Adenine compound

1. An adenine compound of the formula (1):

[wherein R 1 is a halogen atom, a substituted or unsubstituted C 1-12 alkyl group, a substituted or unsubstituted C 2-10 alkenyl group, a substituted or unsubstituted C 2-10 alkynyl group, a substituted or unsubstituted C 3-8 cycloalkyl group, a substituted or unsubstituted 6- to 10-membered aryl group, or a substituted or unsubstituted 5- to 10-membered heteroaryl group,

X is an oxygen atom, a sulfur atom, NR 2 (R 2 is a hydrogen atom or a C 1-6 alkyl group), SO, SO 2 or a single bond (when R 1 is a halogen atom, then X is a single bond),

A 1 is a 4- to 8-membered substituted or unsubstituted, saturated nitrogen-containing heterocycle or an unsaturated non-aromatic nitrogen-containing heterocycle, said heterocycle containing 1 to 2 heteroatom(s) selected from 1 to 2 nitrogen atom(s), 0 to 1 oxygen atom and 0 to 1 sulfur atom,

A 2 is a substituted or unsubstituted 6- to 10-membered aryl group or a substituted or unsubstituted 5- to 10-membered heteroaryl group,

L 1 and L 2 are independently a C 1-12 alkylene group, a C2-12 alkenylene group, or a single bond, and any 1 to 3 methylene group(s) in said alkylene group or alkenylene group may be replaced by an oxygen atom, a sulfur atom, NR 3 (R 3 is a hydrogen atom or a C 1-6 alkyl group), SO, SO 2 , or a carbonyl group],

or a pharmaceutically acceptable salt thereof.

2. The adenine compound according to claim 1 , wherein when the alkyl group, the alkenyl group and the alkynyl group for R 1 are substituted, those groups are substituted by 1 or more groups independently selected from the group consisting of (a), (b) and (c):

(a) a halogen atom, a hydroxy group, a carboxyl group, a mercapto group, an oxo group, a C 1-6 haloalkyl group and a C 1-6 haloalkoxy group;

(b) a C 1-6 alkoxy group, a C 2-6 alkylcarbonyl group, a C 2-6 alkoxycarbonyl group, a C 1-6 alkylsulfonyl group, a C 1-6 alkylsulfinyl group, a C 2-6 alkylcarbonyloxy group and a C 1-6 alkylthio group, wherein a group (b) may optionally and independently be substituted by 1 or more groups selected from a halogen atom, a hydroxy group, a carboxyl group, a C 1-6 alkoxy group, a C 2-6 alkoxycarbonyl group, an amino group being optionally substituted by one or two of the same or different C 1-6 alkyl group(s), a carbamoyl group being optionally substituted by one or two of the same or different C 1-6 alkyl group(s), a sulfamoyl group being optionally substituted by one or two of the same or different C 1-6 alkyl group(s), and a C 1-6 alkylsulfonyl group);

(c) an amino group that may optionally be substituted by 1 or 2 groups selected from the group consisting of (k), (l) and (m), a carbamoyl group that may optionally be substituted by 1 or 2 groups selected from the group consisting of (k), (l) and (m) and a sulfamoyl group that may optionally be substituted by 1 or 2 groups selected from the group consisting of (k), (l) and (m), a 3- to 8-membered cycloalkyl group that may optionally be substituted by 1 or more groups selected from the group consisting of (d), (e) and (f), a 3- to 8-membered cycloalkoxy group that may optionally be substituted by 1 or more groups selected from the group consisting of (d), (e) and (f) and a 4- to 8-membered saturated heterocyclic group that may optionally be substituted by 1 or more groups selected from the group consisting of (d), (e) and (f), and a 6- to 10-membered aryl group that may optionally be substituted by 1 or more groups selected from the group consisting of (g), (h), (i) and (j), a 5- to 10-membered heteroaryl group that may optionally be substituted by 1 or more groups selected from the group consisting of (g), (h), (i) and (j), a 6- to 10-membered aryloxy group that may optionally be substituted by 1 or more groups selected from the group consisting of (g), (h), (i) and (j) and a 5- to 10-membered heteroaryloxy group that may optionally be substituted by 1 or more groups selected from the group consisting of (g), (h), (i) and (j),

wherein when the cycloalkyl group for R 1 is substituted, it is substituted by one or more groups selected from the group consisting of (d), (e) and (f):

(d) a halogen atom, a hydroxy group, a carboxyl group, a mercapto group, an oxo group, a cyano group, a nitro group, a C 1-6 haloalkyl group, and a C 1-6 haloalkoxy group;

(e) a C 1-6 alkyl group, a C 1-6 alkoxy group, a C 2-6 alkenyl group, a C 2-6 alkynyl group, a C 2-6 alkylcarbonyl group, a C 2-6 alkoxycarbonyl group, a C 1-6 alkylsulfonyl group and a C 1-6 alkylthio group, wherein a group (e) may optionally and independently be substituted by 1 or more groups selected from a halogen atom, a hydroxy group, a carboxyl group, a C 1-6 alkoxy group, a C 2-6 alkoxycarbonyl group, an amino group being optionally substituted by one or two of the same or different C 1-6 alkyl group(s), a carbamoyl group being optionally substituted by one or two of the same or different C 1-6 alkyl group(s), a sulfamoyl group being optionally substituted by one or two of the same or different of C 1-6 alkyl group(s), and a C 1-6 alkylsulfonyl group;

(f) an amino group that may optionally be substituted by 1 or 2 groups selected from the group consisting of (k), (l) and (m), a carbamoyl group that may optionally be substituted by 1 or 2 groups selected from the group consisting of (k), (l) and (m) and a sulfamoyl group that may optionally be substituted by 1 to 2 groups selected from the group consisting of (k), (l) and (m), a 6- to 10-membered aryl group that may optionally be substituted by one or more groups selected from the group consisting of (g), (h), (i) and (j), and a 5- to 10-membered heteroaryl group that may optionally be substituted by 1 or more groups selected from the group consisting of (g), (h), (i) and (j);

wherein when the aryl group and heteroaryl group for R 1 are substituted, those groups are substituted by one or more groups selected from the group consisting of (g), (h), (i) and (j):

(g) a halogen atom, a hydroxy group, a mercapto group, a cyano group, a nitro group, a C 1-6 haloalkyl group, and a C 1-6 haloalkoxy group;

(h) a C 1-6 alkyl group, a C 1-6 alkoxy group, a C 2-6 alkenyl group, a C 2-6 alkynyl group, a C 2-6 alkylcarbonyl group, a C 2-6 alkoxy-carbonyl group, and a C 1-6 alkylthio group, wherein a group (h) may optionally and independently be substituted by 1 or more groups selected from a halogen atom, a hydroxy group, a carboxyl group, a C 1-6 alkoxy group, a C 2-6 alkoxycarbonyl group, an amino group being optionally substituted by one or two of the same or different C 1-6 alkyl group(s), a carbamoyl group being optionally substituted by one or two of the same or different C 1-6 alkyl group(s), a sulfamoyl group being optionally substituted by one or two of the same or different C 1-6 alkyl group(s), and a C 1-6 alkylsulfonyl group;

(i) a 3- to 8-membered cycloalkyl group and a 4- to 8-membered saturated heterocyclic group, wherein a group (i) may optionally and independently be substituted by one or more groups selected from a halogen atom, a hydroxy group, a carboxyl group, a C 1-6 alkyl group and a C 1-6 alkoxy group;

(j) an amino group that may optionally be substituted by one or two groups selected from the group consisting of (k), (l) and (m), a carbamoyl group that may optionally be substituted by one or two groups selected from the group consisting of (k), (l) and (m), and a sulfamoyl group that may optionally be substituted by one or two groups selected from the group consisting of (k), (l) and (m);

(k) a C 1-6 alkyl group, a C 2-6 alkenyl group, a C 2-6 alkynyl group, a C 2-6 alkylcarbonyl group, a C 2-6 alkoxycarbonyl group, a C 1-6 alkylsulfonyl group, a C 1-6 alkylsulfinyl group, a 3- to 8-membered cycloalkyl group, a 3- to 8-membered cycloalkylcarbonyl group, a 3- to 8-membered cycloalkoxycarbonyl group, a 3- to 8-membered cycloalkylsulfonyl group, and a 3- to 8-membered cycloalkylsulfinyl group, wherein a group (k) may optionally be substituted by one or more groups selected from a halogen atom, a hydroxy group, a carboxyl group, a C 1-6 alkoxy group and a C 2-6 alkoxycarbonyl group;

(l) a 6- to 10-membered aryl group, a 6- to 10-membered arylcarbonyl group, a 6- to 10-membered aryloxycarbonyl group, a 6- to 10-membered arylsulfonyl group, a 6- to 10-membered arylsulfinyl group, a 5- to 10-membered heteroaryl group, a 5- to 10-membered heteroarylcarbonyl group, a 5- to 10-membered heteroaryloxycarbonyl group, a 5- to 10-membered heteroarylsulfonyl group, and a 5- to 10-membered heteroarylsulfinyl group, wherein a group (l) may optionally be substituted by a halogen atom, a hydroxy group, a mercapto group, a cyano group, a nitro group, a carboxyl group, a C 1-6 alkyl group, a C 1-6 alkoxy group, a C 2-6 alkoxycarbonyl group, or a C 1-6 alkylthio group;

(m) a group where two substituents combine together with a nitrogen atom to form a 4- to 8-membered nitrogen-containing saturated heterocycle containing 1 to 4 heteroatom(s) selected from 1 to 3 nitrogen atom(s), 0 to 1 oxygen atom, and 0 to 1 sulfur atom wherein said nitrogen-containing saturated heterocycle may optionally be substituted on any carbon atoms or nitrogen atoms by one or more of the same or different groups selected from a halogen atom, a hydroxy group, a carboxyl group, a C 1-6 alkyl group, a C 1-6 alkoxy group, a C 2-6 alkoxycarbonyl group and a C 2-6 alkylcarbonyl group,

wherein when the 4- to 8-membered nitrogen-containing heterocycle for A 1 is substituted, it is substituted by one or more group(s) independently selected from the group consisting of a halogen atom, a hydroxy group, an oxo group, a C 1-6 alkyl group, a C 1-6 alkoxy group, a C 2-6 alkylcarbonyl group, and a C 2-6 alkoxycarbonyl group;

wherein when the 6- to 10-membered aryl group and the 5- to 10-membered heteroaryl group for A 2 are substituted, they are substituted by one or more group(s) independently selected from the group consisting of (g′), (h′) and (i′);

(g′) a halogen atom, a hydroxy group, a mercapto group, a cyano group, a nitro group, a C 1-6 haloalkyl group, and a C 1-6 haloalkoxy group;

(h′) a C 1-6 alkyl group, a C 1-6 alkoxy group, a C 2-6 alkyl-carbonyl group, a C 1-6 alkylsulfonyl group, and a C 1-6 alkylthio group, wherein a group (h′) may optionally be substituted by one or more of the same or different groups selected from a halogen atom, a hydroxy group, a C 1-6 alkoxy group, a C 1-6 alkylsulfonyl group, an amino group, a carbamoyl group and a sulfamoyl group, wherein the above amino, carbamoyl and sulfamoyl groups may optionally be substituted by one or two groups selected from the group consisting of (j′) and (k′);

(i′) an amino group, a carbamoyl group, and a sulfamoyl group, wherein a group (i′) may optionally be substituted by one or two groups selected from the group consisting of (j′) and (k′);

(j′) a C 1-6 alkyl group, a C 2-6 alkylcarbonyl group, a C 1-6 alkylsulfonyl group, a C 1-6 alkylsulfinyl group, a 3- to 8-membered cycloalkyl group, a 3- to 8-membered cycloalkylcarbonyl group, a 3- to 8-membered cycloalkoxycarbonyl group, a 3- to 8-membered cycloalkylsulfonyl group, and a 3- to 8-membered cycloalkylsulfinyl group, wherein a group (j′) may optionally and independently be substituted by one or more groups selected from the group consisting of a halogen atom, a hydroxy group, a C 1-6 alkyl group and a C 1-6 alkoxy group;

(k′) a group where two substituents combine together with a nitrogen atom to form a 4- to 8-membered nitrogen-containing saturated heterocycle containing 1 to 4 heteroatom(s) selected from 1 to 3 nitrogen atom(s), 0 to 1 oxygen atom, and 0 to 1 sulfur atom wherein said nitrogen-containing saturated heterocycle may optionally be substituted on any carbon atoms or nitrogen atoms by one or more groups selected from the group consisting of a halogen atom, a hydroxy group, a C 1-6 alkyl group, a C 1-6 alkoxy group and a C 2-6 alkylcarbonyl; or a pharmaceutically acceptable salt thereof.

3. The adenine compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein in the formula (1), A 1 is pyrrolidine, piperidine, azetidine, piperazine, morpholine, thiomorpholine, thiomorpholin-1-oxide, or thiomorpholine-1,1-dioxide, these groups being either substituted or unsubstituted.

4. The adenine compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein in the formula (1), A 2 is a phenyl group, a pyridyl group, a furyl group, an imidazolyl group or a thienyl group, these groups being either substituted or unsubstituted.

5. The adenine compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein in the formula (1), A 1 is pyrrolidine, piperidine or piperazine, and A 2 is a substituted or unsubstituted phenyl group or a substituted or unsubstituted pyridyl group.

6. The adenine compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein in the formula (1), L 1 is a group of the following formula:

(CH2) n -(Y4) m -(CH2) l

[in which n and l are independently an integer of 0 to 5, and m is 0 or 1, provided that when m is 1, then n is 2 or more, and Y 4 is an oxygen atom or NR 3 (R 3 is a hydrogen atom or a C 1-6 alkyl group)],

L 2 is a single bond, an oxygen atom, a carbonyl group, C1-10 straight chain or branched chain alkylene, a C 2-10 straight chain or branched chain alkenylene, or a group of the following formula:

(CH2) a -(CO) p -(CH2) q -(NR3) r -(CH2) t -(O) u

[in which R 3 is a hydrogen atom or a C 1-6 alkyl group, a, t and q are independently an integer of 0 to 4, p, r and u are independently 0 or 1, provided that when r and u are 1, then t is 2 or more.

7. The adenine compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein in the formula (1), L 1 is a C2-8 straight chain or branched chain alkylene, and L 2 is a single bond, an oxygen atom, a carbonyl group, a C 1-6 straight chain or branched chain alkylene or a C 2-6 straight chain or branched chain alkenylene.

8. The adenine compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 3 is a hydrogen atom or a C 1-4 alkyl group.

9. The adenine compound according to claim 1 or a pharmaceutically acceptable salt thereof, wherein the compound is selected from the group consisting of:

2-butoxy-7,8-dihydro-9-(3-[4-(4-methylbenzyl)piperazin-1-yl]-propyl)-8-oxoadenine,

9-(3-[4-benzylpiperidin-1-yl]propyl)-2-butoxy-7,8-dihydro-8-oxoadenine,

2-butoxy-7,8-dihydro-9-(3-[4-(4-fluorobenzoyl)piperidine-1-yl]-propyl)-8-oxoadenine,

2-butoxy-9-(3-[4-cinnamylpiperazin-1-yl]propyl)-7,8-dihydro-8-oxoadenine,

9-(7-[4-(4-acetylphenyl)piperazin-1-yl]heptyl)-2-butoxy-7,8-dihydro-8-oxoadenine,

2-butoxy-7,8-dihydro-9-(7-[4-(4-pyridyl)piperazin-1-yl]heptyl)-8-oxoadenine,

2-butoxy-9-(7-[4-(4-chloro-2-methylphenoxy)piperazin-1-yl]-heptyl)-7,8-dihydro-8-oxoadenine,

2-butoxy-7,8-dihydro-9-(7-[4-(4-methoxyphenyl)piperazin-1-yl]-heptyl)-8-oxoadenine,

6-amino-9-[2-(1-benzylpiperidin-4-yl)ethyl]-2-(2-methoxyethoxy)-7,9-dihydropurin-8-one,

6-amino-9-{2-[1-(4-dimethylaminomethylbenzyl)piperidin-4-yl]-ethyl}-2-(2-methoxyethoxy)-7,9-dihydropurin-8-one,

9-[1-(3-{N-benzyl,N-methylamino}propyl)piperidin-4-yl]methyl-2-butoxy-7,8-dihydro-8-oxoadenine,

2-butoxy-7,8-dihydro-9-{1-[3-(N-2-phenoxyethyl-N-methyl-amino)-propyl]-piperidin-4-ylmethyl}-8-oxoadenine,

2-butoxy-7,8-dihydro-9-[7-(4-{2-[N-methyl-N-benzyl]aminoethyl}-piperazin-1-yl)pentyl]-8-oxoadenine,

2-butoxy-7,8-dihydro-9-[7-(4-{2-[N-methyl-N-benzyl]aminoethyl}-piperazin-1-yl)heptyl]-8-oxoadenine,

2-butoxy-7,8-dihydro-9-(7-{4-[2-phenoxyethyl]piperazin-1-yl}-heptyl)-8-oxoadenine,

9-(3-[2-benzyl-4-methyl-piperazin-1-yl]propyl)-2-butoxy-7,8-dihydro-8-oxoadenine,

9-(3-[3-benzyl-4-methyl-piperazin-1-yl]propyl)-2-butoxy-7,8-dihydro-8-oxoadenine,

2-butoxy-7,8-dihydro-9-(3-{1-(2-phenoxyethyl)piperidin-4-yl}-propyl)-8-oxoadenine, and

2-butoxy-7,8-dihydro-9-[3-{1-(3-phenylpropyl)piperidin}-4-yl]-propyl)-8-oxoadenine.

10. A pharmaceutical composition comprising as an active ingredient an adenine compound as set forth in claim 1 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.