A compound represented by the general formula (I): wherein R 1 is a hydrogen atom, a halogen atom, or the like； R 2 , R 3 , and R 4 are each independently a hydrogen atom, a halogen atom, C1-C15 alkyl optionally substituted with one or more C1-C12 alkyloxy or the like, or the like； R 5 is a hydrogen atom or the like； R 6 and R 7 are a hydrogen atom or the like； R 8 is C1-C3 alkyl or the like； R 9 is a hydrogen atom or the like), a prodrug, a pharmaceutically acceptable salt, or solvate thereof.
