A compound having the general formula (I) or a pharmaceutically acceptable salt thereof: ** Formula ** in which R1 represents a hydrogen atom, a C1-C8 alkyl group, a substituted C1-C8 alkyl group, a group C2-C6 alkenyl, a substituted C2-C6 alkenyl group, a C2-C6 alkynyl group, a substituted C2-C6 alkynyl group, a hydroxyl group, a C1-C6 alkoxy group, a substituted C1-C6 alkoxy group, an alkyl group C1-C6, a substituted C1-C6 alkylthio group, an amino group, a C1-C6 alkylamino group, a substituted C1-C6 alkylamino group, an amino di (C1-C6 alkyl) group (in which the alkyl groups are equal or different), a di (C1-C6 alkyl) substituted amino group (in which the alkyl groups are the same or different), a formyl group, a (C1-C6 alkyl) carbonyl group, a group (C1-C6 alkyl) substituted carbonyl, a (C1-C6) alkoxy group, a substituted (C1-C6) alkoxy group, a C3-C10 cyclic hydrocarbon group, a C3 cyclic hydrocarbon group -C10 substituted, a heterocyclyl group of 3 to 10 members or a substituted heterocyclyl group of 3 to 10 members, the substituent or substituents of each group being different from the cyclic hydrocarbon group, and the heteroaryl group in R1 represent 1 to 3 groups which are same or different and are selected from the Group of Substituents α or β, two substituents can together form a C1-C5 alkylene group, and the substituent or substituents of the cyclic hydrocarbon group and the heterocyclyl group in R1 represent 1 to 3 groups that are equal or different and are selected from the Group of Substituents α； and R2 represents a hydrogen atom, a C1-C6 alkyl group, a substituted C1-C6 alkyl group, a C2-C6 alkenyl group, a substituted C2-C6 alkenyl group, a C2-C6 alkynyl group, a C2- alkynyl group C6 substituted, a C3-C8 cycloalkyl group or a substituted C3-C8 cycloalkyl group, and the substituent or substituents of each group in R2 represent 1 to 3 groups that are the same or different and are selected from the Group of Substituents α or β, or R1 and R2 together w
