Continuous arycyclic compound

1. A continuous arycyclic compound represented by the formula:

wherein Alk represents a linear C 1-6 alkylene group, a branched C 1-6 alkylene group or a C 1-6 alkylene group having a ring structure; where a part of the carbon atoms constituting the ring structure may be optionally substituted by an oxygen atom, a nitrogen atom or a sulfur atom,

in Ring X,

X 1 represents N or CR X1 ,

X 2 represents N or CR X2 ,

X 3 represents N or CR X3 ,

X 4 represents N or CR X4 ,

where R X1 , R X2 , R X3 and R X4 each independently represents a hydrogen atom; a linear or branched C 1-6 alkyl group which may be substituted by a halogen atom(s); a C 3-7 alkyl group having a ring structure which may be substituted by a halogen atom(s); a linear or branched C 1-6 alkoxy group; a halogen atom or a cyano group,

in Ring Y,

Y 1 represents N or CR Y1 ,

Y 2 represents N or CR Y2 ,

Y 3 represents N or CR Y3 ,

Y 4 represents N or CR Y4 ,

R Y1 , R Y2 , R Y3 and R Y4 each independently represents a hydrogen atom; a linear or branched C 1-6 alkyl group which may be substituted by a halogen atom(s); a C 3-7 alkyl group having a ring structure which may be substituted by a halogen atom(s); a linear or branched C 1-6 alkoxy group; a halogen atom or a cyano group,

in Ring Z,

R Z represents a linear or branched C 1-6 alkyl group which may be substituted by a halogen atom(s) or C 3-7 alkyl group having a ring structure which may be substituted by a halogen atom(s),

or a pharmaceutically acceptable salt thereof,

wherein Ring X and Ring Y have structures represented by any one of the following formulae:

wherein R X1 to R X4 and R Y1 to R Y4 have the same meanings as defined above.

2. The continuous arycyclic compound or a pharmaceutically acceptable salt thereof according to claim 1 , wherein R Z is a linear or branched C 1-6 alkyl group which is substituted by a halogen atom(s) or a C 3-7 alkyl group having a ring structure which may be substituted by a halogen atom(s).

3. The continuous arycyclic compound or a pharmaceutically acceptable salt thereof according to claim 1 , wherein Alk is a branched C 2-4 alkylene group.

4. A continuous arycyclic compound which is any one of the following compounds:

2,2-dimethyl-3-(4-{5-[5-(trifluoromethyl)-1H-imidazol-2-yl]pyrazin-2-yl}phenoxy)-propanoic acid;

2,2-dimethyl-3-[(5-{4-[4-(trifluoromethyl)-1H-imidazol-2-yl]phenyl}pyrazin-2-yl)-oxy]propanoic acid; and

2,2-dimethyl-3-[(4-methyl-5-{5-[5-(trifluoromethyl)-1H-imidazol-2-yl]pyrazin-2-yl}pyridin-2-yl)oxy]propanoic acid,

or a pharmaceutically acceptable salt thereof.

5. An acyl coenzyme A: diacylglycerol acyltransferase DGAT1 inhibitor comprising the continuous arycyclic compound or a pharmaceutically acceptable salt thereof according to claim 1 as an effective ingredient.

6. The DGAT1 inhibitor according to claim 5 which is a prophylactic or treatment agent of obesity.

7. The DGAT1 inhibitor according to claim 6 which is a prophylactic or treatment agent of hyperlipidemia or hypertriglyceridemia.

8. The DGAT1 inhibitor according to claim 5 which is a prophylactic or treatment agent of type 2 diabetes or the following obesity-caused diseases: lumbago or knee osteoarthritis.

9. The DGAT1 inhibitor according to claim 8 which is a prophylactic or treatment agent of type 2 diabetes.

10. A prophylaxis or treatment method of hyperlipidemia or obesity, hypertriglyceridemia, type 2 diabetes, or the following obesity-caused diseases; lumbago or knee osteoarthritis which comprises administering therapeutically effective amount of the continuous arycyclic compound or the pharmaceutically acceptable salt thereof according to claim 1 to a patient.

11. The continuous arycyclic compound or a pharmaceutically acceptable salt thereof according to claim 2 , wherein R Z is methyl which is substituted by a halogen atom(s).

12. The continuous arycyclic compound or a pharmaceutically acceptable salt thereof according to claim 3 , wherein Alk is —C(CH 3 ) 2 —.