MURAMYL PEPTIDE DERIVATIVES AND USE THEREOF

Abstract: Muramyl peptide derivatives having the formula (I) wherein R₃ is a long chain acyloxyacyl group, R₁ is hydrogen or hydroxy mercapto, acyloxy or acylthio group, R₂ is hydrogen or alkyl group and R₄ is acyl, which are useful as immuno­ modulators.

Description: 1. Background of the Invention (1) Field of the Invention This invention relates to novel muramyl peptide derivatives. The muramyl peptide derivatives can act on immunological mechanisms (especially on cells relevant to immune responses) in the living body of mammals including human being and are useful as immunomodulators. (2) Description of the Prior Art It is known that muramyl peptides possess a wide variety of biological activities. As their in vitro activities, there are a) activity on cells relevant to immune response (e.g., monocytes and macrophages, B lymphocytes, T lymphocytes, natural killer cells or the like); b) activity on other cells (e.g., thrombocytes, fibroblasts, osteoclasts or the like); c) activation of the complement system and so forth. As in vivo activities, there are a) modulation of immune responses; b) increase of natural resistance against microbial infections and tumor development, and so forth [see S. Kotani and H. Takada: Immunopharmacological activities of bacterial cell walls and related synthetic compounds (muramyl peptides), YAKUGAKU ZASSHI, 103(1) , pp1 - 27(1983)]. Known muramyl peptides are e.g., B30-muramyl dipeptide [S. Kusumoto et al, Tetrahedron Lett. 49 , pp4899 - 4902(1978)], muramyl dipeptidelysin (K. Matsumoto et al., Immunostimulants, Now and Tomorrow p79 - 97, Japan Sci. Soc. Press, Tokyo, 1987), and those disclosed in Japanese patent unexamined publication Nos. 58-172399, 59-20297 and 61-275299. There is still need for other compounds having excellent activities than known muramyl peptide derivatives. 2. Summary of the Invention According to this invention, it provides a muramyl peptide derivative of the formula (I): in which "Ala" is "iso-Gln" is R₁ is hydrogen atom, hydroxy group, mercapto group, a C₂₋₂₀alkanoyloxy group, a C₂₋₂₀alkanoylthio group, R₃O- or R₃S-; R₂ is hydrogen atom or a C₁₋₂₀alkyl group, R₃ is a group of the sub-formula: (n is an integer of 10 - 14 and m is an integer 8 - 12); R₄ is a C₂₋₄alkanoyl group. It also provides an immunomodulator comprising the muramyl peptide derivative of the formula (I) and a pharmaceutically acceptable carrier. 3. Preferred Embodiments of the Invention In the definitions of the formula (I), examples of the C₂₋₂₀alkanoyloxy group or C₂₋₂₀alkanoylthio group in R₁ are acetoxy, acetylthio, propionyloxy, propionylthio, butyryloxy, butyrylthio, valeryloxy, valerylthio, iso-valeryloxy, iso-valerythio, pentanoyloxy, pentanoylthio, pivaloyloxy, pivaloylthio, heptanoyloxy, heptanoylthio, octanoyloxy, octanoylthio, nonanoyloxy, nonanoylthio, decanoyloxy, decanoylthio, undecanoyloxy, undecanoylthio, dodecanoyloxy, dodecanoylthio, tridecanoyloxy, tridecanoylthio, tetradecanoyloxy, tetradecanoylthio, pentadecanoyloxy, pentadecanoylthio, hexadecanoyloxy, hexadecanoylthio, heptadecanoyloxy, heptadecanoylthio, octadecanoyloxy, octadecanoylthio, nonadecanoyloxy, nonadecanoylthio, eicosayloxy and eicosaylthio. The preferred one is tetradecanoyloxy or tetradecanoylthio. Examples of the C₁₋₂₀alkyl group in R₂ are methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, nonyl, decanyl, undecanyl, dodecanyl, tridecanyl, tetradecanyl, pentadecanyl, hexadecanyl, heptadecanyl, octadecanyl, nonadecanyl and eicosanyl. Examples of the group of the sub-formula: are 3-dodecanoyloxydodecanoyl, 3-tridecanoyloxydodecanoyl, 3-tetradecanoyloxydodecanoyl, 3-hexadecanoyloxydodecanoyl, 3-pentadecanoyloxydodecanoyl, 3-dodecanoyloxytridecanoyl, 3-tridecanoyloxytridecanoyl, 3-tetradecanoyloxytridecanoyl, 3-pentadecanoyloxytridecanoyl, 3-hexadecanoyloxytridecanoyl, 3-dodecanoyloxytetradecanoyl, 3-tridecanoyloxytetradecanoyl, 3-tetradecanoyloxytetradecanoyl, 3-pentadecanoyloxytridecanoyl, 3-hexadecanoyloxytetradecanoyl, 3-dodecanoyloxypentadecanoyl, 3-tridecanoyloxypentadecanoyl, 3-tetradecanoyloxypentadecanoyl, 3-pentadecanoyloxypentadecanoyl, 3-hexadecanoyloxypentadecanoyl, 3-dodecanoyloxyhexadecanoyl, 3-tridecanoyloxyhexadecanoyl, 3-tetradodecanoyloxyhexadecanoyl, 3-pentadecanoyloxyhexadecanoyl and 3-hexadodecanoyloxyhexadecanoyl. Among such acyloxyacyl groups, 3-hexadecanoyloxytetradecanoyl, 3-tetradecanoyloxytetradecanoyl and 3-dodecanoyloxytetradecanoyl are preferable. Examples of the C₂₋₄alkanoyl group in R₄ are acetyl, propionyl, butyryl and isobutyryl, among which acetyl is preferable. R₁ is preferred to be hydrogen or hydroxy. R₂ is preferred to be hydrogen or methyl. "Ala" is preferred to be a residue of L-alanine and "iso-Gln" is preferred to be a residue derived from D-isoglutamine. The compounds of the formula (I) in the invention are basically derivatives of muramyl dipeptide, and hence the muramyl dipeptide moiety is desirously to be that having the same configuration as in natural muramyl dipeptide. That is, the muramic acid moiety is D-configuration and the dipeptide moiety is L-alanine-D-isoglutamine. However, muramyl dipeptides having other configurations which may exist are included in this invention. The acyloxyacyl group in R₃ possesses one asymmetric carbon atom and may be D-form, L-form or mixture thereof. Further, the compound of the formula (I) of R₂ being hydrogen atom contains one carboxyl group, which may form a pharmaceutically acceptable salt (e.g., an alkalimetal salt such as sodium or potassium salt). Such salt is also included in this invention. Specifically, interesting compounds according to this invention may be mentioned as follows. N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxydodecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxydodecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxydodecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxyhexadecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxyhexadecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxyhexadecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxydodecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxydodecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxydodecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxyhexadecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxyhexadecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxyhexadecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxydodecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxydodecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxydodecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxyhexadecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxyhexadecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxyhexadecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxydodecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxydodecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxydodecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxyhexadecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxyhexadecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxyhexadecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxydodecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxydodecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxydodecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]- L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadeccanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecadecanoyloxyhexadecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-tetradecanoyloxyhexadecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxyhexadecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxydodecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxydodecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxydodecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]- L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxyhexadecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxyhexadecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxyhexadecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{1-O-tetradecanoyl-2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{1-O-tetradecanoyl-2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{1-O-tetradecanoyl-2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{1-O-tetradecanoyl-2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{1-O-tetradecanoyl-2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine, N-[[2-O-{1-O-tetradecanoyl-2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine and N-[[2-O-{1-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine. The compounds of the formula (I) may be prepared basically by the following method A or B. In the formulae, R₂, R₃ and R₄ have the same meanings as those in the formula (I), X is -OY or -SY (Y is a protecting group) and X′ is hydroxy or mercapto group. Method A consists of acylation step and step for removing a protecting group. The acylation step is conducted by reacting a compound of the formula (II) with an acylating agent (R₃H or its reactive derivative). This step may be generally carried out in an anhydrous organic solvent such as dimethylformamide or dioxane at room temperature or a slightly elevated temperature. When R₃H (free acid) as the acylating agent is used, the reaction is conducted in the presence of an appropriate condensing agent (e.g., N,N-dicyclohexylcarbodiimide, N-cyclohexyl-N′-morpholinolino-ethylcarbodiimide, N-cyclohexyl-N′-(4-diethylaminocyclohexyl)carbodiimide or N,N′-diethylcarbodiimide). As the reactive derivatives of R₃H may be utilized conventional reactive derivatives used in the acylation such as mixed anhydrides, acid active esters or acid halides. Protecting groups for protected hydroxy or mercapto group of X in the compound of the formula (II) are preferred to be easily removed under mild condition after the reaction. Examples of the protecting group are benzyl, phenacyl or trialkylsilyl (e.g., trimethylsilyl). The removal for the protecting group may be generally conducted by solvolysis using water, alcohol or the like,or catalytic reduction in the presence of palladium catalyst, on which conventional conditions may be applied. As the compounds of the formula (II), typical known compound is of R₂ being methyl, R₄ being acetyl and X being hydroxy. Other compounds (II) may be prepared in accordance with the method known for the above mentioned known compound and be utilized. Furthermore, in the above method, it is desired to use the compound of the formula (II) wherein R₂ is a lower alkyl group. When the compound of the formula (IV) wherein R₂ is hydrogen atom is desired, it can be obtained by using the compound of the formula (II) wherein R₂O- is a protected hydroxy group (which can utilize the same protecting group for hydroxy group of X) and removing the protecting group after the acylation step. In the above formulae, X′ is hydroxy group or mercapto group and X″ is C₂₋₂₀alkanoyloxy or, C₂₋₂alkanoylthio, R₃O- or R₃S-, and R₂, R₃ and R₄ have the same meanings as those in the formula (I). Method B consists of two kinds of acylation steps, i.e., acylations at 6th and lst positions of the glucopyranose moiety, and de-acetone step. The two kinds of acylation steps may be conducted under condition similar to that of the acylation step in Method A. The acylation step at 1st position of the glycopyranose moiety includes to use an acylating agent different from one in the acylation at 6th position (C₂₋₂₀alkane carboxylic acid or its reactive derivative). The de-acetone step may be easily conducted by an acidic hydrolysis e.g., using 80% acetic acid aqueous solution at slightly elevated temperature. Besides, the compounds of the formula (V) are known or may be easily prepared by known methods. The compounds as obtained by the above methods may be purified in accordance with conventional methods such as column chromatography using almina or silica gel, or recrystallization. The compounds of the formula (I) possess activities for enhancing functions of cells relating to immune responses in the living bodies or for increasing numbers of the above cells and are useful as immunomodulators. Specifically, they may be, as immunomodulators, used for enhancing in vivo actions of vaccines such as BCG vaccines, hepatitis vaccines or infuluenza vaccines, various anti-bacterial agents or various antitumor agents. The immunomodulator of this invention comprises a compound of the formula (I) and a pharmaceutically acceptable carrier. The immunomodulator may be an oral or parenteral form. The oral form may be generally powders, tablets, emulsions, capsules, granules or liquids (including syrups). Examples of solid carriers for the oral form are lactose, starch, dextrin, calcium phosphate, calcium carbonate, synthetic or natural aluminum silicates, magnesium oxide, dry aluminum hydroxide, magnesium stearate, sodium hydrogen carbonate or dry yeast. Examples of liquid carriers for the oral form are water, glycerin or simple syrup. The parenteral form is typically an injection. A carrier for the injection is generally sterilized distilled water. When the compound of the formula (I) is not easily soluble in water, an appropriate solubilizing agent is used. Each of the preparations mentioned above may be prepared in accordance with conventional methods in the art. The compound of the formula (I), when used for enhancing antitumour agents may be orally or parenterally administered generally in an amount of 150 - 250 µg/once a day for an adult. For enhancing vaccines, it may be generally administered in 0.5 - 2.0 mg/once in a week or two weeks for an adult. For enhancing hepatitis, it may be administered in a single dose of 0.5 - 2.0 mg/one or three times per three months. Further, for enhancing antibacterial agents, it may be administered in 20 - 100 µg/once a day for an adult. The compound of the formula (I) is generally formulated in itself together with an appropriate carrier, as mentioned above but may be formulated in combination with vaccines, antitumour agents or antibacterial agents to be strengthened. Furthermore, the immunomodulator of this invention may be used for human being and also other mammals such as pig, cow, sheep, dog or cat. Example 1 N-[[2-O-{2-Acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester: A compound [(I): R₁ = C₆H₅CH₂O, R₂ = CH₃, R₃ = H, R₄ = CH₃CO], 150.0 mg was dissolved in 1 ml of dimethylformamide (DMF) and 1.5 ml of dioxane, to which 128.8 mg of (3R)-3-dodecanoyloxytetradecanoic acid, 15 mg of 4-dimethylaminopyridine (DMAP) and 78 mg of dicyclohexylcarbodiimide (DCC) were added and stirred for 16 hours at room temperature. After confirming the completion of reaction by a thin-layer chromatography (CH₂Cl₂: CH₃OH = 5 : 1 v/v), 1 ml of methanol was added to the reaction mixture. The mixture was concentrated under reduced pressure to give a syrup. The syrup was subjected to a silica gel column chromatography [9 g of silica gel (Wako gel ®C 200), eluents of CH₂Cl₂ = MeOH v/v: (a) 150 : 1, (b) 70 : 1, (c) 40 : 1 and (d) 30 : 1]. The eluate (c) was concentrated under reduced pressure to obtain a syrup containing DMAP. The syrup was further purified by an almina column chromatograph [eluents of CH₂Cl₂ : MeOH v/v : (a) 100 : 1 and (b) 50 : 1] to afford 119.7 mg (47.3 %) of the compound (I): Rl = C₆H₅CH₂O, R₂ = CH₃, R₃ = (3R)-3-dodecanoyloxytetradecanoyl, R₄ = CH₃CO) having mp 153 - 154.0°C. A solution of 83.1 mg of the above mentioned compound in 2 ml of methanol and 1 ml of hexane was subjected to a catalytic hydrogenation using 100 mg of 10 % Pd-C for 4 days at room temperature. After confirming the completion of reaction by TLC (CH₂Cl₂: MeOH = 6 : 1), the reaction mixture was filtered to remove the catalyst and washed with a mixture of dichloromethane and methanol (1 : 1). The combined filtrate and washing was concentrated under reduced pressure to afford 75.6 mg (quantitative) of the title compound. MP: 115 - 116°C [α] D (C = 1.038, CH₂Cl₂: MeOH = 1 : 1): + 29.06° IRλ max cm⁻¹(KBr): 3400, 2940, 2860, 1730, 1650, 1540. Analysis for C₄₆H₈₂N₄O₁₄ Found (%): C 60.37; H 9.03; N 6.12. Example 2 N-[[2-O-{2-Acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester In using (3R)-3-tetradecanoyloxytetradecanoic acid instead of (3R)-3-decanoyloxytetradecanoic acid, example 1 was repeated to afford 117.2 mg of the title compound. MP: 115.0 - 116.0°C [α] D (C = 1.038, CH₂Cl₂: MeOH = 1 : 1): + 26.95° IRλ max cm⁻¹ (KBr): 3400, 2940, 2860, 1730, 1650, 1540. Analysis for C₄₈H₈₆N₄O₁₄ Found (%): C 61.12; H 9.18; N 5.94. NMR (CDCl₃-CD₃OD), δ(ppm): 0.88(t,6H,J=6.6Hz), 1.25-1.58(m,42H), 1.38(d,3H,J=6.6Hz), 1.40(d,3H,J=7.0Hz), 1.98(s,3H), 2.28(t,2H,J=7.7Hz), 2.44-2.61(m,4H), 3.69(s,3H). 5.76(m,1H), 5.34(d,1H,J=2.6Hz). Example 3 N-[[2-O-{2-Acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester: In using 194.4 mg of (3R)-3-hexadecanoyloxytetradecanoic acid instead of (3R)-3-dodecanoyloxytetradecanoic acid and 200.0 mg of the compound [(I): R₁ = C₆H₅CH₂O, R₂ = CH₃, R₃ = H, R₄ = CH₃CO], example 1 was repeated to afford 147.7 mg (41.5 %) of the (3R)-3-hexadecanoyloxytetradecanoyl compound as intermediate and 105.0 mg of the title compound. MP: 115.0 - 116°C [α] D (C = 0.864, CH₂Cl₂: MeOH = 1 : 1): + 25.95° IRλ max cm⁻¹ (KBr): 3400, 2940, 2860, 1730, 1600, 1540. Analysis for C₅₀H₉₀N₄O₁₄ Found (%): C 61.83; H 9.33; N 5.77. NMR (CDCl₃-CD₃OD), δ(ppm): 0.88(t,6H,J=6.6Hz), 1.25-1.58(m,46H), 1.38(d,3H,J=6.6Hz), 1.40(d,3H,7.0Hz), 1.98(s,3H), 2.28(t,2H,J=7.5Hz), 2.44-2.61(m,4H), 3.69(s,3H), 5.26(m,1H), 5.35(d,1H,J=2.9Hz). Example 4 N-[[2-O-{2-Acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester: A compound [(I): R₁ = H, R₂ = CH₃, R₃ = H, R₄ = CH₃CO] 150 mg was dissolved in 1 mg of DMF under warming, to which 144.9 mg of (3R)-3-dodecanoyloxytetradecanoic acid, 17 mg of DMAP and 117 mg of DCC were added and stirred for 24 hours at room temperature. After completing the reaction, the mixture was subjected to a silica gel chromatography [eluents of CH₂Cl₂ : MeOH = (a) 150 : 1, (b) 60 : 1, (c) 40 : 1 and (d) 30 : 1 ] and the eluate (c) was concentrated under reduced pressure to obtain a syrup remaining DMAP. The syrup was subjected an alumina chromatography using eluents of CH₂Cl₂: MeOH being (a) 100 : 1 and (b) 50 : 1. The title compound, 85.8 mg (33.7 %) was obtained from the eluate (b). MP: 128.0 - 129.0°C [α] D (C = 1.232, CH₂Cl₂: MeOH = 1 : 1): + 15.58° IRλ max cm⁻¹ (KBr): 3300, 2940, 2860, 1740, 1660, 1550. Analysis for C₄₆H₈₂N₄O₁₃ Found (%): C 61.44; H 9.19; N 6.23. NMR (CDCl₃-CD₃OD), δ(ppm): 0.88(t,6H,J=6.6Hz), 1.26-1.59(m,38H), 1.38(d,3H,J=5.9Hz), 1.40(d,3H,J=6.6Hz), 1.96(s,3H), 2.28(t,2H,J=7.5Hz), 2.42-2.62(m,4H), 3.06(t,1H,J=11.0Hz), 3.69(s,3H), 4.17(dd,1H,J=11.0,5.1Hz), 5.24(m,1H). Example 5 N-[[2-O-{2-Acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-tetradodecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester: In using (3R)-3-tetradecanoyloxytetradecanoic acid instead of (3R)-3-dodecanoyloxytetradecanoic acid, example 4 was repeated to afford 117.3 mg (44.6 %) of the title compound. MP: 128.0 - 129°C [α] D (C = 1.005, CH₂Cl₂: MeOH: 1 : 1): + 14.62° IRλ max cm⁻¹ (film): 3400, 3300, 2940, 2860, 1740, 1640, 1550. Analysis for C₄₈H₈₆N₄O₁₃ Found (%): C 62.17; H 9.34; N 6.04. NMR (CDCl₃-CD₃OD), δ(ppm) 0.88(t,6H,J=6.6Hz), 1.26-1.59(m,42H), 1.38(d,3H,J=6.2Hz), 1.40(d,3H, J=6.2Hz), 1.96(s,3H), 2.28(t,2H,J=7.7Hz), 2.42-2.62(m,4H), 3.06(t,1H,J=11.0Hz), 3.69(s,3H), 4.16(dd,1H,J=11.0,5.1Hz), 5.24(m,1H). Example 6 N-[[2-O-{2-Acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester: In using 164.0 mg of (3R)-3-hexadecanoyloxytetradecanoic acid instead of (3R)-3-dodecanoyloxytetradecanoic acid, example 4 was repeated to afford 100.1 mg of the title compound. MP: 128 - 129°C [α] D C = 0.818, CH₂Cl₂: MeOH = 1 : 1): + 13.81° IRλ max cm⁻¹ (film): 3400, 3300, 2940, 2850, 1740, 1650, 1540. NMR (CDCl₃-CD₃OD), δ(ppm): 0.88(t,6H,J=5.7Hz), 1.26-1.60(m,46H), 1.38(d,3H,J=6.2Hz), 1.40(d,3H,J=6.2Hz), 1.96(s,3H), 2.28(t,2H,J=7.3Hz), 2.44-2.62(m,4H), 3.69(s,3H), 4.15(dd,1H,J=11.4,5.1Hz), 5.24(m,1H). Example 7 N-[[2-O-{2-Acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester: To a solution of 200.0 mg of a compound [(I): R₁ = SCOCH₃, R₂ = CH₃, R₃ = H, R₄ = CH₃ CO ] in 1 ml of DMF and 1.5 ml of dioxane were added 181.3 mg of (3R)-3-dodecanoyloxytetradecanoic acid, 22 mg of DMAP and 146 mg of DCC, followed by stirring for 3 hours at room temperature. After completing the reaction, 1 ml of methanol was added to the reaction mixture and the mixture was concentrated under reduced pressure. The resulting syrup was subjected to a silica gel chromatography [eluents of CH₂C₁₂: MeOH = (a) 150 : 1, (b) 60 : 1, (c) 40 : 1 and (d) 30 : 1]. The eluate (c) was concentrated under reduced pressure to obtain syrup remaining DMAP. The syrup was further purified through an almina chromatography [eluents of CH₂Cl₂: MeOH = (a) 100 : 1, (b) 50 : 1]. The title compound, 96.9 mg (28.6 %) was obtained from the eluate (b). MP: 102.0 - 103.0°C [α] D (C = 0.960, CH₂Cl₂: MeOH = 1 : 1): + 8.75° IRλ max cm⁻¹ (film): 3300, 2940, 2860, 2550, 1740, 1660, 1540. Analysis for C₄₆H₈₂N₄O₁₃S Found (%): C 59.33; H 8.87; N 6.02. NMR (CDCl₃-CD₃OD), δ(ppm): 0.88(t,6H,J=6.4Hz), 1.26-1.60(m,38H), 1.36(d,3H,J=7.0Hz), 1.42(d,3H,J=7.3Hz), 1.96(s,3H), 2.30(t,2H,J=7.5Hz), 2.36-2.64(m,4H), 3.70(s,3H), 4.48(d,1H,J=9.9Hz), 5.25(m,1H). Example 8 N-[[2-O-{2-Acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester: In using 193.2 mg of (3R)-3-tetradecanoyloxytetradecanoic acid instead of (3R)-3-dodecanoyloxytetradecanoic acid, example 7 was repeated to afford 111.4 mg (31.9 %) of the title compound. MP: 102.0 - 103.0°C [α] D (C = 1.294, CH₂Cl₂: MeOH = 1 : 1): + 8.19° IRλ max cm⁻¹ (film): 3400, 3300, 2940, 2860, 2550, 1740, 1660, 1540. Analysis for C₄₈H₈₆N₄O₁₃S Found (%): C 60.09; H 9.03; N 5.84. NMR (CDCl₃-CD₃OD), δ(ppm): 0.88(t,6H,J=6.6Hz), 1.26-1.60(m,42H), 1.36( ,3H,J=7.0Hz), 1.42(d,3H,J=7.0Hz), 1.97(s,3H), 2.30(t,2H,J=7.6Hz), 2.42-2.62(m,4H), 3.70(s,3H), 4.50(d,1H,J=9.9Hz), 5.25(m,1H). Example 9 N-[[2-O-{2-Acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadodecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester: In using 205.1 mg of (3R)-3-hexadecanoyloxytetradecanoic acid instead of (3R)-3-dodecanoyloxytetradecanoic acid, example 7 was repeated to afford 106.6 mg of the title compound. Mp: 102.0 - 103.0°C [α] D (C = 1.066, CH₂Cl₂: MeOH = 1 : 1): + 7.58° IRλ max cm⁻¹ (film): 3400, 3300, 2940, 2860, 2550, 1740, 1640, 1540. Analysis for C₅₀H₉₀N₄O₁₃S Found (%): C 60.82; H 9.18; N 5.67. According to one aspect of the invention, it provides a method for treating a patient suffering immune depression due to tumors or hepatitis which comprises administering to the patient an immunomodulator of the invention and an antitumor agent or antihepatitic agent, simultaneously or separately. It also provides a method for preventing infection of influenza virus to human being which comprises administering to the human being an immunomodulator of the invention and a vaccine for influenza virus, simultaneously or separately. Next, pharmacological activities on typical compounds of the invention are shown as follows. (1) Enhancing action on BCG vaccine (adjuvant activity) 0.2 ml of an equivalent weight mixture of a solution of BCG killed vaccine in physiological saline (100 µg/ml) and a solution of a compound of the invention in Freund's incomplete adjuvant (1000 µg/ml) was subcutaneously injected to the back of ICR mouse (one group consisting of 7 mice). After 14 days, 10 µg of tuberculin was intradermally injected into the hind foot-pad. Swelling of the foot-pad was measured after 24 hours (24 hours foot-pad test). The control is the above mentioned mixture excluded a compound of the invention. The results of the foot-pad test are shown in Table. Test Compound Swelling of Foot-pad (x 0.01 mm) Example 1 59.2 ± 15.1 2 57.4 ± 16.3 3 66.2 ± 12.3 4 78.6 ± 19.1 5 69.3 ± 18.8 6 86.4 ± 22.1 7 50.6 ± 13.6 8 51.8 ± 11.0 9 49.1 ± 12.0 Control 46.0 ± 16.5 (2) Enhancing effect on hepatitis vaccine (adjuvant activity) A compound of the invention was dissolved or suspended in physiological saline (100 µg/ml), and mixed with a solution of B type hepatitis vaccine (HBs) in physiological saline (100 µg/ml) at an equivalent weight ratio to obtain the test solution. A solution excluded the compound of the invention from the test solution was used as control. The test solution (0.2 ml) was intraperitoneally injected into CDF₁ mouse (one group consisting of 10 mice). At 3 weeks after the administration, a blood was taken from the intravenus vein in eyeground of each the mice and centrifuged to obtain serum (primary response serum). Further, 0.2 ml of the test solution was again intraperitoneally injected into each mice, and at 2 weeks stage, serum was separated in the similar way (secondary response serum). Value for IgG antibody against B type hepatitis virus of the resulting serum was measured by ELISA method. The results are shown in Table. Test compound Anti HBs-ELISA unit Primary response serum Secondary response serum Example 1 10,800 150,000 2 6,000 195,000 3 24,000 575,000 4 5,200 175,000 5 3,600 120,000 6 6,200 220,000 7 2,500 110,000 8 2,200 105,000 9 3,400 150,000 Control 1,500 30,000 (3) Enhancing effect on influenza HA vaccine (adjuvant activity) A compound of the invention was dissolved or suspended in physiological saline (100 µg/ml). Separately, influenza HA vaccine (A/Bangkok/10/83 strain, H1N1) was dissolved in physiological saline (100 CCA/ml). These two solutions were mixed in an equivalent weight to make the test solution. Control is a solution excluded the compound of the invention from the test solution. The test solution was administered into CDF₁ mouse in a similar way to that of the test of enhancing action for hepatitis vaccine as mentioned above, to obtain primary and secondary response sera. The results are as in Table Test compound Anti-influenza HA virus ELISA unit Primary response serum Secondary response serum Example 1 4,800 34,000 2 3,100 33,000 3 5,200 57,000 4 2,300 32,000 5 1,800 28,000 6 2,500 30,000 7 2,000 26,000 8 2,100 22,000 9 1,900 25,000 Control 1,100 8,300 (4) Activation for macrophages A test solution of a compound of the invention in physicological saline (500 µg/ml, 0.2 ml) was intraperitoneally injected into CDF₁ mouse (one group consisting of 10 mice). Intraperitoneal macrophages which were collected after 4 days and leukemia cells of L-1210 mouse were mixed at the cell ratio of 20 and 1. Each 200 µl of the mixture was put on a microplate having 96 holes. After 72 hours, numbers of cells in each holes were counted, and cytostatic rate of the mixture was measured. Test compound Cytostatic rate (%) Example 1 40.0 ± 1.2 2 45.2 ± 1.1 3 22.3 ± 1.0 4 55.2 ± 2.8 5 58.6 ± 2.9 6 42.6 ± 3.2 7 22.8 ± 2.6 8 31.6 ± 1.6 9 38.2 ± 2.2 Control (saline) 5.8 ± 0.8 (5) Stimulation effect on anti-body procuding cells A solution of sheep leukocytes (SRBC) in phosphate buffered physiological saline (5 x 10⁷ cells/ml), 0.2 ml was injected into tail intravenous vein of ICR mouse (7 mice per group). At the same time, a solution of a compound of the invention in physiological saline (500 µg/ml), 0.2 ml was similarly injected. After 4 days, lien was picked up from the treated mouse to obtain splenic cells. Plaque numbers were measured by Cunningham technique. The results are shown in Table. Test compound Plaque No. (x 10³) Stimulation Index Example 1 10.56 ± 8.3 2.2 2 8.23 ± 7.2 1.7 3 21.23 ± 9.9 4.4 4 6.67 ± 3.6 1.4 5 5.83 ± 3.2 1.2 6 6.81 ± 4.8 1.4 7 10.88 ± 9.8 2.3 8 8.63 ± 7.9 1.8 9 11.00 ± 10.1 2.3 Control (saline) 4.78 ± 2.46 1 (6) Phylactic effect A solution of a compound of the invention in physiological saline (500 µg/ml), 0.2 ml was intraperitoneally injected into ICR mouse (20 mice per group). After a day, E. coli (JC-2) and Pseud. aeruginosa (NCTC 10490) were incubated through intraperitoneal route so as to be at concentration of 1 x 10⁷/mouse. Survival rate after 7 days of infection was measured. Test compound Survival rate % E. coli Pseud. aeruginosa Example 1 50 45 2 55 45 3 45 40 4 65 50 5 70 55 6 60 50 7 30 20 8 35 20 9 40 15 Control (saline) 0 5 (7) Antitumour effect Meth A fibrosarcomas were suspended in phosphate buffered physiological saline (1 x 10⁶ cells/ml). Separately, a solution of a compound of the invention in physiological saline was prepared (1,000 µg/ml). An equivalent weight mixture of these two solution (0.2 ml) was subcutaneously injected into BALB/C mouse (20 mice per group). Survival rate after 35 days was measured. The results are shown in Table. Test Compound Survival rate (%) Example 1 30 2 30 3 20 4 35 5 35 6 30 7 10 8 5 9 5 Control 0

Claims: A muramyl peptide derivative having the formula (I): in which "Ala" is "iso-Gln" is R₁ is hydrogen atom, hydroxy group, mercapto group, a C₂₋₂₀alkanoyloxy group, a C₂₋₂₀alkanoylthio group, R₃O- or R₃S-; R₂ is hydrogen atom or a C₁₋₂₀alkyl group, R₃ is a group of the sub-formula: (n is an integer of 10 - 14 and m is an integer of 8 - 12); and R₄ is a C₂₋₄alkanoyl group. A compound of claim 1 wherein R₃ is 3-dodecanoyloxytetradecanoyl or 3-hexadecanoyloxytetradecanoyl group. A compound of claim 1 wherein R₁ is hydrogen atom or hydroxy group. A compound of claim 1 wherein R₄ is acetyl group. A compound of claim 1 wherein R₂ is hydrogen atom or methyl group. A compound of claim 1 wherein "Ala" is a residue of L-alanine and "iso-Gln" is a residue derived from D-isoglutamine. A compound of claim 1 which is N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-1,5-anhydro-2,3-dideoxy-6-O-[(3R)-3-hexadecanoyloxytetradecanoyl]-D-glucitol-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester, N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-dodecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester or N-[[2-O-{2-acetamido-2,3-dideoxy-6-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-1-thio-β-D-glucopyranos-3-yl}-D-lactoyl]]-L-alanyl-D-isoglutamine methyl ester. An immunomodulator which comprises a compound of the formula (I) in claim 1 and a pharmaceutically acceptable carrier. An immunomodulator of claim 8 wherein the compound of the formula is a compound of any of claims 2 - 7. An immunomodulator of Claims 1 to 8 which is used to enhance activities in living body of BCG, hepatitis or influenza virus vaccines. An immunomodulator of Claims 1 to 8 which is used to enhance activities in living body of antibacterial agents. An immunomodulator of Claims 1 to 8 which is used to enhance activities in living body of antitumor agents.

Inventors: HASEGAWA, AKIRA
Applicants: HASEGAWA, AKIRA, THE NISSHIN OIL MILLS, LTD.
Application year: 1988
Main classification: C07K9
IPC codes: C07K9