The present invention provides compounds of formula (I), their use as PARP inhibitors as well as pharmaceutical compositions comprising said compounds of formula (I) wherein R1, R2, R3, L, X, Y and Z have defined meanings.本發明提供式(I)化合物,其作為PARP抑制劑之用途以及含該式(I)化合物之醫藥組成物其中R1、R2、R3、L、X、Y及Z具有定義之意義。