A compound of formula in which, A is a C-R1 b group or a nitrogen atom; R1a is a hydrogen atom, a halogen atom, a nitrile group, a nitro group, an alkyl group, an alkyloxy group, an alkylthio group, an amino group, an alkylamino group, a dialkylamino group or a heterocyclic group; R1b is a hydrogen atom, an alkyloxy group, an alkyl group or a heterocyclic group; or R1a and R1b can form, together with the carbon atoms to which they are attached, an aryl group or a heterocyclic group; R1c is a hydrogen atom, a halogen atom, an alkyl group, an alkyloxy group, an alkylthio group, a heterocyclic group, a cyano group, an amido group or a hydroxyl group; R1d is a hydrogen atom, a halogen atom, an alkyloxy group or an alkyl group; R2 and R'2 are independently a hydrogen atom, an alkyl group, an alkynyl group, a cycloalkyl group, an aryl group or a heterocyclic group, with the proviso that R2 and R'2 are not simultaneously a hydrogen atom, or R2 and R2' can form, together with the carbon atom to which they are attached, a cycloalkyl group or a heterocycloalkyl group; L is a CO-NH-CH2, NH-CO-CH2 or a NH-CO-NH group; HET is a heterocyclic group selected from: B1 and B2 are independently a nitrogen atom or a carbon atom; R3 is a COR5 group, a CO-Alkyl-COR5 group or an alkyl group substituted by a COR5 group; R4 is a hydrogen atom, an alkyl group or a hydroxyl group; R5 is a hydroxyl group, an alkyloxy group, an alkyl group, a NR8R8'group or a -O-CH-(CH2-O-CO-R6)2 group; R6 is aC10-C20 alkyl group; R8 is a hydrogen atom or an alkyl group; R8' is a hydrogen atom, an alkyl group, a C(=NH)NH2 group, a C(=NH)NHCOOtBu group or an alkoxy group; and R9 is a hydrogen atom, an alkyl group or a halogen atom. A is a C-R1 b group or a nitrogen atom; R1a is a hydrogen atom, a halogen atom, a nitrile group, a nitro group, an alkyl group, an alkyloxy group, an alkylthio group, an amino group, an alkylamino group, a dialkylamino group or a heterocyclic group; R1b is a hydrogen atom, an alkyloxy group, an alkyl group or a heterocyclic group; or R1a and R1b can form, together with the carbon atoms to which they are attached, an aryl group or a heterocyclic group; R1c is a hydrogen atom, a halogen atom, an alkyl group, an alkyloxy group, an alkylthio group, a heterocyclic group, a cyano group, an amido group or a hydroxyl group; R1d is a hydrogen atom, a halogen atom, an alkyloxy group or an alkyl group; R2 and R'2 are independently a hydrogen atom, an alkyl group, an alkynyl group, a cycloalkyl group, an aryl group or a heterocyclic group, with the proviso that R2 and R'2 are not simultaneously a hydrogen atom, or R2 and R2' can form, together with the carbon atom to which they are attached, a cycloalkyl group or a heterocycloalkyl group; L is a CO-NH-CH2, NH-CO-CH2 or a NH-CO-NH group; HET is a heterocyclic group selected from: B1 and B2 are independently a nitrogen atom or a carbon atom; R3 is a COR5 group, a CO-Alkyl-COR5 group or an alkyl group substituted by a COR5 group; R4 is a hydrogen atom, an alkyl group or a hydroxyl group; R5 is a hydroxyl group, an alkyloxy group, an alkyl group, a NR8R8'group or a -O-CH-(CH2-O-CO-R6)2 group; R6 is aC10-C20 alkyl group; R8 is a hydrogen atom or an alkyl group; R8' is a hydrogen atom, an alkyl group, a C(=NH)NH2 group, a C(=NH)NHCOOtBu group or an alkoxy group; and R9 is a hydrogen atom, an alkyl group or a halogen atom. B1 and B2 are independently a nitrogen atom or a carbon atom; R3 is a COR5 group, a CO-Alkyl-COR5 group or an alkyl group substituted by a COR5 group; R4 is a hydrogen atom, an alkyl group or a hydroxyl group; R5 is a hydroxyl group, an alkyloxy group, an alkyl group, a NR8R8'group or a -O-CH-(CH2-O-CO-R6)2 group; R6 is aC10-C20 alkyl group; R8 is a hydrogen atom or an alkyl group; R8' is a hydrogen atom, an alkyl group, a C(=NH)NH2 group, a C(=NH)NHCOOtBu group or an alkoxy group; and R9 is a hydrogen atom, an alkyl group or a halogen atom.