-1) to (I-5) or a salt thereof. BACKGROUND ART Because many of antitumor agents which have heretofore been clinically used are inherently cytotoxic substances, they are accompanied by the drawbacks that they generally have strong toxicity, can give damages to normal cells along with their ability to prevent growth of cancer cells, and hence can induce strong side-effects. There is accordingly an outstanding demand for novel antitumor agents which have such a mechanism of the activity as different from that of the conventional antitumor agents, show low toxicity and weaker side-effects and are effective for therapeutic treatment of human tumors. DISCLOSURE OF THE INVENTION As a result of an extensive investigation, we, the present inventors, have succeeded in synthesizing novel amino acid derivatives which can be represented by the general formulae (I-1) to (I-5) shown hereinafter, and we have also found that these amino acid derivatives stimulate activation of T cell of mammals and hence have one or more of the immunomodulating activity and the antitumor and/or carcinostatic activities against various tumors and/or cancers, as well as the hematopoietic stem cell-amplifying activity. Based on these findings, the present invention has been completed. According to a first aspect of the present invention, therefore, there is provided a novel amino acid derivative of the hereinafter described formulae (I-1) to (I-5) or a salt thereof, as a novel substance. This novel amino acid derivative according to the present invention is a compound which is represented by the following general formulae (I-1) to (I-5), namely an amino acid derivative having the general formulae (I-1) to (I-5): wherein R 1a is selected from the group consisting of the alkyl groups and mono- or di-hydroxy-substituted alkyl groups which are represented by the formulae (i) - (vii): wherein R 1b is a hydroxy- and amino-substituted alkyl group of the formula: wherein R 3a is a group represented by the formula -(CH 2 ) c R 14a (where R 14a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group and c is an integer of 1, 2 or 3); or R 3a is a C 1 -C 4 alkyl group having one to three hydroxyl groups as substituents on the non-terminal carbon atom(s) in the chain of the alkyl group, wherein R 3b is a C 1 -C 8 alkyl group, wherein R 3c is a group of the formula -(CH 2 ) c -R 14b (where R 14b is thiol group -SH, a C 1 -C 3 alkylthio group or an aralkylthio group, and c is an integer of 1, 2 or 3), wherein R 3d is a C 1 -C 8 alkyl group or a group of the formula -(CH 2 ) c -R 14a (where R 14a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, and C is an integer of 1, 2 or 3), wherein R 3e is a group of the formula -(CH 2 ) c -R 14a (where R 14a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, and c is an integer of 1, 2 or 3), wherein R 4a is a hydrogen atom or C 1 -C 3 alkyl group, and wherein R 5a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, with the proviso that when R 3a is a -CH 2 OH and R 4a is a methyl group, R 1a does not stand for the group (v): or a pharmaceutically acceptable salt thereof. Illustrative salts of the novel amino acid derivative according to the present invention include the following salts: (1) salts with metals such as alkali metals, alkaline earth metals and aluminum; (2) ammonium salt; (3) salts with organic bases such as methylamine, ethylamine, diethylamine, triethylamine, pyrrolidine, piperidine, morpholine, hexamethyleneimine, aniline and pyridine; (4) salts with organic acids such as formic acid, acetic acid, trichloroacetic acid, maleic acid, tartaric acid, methanesulfonic acid, benzenesulfonic acid and toluenesulfonic acid; (5) salts with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid and phosphoric acid; and (6) salts with amino acids such as arginine, glutamic acid and ornithine. When it is desired to use such salts as immunomodulators, antitumor agents or hematopoietic stem cell amplifiers, it is possible to select pharmacologically acceptable salts of the amino acid derivative of the general formulae (I-1) to (I-5). Compounds which are representative examples of the novel amino acid derivative of the general formula (I-1) to (I-b) according to the present invention are presented in the following Table 1a to Table 1b. Further, elemental analysis data of each of these illustrative compounds shown in Table 1a to Table 1b are mentioned in Table 2a to Table 2b below, and proton nuclear magnetic resonance absorption spectrum ( 1 H-NMR) data of each of these compounds are described in Table 3a to Table 3b below. The compound numbers shown in Table 1a to Table 1b are referred to in Tests and Experiments which will be described hereinafter. Compound No. Elemental Analysis C H N Found value Theoretical value Found value Theoretical value Found value Theoretical value 1 55.61 55.28 9.08 8.82 6.10 6.45 2 66.17 66.42 8.32 8.20 4.25 4.56 3 49.64 49.30 8.14 7.82 6.70 6.39 4 56.41 56.70 9.37 9.15 4.73 5.09 5 46.57 46.82 7.14 7.37 7.16 6.83 6 68.21 68.55 7.27 7.06 3.25 3.63 7 48.98 49.30 7.63 7.82 6.02 6.39 8 62.43 62.12 7.35 7.49 4.88 4.53 13 48.41 48.18 7.83 7.68 5.39 5.62 14 50.39 50.18 7.85 8.04 5.06 5.32 15 60.48 60.16 7.24 7.43 4.48 4.13 16 52.29 51.97 8.66 8.36 4.79 5.05 17 62.44 62.10 8.04 7.96 3.52 3.81 18 47.01 47.30 7.36 7.58 5.23 5.01 19 57.27 57.45 7.18 7.09 4.26 3.94 20 63.63 64.02 6.91 6.77 2.90 3.25 Compound No. Elemental Analysis C H N Found value Theoretical value Found value Theoretical value Found value Theoretical value 27 43.88 43.63 7.59 7.32 12.77 12.72 Compound No. 1 H-NMR(δ)(ppm) 1 (CDCl 3 ); 0.87 (t, J=7Hz, 3H), 0.90 (d, J=7Hz, 3H), 1.19 (m,1H), 1.35 (m, 1H), 1.50 (s, 3H), 1.80 - 2.30 (m, 3H), 3.70 - 4.10 (brd, 2H) 2 (CDCl 3 ); 0.87 (t, J=7Hz, 3H), 0.92 (d, J=7Hz, 3H), 1.10 - 145 (m, 2H),153 (s,3H), 1.60 - 2.33 (m, 3H), 3.80, 4.07 (AB system, J=12Hz, 2H), 5.17 (s, 2H), 7.33 (s, 5H) 3 (CDCl 3 ); 1.18 (d, J=6Hz, 3H), 1.47 (s, 3H), 1.75 (td, J=6Hz, 2H), 2.37 (t, J=7Hz, 2H), 3,82 (qt, J=6.6Hz, 1H), 3.87 (brs, 2H) 4 (CDCl 3 ); 0.98 (t, J=7Hz, 3H), 1.23 (d, J=6Hz, 3H), 1.25 - 2.06 (m, 6H), 1.53 (s, 3H), 2.41 (t, J=6Hz, 2H), 3,70 - 4.02 (m, 1H), 3.90 (brs, 2H), 4,22 (t, J=6Hz, 2H) 5 (CD 3 OD); 1.24 (d, J=6Hz, 3H), 1.51 (s, 3H), 2.36 (d, J=6Hz, 2H), 3.66 - 4.3 2(m,3H) 6 (CDCl 3 ); 1.16 (d, J=6Hz, 3H), 1.57 (s, 3H), 2.30 (d, J=5Hz, 2H), 3.80 (m, 2H), 4.11 (m, 1H), 4.43 (s, 2H), 5.14 (s, 2H), 7.24 (s, 5H), 7.30 (s, 5H) 7 (CD 3 OD); 0.92 (d, J=7Hz, 3H), 1.05 (d, J=7Hz, 3H), 1.57(s, 3H), 1.84 - 2.36 (m, 1H), 3.85, 4.08 (AB system, J=12Hz, 2H), 3.90 (d, J=4Hz, 1H) 8 (CDCl 3 ); 0.82 (d, J=7Hz, 3H), 0.97 (d, J=7Hz, 3H), 1.62 (s, 3H), 1.70 - 2.21 (m, 1H), 3.97 (d, J=4Hz, 1H), 4.53, 4.92 (AB system, J=12Hz, 2H), 5.20 (d, J=2Hz, 2H), 7.37 (s,5H) 13 (CD 3 OD); 0.96 (s, 3H), 1.03 (s, 3H), 1.52 (s, 3H), 3.44 (s, 2H), 3.91 (m, 3H) 14 (CDCl 3 ); 0.94 (s, 3H), 1.03 (s, 3H), 1.53 (s, 3H), 3.47 (s, 2H), 3.70 - 3.95 (m, 3H), 3.78 (s, 3H) 15 (CDCl 3 ); 0.92 (s, 3H), 0.98 (s, 3H), 1.54 (s, 3H), 3.43 (s, 2H), 3.92 (s, 2H), 3.94 (s, 1H), 5.20 (s, 2H), 7.36 (s, 5H) 16 (CD 3 OD); 0.84 (d, J=6Hz, 3H), 0.97 (d, J=6Hz, 3H), 1.03 (d, J=6Hz, 3H), 1.33 - 1.90 (m, 1H), 1.53 (s, 3H), 1.96 - 2.40 (m, 1H), 2.33 - 3.56 (m, 1H), 3.91 (br s, 2H), 4.02 (d, J=4Hz, 1H) 17 (CD 3 OD); 0.81 (d, J=7Hz, 3H), 0.94 (d, J=7Hz, 3H), 0.97 (d, J=7Hz, 3H), 1.32 - 1.90 (m, 1H), 1.53 (s, 3H), 1.96 - 2.34 (m, 1H), 3.30 - 3.73 (m, 1H), 3.86 (br s, 2H), 3.99 (d, J=4Hz, 1H), 5.17 (s, 2H), 7.36 (s, 5H) 18 (CD 3 OD); 0.89 (d, J=6Hz, 3H), 1.21 (d, J=6Hz, 3H), 1.80 - 2.20 (m, 1H), 2.09 (s, 3H), 2.99 (d, J=5Hz, 2H), 3.87 (s, 3H), 4.38 (d, J=2Hz, 1H), 4.87 (m, 1H) 19 (CDCl 3 ); 0.91 (d, J=6Hz, 3H), 1.28 (d, J=6Hz, 3H), 2.11 (s, 3H), 3.01 (d, J=5Hz, 2H), 4.24 (m, 1H), 4.41 (d, J=2Hz, 1H), 4.76 - 5.06 (m, 1H), 5.23 (s, 2H), 7.40 (s, 5H) 20 (CDCl 3 ); 0.86 (d, J=6Hz, 3H), 1.19 (d, J=6Hz, 3H), 2.02 (m, 1H), 2.85 (d, J=6Hz, 2H), 3.67 (s, 2H), 4.14 (m, 1H), 4.34 (d, J=2Hz, 1H), 4.66 - 4.96 (m, 1H), 5.13 (s, 2H), 7.24 (s, 5H), 7.32 (s, 5H) Compound No. 1 H-NMR(δ)(ppm) 27 (CD 3 OD); 1.45 (s,3H), 2.06 (m, 2H), 3.34, 3.81(AB system, J=12Hz, 2H), 3.81(t, J=6Hz, 2H), 4.09(m, 1H) Incidentally, the amino acid derivative of the general formulae (I-1) to (I-5) according to the present invention embraces, as preferred embodiments thereof, two types of such amino acid derivatives represented by the following general formulae (I-1') and (I-1''), respectively: wherein R 3e is a group of the formula -(CH 2 )c-R 14a (where R 14a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, and c is an integer of 1, 2 or 3), R 4a is a hydrogen atom or a C 1 -C 3 alkyl group, and R 5a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, or a pharmaceutically acceptable salt thereof. or a pharmaceutically acceptable salt thereof or a methyl or benzyl ester thereof. The amino acid derivative of the general formulae (I-1) to (I-5) according to the present invention is other than (2S)N-[(2R,3S,4R)-2,4-dihydroxy-3-methylpentanoyl]-2-methylserine known under the name "conagenin" (see U.S. Patent No. 5,098,935, The Journal of Antibiotics, vol, 44, no. 5, 1991, PP. 557-559), because the meanings of R 1 , R 3 , R 4 and y are restricted by the "proviso" clause, as defined in the general formulae (I-1) to (I-5). BEST MODE FOR CARRYING OUT THE INVENTION The novel amino acid derivative according to the present invention, which is represented by the formulae (I-1) to (I-5), can be synthesized by several processes as will be described below. According to one of such synthesis processes, the amino acid derivative of the general formulae (I-1) to (I-5) can be synthesized by reacting a compound of the following general formula (II): R 1 COOH wherein R 1 has the same meaning as defined above in the general formulae (I-1) to (I-5) with an amine compound of the following general formula (III): wherein R 2 , R 3 , R 4 , R 5 and y have the same meanings as defined above in the general formulae (I-1) to (I-5) in accordance with a usual reaction for amidating carboxylic acid compounds. This amidating reaction can be conducted, for example, in the absence of any catalyst, or in the presence of a dehydrating condensation agent or in the presence of a base. As said dehydrating condensation agent, a conventional dehydrating condensation agent can be used such as dicyclohexylcarbodiimide or 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. Illustrative examples of the base include a metal alcoholate such as sodium methoxide, an alkyl metal such as butyl lithium, and a metal hydride such as sodium hydride. Also employable is such a process in which the carboxylic acid compound of the formula (II) is converted into an acid halide by a halogenating reagent such as phosphorus pentachloride or thionyl chloride, followed by the reaction of the acid halide with the amine compound of the formula (III). In this reaction, the synthetic reaction can occasionally be promoted by adding 1-hydroxybenzotriazole, N-hydroxysuccinimide or the like in some instances. For said reaction with the amine compound of the formula (III), an ester of the following formula (IV): R 1 CO 2 R 45 wherein R 45 represents an alkyl group, a phenyl group or a substituted phenyl group and R 1 has the same meaning as defined above can be used in place of the carboxylic acid compound of the formula (II). As an alternative, where the carboxylic acid compound of the formula (II) contains a hydroxyl-substituted alkyl group as R 1 and can form a lactone ring between the hydroxyl group and the carboxyl group, it is possible to use a lactone compound for said carboxylic acid derivative. For instance, when a carboxylic acid compound of the general formula (II) used is such a carboxylic acid containing a group of the following formula (V): as R 1 , the reaction of a lactone of the following formula (VI): namely, 2-hydroxy-3,4-dimethyl-γ-butyrolactone (see Example 5 given hereinafter) with the amine compound of the formula (III) may be conducted in the presence of an inorganic catalyst or a base. In this reaction, the base usable includes metal alcoholates such as sodium methoxide, an alkyl metal such as butyl lithium, and metal hydrides such as sodium hydride. Further, usable is such a process in which, similarly to the case with making use of the carboxylic acid compound of the formula (II), an ester compound of the aforesaid formula (IV) or a lactone compound such as that of the formula (VI) is converted into an acid halide by a halogenating reagent e.g. phosphorus pentachloride or thionyl chloride, followed by reaction of the acid halide with the amine compound of the formula (III). For conducting each of these reactions, if necessary, it is possible to introduce beforehand the conventional protecting group(s) into the compound(s) to be used in the reaction, and after the reaction, to remove the protecting group(s) from the reaction product so obtained. In the carboxylic acid compound of the formula (II) or the amine compound of the formula (III) to be used, for example, it is possible to protect a hydroxyl group of said compound by tetrahydropyranyl group, trimethylsilyl group, to protect an amino group of said compound by acetyl group, carboxybenzyl group, t-butoxycarbonyl group or the like, to protect a mercapto group of said compound by acetyl group, t-butoxycarbonyl group, and to protect a carboxyl group of said compound by benzyl group, methyl group. To synthesize such an amino acid derivative of the formula (I) in which R 3 is a group -(CH 2 ) c -R 14 , where R 14 is -OR 15 and R 15 is a C 1 -C 3 alkyl group or a group (d being an integer of 0 to 3), there can be used a process comprising a general etherifying reaction, including such a process in which a corresponding amino acid compound of the formulae (I-1) to (I-5) where R 15 is a hydrogen atom is reacted with a halide compound of the formula R 50 X 7 (R 50 is a C 1 -C 3 alkyl group and X 7 is a halogen atom) in the presence of a base. Next, in order to synthesize such an amino acid derivative of the formula (I) in which R 5 is a group -OR 42 where R 42 is a C 1 -C 3 alkyl group or is a group (q is an integer of 0-2), it is possible to use a process comprising a general esterifying reaction, including, for example, such a process in which a corresponding amino acid compound of the formula (I) where R 42 is a hydrogen atom is reacted with an alcohol compound of the formula HOR 55 (R 55 is a C 1 -C 3 alkyl group or a group in the presence of an acid or a base or in the presence of an esterifying condensation agent or such a process in which the corresponding compounds (I-1) to (I-5) where R 42 is a hydrogen atom is converted into an acid halide by reaction with a halogenating agent such as thionyl chloride or phosphorus pentachloride, followed by the reaction of the resulting halide with an alcohol of the formula HOR 55 (R 55 is as defined above). According to a second aspect of the present invention, there is also provided an immunomodulating agent which comprises as active ingredient at least one of a novel amino acid derivative represented by the general formulae (I-1) to (I-5) salts thereof. The novel amino acid derivatives of the general formulae (I-1) to (I-5) have a characteristic feature of their action that they stimulate specifically the proliferation of the activated T cells obtained from mouse spleen cells but do not act on the resting T cells. For example, the amino acid derivatives of this invention stimulate the proliferation of such T cells which have been treated with Concanavalin A, or the proliferation of such T cells which co-exist with macrophages. In view of this, the amino acid derivatives of the general formulae (I-1) to (I-5) are expected to modulate the immunological activities of a living mammal owing to that they can increase and activate the clones of helper T cells or effecter T cells. Thus, the amino acid derivative of the formulae (I-1) to (I-5) have potential utility that they are useful as therapeutics and/or preventives for tumors, auto-immune diseases, hematopoietic disorders and the like. The activities of the novel amino acid derivative of the general formulae (I-1) to (I-5) to stimulate the proliferation of T cells will be demonstrated by the following test. Test 1 Effects of the novel amino acid derivatives of the general formulae (I-1) to (I-5) on the proliferation of T cells were investigated by the following procedure. The spleens, which had been excised in sterility from female Fisher 344 rats (12-16 weeks old, purchased from CHARLES RIVER JAPAN, INC), were squeezed in RPMI 1640 medium (a product of NISSUI PHARMACEUTICAL CO., LTD.) supplemented with 10% of fetal bovine serum, followed by passage of the resulting cell suspension through a column containing nylon wool fibres, whereby a cell suspension containing an abundant amount of T cells was obtained. This cell suspension was diluted to a level of 1 x 10 6 cells/mℓ with addition of a medium of the same composition as above. The cell-containing medium so obtained was then added with 5 µg/mℓ of Concanavalin A (product of Pharmacia AB), followed by incubation at 37°C for 4 hours. Four hours later, α-methylmannoside was added to the incubated medium to give a concentration of 20 mg/mℓ of α-methylmannoside. After stirring the medium, cells were separated and collected therefrom by centrifugation. The collected cells were suspended at a level of 3 x 10 6 cells/mℓ in a medium of the same composition as above, followed by placing the resulting cell suspension in 100 µℓ portions in a 96-well microplate. Novel amino acid derivatives at various concentrations, which are shown in Table 4, were incorporated in an amount of 100 µℓ as the test compounds to the respective cell suspensions in the plate, followed by incubation at 37°C for 3 days in an incubator under air atmosphere containing 5% of carbon dioxide. Meanwhile, eighteen hours before the completion of the incubation, a solution of 10 µ Ci/mℓ of radioactively labeled thymidine (Thymidine "6- 3 H", a product of NEN Company) was added in an amount of 10 µℓ to the cell suspensions under incubation. The cells after the incubation were collected on a filter paper by means of a cell harvester, washed with water and radioactivity of the cells so treated was determined by a liquid scintillation counter. The determined values of the radioactivity of the cells as treated with the test compounds were evaluated on the assumption that the determined value of the radioactivity of the cells untreated, namely tested without addition of the test compound during the incubation of cells was amounting to 100. The so evaluated values are recorded and expressed as rates (%) for stimulating the T cell proliferation which show such extent that the proliferation of T cells is enhanced by the new amino acid derivative of this invention. The test results obtained are shown in Table 4 below. From the results of Table 4, it is evident that the compounds of the general formulae (I-1) to (I-5) according to this invention have excellent activity of stimulating the proliferation of T cells and hence have excellent activities for immunomodulation. Activity of new amino acid derivatives for stimulating T cell proliferation Compound No. Concentration of compound (µg/ml) Rate of stimulating proliferation of T cells (%) Compound No. Concentration of compound (µg/ml) Rate of stimulating proliferation of T cells (%) 1 10 332 1 297 0.1 292 2 10 275 1 190 0.1 208 3 10 101 13 10 465 1 100 1 352 0.1 123 0.1 405 4 10 100 14 10 443 1 135 1 335 0.1 133 0.1 356 5 10 439 15 10 442 1 370 1 349 0.1 313 0.1 350 6 10 169 16 10 201 1 171 1 239 0.1 142 0.1 200 7 10 323 17 10 245 1 222 1 273 0.1 240 0.1 201 8 10 372 18 10 427 1 226 1 355 0.1 251 0.1 268 19 10 251 1 310 0.1 289 20 10 261 1 227 0.1 153 Further, according to a third aspect of the present invention, there is also provided an antitumor agent which comprises as active ingredient at least one of the new amino acid derivative represented by the general formulae (I-1) to (I-5) or a salt thereof. The antitumor activity of the novel amino acid derivatives of the general formula (I-1) to (I-5) will be demonstrated by the following test. Test 2 The antitumor activity of some amino acid derivatives of the general formulae (I-1) to (I-5) according to this invention was tested in the following manner. A suspension of Ehrlich ascites carcinoma cells was subcutaneously injected to one of the inguinal parts of each ICR mouse to transplant 4 x 10 6 cells/mouse. From the seventh day after the transplantation, a test compound was intraperitoneally injected daily for 7 days at a dose of 50, 5 or 0.5 mg/kg (4 mice per treated group of mice, but 8 mice per untreated control group of mice). On the fifteenth day after the transplantation, a solid cancer was cut out and weighed. A reduction in the weight of solid cancers of the mice in each treated group of mice which was evaluated in comparison with the control group is expressed as rate of inhibiting the tumor growth (%) in Table 5 below. As is presented in Table 5, each compound of the present invention exhibited remarkable activity for inhibition of tumor growth against mouse Ehrlich solid cancer. Compound No. of Invention Dose (mg/kg) Tumor growth inhibiting rate, % 19 5 12 Further, according to a fourth aspect of the present invention, there is also provided a hematopoietic stem cell amplifier which comprises as active ingredient at least one of the novel amino acid derivative represented by the general formulae (I-1) to (I-5) or a salt thereof. The novel amino acid derivatives have such another characteristic feature of their activities that they have property to stimulate the proliferation of T cells and also physiological activities of T cells. These amino acid derivatives also show an activity to stimulate production of interleukin-3 (IL-3) and interleukin-6 (IL-6) from T cells [see "Zoketsu Inshi - Kenkyu no Choryu (in English: Hematopoietic Factors - Trend of Research)", compiled and edited by Miura Yoshisada and published from the Chugai Igakusha, Inc. (1991)]. Cytokines as these interleukins are known to exhibit an activity for stimulating the proliferation and differentiation of hematopoietic stem cells. Because the amino acid derivatives of the general formulae (I-1) to (I-5) according to this invention show the activities to stimulate the proliferation of hematopoietic stem cells, they are expected to be useful as therapeutics for treating leukopenia, trombocytopenia and the like. The activity of the novel amino acid derivatives of the general formula (I-1) to (I-5) for inducing proliferation of hematopoietic stem cells will be demonstrated by the following test. Test 3 The activity of some amino acid derivatives of the general formulae (I-1) to (I-5) according to this invention which induces proliferation of hematopoietic stem cells was tested in the following manner. Thus, bone-marrow cells had been prepared from the femurs of male BALB/c mouse (6-7 weeks old), and then a suspension of the bone-marrow cells was overlayed on "Lympholite M" (product of Cefalane Company), followed by centrifugation under 1500 g for 20 minutes. A lymphocyte fraction was collected, washed three times with "alpha MEM medium" (product of Gibco Company), and then diluted and suspended in the same medium as above to give a lymphocyte concentration of 7 x 10 6 cells/mℓ. 50 mℓ of the resulting cell suspension, 50 µℓ of a solution of a test compound in physiological saline, 50 µℓ of a culture supernatant of WEHI-3, 100 µℓ of phosphate-buffered physiological saline, 50 uℓ of a predeionized 10% bovine serum albumin solution, 50 µℓ of an L-asparagin solution (200 µg/mℓ), 50 µℓ of a calcium chloride solution (260 µg/mℓ) and 50 µℓ of bovine plasma containing sodium citrate were combined together. The liquid mixture so obtained was poured in portions of 50 µℓ/well on a slide glass ("Glass Ware", product of Flaw Laboratory Company). After coagulation of the mixture, the slide glass bearing the coagulated masses was immersed in 10% FBS-added alpha MEM medium, followed by incubation at 37°C under 5% CO 2 for 7 days. After completion of the incubation, the cells on the slide glass were immobilized with a 25% glutaraldehyde solution. In accordance with the methods proposed by Nagasawa et al. ["Zoketsu Kan Saibo (Hematopoietic Stem Cells)" compiled by takahisa Shimamaro, page 128 (The Nishimura Shoten Co., Ltd.)], the immobilized cells were stained for acetylcholinesterase activity which is specific for mouse megakaryocytes, and also the cells were stained with Mayer hematoxylin. Each cell culture so stained was dried and then sealed with a sealing agent. Under a microscope of x100 magnification, the number of megakaryocytic colonies (i.e., the number of cells stained in an orange color) per well was counted. The results are presented in Table 6. As is shown in Table 6, it is evident that the compounds according to the present invention significantly increase the number of colonies of megakaryocytes, in other words, significantly stimulate the formation of megakaryocyte colonies and hence exhibit a remarkable activity to induce proliferation of hematopoietic stem cells. Activity of new amino acid derivatives for stimulating the formation of colonies of megakaryocytes Compound No. of Invention Concentration of test compound (µg/ml) Number of colonies of megakaryocytes (%) No addition 0 100 1 5 147 2 5 122 5 50 178 6 5 126 7 50 166 8 5 111 13 5 177 14 5 167 15 50 135 16 50 143 17 5 107 18 5 146 19 50 156 20 5 129 27 50 143 28 5 121 29 50 121 In addition, in order to evaluate toxicity of the amino acid derivatives of the formulae (I-1) to (I-5) according to this invention to mammals, the representative examples of the amino acid derivatives of this invention listed in Table 1a to Table 1b were orally administered at a dose of 500 mg/kg to mice. The compounds so tested did not show any toxicity to mice, indicating that the novel amino acid derivatives (I-1) to (I-5) of this invention has low acute toxicity. The novel amino acid derivative of the general formulae (I-1) to (I-5) according to this invention can be administered in the form of a composition comprising said derivative as active ingredient and also a pharmaceutically acceptable, solid or liquid carrier so that said composition is given as antitumor agents, immunomodulating agents or hematopoietic stem cell-amplifying agents. The form of formulation of these medicaments may be chosen to be any of preparations which are administerable orally, rectally or parenterally. Described specifically, the new compounds of this invention can be formulated into injections, tablets, capsules, fine granules, syrups, suppositories, ointments and the like. The usable carriers, which can be incorporated in the compositions for antitumor agents, immunomodulators and hematopoietic stem cell amplifiers according to this invention, may include an organic or inorganic, solid or liquid carrier which is suited for oral, rectal or other parenteral administration, and which is generally inert and is pharmaceutically acceptable. Specific examples of such carriers include crystalline cellulose, gelatin, lactose, starch, magnesium stearate, talc, vegetable or animal fats and oils, gum, and polyalkylene glycols. In the composition for the antitumor agent, immunomodulator or hematopoietic stem cell amplifier according to this invention, the proportion of the compounds (I-1) to (I-5) of the present invention relative to the associated carrier can vary in a range of from 0.2% to 100% by weight. Further, the composition for the antitumor agent, immunomodulator or hematopoietic stem cell amplifier according to this invention can contain any other antitumor agent, immunomodulator, hematopoietic stem cell amplifier or other medicaments which is compatible with the compound of the present invention. In this case, needless to say, the novel amino acid derivative (I-1) to (I-5) according to this invention may not necessarily be a principal ingredient in the composition prepared. The amino acid compound of the general formulae (I-1) to (I-5) according to this invention can be administered at such a dosage that its desired action can be achieved generally without showing side-effects. Its specific dose should be determined under the physician's own judgment. In general, however, it may usually be administered at a dose of 1 mg to 10 g, preferably about 2 mg to 5 g per adult for the purposes of antitumor, immunomodulating or hematopoietic stem cell-amplifying treatments. Incidentally, the composition for the antitumor agent, immunomodulator or hematopoietic stem cell amplifier according to this invention can be administered in the form of pharmaceutical preparation units containing the amino acid compound of the general formulae (I-1) to (I-5) in an amount of 1 mg to 5 g, preferably 3 mg to 1 g as an active ingredient. It is to be noted that further subjects of the present invention embrace a use of the novel amino acid derivative of the general formulae (I-1) to (I-5) or a salt thereof for the manufacture or formulation of an antitumor agent, immunomodulator or hematopoietic stem cell amplifier. The present invention will next be described particularly with reference to Examples for production of certain compounds of this invention. Example 1 Synthesis of Compound No. 1 3-Methylvaleric acid (0.35 g) and α-methylserine benzyl ester (0.63 g) were dissolved in 10 mℓ of dimethylformamide (DMF). The resultant solution was added with 0.40 g of 1-hydroxybenzotriazole and 0.60 g of dicyclohexylcarbodiimide (DCC) and was then stirred at room temperature for 4 hours. The resulting reaction mixture was filtered to eliminate insoluble matter and the filtrate so obtained was concentrated under reduced pressure. The residue was added with 100 mℓ of chloroform. After the resulting solution was washed with 1N hydrochloric acid, chloroform was distilled off under reduced pressure to concentrate the solution. The residue so obtained was subjected to column chromatography with silica gel as a solid support, followed by elution with chloroform. Fractions containing the target compound were collected and the solvent was then distilled off, whereby 80 mg of the benzyl ester (Compound No. 2) of target Compound No. 1 were obtained (yield: 8.7%). Compound No. 2 so obtained (80 mg) was dissolved in 5 mℓ of methanol and reduced in the presence of 10 mg of 10% palladium-carbon at room temperature for 4 hours under a hydrogen atmosphere. The resulting reaction mixture was filtered and the solvent was distilled off, affording 50 mg of target Compound No. 1 (yield: 88.5%). Example 2 Synthesis of Compound No. 3 α-Methylserine (0.6 g) was dissolved in 1 mℓ of a 28% methanolic solution of sodium methoxide, followed by the addition of 0.47 mℓ of γ-valerolactone. The resultant mixture was heated on oil bath and refluxed for 4 hours with stirring. After completion of the reaction, the solvent was distilled off from the reaction mixture under reduced pressure. The residue was added with a saturated aqueous NaCl solution. The mixture so obtained was acidified with dilute hydrochloric acid and then extracted four times with 30-mℓ portions of n-butanol. The resulting extracts were concentrated under reduced pressure and the residue was subjected to column chromatography with silica gel as a solid support. Elution was conducted with ethyl acetate containing 10% of methanol, so that the relevant fractions were collected. The solvent was removed from those fractions, whereby 80 mg of target Compound No. 3 were obtained (yield: 5.8%). As a by-product, 21 mg of the n-butyl ester (Compound No. 4) of target Compound No. 3 were also obtained (yield: 2.0%). Example 3 Synthesis of Compound No. 5 3-Hydroxybutyric acid (0.33 g) and O-benzyl-α-methylserine benzyl ester (1.25 g) were dissolved in 10 mℓ of DMF, followed by the addition of 0.56 g of 1-hydroxybenzotriazole and 0.83 g of dicyclohexylcarbodiimide (DCC). The resulting mixture was stirred at room temperature for 5 hours. The reaction mixture so obtained was filtered, and after removal of insoluble matter, the filtrate obtained was concentrated under reduced pressure. The residue was subjected to column chromatography with silica gel as a solid suppport. Elution was conducted with n-hexane containing 50% of ethyl acetate, whereby 120 mg of the benzyl ester derivative (Compound No. 6) of target Compound No. 5 were obtained (yield: 12.8%). Compound No. 6 so obtained (100 mg) were dissolved in 15 mℓ of methanol and reduced in the presence of 10% palladium-carbon with stirring at room temperature for 16 hours under a hydrogen atmosphere (2.5 atm). The resulting reaction mixture was filtered and the solvent was distilled off from the filtrate, affording 50 mg of target Compound No. 5 (yield: 91.1%). Example 4 Synthesis of Compound No. 7 The reaction and processing treatments were conducted in a similar manner to Example 1 except that 0.35 g of 2-hydroxy-3-methylbutyric acid was used in place of 3-methylvaleric acid employed in Example 1, whereby 0.28 g of the benzyl ester (Compound No. 8) of target Compound No. 7 were obtained (yield: 30.1%). Compound No. 8 so obtained (80 mg) was catalytically reduced as in Example 1, yielding 40 mg of target Compound No. 7 (yield: 70.6%) Example 5 Synthesis of Compound No. 13 α-methylserine (0.84 g) was dissolved in 7 ml of a IM ethanolic solution of sodium ethoxide, followed by the addition of pantolactone (0,46 g). After the resultant mixture was heated on oil bath and refluxed for 2 hours with stirring, the solvent was removed from the resulting reaction mixture by distillation. The residue obtained was heated at 120°C for 2 hours on oil bath and was then cooled. The resulting material was added with 15 ml of DMF and 1.2 ml of benzyl bromide, followed by stirring at room temperature for 16 hours. After completion of the reaction, the solvent was eliminated from the resulting reaction mixture under reduced pressure. The residue was subjected to column chromatography with silica gel as a solid support. Elution was conducted with a I:I mixed solvent of ethyl acetate and n-hexane, whereby 0.19 g of the benzyl ester (Compound No. 15) of target Compound No. 13 was obtained (yield : 15.6%). Compound No. 15 so obtained (150 mg) was dissolved in 30 ml of methanol, followed by the reduction in the presence of 10 mg of 10% palladium-carbon, at room temperature under a hydrogen atmosphere for 3 hours. The reaction mixture obtained was filtered and the solvent was distilled off from the filtrate under reduced pressure, affording 105 mg of target Compound No. 13 (yield : 92.3%). Example 6 Synthesis of Compound No. 14 The reactions and processing treatments were conducted in a similar manner to Example 5 except that 0.5 g of methyl iodide was used in place of benzyl bromide. Thus, 0.13 g of target Compound No. 14 was obtained (yield : 14.3%). Example 7 Synthesis of Compound No. 16 The reactions and processing treatments were conducted in a similar manner to Example 5 except that 0.55 g of 2-hydroxy-3-methyl-4-iso-propyl-γ-butyrolactone was used in lieu of pantolactone, whereby 290 mg of the benzyl ester (Compound No. 17) of target Compound No. 16 were obtained (yield : 11.4%). Compound No 17 was obtained (170 mg) was catalytically reduced as in Example 5, affording 100 mg of target Compound No. 16 (yield : 81.0%). Example 8 Synthesis of Compound No. 18 The reactions and processing treatments of Example 5 were repeated similarly except that 0.94 g of s-methylcysteine was used instead of α-methylserine employed in Example 5 and 0,40 g of 2-hydroxy-3,4-dimethyl-γ-butyrolactone was used in lieu of pantolactone (0,46 g), and 1.0 g of methyl iodide in place of benzyl bromide. Thus, 30 mg of target Compound No. 18 were obtained (yield : 3.2%). Example 9 Synthesis of Compound No. 19 The reactions and processing treatments of Example 5 were repeated similarly except that 0.94 g of s-methylcysteine was used instead of α-methylserine employed in Example 5 and 0,40 g of 2-hydroxy-3,4-dimethyl-γ-butyrolactone was used in lieu of pantolactone (0,46 g). Thus, 0.54 g of target Compound No. 18 were obtained (yield : 43.8%). Example 10 Synthesis of Compound No. 20 The reactions and processing treatments were conducted in a similarly manner to Example 5 except that 1.0 g of s-benzylcysteine was used instead of α-methylserine employed in Example 5 and 0,40 g of 2-hydroxy-3,4-dimethyl-γ-butyrolactone was used in lieu of pantolactone (0,46 g). In this way, 0.78 g of the aimed Compound No. 20 were obtained (yield : 52.1%). Example 11 Synthesis of Compound No. 27 α-Methylserine (0.3 g) was dissolved in a solution of 0.17 g of sodium ethoxide in 50 mℓ of ethanol, followed by the addition of 0.58 g of α-(N-carbobenzoxyamino)-γ-butyrolactone. The resulting mixture was heated on oil bath and refluxed for 4 hours under stirring. After completion of the reaction, the resulting reaction solution was distilled under reduced pressure to remove the solvent from the reaction solution. Water was added to the residue, followed by washing with ethyl ether. The resulting mixture as washed was acidified with 2N hydrochloric acid and was then extracted with ethyl acetate. The solvent was distilled off from the resultant extract under reduced pressure. The residue was added with a solution of 0.28 g of tetramethylammonium hydroxide pentahydrate in 30 mℓ of DMF, followed by the addition of 0.24 mℓ of benzyl bromide and then by the reaction at room temperature for 18 hours. Water was added to the resulting reaction solution, followed by extraction with ethyl acetate. The solvent was distilled off and the residue was subjected to column chromatography with silica gel as a solid support. Elution was conducted with chloroform, the relevant fractions were collected and the solvent was then eliminated from the combined fractions, whereby 640 mg of the N-carbobenzoxylated derivative of the benzyl ester of target Compound No. 27 were obtained (yield: 57.7%). The compound so obtained (400 mg) was dissolved in 100 mℓ of methanol and reduced in the presence of 0.1 g of 10% palladium-carbon at room temperature for 2 days under hydrogen gas at 4 kg/cm 2 . The reaction mixture so obtained was then filtered and the solvent distilled off from the filtrate under reduced pressure, whereby 123 mg of target Compound No. 27 were obtained (yield: 62.1%). INDUSTRIAL UTILITY The new amino acid derivatives of the general formulae (I-1) to (I-5) provided in accordance with the present invention have an activity for stimulating the proliferation of T cells and show the effects to modulate the immunological activities of living mammals. The new amino acid derivatives also have antitumor activities and/or carcinostatic activities against various tumors and/or cancers. They also exhibit activities for stimulating both the proliferation and physiological activities of T cells, whereby consequently they act to stimulate the proliferation of hematopoietic stem cells. Accordingly, the novel amino acid derivatives according to this invention are useful as immunomodulators, antitumor agents, carcinostatic agents or hematopoietic stem cell amplifiers.

Claims: An amino acid derivative having the formula: wherein R 1a is selected from the group consisting of the alkyl groups and mono- or di-hydroxy-substituted alkyl groups which are represented by the formulae (i) - (vii): wherein R 3a is a group represented by the formula -(CH 2 ) c R 14a (where R 14a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group and c is an integer of 1, 2 or 3); or R 3a is a C 1 -C 4 alkyl group having one to three hydroxyl groups as substituents on the non-terminal carbon atom(s) in the chain of the alkyl group, wherein R 4a is a hydrogen atom or C 1 -C 3 alkyl group, and wherein R 5a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, with the proviso that when R 3a is a -CH 2 OH and R 4a is a methyl group, R 1a does not stand for the group (v): or a pharmaceutically acceptable salt thereof. An amino acid derivative according to Claim 1, which is of the formula: wherein R 3e is a group of the formula -(CH 2 ) c -R 14a (where R 14a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, and c is an integer of 1, 2 or 3), R 4a is a hydrogen atom or a C 1 -C 3 alkyl group, and R 5a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, or a pharmaceutically acceptable salt thereof. A compound according to claim 1, which is of the formula or a pharmaceutically acceptable salt thereof or a methyl or benzyl ester thereof. An amino acid derivative having the formula: wherein R 1a is selected from the group consisting of the alkyl groups and mono- or di-hydroxy-substituted alkyl groups which are represented by the formulae (i) - (vii) :- R 3b is a C 1 -C 8 alkyl group, R 4a is a hydrogen atom or a C 1 -C 3 alkyl group, and R 5a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, or a pharmaceutically acceptable salt thereof. An amino acid derivative having the formula: wherein R 1a is selected from the group consisting of the alkyl groups and mono- or di-hydroxy-substituted alkyl groups which are represented by the formulae (i) - (vii):- R 3c is a group of the formula -(CH 2 ) c -R 14b (where R 14b is thiol group -SH, a C 1 -C 3 alkylthio group or an aralkylthio group, and c is an integer of 1, 2 or 3), R 4a is a hydrogen atom or a C 1 -C 3 alkyl group, and R 5a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, or a pharmaceutically acceptable salt thereof. An amino acid derivative having the formula: wherein R 1a is selected from the group consisting of the alkyl groups and mono- or di-hydroxy-substituted alkyl groups which are represented by the formulae (i) - (vii):- R 3d is a C 1 -C 8 alkyl group or a group of the formula -(CH 2 ) c -R 14a (where R 14a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, and C is an integer of 1, 2 or 3), R 4a is a hydrogen atom or a C 1 -C 3 alkyl group, and R 5a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, or a pharmaceutically acceptable salt thereof. An amino acid derivative having the formula: wherein R 1b is a hydroxy- and amino-substituted alkyl group of the formula: R 3e is a group of the formula -(CH 2 ) c -R 14a (where R 14a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, and c is an integer of 1, 2 or 3), R 4a is a hydrogen atom or a C 1 -C 3 alkyl group, and R 5a is a hydroxyl group, a C 1 -C 3 alkoxy group or an aralkyloxy group, or a pharmaceutically acceptable salt thereof". A pharmaceutical composition which comprises as an active ingredient the amino acid derivative having the formula (I-1) according to Claim 1, having the formula (I-1') according to Claim 3, having the formula (I-2) according to Claim 4, having the formula (I-3) according to Claim 5, having the formula (I-4) according to Claim 6 or having the formula (I-5) according to Claim 7, and which is for use as an immunomodulator, an antitumor agent or a hematopoietic stem cell-amplifying agent, and a pharmaceutically acceptable carrier for said active ingredient. Use of the amino acid derivative having the formula (I-1) according to Claim 1, having the formula (I-1') according to Claim 3, having the formula (I-2) according to Claim 4, having the formula (I-3) according to Claim 5, having the formula (I-4) according to Claim 6 or having the formula (I-5) according to Claim 7 or a salt thereof, for the manufacture of an immunomodulating agent, an antitumor agent or a hematopoietic stem cell amplifier.

Inventors: FUSE YOSHIHIDE, ISHIZUKA MASAAKI, KATSUMI TOSHIAKI, KAWAZU MASAJI, MAEDA KENJI, TAKEUCHI TOMIO, FUSE, YOSHIHIDE, ISHIZUKA, MASAAKI, KATSUMI, TOSHIAKI, KAWAZU, MASAJI, MAEDA, KENJI, TAKEUCHI, TOMIO, ISHIZUKA, MASAAKI PASTRAL HEIM ICHIBANKAN 411, KAWAZU, MASAJI MARUKEI MANSION 201
Applicants: KANEGAFUCHI CHEMICAL IND, ZAIDAN HOJIN BISEIBUTSU, KANEGAFUCHI KAGAKU KOGYO KABUSHIKI KAISHA, ZAIDAN HOJIN BISEIBUTSU KAGAKU KENKYU KAI
Application year: 1993
Main classification: C07C233
IPC codes: C07C323, C07C235, C07D233, C07C233, C07C237