y the following general formula (I): R1-A-X-NHCO???Y???R2 [0005] wherein [0006] R1 is heterocyclic group which may have suitable substituents, or phenyl which may have suitable substituents, [0007] R2 is condensed phenyl which may have suitable substituents, phenyl which may have suitable substituents, or thienyl which may have suitable substituents, [0008] A is a group of the formula: ???(CH2)t??