The present invention relates to compounds of formula (I), combinations and uses thereof for disease therapy, wherein R1 represents heteroaryl, -carbocyclyl-heteroaryl, -alkenylheteroaryl or -alkylheteroaryl； R2 represents alkyl； carbocyclyl which may optionally be substituted by alkyl； alkenyl； alkynyl, provided a triple bond is not adjacent to X； -alkyl-aryl； -alkyl-heteroaryl； -alkyl-heterocyclyl in which heterocyclyl may optionally be substituted by alkyl； -alkyl-carbocyclyl in which carbocyclyl may optionally be substituted by alkyl； aryl； heteroaryl； or H； X represents S or NR3； R3 represents H or C1-4 alkyl.
