This invention provides a compound of the formula (I): a pharmaceutically acceptable salt or solvate thereof, wherein R 1 is optionally substituted lower alkyl, Y is -S(O)n- wherein n is 1 or 2, or -CO-, R 2 is hydrogen or lower alkyl, R 7 is hydrogen or lower alkyl, X is lower alkylene, lower alkenylene, arylene, cycloalkylene or the like, and Z is lower alkyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl or the like.提供如下式(I)化合物、這些之其製藥容許鹽或這些之溶劑合物：；(I)；R1為可有取代基之低烷基，Y為-S(O)n-(n為1或2)或-CO-，R2為氫或低烷基，R7為氫或低烷基，X為低伸烷基、低伸烯基、伸芳基或環伸烷基等，Z為低烷基、可有取代基之烴環式基或可有取代基之雜環式基等]。
