| abstract |
Compounds of the formula (I), [wherein, R1: a hydrogen atom, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group etc.; R2 and R4: the same or different, each represents a hydrogen atom, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, C1-C20 alkanoyl group, a C2-C20 alkanoyl group, a C2-C20 alkenoyl group etc.; R3: a C1-C20 alkanoyl group, a C2-C20 alkenoyl group, a C2-C20 alkynoyl group etc.; R5 a hydrogen atom, a halogen atom, a hydroxy group, a C1-C6 alkoxy group, a C2-C6 alkenyloxy group, a C2-C6 alkynyloxy group etc.], or the pharmaceutically acceptable esters or the pharmaceutically acceptable salts thereof, which are useful as the active component. |