ANT-ligands having a substituted nitrogeneous heterocycle A wherein A is a substituted pyrimidinone of formula I wherein R1 is —(CH2)n-CO—OH; —(CH2)n-CO—OR; —(CH2)n-CO—NHR; —(CH2)n-CO—N(R, R′); —(CH2)n-OH; —(CH2)n-OR; —(CH2)n-OAr; —(CH2)n-C(R,R′)—(CH2)n-OH, R and R′, in the above radicals, being identical or different and representing H or a C1-C12 alkyl or cycloalkyl radical; and Ar is a phenyl or Het., Het. representing an heterocyclic radical with one or several hetero atoms selected between N, S and O, said phenyl or heterocycle being optionally substituted by one or several atoms, groups or radicals selected from halogen atoms such as Cl, Br, I, or halogenated groups such as —CCl3 or —CF3; one or several —OH, —OR, —COOH or —COOR groups; a phenyl; a linear or branched C1-C12 alkyl radical; —NH—COR; or —CN; said groups occupying the same or different positions on the phenyl or heterocyclic radical; a linear or branched C1-C12 alkyl radical; a linear or branched C2-C12 alkylene radical; —(CH2)n-C3-C6 cycloalkyl radical; —(CH2)n Ar or —(CH2)n-Het.; —(CH2)n-NH—CO—R; —(CH2)n-NH2; —(CH2)n-N(R,R′); —(CH2)n-NH—CO—OH; —(CH2)n-NH—CO—OR; —NH—(CH2)n-CO—OH; —NH—(CH2)n-CO—OR; R2 is —(CH2)n-Ar, Ar being such as above defined and being optionally substituted such as above defined; a linear or branched C1-C12 alkyl or C2-C12 alkenyl radical, —(CH2)n-OH; —(CH2)n-OR; —(CH2)n-CO-Het; —(CH2)n-NH—CO—R; —(CH2)n-NH2; —(CH2)n-N(R,R′); —(CH2)n-CO—OH; —(CH2)n-CO—OR; a linear or branched C1-C12 alkyl radical; —(CH2)n-C(R)═CH—C(R)═CH2; R3 forms a phenyl or an heterocyclic condensed group with the two adjacent carbons of the pyrazinone residue, said condensed group being optionally substituted such as above defined for Ar and Het.; and/or condensed to a cyclohexyl or oxanyl group, in turn optionally substituted such as above defined for Ar; n is 0 or an integer from 1 to 5; or A is a substituted pyrimidine of formula II wherein R4 is a —CO—NH—Ar radical, optionally substituted such as above defined; R5 forms a phenyl or heterocyclic group condensed to the two adjacent carbon groups of the pyrazine residue, said phenyl or heterocyclic group being optionally substituted such as above defined, and Ar being such as above defined with respect to formula I or A is a substituted pyridine group of formula III wherein, Ar and R2 are as above defined with respect to formula I.