Sterol derivative

1. A sterol derivative represented by the general formula (I):

[wherein Y represents optionally substituted lower alkyl or optionally substituted lower alkenyl,

X a and X b are the same or different, and represent a bond or —NR a — (wherein R a represents a hydrogen atom, optionally substituted lower alkyl, optionally substituted cycloalkyl, optionally substituted lower alkanoyl, or optionally substituted aroyl),

R 1 , R 2 , R 3 , R 4 , R 7 and R 8 are the same or different, and represent a hydrogen atom or hydroxy, or

R 1 and R 2 , R 3 and R 4 , or R 7 and R 8 together represent ═O,

R 5 and R 6 are the same or different, and represent a hydrogen atom, halogen, azido, hydroxy, optionally substituted lower alkoxy, optionally substituted cycloalkyloxy, optionally substituted lower alkenyloxy, optionally substituted lower alkynyloxy, optionally substituted aryloxy, optionally substituted aromatic heterocyclyloxy, optionally substituted aliphatic heterocyclyloxy, optionally substituted lower alkanoyloxy, optionally substituted aroyloxy, optionally substituted aromatic heterocyclylcarbonyloxy, or —NR b R c (wherein R b and R c are the same or different, and represent a hydrogen atom, optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted cycloalkyl, optionally substituted aryl, an optionally substituted aromatic heterocyclic group, an optionally substituted aliphatic heterocyclic group, optionally substituted lower alkanoyl, optionally substituted aroyl, optionally substituted lower alkoxycarbonyl, optionally substituted aryloxycarbonyl, optionally substituted aromatic heterocyclyloxycarbonyl, optionally substituted lower alkylcarbamoyl, optionally substituted di-lower alkylcarbamoyl, optionally substituted arylcarbamoyl, optionally substituted aromatic heterocyclylcarbamoyl, optionally substituted arylsulfonyl, or optionally substituted lower alkylsulfonyl), or R 5 and R 6 together represent O═, R d ON═ (wherein R d represents a hydrogen atom, optionally substituted lower alkyl, optionally substituted cycloalkyl, optionally substituted aryl, an optionally substituted aromatic heterocyclic group, or an optionally substituted aliphatic heterocyclic group), or R e R f C═ (wherein R e and R f are the same or different, and represent a hydrogen atom, halogen, optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted lower alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, an optionally substituted aromatic heterocyclic group, an optionally substituted aliphatic heterocyclic group, optionally substituted lower alkoxy, optionally substituted aryloxy, optionally substituted aromatic heterocyclyloxy, optionally substituted lower alkanoyl, optionally substituted aroyl, optionally substituted lower alkanoyloxy, or optionally substituted aroyloxy),

R 9 represents a hydrogen atom, optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted lower alkynyl, or optionally substituted cycloalkyl, or

R 1 and R 3 , R 3 and R 5 (provided that this is only when X a is a bond), R 5 and R 7 (provided that this is only when X b is a bond), or R 7 and R 9 together represent a bond or an oxygen atom, and

regarding R 10 , R 11 and R 12 , R 10 and R 11 together represent a bond or an oxygen atom and R 12 represents a hydrogen atom, or R 10 and R 12 together represent a bond or an oxygen atom and R 11 represents a hydrogen atom] (provided that compounds represented by the following formulas (P) and (Q) are excluded), or a pharmaceutically acceptable salt thereof

2. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein R 10 and R 11 together represent a bond and R 12 is a hydrogen atom.

3. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein X a and X b are bonds.

4. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein R 7 and R 8 are hydrogen atoms.

5. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein R 5 is a hydrogen atom.

6. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein R 6 is hydroxy, optionally substituted lower alkoxy, optionally substituted cycloalkyloxy, optionally substituted lower alkenyloxy, optionally substituted lower alkynyloxy, optionally substituted aryloxy, optionally substituted aromatic heterocyclyloxy, optionally substituted aliphatic heterocyclyloxy, optionally substituted lower alkanoyloxy, optionally substituted aroyloxy, or —NR b1 R c1 (wherein R b1 and R c1 are the same or different, and represent a hydrogen atom, optionally substituted lower alkyl, optionally substituted lower alkanoyl, or optionally substituted aroyl).

7. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein R 6 is hydroxy, optionally substituted lower alkoxy, optionally substituted aryloxy, optionally substituted aromatic heterocyclyloxy, optionally substituted aliphatic heterocyclyloxy, or —NR b1 R c1 (wherein R b1 and R c1 have the same meanings as defined above, respectively).

8. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein R 6 is hydroxy or optionally substituted lower alkoxy.

9. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein R 5 and R 6 together represent O═ or R d ON═ (wherein R d has the same meaning as defined above).

10. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein R 9 is a hydrogen atom or optionally substituted lower alkyl.

11. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein Y is optionally substituted lower alkyl.

12. The sterol derivative or the pharmaceutically acceptable salt thereof according to claim 1 , wherein Y is optionally substituted lower alkenyl.