JPH0745503B2 - Mitomycin derivatives - Google Patents

Description

TECHNICAL FIELD The present invention relates to mitomycin derivatives having antitumor activity and pharmaceutical agents containing the mitomycin derivatives.

BACKGROUND ART Mitomycin has excellent antitumor activity, but also has undesirable side effects such as a decrease in leukocytes. Therefore, attempts have been made to provide various derivatives with the aim of enhancing the activity or reducing the toxicity.

Among known mitomycin derivatives are mitomycin C derivatives and porfiromycin derivatives in which the amino group at the 7-position is modified, and these are described, for example, in U.S. Pat. No. 4,268,676, Japanese Patent Application Laid-Open Nos. 56-92288 and 57-188590, and Journal of Medicinal Chemistry.
edicinal Chemistry) 24 , 975-981 (1981), edicinal Chemistry 26 , 16-
20 (1983), 26 , 1453-1457 (1983), etc. These documents state that mitomycin derivatives in which the amino group at the 7-position is modified also exhibit antitumor activity in vivo.

Among mitomycin derivatives in which the amino group at the 7th position is modified, examples in which the substituent at the 7th position contains sulfur include those in which the substituent at the 7th position is a 2-thiazoleamino group, a 2-thienylmethylamino group, or a (4-sulfonamidophenyl)methylamino group (see JP-A-56-92288), a 2-mercaptoethylamino group, a 2-ethylthioethylamino group, a thiomorpholino group, a thiazolidinyl group, a 4-mercaptoanilino group, a 2-(4-methylthiazolyl)amino group, a 2-(5-methyl-1,3,4-thiadiazolyl)amino group, or a 4-(2,1,3-benzothiadiazolyl)amino group (see JP-A-57-11125).
(See Publication No. 88590).

Examples of mitomycin derivatives in which the substituent at the 7-position is RSS(CH ₂ ) ₂ NH— include 7-N-(2-propyldithioethyl)mitomycin C, 7-N-(2-methoxycarbonylmethyldithioethyl)mitomycin C, 7-N-[2-(2-
and 7-N-[2-(4-acetamidophenyldithio)ethyl]mitomycin C (see EP 0116208A1 and JP 59-175493 A), and those in which R is an aromatic ring having a substituent, such as 7-N-[2-(4-acetamidophenyldithio)ethyl]mitomycin C (see EP 0116208A1 and JP 59-175493 A).
59-175493), 7-N-[2-(4-fluorophenyldithio)ethyl]mitomycin C (see EP 016
3550A2, JP-A-60-255789), those in which R is a residue of an amino acid containing a thiol group or a peptide containing such an amino acid residue, for example, 7-N-[2-
[(L-cysteine-S-yl)thio]ethyl]mitomycin D, 7-N-[2-[(glycino-L-cysteine-S-yl)thio]ethyl]mitomycin C, etc. (see EP 0163550A2, JP-A 60-255789).

Examples of mitomycin derivatives having a group represented by _{-NHCH2CH2SSCH2CH2NH-} at the 7-position _{include 7} -N, _7'-
N'-dithiodiethylenedimitomycin C, 7-N,
7'-N'-dithiodiethylenedimitomycin D, 7
7-N-[2-(2-aminoethyldithio)ethyl]mitomycin C, 7-N-[2-(2-aminoethyldithioethyl]mitomycin D (EP 0116208A1, JP 5984-10226 A1),
-104386, and 59-175493).

Furthermore, a compound reported as a derivative of mitomycin C having an R ⁹ -SS-alk ₂ -NH group at the 7-position (JP-A-59-205382)
As an example, in 7th place There are derivatives of mitomycin C having the formula:
_CH3- , The example given is, specifically, the 7th place Only examples of mitomycin C derivatives having the formula and 1a-acetylmitomycin C derivatives are given, and there are no examples for other compounds, and no description of physical property data or antitumor data.

An object of the present invention is to provide a mitomycin derivative in which the amino group at position 7 is modified, which has superior antitumor activity, reduced side effects, and/or advantageous solubility in terms of formulation, and an antitumor composition containing the derivative.

DISCLOSURE OF THE INVENTION The present invention provides a mitomycin derivative represented by the following formula (I):

wherein X' and X" represent a hydrogen atom or a lower alkyl group; Y and Z represent a hydrogen atom or a methyl group; provided that when Z is a hydrogen atom, Y is limited to a methyl group.
one of _R1 and _R2 is a carbamoyloxymethyl group,
The other represents a hydrogen atom. n is an integer of 1 to 4.
X is selected from the following definitions (1) to (4).

(1) X is R ₃ NH, R ₃ O or R ₃ S.

[wherein _R3 represents a residue excluding OH of the carboxyl group of an organic acid, a lower alkanoyl group or a halogen-substituted lower alkanoyl group.

The organic acid is selected from α-amino acids, orotic acid, isoorotic acid, nicotinic acid, isonicotinic acid, thiophenecarboxylic acid, furancarboxylic acid, vitamin A acid, saturated aliphatic mono- or dicarboxylic acids, and unsaturated aliphatic mono- or dicarboxylic acids.

When the α-amino acid has a second carboxyl group, the carboxyl group may be protected with a lower alkyl group or may form a salt with an alkali metal, ammonium or organic amine.

The amino group of the α-amino acid may be protected with a lower alkanoyl group, and may form a salt with an inorganic or organic acid.

When the dicarboxylic acid has a second carboxyl group, the second carboxyl group may be protected by a lower alkyl group, or may be ester-linked with the phenolic hydroxyl group of the tocopherol, or may form a salt with an alkali metal, ammonium or organic amine.

However, when R ₁ is a carbamoyloxymethyl group and R ₂ is a hydrogen atom, R ₃ of R ₃ NH is not a lower alkanoyl group.

(2) X is Represents.

[wherein R ₄ represents a residue excluding a hydrogen atom of an alcohol or organic amine.

The alcohol is selected from β-estradiol, β-estradiol 3-benzoate, retinol, cortisone or corticosterone.

The organic amine is selected from ammonia, a primary amine, a secondary amine, an α-amino acid, isoproterenol, epinephrine, or norepinephrine.

If the α-amino acid has a second amino group,
The amino group may be protected by a lower alkanoyl group, and may form a salt with an inorganic or organic acid.

The carboxyl group of the α-amino acid may be protected with a lower alkyl group or may form a salt with an alkali metal, ammonium or organic amine.

(3) X is Represents.

(4) X is Represents.

[wherein _R5 represents a hydrogen atom, a ribofuranosyl group, or a 2-deoxyribofuranosyl group; (CX'X'') _n represents _CH2
is].

The mitomycin derivative represented by formula (I) will hereinafter be referred to as compound I. The same applies to compounds having other formula numbers.

In the definition of Compound I, the lower alkyl group is a group having 1 carbon atom
-4 alkyl groups such as methyl, ethyl, n-propyl, t-butyl, etc. are suitable.

Suitable α-amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, etc. The stereoconfiguration of these α-amino acid residues may be any of the LDDL configurations.

Examples of saturated aliphatic monocarboxylic acids include tetradecanoic acid,
Hexadecanoic acid, octadecanoic acid, etc. are suitable.

Suitable aliphatic saturated dicarboxylic acids include malonic acid, succinic acid, and glutaric acid.

Suitable aliphatic unsaturated monocarboxylic acids include oleic acid and linoleic acid.

Suitable aliphatic unsaturated dicarboxylic acids include maleic acid and fumaric acid.

The lower alkanoyl group includes an alkanoyl group having 1 to 4 carbon atoms, such as formyl, acetyl, propanoyl,
Suitable examples include n-butanoyl and t-butanoyl.

Suitable examples of the halogen-substituted lower alkanoyl group include chloroacetyl, dichloroacetyl, trichloroacetyl, fluoroacetyl, difluoroacetyl, trifluoroacetyl, 2-chloropropionyl, 3-chloropropionyl, 2,3-dichloropropionyl, and the like.

Suitable primary amines include ethylamine and monoethanolamine, and suitable secondary amines include pyrrolidine, piperidine, morpholine, and thiomorpholine.

Suitable alkali metals include sodium and potassium.

Suitable organic amines used to form salts include monoethanolamine, N-methylglucamine, triethanolamine, and the like.

Suitable inorganic acids used to form salts include carbonic acid, sodium hydrogen sulfate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, etc., and suitable organic acids include ascorbic acid, citric acid, succinic acid, acetic acid, tartaric acid, lactic acid, etc.

It has been found that when Z in compound (I) is a hydrogen atom, a novel albomitomycin-type compound (I') represented by the formula (I') below can be obtained by a rearrangement reaction (equilibration reaction) of compound (I).

[wherein X, X', X'', R ₁ , R ₂ , Y and n are as defined above].

It is known that mitomycin A and mitomycin C exist in two forms, the mitomycin type and the albomitomycin type (27th Symposium on Natural Organic Compounds, Abstracts, pp. 672-679, 1985, Hiroshima). The compound of the present invention was also found to exist in these two forms.

When Compound 1 of Example 1 was allowed to stand in an aqueous solution (5 mg/ml) at 25°C for 24 hours to reach equilibrium, the molar ratio of the albomitomycin-type substance was 8.5%. It was found that the albomitomycin-type substance in the compounds of the present invention gradually changes to the mitomycin-type substance. For example, in the case of Compound I, the half-life of an aqueous solution (5 mg/ml) at 26°C was 50 minutes, and equilibrium was reached in 5 hours. Therefore,
The albomitomycin-type substance in the compounds of the present invention is believed not to adversely affect the antitumor activity of the corresponding mitomycin-type substance, as has already been observed with mitomycin C. Furthermore, by selecting the reaction conditions, the ratio of the two substances in the various compounds of the present invention can be maintained constant. Therefore, the fact that the compounds of the present invention consist of two types of substances is not expected to have any clinically significant adverse effects. The names and structures of Compound I are shown in Tables 1 and 2.

Table 1 Compound Name 1 7-N-[2-[[2-( ^N5 -L-glutamino)ethyl]dithio]ethyl]mitomycin C 2 7-N-[2-[[2-( ^N5 -L-glutamino)ethyl]dithio]ethyl]mitomycin D 3 7-N-[2-[[2-( ^N5 -D-glutamino)ethyl]dithio]ethyl]mitomycin C 4 7-N-[2-[[3-( ^N5 -L-glutamino)propyl]dithio]ethyl]mitomycin C 5 7-N-[2-[[4-( ^N5 -L-glutamino)butyl]dithio]ethyl]mitomycin C 6 7-N-[2-[[2-( ^N4 -L-asparagino)
ethyl]dithio]ethyl]mitomycin C7 7-N-[2-[[2-( ^N2 -L-asparagino)
ethyl]dithio]ethyl]mitomycin C 8 7-N-[2-[[2-(L-pyroglutamylamino)ethyl]dithio]ethyl]mitomycin C 9 7-N-[2-[[2-(N ² -L-glutamino)ethyl]dithio]ethyl]mitomycin C 10 7-N-[2-[[2-(N ⁴ -L-asparagino)
ethyl]dithio]ethyl]mitomycin D 11 7-N-[2-[[4-(N ⁵ -D-glutamino)ethyl]dithio]ethyl]mitomycin D 12 7-N-[2-[[2-(L-pyroglutamylamino)ethyl]dithio]ethyl]mitomycin D 13 7-N-[2-[[2-(L-prolylamino)ethyl]dithio]ethyl]mitomycin C 14 7-N-[2-[(2-orotamidoethyl)dithio]ethyl]mitomycin C 15 7-N-[2-[(2-retinamidoethyl)dithio]ethyl]mitomycin C 16 7-N-[2-[[2-[[2-[(2R)-2,
5,7,8-tetramethyl-2-[(4R,8R)-4,
8,12-trimethyltridecyl]-2H-1-benzopyran-6-yloxycarbonyl]ethyl]carboxamido]ethyl]dithio]ethyl] mitomycin C 17 7-N-[2-[(2-acetamidoethyl)dithio]ethyl] mitomycin D 18 7-N-[2-[(2-formamidoethyl)dithio]ethyl] mitomycin D 19 7-N-[2-[(2-trifluoroacetamidoethyl)dithio]ethyl] mitomycin C 20 7-N-[2-[(2-trifluoroacetamidoethyl)dithio]ethyl] mitomycin D 21 7-N-[2-[(2-carbamoylethyl)dithio]ethyl] mitomycin C 22 7-N-[2-[[2-[[(1S)-4-amino-
1-carboxybutyl]carbamoyl]ethyl]dithio]ethyl]mitomycin C 23 7-N-[2-[[2-[[(1S)-5-amino-
1-carboxypentyl]carbamoyl]ethyl]dithio]ethyl]mitomycin C 24 7-N-[2-[[2-[[(1S)-4-amino-
1-carboxybutyl]carbamoyl]ethyl]dithio]ethyl]mitomycin D 25 7-N-[2-[[2-[[(1S)-5-amino-
1-carboxypentyl]carbamoyl]ethyl]dithio]ethyl]mitomycin D 26 7-N-[2-[[[[17β-(3-benzoyloxy-1,3,5(10)-estratrienyloxy]
mitomycin C 27 7-N-[2-[[2-[[17β-(3-benzoyloxy-1,3,5(10)-estratrienyl)oxy]carbonyl]methyl]dithio]ethyl] mitomycin C 28 7-N-[2-[[[[17β-(3-benzoyloxy-1,3,5(10)-estratrienyl)oxy]carbonyl]methyl]dithio]ethyl] mitomycin D 29 7-N-[2-[[2-[[(ethoxycarbonyl)methyl]carbamoyl]ethyl]dithio]ethyl]
Mitomycin C 30 7-N-[2-[[1-[[(ethoxycarbonyl)methyl]carbamoyl]ethyl]dithio]ethyl]
Mitomycin C 31 7-N-[2-[[2-[[2-(3,4-dihydroxyphenyl)ethyl]carbamoyl]ethyl]dithio]ethyl]mitomycin C 32 7-N-[2-[[2-[(2S)-2-(3,4-
(dihydroxyphenyl)-2-hydroxy]ethyl]dithio]ethyl]mitomycin C 33 7-N-[2-[[2-(acetylthio)ethyl]
dithio]ethyl]mitomycin C 34 7-N-[2-[[2-(acetylthio)ethyl]
dithio]ethyl]mitomycin D 35 7-N-[2-[[2-(retinoyloxy)ethyl]dithio]ethyl]mitomycin C 36 7-N-[2-[(2-sulfoethyl)dithio]ethyl]mitomycin C {sodium salt} 37 7-N-[2-[[(2,4-dioxopyrimidin-5-yl)methyl]dithio]ethyl]mitomycin C 38 7-N-[2-[[(2,4-dioxopyrimidin-5-yl)methyl]dithio]ethyl]mitomycin D 39 7-N-[2-[[(2'-deoxyuridine-5
-yl)methyl]dithio]ethyl]mitomycin C 40 7-N-[2-[[(2'-deoxyuridine-5
[-yl]methyl]dithio]ethyl]mitomycin D Next, the production methods of Compound I will be explained by classifying them into three types, Methods A, B and C.

Method A Compound I is a compound of formula (II) [wherein _R1 , _R2 , Y and Z are as defined above] (see EP 0116208A1, JP-A-59-175493) with a compound of formula (III): X-(CX'X") _nSH (III) [wherein X, X'X" and n are as defined above] in an inert solvent.

The solvent used in the reaction includes halogenated lower alkanes such as chloroform and dichloromethane, methanol,
Suitable solvents include lower alkanols such as ethanol and isopropanol, as well as tetrahydrofuran, ethylene glycol dimethyl ether, dioxane, acetonitrile, dimethylformamide, dimethyl sulfoxide, and water. These can be used alone or in combination. The reaction temperature and reaction time vary depending on the compound (III), but are usually between 0 and 30°C and last for several minutes to several hours. Compound (I) can be purified by column chromatography, high-performance liquid chromatography, TLC, or other methods using various carriers.

The above steps are referred to as step A.

Compound III, in which X is R ₃ NH and R ₃ is a residue obtained by removing OH from the carboxyl group of an α-amino acid, is novel and can be obtained, for example, by the following step (A-1) or (A-2).

[wherein _R3 is a residue of an α-amino acid excluding the OH of the carboxyl group, all amino groups being protected with protecting groups commonly used in peptide synthesis, and when the α-amino acid has two carboxyl groups, one of the carboxyl groups is protected with a protecting group commonly used in peptide synthesis. Furthermore, functional groups in the side chain are also protected as necessary.]

R ₃ ″ is the residue of an α-amino acid excluding the OH of the carboxyl group (all protecting groups have been removed).

_R3 is a residue excluding the OH group of the carboxyl group of an α-amino acid, and when the α-amino acid has an amino group and a carboxyl group, the amino group is protected with a lower alkanoyl group or the carboxyl group is protected with a lower alkyl group.

X', X'' and n are as defined above.

Regarding the definition of R ₃ ' above, examples of the amino protecting group commonly used in peptide synthesis include benzyloxycarbonyl,
Suitable protecting groups for carboxyl groups include t-butyloxycarbonyl and the like. Examples of protecting groups for carboxyl groups commonly used in peptide synthesis include:
Suitable groups include benzyl and t-butyl.

The steps (A-1-1) to (A-1-5) will be explained in more detail.

Step (A-1-1) Compound III-1 and compound III-2 are condensed by a method commonly used in peptide synthesis, such as the active ester method or the acid chloride method.

The N,N'-dicyclohexylcarbodiimide (hereinafter referred to as DCC)-adduct method, which corresponds to the active ester method, will be explained in detail below.

To a solution of compound III-1 in an inert solvent (dichloromethane, chloroform, tetrahydrofuran, dioxane, dimethylformamide, etc.), about 1 equivalent of a condensing agent such as DCC and 1 equivalent of N-hydroxysuccinimide, 1-hydroxybenzotriazole, etc. are added and reacted at 0°C to room temperature for several to 12 hours to form an activated ester, to which compound III-2 is then added and reacted at 0°C to room temperature to obtain compound III-3. This reaction takes several tens of minutes to several hours. After isolating and purifying the activated ester, compound II
The resulting compound III-3 may be subjected to a reaction with I-2.
is purified by recrystallization or chromatography using silica gel, alumina, etc.

An example of compound III-3 is N,N'-bis-[N-
Benzyloxycarbonyl-γ-(α-benzyl)-L
[-glutamyl]cystamine is disclosed by Laszlo Feuer et al. in JP-A-51-4121,
It is described in E 2518160.

Step (A-1-2) The protecting group of R ₃ ' is removed by treatment with trifluoroacetic acid, trifluoromethanesulfonic acid, hydrofluoric acid or the like in a conventional manner.

In compound III-3, when the amino group is protected with a benzyloxycarbonyl group and the carboxyl group is protected with a benzyl group, the protecting groups are removed by treating with 1 to 10 equivalents of trifluoromethanesulfonic acid in the presence of an equal molar amount of anisole or thioanisole in dichloromethane or trifluoroacetic acid at 0°C to room temperature for several tens of minutes to several hours.

In compound III-3, when the amino group is protected with a t-butyloxycarbonyl group and the carboxyl group is protected with a t-butyl group, the protecting groups are removed by treating with trifluoroacetic acid or trifluoroacetic acid-dichloromethane in the same manner. The resulting compound III-4 is purified by recrystallization, various chromatographic methods including ion exchange, and the like.

Step (A-1-3) The amino group of compound III-4 is protected with a lower alkanoyl group, and/or the carboxyl group, if present, is protected as a lower alkyl ester group to obtain compound III-5.
get.

Lower alkanoylation of the amino group can be achieved by reacting one equivalent of an alkanoyl halide or the corresponding acid anhydride in an aqueous solution of compound III-4 in the presence of a small excess of potassium hydroxide, sodium hydroxide, sodium bicarbonate, or the like at 0°C to room temperature for several tens of minutes to several hours. Lower alkyl esters of the carboxyl group can be obtained by the thionyl chloride method, azeotropic method, transesterification method, or the like. For example, in the thionyl chloride method, a small excess of thionyl chloride is added to a lower alkanol to be esterified, and the reaction is carried out at 0°C to room temperature for several hours to a day to obtain a protected carboxyl group. The obtained compound III-5 can be purified by various chromatographic methods, such as recrystallization, ion exchange, and high-performance reversed-phase liquid chromatography using chemically bonded silica as a carrier.

Steps (A-1-4) and (A-1-5) Compound III-4 and Compound III-5 are converted to Compound III by reacting them with excess ethanethiol, 2-mercaptoethanol, dithiothreitol, etc. at room temperature for several hours to several days in a solvent such as water, methanol, ethanol, tetrahydrofuran, dioxane, acetonitrile, or dimethylformamide.
It is purified by various chromatographic techniques, including recrystallization, ion exchange, and high performance reversed-phase liquid chromatography using chemically bonded porous silica as a carrier.

Next, the step (A-2) will be described.

[wherein R ₃ ', R ₃ '', X', X '' and n are the same as defined above.] Step (A-2-1) Compound III-1 and Compound III-6 are reacted in the reaction mixture of Step (A-1-1)
Compound III-7 is obtained by a condensation reaction similar to that described above.

2-[(p-methoxybenzyl)thio]ethylamine, a specific example of compound III-6, and its preparation method are described in Armyansky, Chmiečesky, and Jurnal.
anskii Khimicheskii Zhurnal) 1968, 21 (10), 858−86
3 is described in

Step (A-2-2) The amino-protecting group of R ₃ ', and the carboxyl-protecting group, if present, and the methoxybenzyl group bonded to sulfur are cleaved with trifluoromethanesulfonic acid/anisole, trifluoromethanesulfonic acid/thioanisole,
Compound II is obtained by treating with hydrogen fluoride or the like to remove the compound.
Get I-8.

Compound III-8 can be obtained, for example, by the following method: Compound III-7 is reacted with 1 to 10 equivalents of trifluoromethanesulfonic acid in the presence of an equal mole number of anisole or thioanisole in trifluoroacetic acid or trifluoroacetic acid-dichloromethane at 0° C. to room temperature for several tens of minutes to several hours to remove the protecting group.
Alternatively, the protecting group can be removed by adding anisole in an amount equivalent to one-tenth the amount of hydrogen fluoride to liquid hydrogen fluoride at 0° C. for 30 to 60 minutes. Compound III-8 can be purified by various chromatographic methods, such as recrystallization, ion exchange, and high-performance liquid chromatography using chemically bonded porous silica as a carrier.

Compound III, in which R ₄ is a residue obtained by removing H from the amino group of an α-amino acid, is a novel compound and can be obtained by the following step (A-3).

[wherein _R4 ' is a residue of the α-amino acid excluding H, all carboxyl groups are protected with protecting groups commonly used in peptide synthesis, and when the α-amino acid has two amino groups, one of the amino groups is protected with a protecting group commonly used in peptide synthesis. Furthermore, functional groups in the side chain are also protected as necessary.

R ₄ ″ is a residue of the α-amino acid excluding H from the amino group (all protecting groups have been removed).

_R4 is a residue excluding H from the amino group of an α-amino acid, and when the α-amino acid has a carboxyl group and an amino group, the carboxyl group is protected as a lower alkyl ester group, or the amino group is protected with a lower alkanoyl group.

X', X'' and n are as defined above.

Regarding the definition of R ₄ ', examples of the protecting group for an amino group commonly used in peptide synthesis include benzyloxycarbonyl and t-butyloxycarbonyl, and examples of the protecting group for a carboxyl group commonly used in peptide synthesis include:
Examples include benzyl and t-butyl groups.

Steps (A-3-1) to (A-3-5) are the same as Step (A-1
The same as (A-1-1) to (A-1-5), except that step (A-3
The only difference between the process (A-1) and the process (A-1-1) is the process (A-1-2), which will be explained below.

In step (A-1-1), the carboxyl group of the α-amino acid derivative R ₃ OH is activated, whereas in step (A-
In 3-1), compound III-10 is activated and condensed with the amino group of an amino acid derivative R ₄ 'H.

Compound III, in which _R3 is a formyl group, a lower alkanoyl group, or a halogen-substituted lower alkanoyl group, can be easily obtained by formylation, lower alkanoylation, or halogen-substituted lower alkanoylation of _H2N (CX'X") _n -SH (III-14) (wherein X', X" and n are as defined above). It can also be easily obtained by subjecting _H2N (CX'X") _n - _SR3 ' (III-15) (wherein _R3 ' is a lower alkanoyl group or a halogen-substituted lower alkanoyl group, and X', X" and n are as defined above) to acyl migration in solution. For example, (2-acetylthioethylamine hydrochloride) is reported in the Journal of Chemical Society.
The article is described in Journal of the American Chemical Society, Vol. 3425 (1951).

One of the compounds III, 5-mercaptomethyluracil, is described in Journal of Medicinal Chemistry, 9 , 97 (1966). 1-(2-deoxy-β-D-ribofuranosyl)-5-mercaptomethyluracil is also described in the same journal.
18,973 (1975).

Next, Method B will be described.

[wherein R ₁ , R ₂ , Y and Z are as defined above], for example, mitomycin A, mitomycin B (Merck Index, 10th Edition),
Edit., 6079, 1983), mitomycin F, or mitomycin J (see Japanese Patent Application Laid _- Open No. 55-45322) is reacted with a compound of the formula X-(CX'X") _n -SS( _CH2 ) _2NH2 (V) (wherein X, X'X" and n are as defined above) in an inert solvent to produce compound I. This step is referred to as step B.

The solvent used in the reaction may be the same as that used in the above Method A. The reaction temperature and time depend on the type and concentration of compound V, but the reaction is usually completed within several tens of minutes to several hours at a temperature in the range of 0 to 80°C. Compound I can be purified by column chromatography using various carriers, high performance liquid chromatography, TLC, etc.

Compound V can be prepared by the following step (B-1) or step (B-2):
is obtained by

[wherein R ₃ ' is a residue excluding OH from the carboxyl group of the organic acid, and X', X" and n are the same as above]. The organic acid described above can be used.
1) is carried out in accordance with step (A-1-1), and step (B-1
Step 2) can be carried out in accordance with Step A. Compound V
An example of -2 is 2-pyridyldithioethylamine dihydrochloride (see JP-A-55-136261).

[wherein R ₄ ' is a residue of an organic amine from which one hydrogen atom has been removed, and X, X" and n are the same as those defined above]. The organic amines described above can be used.
-1) is carried out in accordance with step (A-1-1), and step (B-
2-2) can be carried out in accordance with step A. Examples of succinimide esters of carboxylic acids of compound V-7 include:
N-succinimidyl 3-(2-pyridyldithio)propionate (Sigma P9398).

Next, Method C will be described.

Compound I is obtained by reacting a compound represented by the formula: [wherein X', X", _R1 , _R2 , Y, Z and n are as defined above] with a compound represented by the formula: _R3OH or _R3SH (VII) [wherein _R3 is as defined above] in an inert solvent in the presence of triphenylphosphine and a dialkyl azodicarboxylate.

[An example of compound (VI), in which X′ and X″ are hydrogen atoms and n is 2, is described in JP-A-59-175493.] Examples of the solvent used in this reaction include ether solvents such as diethyl ether and tetrahydrofuran, and anhydrous solvents such as benzene, methylene chloride and hexamethylphosphorastriamide. Examples of dialkyl azodicarboxylates include diethyl azodicarboxylate and diisopropyl azodicarboxylate.

The amounts of Compound VII, triphenylphosphine and dialkyl azodicarboxylate used relative to Compound VI may be, for example, 1 equivalent each, but they may be used in excess of up to about 3 equivalents to increase the yield from Compound VI.

The reaction temperature and time vary depending on the compound VI or VII, but typically range from -20 to 30°C for several minutes to about 1 hour. The post-reaction treatment varies depending on the compound VII used, but for example, the reaction solution may be directly concentrated under reduced pressure, or extracted with a non-aqueous solvent such as chloroform, methylene chloride, or ethyl acetate, washed with water, aqueous sodium bicarbonate, or the like, and then concentrated and purified. Purification can be performed by column chromatography, TLC, recrystallization, or the like.

Compound I has excellent antibacterial and antitumor activities and is useful as an antibacterial agent and an antitumor agent. Compared with mitomycin C, which is widely used clinically as an antitumor agent,
Compound I generally has high antitumor activity and low bone marrow toxicity, i.e., Compound I has a chemotherapy index of C.
I. (LD ₅₀ /ED ₅₀ ) is superior to that of mitomycin C, and the safe effective dosage range is wider than that of mitomycin C.
In addition, the WBC ₄₀₀₀ (the minimum dose of drug that reduces the peripheral white blood cell count to 4000/ ^mm3 ) is greater than that of mitomycin C, and bone marrow suppression is less severe than that of mitomycin C.

Among water-soluble compounds I, when _R3 is a residue other than the OH of the carboxyl group of an amino acid, those having glutamic acid or aspartic acid residues exhibit favorable antitumor activity. Among these, those with n=2-4 generally have high water solubility and are suitable for injection. Particularly excellent are compounds I [X is the residue at the γ position of glutamic acid, n=2,
R ₁ = CH ₂ OCONH ₂ , R ₂ = H, Y = CH ₃ , Z = H], and it has extremely high CI values (LD ₅₀ /ED ₅₀ ) and (WBC ₄₀₀₀ /ED ₅₀ ) and also exhibits high water solubility, which far surpasses mitomycin C in these respects.

Lipid-soluble antitumor agents have recently attracted attention, and lipophilic mitomycin derivatives have been proposed. For example, lipophilic anthracycline derivatives have been studied [see, for example, Journal of Medicinal Chemistry (Journal of
al Chemistry, 28 , 451 (1985)], and lipid-soluble mitomycin derivatives have also been studied [for example, Chemical and Pharmaceutical Bulletin,
ical and Pharmaceutical Bulletin, 31 , Journal of Pharmacobiodynamics
of Pharmacobio-Dynamics, 7 , 120 (1984)]. Such fat-soluble derivatives are useful in chemotherapy using lipiodol [for chemotherapy using anthracyclines dissolved in lipiodol, see, for example, Journal of
Journal of Surgical Oncology
logy) 25 , 218, (1984)
Much more suitable than water-soluble derivatives.

Some compounds I have high lipid solubility, high CI values, and high WBC ₄₀₀₀ /ED ₅₀ values. In these respects, compounds Nos. 26, 27, 28, etc. are superior to mitomycin C. The following experimental examples demonstrate the pharmacological properties of the compounds of the present invention (compound I).

Experimental Example 1 Table 3 shows the antibacterial activity of some compounds I according to the present invention in terms of minimum inhibitory concentration (μg/ml) (agar dilution method, pH 7.0). In the table, the names of bacteria are abbreviated as follows:

SF: Streptococcus faecalis ATCC 10541 SA: Staphylococcus aureus ATCC 6538P EC: Escherichia coli ATCC 26 PV: Proteus vulgaris ATCC 6897 KP: Klebsiella pneumoniae ATCC 10031 Experimental Example 2: Sarcoma 180 of compounds selected from Compound I of the present invention
Antitumor activity (ED ₅₀ ) and acute toxicity (L
The effects on the leukocyte count (D ₅₀ ) and peripheral leukocyte count (WBC ₄₀₀₀ ) are shown in Table 4.

In addition, in mitomycin A and mitomycin C,
It is already known that two types of substances exist: mitomycin type and albomitomycin type (27th Symposium on Natural Organic Compounds, Abstracts, pp. 672-679, 1985, Hiroshima). As will be described in Example 1 below, it has been found that the various mitomycin derivatives of the present invention also contain these two types of substances.

The results in Table 4 were obtained from the following experiment.

1) Effect on Sarcoma 180 solid tumors 5 x ¹⁰⁶ Sarcoma 180 solid tumor cells were transplanted into the abdominal cavity of male ddy mice, and cells were collected from the ascites on the 7th day.
After washing once with sterile saline,
A cell suspension of ⁷ cells/ml was prepared. 0.1 ml of this suspension was added to 20 ± 2
The drug was dissolved in saline or saline containing Tween 80, and 0.1-0.2 ml of the drug was injected intraperitoneally into the peritoneal cavity of five mice per group 24 hours after implantation.
The antitumor activity of the drug was evaluated by measuring the long diameter (a) and short diameter (b) of the tumor 7 days after implantation and calculating the value of " ^aXb2 /2", which corresponds to the tumor volume. The antitumor effect was expressed as the volume ratio (T/C) of the drug-administered group (T) to the control group (C).

2) How to calculate _ED50 The dose that reduces the volume of Sarcoma 180 solid tumors to 50% of that of the non-administered group (control group) was defined as _ED50 . T/C at each dose was plotted on a graph with T/C on a normal scale on the vertical axis and dose on a logarithmic scale on the horizontal axis, and the relationship between dose and T/C was determined as a straight line using the least squares method.
The dose at which T/C was 0.5 was calculated from the linear regression equation obtained.

3) Acute toxicity (LD ₅₀ ) The drug was administered intraperitoneally once to 5 ddy mice per group, and the survival rate was observed for 14 days.
The _LD50 was determined by the Behrens-Körber method.

4) Effect on peripheral white blood cell count (WBC ₄₀₀₀ ) 5 x ¹⁰⁶ Sarcoma 180 solid tumor cells were implanted subcutaneously in the right axilla of male ddy mice (5 mice per group, body weight 20±2 g).
After 24 hours, the drug was administered intraperitoneally. Four days after the transplantation, 0.02 ml of blood was collected from the orbital venous plexus of the tumor-bearing mice, and 9.98 ml
The saponin solution was dispersed in 100 ml of Cellkit Seven solution.
After adding 100 drops to lyse the red blood cells, the peripheral white blood cell count was measured using a microcell counter. The peripheral white blood cell count at each dose was plotted on a graph with the vertical axis showing the peripheral white blood cell count in normal scale and the horizontal axis showing the dose in logarithmic scale. The relationship between the dose and the peripheral white blood cell count was determined, and a peripheral white blood cell count of 4000/m
The dose required to give ₄₀₀₀ WBC m ³ (approximately half the number of peripheral white blood cells in a normal mouse) was determined.

5) Effect on leukemia P388 Ascites fluid was collected from the peritoneal cavity of P388 ascites tumor-bearing mice (DBA/2) 7 days after transplantation. The number of P388 cells in the ascites fluid was counted, and a tumor cell suspension of 5 x ¹⁰⁶ cells/ml was prepared in sterile saline. 0.2 ml of this suspension (containing 1 x ¹⁰⁶ tumor cells) was added to _CDF1 ,
Tumors were transplanted intraperitoneally into mice (weight 20-25 g).
Four hours later, the test drug was administered intraperitoneally once to six _CDF1 mice per group, and survival was monitored for 33 days. The efficacy of the drug was assessed by the ratio of the mean survival time after transplantation to the mean survival time of the control group (untreated group) (survival rate, ILS%, Increased Life Span). The ratio of the ILS% of each drug to the ILS% of mitomycin C (ILS ⁺ ), a control group run under the same conditions, is shown in Table 5.

The present invention provides an antitumor agent containing the compound of the present invention as an active ingredient. The compound is used as an injection by dissolving it in, for example, physiological saline, glucose injection, lactose injection, mannitol injection, etc. Furthermore, it may be used as a freeze-dried injection or a powder injection containing sodium chloride according to the Japanese Pharmacopoeia. Furthermore, well-known pharmaceutically acceptable diluents such as salts that meet pharmaceutical uses (Ringer's solution), adjuvants [polyethylene glycol, HCO-60 (surfactant, manufactured by Nikko Chemicals)], ethanol, and/or carriers (liposomes,
The dosage can be adjusted depending on the patient's age and symptoms. The dosage schedule can also be adjusted depending on the symptoms and dosage. For example, a dose of 0.06 to 6 mg/week at intervals of once a week or once every three weeks is recommended.
The compound is usually injected intravenously in the range of 1 kg. Similar amounts can also be administered intraarterially, intraperitoneally, or intrathoracically. Oral and rectal administration is also possible, and in these cases, it can be administered in the form of tablets, powders, granules, syrups, suppositories, etc., together with appropriate adjuvants. The compounds of the present invention generally have higher solubility in water or oils and lower toxicity than mitomycin C, making them excellent antitumor agents.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be explained in more detail with reference to the following examples. The physicochemical data shown in the following examples and reference examples were measured using the following instruments.

IR: JASCO IR-810 (Japan Spectroscopy) NMR: Bruker AM400 Varian EM 390 JEOL FX100 MS: Hitachi M-80B (Hitachi) Specific rotation: Perkin-Elmer 141 Polarimeter Example 1 7-N-[2-(2-pyridyldithioethyl)]mitomycin C [EP 0116208A1; JP 59-175493 A] (503 mg) was dissolved in 15 ml of methanol. While stirring at room temperature, 15 ml of an aqueous solution of γ-L-glutamylcysteamine (200 mg) described in Reference Example 2 below was added dropwise. Water (120 ml) was then added, and the resulting reaction mixture was passed through a Diaion HP-20 (Mitsubishi Chemical Industries; 100 ml). After passing water/methanol (7:3 v/v; 300 ml) through the column, water/methanol (4:6 v/v; 300 ml) was passed through the column to obtain a blue fraction. This was concentrated under reduced pressure and further lyophilized to obtain Compound I (263 mg). Yield: 44%.
is a mixture of the following mitomycin-type substance A and the following albomitomycin-type substance B, in a molar ratio of 9:
The ratio was 5:5.

The physicochemical data of Compound I were as follows:

SIMS: m/z 599 ₍ M+1) ⁺ , 600(M+2) ⁺ , 601(M+3) ⁺ (molecular formula _C24H34N6O8S2 ; molecular weight _598.7 ) In the SIMS method, a sample mixed with glycerin is ionized _by colliding with Xe ⁺ _, and the quinone portion of mitomycin is reduced by hydrogen radicals generated from the glycerin during this process. Therefore, in the case of this compound, the mass number may increase by 2. Furthermore, the addition of hydrogen ions and hydrogen radicals, which are often seen in normal EI mass spectra, may also occur. Therefore, the observation of (M+2) ⁺ and (M+3) ⁺ indicates that
This strongly supports the molecular formula of this compound (Patent Publication No. 1985).
(A similar example is described in Publication No. 33880.)

Elemental analysis: _{C24H34N6O8S2 ·H2O C} (%) H (%) N (%) Calculated value 46.74 5.88 13.63 Found value 46.51 5.97 13.60 ^1H _- NMR (400MHz): _{( D2O} ) δ 1.94 _* (s), 2.00 ₍ 3H,
s),2.15(2H,m),2.44(2H,m),2.86(2H,t,J=6.3H
z),3.00(2H,t,J=6.3Hz),3.02(1H,br,),3.05(1H,
br,),3.30(3H,s),3.45 _* (s),3.53(2H,t,J=6.3H
z),3.65(1H,br,d),3.65(1H,dd,J=10.7,4.5Hz),3.
78 (2H,t,J=6.2Hz),4.00(2H,t,J=6.3Hz),4.19(1
H,br,d,J=13.7Hz),4.26(1H,t,J=10.7Hz),4.60(1
H, dd, J = 10.7, 4.5 Hz) [In ^{the 1} H-NMR described herein, * denotes albomitomycin-type substances.] IR: (KBr) cm ⁻¹ 3450, 3300, 3080, 2950, 1707, 1631, 156
0,1510,1460,1328,1062 Water solubility: >20mg/ml Next, to isolate a highly pure mitomycin-type substance,
The following operations were performed:

45 mg of powder of Compound I was dissolved in distilled water (1.8 ml) and subjected to preparative high performance liquid chromatography [carrier: YMC (Yamamura Chemical) D-ODS-7; eluent: water/acetonitrile (3:1)].
v/v), flow rate 9.6 ml/min. The blue fraction eluted 11.7-13.5 min after the start of elution was collected and freeze-dried to obtain a gray-blue powder (33 ml).
This powder gave a single peak at 254 nm with a retention time of 6.0 minutes and an area intensity ratio of >99% when measured by high-performance liquid chromatography (column support: YMC AM-312; eluent: water/methanol (1:1 v/v), flow rate: 1 ml/min).

The physicochemical data of this substance were as follows:

SIMS:m/z 599(M+1) ⁺ ,600(M+2) ⁺ ,601(M+3) ⁺ (Molecular formula C ₂₄ H ₃₄ N ₆ O ₈ S ₂ ; Molecular weight 598.7) ¹ H-NMR (400MHz): (D ₂ O) δ 2.00 (3H,s), 2.15 (2
H,m),2.44(2H,m),2.86(2H,t,J=6.3Hz),3.00(2H,
t,J=6.3Hz),3.02(1H,br,),3.05(1H,br,),3.30(3
H,s),3.53(2H,tJ=6.3Hz),3.65(1H,br,d),3.65
(1H, dd, J = 10.7, 4.5Hz), 3.78 (2H, t, J = 6.2Hz), 4.00
(2H,t,J=6.3Hz),4.19(1H,br,d,J=13.7Hz),4.26
(1H,t,J=10.7Hz),4.60 (1H,dd,J=10.7,4.5Hz), IR:(KBr)cm ^-1 3450,3300,3080,2950,1707,1631,156
0,1510,1460,1328,1062 To isolate highly pure albomitomycin-type substances,
The following operations were performed:

In the preparative high-performance liquid chromatography, the colorless fraction eluted 7.8 to 8.4 minutes after the start of elution was immediately frozen with dry ice/acetone. Then, by lyophilization, a slightly bluish powder (1.5 mg) was obtained. When this powder was measured in the same manner as the mitomycin-type substance, the retention time was
A major peak was observed at 4.2 minutes with an area intensity ratio of >95%.

The physicochemical data of this substance were as follows:

SIMS: m/z 599(M+1) ⁺ , ¹ H-NMR (400MHz): (D ₂ O) δ 1.92 (3H,s), 2.14 (2
H,m),2.43(2H,m),2.70(1H,d),2.84(1H,d),2.85
(2H,m),2.95(1H,d),3.00(2H,m),3.02(1H,d),3.
44 (3H, s), 3.51 (2H, m), 3.53 (2H, t), 3.76 (1H, t),
3.82 (1H, m), 3.94 (1H, m), 4.31 (1H, dd), 4.41 (1H, d
d) IR:(KBr) cm ^-1 3400,3350,3080,2950,1705,1630,157
Example 2 In Example 1, 7-N-[2-(2-pyridyldithio)ethyl]mitomycin C was replaced with 7-N-[2-
(2-pyridyldithio)ethyl]mitomycin D (50
Compound 2 (275 mg; yield 46.3 mg) (see EP 0116280A1, JP-A-59-175493) was used in the same manner as above, but Compound 3 (275 mg; yield 46.3 mg) (see EP 0116280A1, JP-A-59-175493) was used in the same manner as above.
%) was obtained.

The physicochemical data of Compound 2 were as follows:

SIMS: m/z 599 ₍ M+1) ⁺ , 600(M+2) ⁺ , 601 ₍ M+3) ⁺ (molecular formula _C24H34N6O8S2 ; molecular weight _598.7 ) As explained in Example ₁ , this data strongly supports the molecular formula of this compound.

Elemental analysis: _{C24H34N6O8S2 ·H2O C} (%) H (%) N (%) Calculated value 46.74 5.88 13.63 Found value 46.59 5.82 13.39 ^1H _- NMR (400MHz): ₍ D2O) δ 1.98 ( _3H ,s), 2.11 ( ₂
H,m),2.30(3H,s),2.42(2H,m),2.60(1H,d,J=4.9H
z),2.70(1H,dd,J=4.9,2.0Hz),2.84(2H,t,J=6.2H
z),3.00(2H,t,J=6.3Hz),3.51(2H,t,J=6.3Hz),3.
65 (1H, dd, J = 13.7, 2.1Hz), 3.73 (1H, dd, J = 9.3, 3.6H
z),3.75 (1H,t,J=6.2Hz),4.02(2H,t,J=6.3Hz),4.
08 (1H, d, J = 13.6Hz), 4.40 (1H, dd, J = 10.9, 9.3Hz),
4.68 (1H, dd, J = 10.9, 3.6Hz) IR: (KBr) cm ^-1 3410,3300,3100,2950,1705,1629,154
5,1509,1467,1412,1333 Water solubility: >5 mg/ml Example 3-13 SIMS and IR of compound 3-13 obtained in the same manner as in Example 1
The data of ^1H -NMR and 1H-NMR are shown in Table 6. All of these compounds are soluble in water, and among them, compounds 3, 4,
The aqueous solubilities of 5, 6, 7 and 9 were >20 mg/ml.

Table 6-2 shows the molar ratio of mitomycin-type substance (A) and albomitomycin-type substance (B) further isolated from compound 3-9.

Example 14 Compound "1" (L) (328 mg) obtained in Reference Example 6 below
was dissolved in dimethylformamide (8 ml). To this was added cysteamine hydrochloride (116 mg) and triethylamine (140 μg).
1) was added and stirred at room temperature for 5 minutes, then mitomycin A (345 mg) was added and stirred at room temperature for 24 hours, after which water (30 ml) was added.
The product was extracted from the reaction mixture with chloroform (150 ml). The chloroform solution was dried over sodium sulfate, the solvent was removed by distillation, and the extract was transferred to silica gel (Wako C200; 30 ml).
Column chromatography was performed using a chromatograph. After passing chloroform/methanol (9:1 v/v; 100 ml) through the column, elution was performed with chloroform/methanol (8:2 v/v; 200 ml) and chloroform/methanol (7:3 v/v; 200 ml). The blue fraction was concentrated under reduced pressure and further purified by silica gel (Fuji-Daviso
The blue fraction eluted with chloroform/methanol (85:15 v/v) was concentrated under reduced pressure to give compound 14 (248 mg; yield 41%) as a dark blue powder.

The molar ratio of this compound to mitomycin-type substances is >99%,
The physicochemical data were as follows:

SIMS:m/z 610(M+3) ⁺ (Molecular formula C ₂₄ H ₂₉ N ₇ O ₈ S ₂ , molecular weight 607.7) ¹ H-NMR (400MHz): (Py-d ₅ ) δ 2.11 (3H,s),2.75
(1H, dd, J = 4.4, 1.8Hz), 2.97 (2H, t, J = 6.8Hz), 3.14
(1H, d, J = 4.4Hz) 3.14 (2H, t, J = 6.7Hz), 3.23 (3H,
s), 3.61 (1H, dd, J = 12.7, 1.8Hz), 3.92 (2H, q, J = 6.8H
z),3.94(2H,q,J=6.7Hz),4.00(1H,ddJ=11.1,4.2H
z),4.52 (1H,d,J=12.7Hz),5.04(1H,dd,J=11.1,10.
4Hz), 5.38 (1H, dd, J=10.4, 4.2Hz), 6.61 (1H, s), 7.2
5 (1H,t,J=6.6Hz),7.63(2H,br,),10.07(1H,t,J=
5.5Hz), 13.29 (2H,br,) IR:(KBr)cm ^-1 3450,3405,3270,1715,1635,1560,154
0, 1510, 1445, 1420, 1325, 1060 Examples 15-16 ^{The 1} H-NMR and IR data of compounds 15-16 obtained in the same manner as in Example 14 are shown in Table 7. The molar ratio of mitomycin type in the obtained compounds was >99%.

Example 17 7-N-[2-(2-pyridyldithio)ethyl]mitomycin D (EP 0116208A1, JP-A 59-175493) (503 mg) was dissolved in acetonitrile (10 ml).
While stirring under ice cooling, 2-acetylthioethylamine
A solution of hydrochloride (148 mg) and triethylamine (150 μl) in acetonitrile (10 ml) was added dropwise.
The reaction mixture was passed through a silica gel column (Fuji-Davison, BW-300; 200 mL). A blue fraction was obtained using chloroform/methanol (9:1 v/v) as the developing solvent. This fraction showed an Rf of 0.22 on silica gel TLC [Merck 60F ₂₅₄ Art 5719; chloroform/methanol (9:1 v/v)]. The solvent from this fraction was evaporated under reduced pressure. The residue was dissolved in chloroform and added dropwise to n-hexane. The resulting precipitate was dried under reduced pressure to give compound 17 (360 mg; yield 70%) as a gray-blue powder.

The physicochemical data of this compound were as follows:

SIMS:m/z 513(M+2) ⁺ ,514(M+3) ⁺ (Molecular formula C ₂₁ H ₂₉ N ₅ O ₆ S ₂ , molecular weight 511.6) ¹ H-NMR (400MHz): (Py-d ₅ ) δ 2.07 (6H,s),2.13
(3H,s),2.24(1H,dd,J=4.1,1.9Hz),2.47(1H,d,J=
4.7Hz), 2.90 (2H,t,J=6.8Hz),3.02(2H,t,J=6.6H
z),3.68(1H,dd,J=12.9,1.9Hz),3.77(2H,q,J=6.3H
z),3.85(2H,q,J=6.7Hz),4.22(1H,dd,J=10.0,3.4H
z),4.43(1H,d,J=12.9Hz),5.21(1H,t,J=10.3Hz),
5.47 (1H, dd, J = 10.6, 3.4Hz), 7.23 (1H, t, J = 6.5H
z), ~7.5(2H,br,s),8.34(1H,br,s),8.77(1H,br,
t) IR:(KBr) cm ^-1 3350,1716,1649,1557,1548,1511,132
0, Examples 18-20 SIMS, ¹ H- of compounds 18-20 obtained in the same manner as in Example 17
NMR and IR data are shown below in Table 8. The isolated compound 19 was >99% mitomycin-type material.

Example 21 N-succinimidyl 3-[2-pyridyldithio]propionate (180 mg) was dissolved in methanol (4.5 ml). To this solution was added a solution of ammonia in methanol (5% v/v; 1 ml).
After stirring at 0°C for 30 minutes, the mixture was concentrated to 1 ml under reduced pressure. 3-(2-pyridyldithio)propanamide was formed in the reaction mixture [see JP-A-61-57595, CA 105(19)173000q]. Triethylamine (80 ml) and cysteamine hydrochloride (65 mg) were added to the reaction mixture, which was then stirred at room temperature for 10 minutes. Next, mitomycin A
(50 mg) was added, and the mixture was stirred at room temperature for 2 hours. After that, water (10 ml) was added.
The product was extracted from the reaction mixture with chloroform (50 ml).

The chloroform solution was dried over sodium sulfate, and the solvent was removed under reduced pressure. Chromatography was then performed using silica gel (Wako C200; 10 ml). The blue fraction eluted with chloroform/methanol (9:1 v/v) was concentrated, dissolved in acetone, and added dropwise to cyclohexane. The resulting precipitate was dried under reduced pressure to obtain Compound 21 as a yellow-green powder.
(15 mg; 21% yield). The molar ratio of mitomycin-type substance in the isolated compound was >99%.

The physicochemical data of this compound 21 were as follows:

SIMS: m/z 499(M+2) ^{+ 1} H-NMR (400MHz): (Py-d ₅ ) δ 2.10 (1H,br),2.12
(3H,s),2.74(1H,br,s),2.90(2H,t,J=7.4Hz),2.9
5 (2H, tJ = 6.9Hz), 3.13 (1H, br, s), 3.22 (3H, s), 3.
26 (2H,t,J=7.1Hz),3.59(1H,br,d,J=12.6Hz),3.91
(2H,q,J=6.6Hz),3.99(1H,dd,J=11.3,4.4Hz),4.52
(1H,d,J=12.6Hz),5.05(1H,br,dd,J=11.3,10.3H
z),5.38(1H,dd,J=10.3,4.4Hz),7.20(1H,br,),7.7
8(2H,br,),8.33(2H,br,) IR:(KBr)cm ^-1 3400,3280,2930,1720,1700,1670,163
0,1560,1505,1445,1315,1200,1050,850,760 Examples 22-25 SIMS, ¹ H- of compounds 22-25 obtained in the same manner as in Example 1
NMR and IR data are shown in Table 9. Compounds 22 and 23 were isolated as mixtures of mitomycin-type and albomitomycin-type substances in the following molar ratios:

Compound Mitomycin type Albomitomycin type 22 85 15 23 87 13 Example 26 β-Estradiol 3-benzoate (376 mg) and thioglycolic acid (69.4 μl) were dissolved in dry toluene (5 ml).
The mixture was heated under reflux in a 1:1 v/v mixture under an argon atmosphere for 1.5 hours to obtain Solution A (containing Compound III). 7-N-[2-(2-pyridyldithio)ethyl]mitomycin C (252 mg) was dissolved in methanol/chloroform (1:1 v/v; 4 ml), triethylamine (0.2 ml) was added, and Solution A was added dropwise at room temperature, followed by stirring for an additional 5 minutes. Water (10 ml) was added, and the product was extracted from the reaction mixture using chloroform (100 ml). The chloroform solution was dried over sodium sulfate, the solvent was distilled off under reduced pressure, and the extract was passed through silica gel (Wako C200; 5 ml).
Column chromatography was carried out using a 100 ml column (0 ml).
The fraction eluted with chloroform/acetone/methanol (70:25:5 v/v) was concentrated, dissolved in a small amount of chloroform, and added dropwise to n-hexane to form a precipitate. The precipitate was dried under reduced pressure to give compound 26 (260 mg) as a blue-purple powder. The yield was 62%. The isolated compound was a mitomycin-type substance with a purity of >99%.

The physicochemical data of this compound were as follows:

SIMS: m/z 844(M+2) ^{+ 1} H-NMR (400MHz): (CDCl ₃ ) δ 0.87 (3H, s), 2.03 (3H, s), 2.81 (1H, bs,), 2.96 (2H,
t,J=6.6Hz),3.20(3H,s),3.51(1H,br,d,J=12.9H
z),3.51(2H,AB,J=14.7Hz),3.60(1H,dd,J=10.5.4.
3Hz).3.90(2H,br,q,J=6.5Hz),4.27(1H,d,J=12.9H
z),4.49(1H,br,t,J=10.7Hz),4.70(1H,dd,J=10.7,
4.3Hz), 4.76 (1H, dd, J=8.9, 7.9Hz), 4.82 (2H, br,
s).6.49(1H,t,J=6.3Hz),6.92(1H,br,d,J=2.5H
z),6.97(1H,dd,J=8.4,2.5Hz),7.33(1H,br,d,J=8.
4Hz), 7.50 (2H,t,J=7.7Hz),7.63(1H,tt,J=7.4,1.3
Hz),8.19 (2H,d,J=8.3Hz) IR:(KBr)cm ^-1 3420,3290,2925,1720,1710,1555,150
Table 10 below shows ^{the 1} H-NMR and IR data for compounds 27-32. Compounds 27-30 are the same as those in Example 26, and compounds 31-32 are the same as those in Example 27.
32 was obtained in the same manner as in Example 21.

Example 33 7-N-[2-[(2-hydroxyethyl)dithio)ethyl]mitomycin C (described in JP-A-59-175493)
(200 mg) was dissolved in dry tetrahydrofuran (6 ml),
Triphenylphosphine (257 mg) was added under a nitrogen stream. Diisopropyl azodicarboxylate (193 μL) was added at 0°C, followed by thiolacetic acid (70 μL) and stirring for 10 minutes. Water (20 mL) was added, and the product was extracted from the reaction mixture with chloroform (100 mL). The chloroform solution was dried over sodium sulfate, and the solvent was removed under reduced pressure. The residue was subjected to column chromatography on silica gel (Wako C200; 50 mL). The blue fraction eluted with chloroform/methanol (98:2 v/v) was concentrated, dissolved in a small amount of acetone, and added dropwise to cyclohexane. The resulting precipitate was dried under reduced pressure to give gray-blue compound 33 (49 mg). The yield was 22%. The isolated compound was >99% mitomycin-type.

The physicochemical data of this compound were as follows:

SIMS: m/z 530(M+2) ^{+ 1} H-NMR (400MHz): (Py−d ₅ ) δ 2.10 (1H,br,),2.1
4(3H,s),2.27(3H,s),2.75(1H,br,),2.95(1H,t,J
=7.4Hz,2.99(2H,t,J=6.6Hz),3.15(1H,br,),3.22
(3H,s),3.31(2H,t,J=7.4Hz),3.59(1H,br,d,J=1
2.3Hz), 3.93 (2H, 9, J = 6.6Hz), 4.00 (1H, dd, J = 11.1,
4.2Hz) 4.52 (1H,d,J=12.8Hz),5.08(1H,br,dd,J=1
1.1, 10.8Hz), 5.38 (1H, dd, J = 10.4, 4.2Hz), 7.26 (1H,
t,J=6.6Hz),7.60(2H,br,) IR:(KBr)cm ^-1 3450,3280,2930,1715,1700,1630,156
0, 1510, 1440, 1320, 1060, 935, 855 Examples 34-35 ^{The 1H} -NMR and IR data of compounds 34-35 obtained in the same manner as in Example 33 are shown in Table 11 below. Isolated compound 35
was >99% mitomycin-type substance.

Example 36 Compound 36 having the following physical properties was obtained in the same manner as in Example 1. The isolated compound, a mitomycin-type substance, was
The ratio was 9:11%.

SIMS: m/z 579(M+2) ^{+ 1} H-NMR (400MHz): (D ₂ O) δ 1.93 _* (s), 2.01 (3H, s), 3.02 (2H, t, J = 6.2Hz), 3.0
4 (2H, m), 3.06 (1H, dd, J = 4.6, 2.1Hz), 3.09 (1H, d, J
=4.6Hz),3.27(3H,s),3.44 _* (s),3.62(1H,dd.J
=13.3,2.1Hz),3.65(1H,dd,J=10.7,4.6Hz),4.03(2
H,t,J=6.4Hz),4.18(1H,d,J=13.3Hz),4.26(1H,t,J
=10.7Hz),4.59(1H,dd,J=10.7,4.6Hz) IR:(KBr)cm ^-1 3450,1705,1630,1550,1510,1460,133
0,1210,1180,1045 Example 37 7-N-[2-(2-pyridyldithioethyl)mitomycin C (EP 0116208, JP-A-59-185493)
(200 mg) was dissolved in methanol (50 ml), and 5-mercaptomethyluracil (62 mg) was added and stirred at room temperature for 30 minutes. After the solvent was distilled off under reduced pressure, the resulting solution was transferred to a silica gel column (Wako C20
The resulting mixture was subjected to column chromatography using a 100 ml/100 ml aqueous solution of chloroform/methanol (9:1 to 4:1 v/v). The solvent was removed from the blue fraction eluted with chloroform/methanol (9:1 to 4:1 v/v) under reduced pressure to give compound 37 (155 mg). The yield was 70%. The isolated compound 37
The mitomycin-type substance in the sera was >99%.

The physicochemical data of this compound were as follows:

SIMS: m/z 551(M+2) ^{+ 1} H-NMR (100MHz): (Py−d ₅ ) δ 2.05 (1H,br),2.76(1H,br),3.01(2H,t,J=6.6Hz),
3.11 (1H, br), 3.22 (3H, s), 3.70 (1H, br, d, J = 12.7H
z), 3.92 (3H, m), 3.96 (2H, q, J = 6.6Hz), 4.53 (1H, d.
J=12.7Hz),5.02(1H,br),5.38(1H,dd,J=10.5,4.4H
z),7.25(1H,br,t,J=7.3Hz),7.64(2H,br),7.82(1
H,s) IR:(KBr) cm ^-1 3440,3280,2950,1710,1700,1680,155
5,1505,1455,1330,1210,1060 Examples 38-40 SIMS, ¹ H- of compounds 38-40 obtained in the same manner as in Example 37
NMR and IR data are shown below in Table 12. The isolated compound 39 was >99% mitomycin-type material.

Example 41 Preparation of Compound 6 (Alternative Method) Compound "C" (600 mg) obtained in Reference Example 3 below was dissolved in dichloromethane (28 ml).
After adding trifluoroacetic acid (28 ml) and trifluoromethanesulfonic acid (1.68 ml) at 0°C, the mixture was stirred for 30 minutes, and then stirred at room temperature for a further 4 hours. Water (50 ml) was added to the reaction mixture, which was then extracted three times with ether (50 ml). The aqueous layer was concentrated under reduced pressure and diluted with phosphate buffer (M/10; pH 7.5; 3
0 ml) was added, and then a small amount of saturated aqueous sodium bicarbonate solution was added to adjust the pH to 5.5.
(Mitsubishi Chemical; 100 ml), washed with water (200 ml),
The mixture was eluted with water/methanol [5:95-10:90] (300 ml). The resulting fraction was concentrated under reduced pressure and lyophilized to give crude powder of N-(β-L-aspartyl)cysteamine (130 mg; yield: 60%). This was then purified without further purification in the same manner as in Example 1 to give 7-N-[2-
(2-pyridyldithio]ethyl]mitomycin C (34
This was reacted with 168 mg of the compound 6 (42% yield).

Example 42 Injection The compound of Example 1 (Compound 1; 20 g) and purified mannitol (40 g) were dissolved in distilled water for injection to make up a total volume of 20 liters.
After sterile filtration, 5 ml of the solution was dispensed into brown vials and lyophilized in a conventional manner to obtain lyophilized injections (5 ml/vial).

Lactose (40 g), calcium carbonate (1200 g), and carboxymethylcellulose calcium (300 g) were mixed, and hydroxypropylmethylcellulose (16% aqueous solution; 500 g) was added as a binder. The mixture was mixed, granulated, and dried to obtain granules. The compound of Example 17 (compound 17; 10 g) was added and mixed, and magnesium stearate (10 g) was further added and mixed. The mixture was compressed using a tablet press (Kikusui RI-15) equipped with an 8 mm diameter punch to obtain tablets. Each tablet (weight 200 mg) contained 1 mg of compound 17.

Reference Example 1 Synthesis of Compound "a"N,N'-bis[N-carbobenzyloxy-γ-(α-
[benzyl]-L-glutamylcystamine (859 mg, described in JP-A-51-4121) was dissolved in dichloromethane (25 ml). Anisole (2.5 ml) was added to the solution under ice cooling, and trifluoromethanesulfonic acid (1.5 ml) was then added.
After stirring for 30 minutes under ice cooling, the reaction mixture was stirred for another hour at room temperature. The reaction mixture was concentrated under reduced pressure and decanted twice with ether (30 ml). The residue was dissolved in a buffer solution (50 ml) consisting of M/15 _{Na2HPO4 and} M/15 _KH2PO4 [ ₁ :1 v/v].
The column was passed through a 50 ml column of Mitsubishi Chemical Corporation's PEG-1000.
After flushing with water (150 ml), water/methanol (4:1 v/v; 100 ml
The resulting fraction was concentrated under reduced pressure and then freeze-dried to give N,N'-bis(γ-L-glutamyl)cystamine (compound "a"; 402 mg; yield 98%).

The physicochemical data of the trifluoroacetate salt of this compound were as follows:

SIMS:m/z 411(M+1) ⁺ (Molecular formula C ₁₄ H ₂₆ N ₄ O ₆ S ₂ ; Molecular weight 410.5) ¹ H-NMR (400MHz): (D ₂ O) δ 2.18 (4H,m),2.45 (4
H,m),2.84(4H,m),3.51(4H,m),3.92(2H,m), IR:(KBr)cm ^-1 3450,3100,2940,1680,1638,1200,113
6, specific rotation: ▲[α] ²⁷ _D ▼+11.5° (c 0.47, H ₂ O) Reference Example 2 Synthesis of Compound “b” Compound “a” (205 mg) from Reference Example 1 was dissolved in water/ethanol [20 ml
1:3:1 v/v], ethanethiol (3 ml) was added, and the mixture was stirred at room temperature for 3 days. After removing the solvent under reduced pressure,
The residue was dissolved in a small amount of water and passed through a column containing Diaion SP-207 (Mitsubishi Chemical) (25 ml) as a carrier.
After passing a solution of 100 ml of water/methanol (9:1 v/v; 50 ml) through the column, the resulting fraction was concentrated under reduced pressure and then freeze-dried to obtain γ-L-glutamine cysteamine (compound "b"; 190 ml).
mg (92% yield).

The physicochemical data of this compound as a trifluoroacetate salt were as follows:

SIMS:m/z 207(M+1) ⁺ (Molecular formula C ₇ H ₁₄ N ₂ O ₃ S; Molecular weight 206.3) ¹ H-NMR (400MHz): (D ₂ O) δ 2.18 (4H,m),2.46 (4
H,m),2.62(4H,m),3.34(4H,m),3.97(2H,m), IR:(KBr)cm ^-1 3400,3100,2940,1640,1530,1410,120
5,1135, Specific rotation: ▲[α] ²⁷ _D ▼+11.2° (c 0.99, H ₂ O) Reference Example 3 Synthesis of compound "c" N-carbobenzoxy-α-benzyl-L-aspartic acid (1.617 g; Domestic Chemical 2509181) was dissolved in dichloromethane (20
ml), to which N-hydroxysuccinimide (522 mg) and dicyclohexylcarbodiimide (933 mg) were added.
The reaction mixture was stirred at 0°C for 2 hours and then at room temperature for a further 18 hours.
Ethylamine hydrochloride (1 g) and triethylamine (623 μL) were added, and the mixture was stirred at room temperature for 2 hours. After filtering off the resulting precipitate, 10% aqueous citric acid solution (30 mL) was added, followed by extraction with ethyl acetate (150 mL). The mixture was washed with 5% aqueous sodium bicarbonate solution (30 mL) and an equal volume of saturated saline solution.
After drying with sodium sulfate, the solvent was removed under reduced pressure.
The residue was subjected to silica gel chromatography using a column packed with silica gel (Wakogel-C200; 150 g) and developed with chloroform/methanol (99:1 v/v) to give N-[N-carbobenzoxy-β-(α-benzyl)-L-aspartyl]-S-(p-methoxybenzyl)cysteamine (1.929 g; compound "c"; yield 80%).

The physicochemical data of this compound were as follows:

SIMS:m/z 537(M+1) ⁺ (Molecular formula C ₂₉ H ₃₂ N ₂ O ₆ S; Molecular weight 536.6) ¹ H-NMR (400MHz): (CDCl ₃ ) δ 2.50 (2H,t,J=7H
z), 2.78 (2H, AB, J = 16.4Hz), 3.33 (2H, q, J = 7.0Hz),
3.64 (2H, s), 3.79 (3H, s,), 4.63 (1H, dt, J = 8.5, 5.4H
z）5.12(2H,s),5.19(2H,s),5.83(1H,br)6.07(1
H,br,d),6.88(2H,d,J=9.0Hz),7.24(2H,d,J=9.0H
z),7.36(10H,s) IR:(KBr) cm ^-1 3300,2900,1735,1695,1635,1535,1510,
Reference Example 4 The following compounds were obtained by treating in the same manner as in Reference Example 3, except that homocystamine [Me] was used for compound "d" instead of 2-[(p-methoxybenzyl)thio]ethylamine.
rck Index 10th Edit., 2771 (1983)] as compound "e"
Bishomocystamine (described in Japanese Patent Publication No. 56-54314) was used for compound "f", and cystamine was used for compounds "f" and "g". The reaction required twice the number of equivalents of the protected amino acid used in Reference Example 3. Pyroglutamic acid was used for compound "f". SIMS, IR and ^1H -NM of the obtained compounds were analyzed.
The data for R are shown in Table 13 below.

Compound "d": N,N'-bis[N-carbobenzoxy-γ-
(α-benzyl)-L-glutamyl]homocystamine Compound "e": N,N'-bis[N-carbobenzoxy-γ-
Compound "f": N,N'-bis(L-pyroglutamyl)cystamine Compound "g": N,N'-bis(N-t-butyloxycarbonyl-L-prolyl)cystamine Compounds "d" and "e" were prepared in the same manner as in Reference Examples 1 and 2.
The target mercaptan III was obtained from compound "f" in the same manner as in Reference Example 2.
After treating compound "g" with trifluoroacetic acid,
The desired mercaptan III was obtained in the same manner as in Reference Example 2.

Reference Example 5 The following compounds were obtained in the same manner as in Reference Example 3.
The SIMS, IR and ¹ H-NMR data are shown in Table 14 below.

Compound "h": N-[N-t-butyloxycarbonyl-α
-(β-benzyl)-L-aspartyl]-S-(p-
methoxybenzyl)cysteamine compound "i": N-[N-t-butyloxycarbonyl-α
Compound "j": N-[N-carbobenzoxy-α-(γ-benzyl)-L-glutamyl]-S-(p-methoxybenzyl)cysteamine Compound "k": N-[N-carbobenzoxy-γ-(α-benzyl)-D-glutamyl]-S-(p-methoxybenzyl)cysteamine The target mercaptan was obtained from these compounds by the same procedure as in Reference Example 1.

Reference Example 6: Orotic acid and 2-(2-pyridyldithio)ethylamine dihydrochloride (described in JP-A-55-136261) were used to prepare N-
2-(2-pyridyldithio)ethyl-6-uracilamide (compound "1") was obtained in the same manner as in Reference Example 3. This compound could be used as the starting compound for Example 14 without purification. The physicochemical data of the crude product of this compound were as follows:

SIMS: (m/z) 325(M+1) ^{+ 1} H-NMR (90MHz): (Py−d ₅ ) δ 3.11 (2H,t),3.79
(2H,q),6.43(1H,s),6.98(1H,m),7.54(2H,m),8.
46 (1H,m), 9.87 (1H,m) Similarly, the unstable N-2-(2-pyridyldithio)
Ethyl retinamide (compound "m") was obtained.
-[2-(2-pyridyldithio)ethylcarbamoyl]
The [propanoyl] tocopherol (compound "n") was relatively stable, and SIMS was not observed, but ¹ H-NMR and IR were as follows: ¹ H-NMR (90 MHz): (CDCl ₃ ) δ 0.88 (12H, d), 1.00-
1.64 (21H, m), 1.76 (2H, t), 1.94 (3H, s), 1.98 (3H,
s),2.02(3H,s),2.07(3H,s),2.62(4H,m),2.95(4
H,q),3.56(2H,q),7.15(2H,m),7.50(2H,m),8.48
(1H, m) IR: (KBr) cm ^-1 3240, 2930, 1745, 1665, 1455, 1415, 1150. Reference Example 7: To 3-mercaptopropionic acid (8.71 ml), hydrogen peroxide (35%, w/w; 9.72 g) was added dropwise over 30 minutes with stirring under ice cooling, and the mixture was further stirred at 0°C for 1 hour. The resulting white precipitate was dried under reduced pressure over phosphorus pentoxide for 2 days to give 3,3'
A crude powder of dithiopropionic acid (10.6 g) was obtained.
4.27 g of the product was dissolved in dioxane (70 ml), and N-hydroxysuccinimide (5.16 g) and dicyclohexylcarbodiimide (10.52 g) were added thereto and stirred at room temperature for 5 hours. The resulting precipitate was filtered off, and the mother liquor was diluted with ethyl acetate (300 ml).
After adding 1) and washing with 5% sodium bicarbonate water (50 ml), the mixture was further washed with saturated saline (50 ml). After drying with sodium sulfate,
The solvent was removed under reduced pressure, and the residue was subjected to column chromatography using silica gel (Wako C200).
The fraction eluted with methanol (99:1 v/v) was concentrated.
White powder of bis[N-3,3'-dithiopropionic acid
hydroxysuccinimide ester] (compound "B"; 5.5
7 g) was obtained. The yield from 3-mercaptopropionic acid was
The figure was 67%.

The physicochemical data of this compound were as follows:

SIMS: m/z 405(M+1) ^{+ 1} H-NMR (90MHz): (CDCl ₃ ) δ 2.82 (8H,s), 3.06 (8
H,s), and dibenzyl N', from compound "B" and benzyl N ⁵ -carbobenzoxy-L-ornithinate hydrochloride [described in Annalen der Chemie, 676, 232 (1964)] in the same manner as in Reference Example 3.
N"-(2,2'-dithioethylene-1,1'-dicarbonyl)-bis(N ⁶ -benzyloxycarbonyl-L-ornithinate) (compound "o") was obtained.

Compound "B" and benzyl N ⁶ -carbobenzoxy-L-lysinate p-toluenesulfonate [Bulletin of the Chemical Society of Japan 40 , 19
45 (1967)] to give dibenzyl N',N"-
(2,2'-dithiodiethylene-1,1'-dicarbonyl)-
Bis(N ⁶ -benzyloxycarbonyl-L-lysinate) (compound "p") was obtained.

The physicochemical data for compounds "o" and "p" are shown in Table 15 below.

Reference Example 8 Compound "o" was converted to N',N"-(2,
2'-Dithiodiethylene-1,1'-dicarbonyl)-bis(L-ornithine) (compound "q") was obtained. Also, N',N"-(2,2'-dithiodiethylene-1,1'-dicarbonyl)-bis(L-
From these dimers, the corresponding monomeric mercaptans were obtained in the same manner as in Reference Example 2.

The physicochemical data of compound "q" and compound "r" are shown below.
This is shown in Table 16.

INDUSTRIAL APPLICABILITY The mitomycin derivatives of the present invention generally have higher antitumor activity, lower toxicity, and higher solubility in water or oils than mitomycin C, and are therefore useful as antitumor agents.

──────────────────────────────────────────────────── Continued from the front page (72) Inventor: Makoto Morimoto 203-5 Shimodokari, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture (72) Inventor: Tadashi Ashizawa 3236-13 Ooka, Numazu City, Shizuoka Prefecture (56) References: JP 59-205382 (JP, A) JP 59-175493 (JP, A)

Claims (1)

[Claims] Claim 1: A mitomycin derivative represented by the following formula (I): wherein X' and X" represent a hydrogen atom or a lower alkyl group; X and Z represent a hydrogen atom or a methyl group; provided that when Z is a hydrogen atom, Y is limited to a methyl group.
one of _R1 and _R2 is a carbamoyloxymethyl group,
The other represents a hydrogen atom. n is an integer of 1 to 4.
X is _R3NH , _R3O , or _R3S (wherein _R3 represents a residue excluding the OH of the carboxyl group of the α-amino acid. If the α-amino acid has a second carboxyl group, the carboxyl group may be protected with a lower alkyl group or may form a salt with an alkali metal, ammonium, or organic amine. Also, the amino group of the α-amino acid may be protected with a lower alkanoyl group or may form a salt with an inorganic or organic acid.)