A compound which has a 6-aminopurine backbone, characterized in that it has the formula: wherein R 1 and R 2, which may be identical or different, represent, independently of one another, hydrogen, alkyl, alkenyl, alkynyl, aryl, acyl (-COR 9), amino (-NH 2), alkylamino (-NHR 9), dialkylamino (-NR 9 R' 9), acylamino (-NHCOR 9), diacylamino (-N(COR 9)(COR' 9)), trifluoromethyl (-CF 3), halogen, hydroxyl (-OH), alkoxy (-OR 9), thio (-SH) or thioalkyl (-SR 9), with R 9 and R' 9, which may be identical or different, representing, independently of one another, alkyl, alkenyl, alkynyl or aryl, Z is on either of the positions N 7 and N 9 of the purine, and represents hydrogen, alkyl, alkenyl, alkynyl, aryl, -COR 9, halogen, -(CH 2) n -OR 5, -(CH 2) n1 -O-(CH 2) n2 R 5, -(CH 2) n' -COOR 5 or -(CH 2) n -P(=O)(OR 6)(OR 7), with: n, n 1 and n 2, which may be identical or different, representing, independently of one another, an integer ranging from 1 to 10 and n' an integer ranging from 0 to 10, R 5 representing hydrogen, alkyl, alkenyl, alkynyl, aryl or -COR 9, R 6 and R 7, which may be identical or different, representing, independently of one another, hydrogen, alkyl, alkenyl, alkynyl, aryl, -COR 9, an organic cation or a metal cation, X representi a divalent radical chosen from C=O, C=S, C=NR 8 or SO 2, with: R 8 representing hydrogen, alkyl, alkenyl, alkynyl, -OH or -OR 9, Y has the same meaning as R 5, Ar represents a biphenyl which may be substituted with a substituent R 3, R 3 represents hydrogen, alkyl, alkenyl, alkynyl, aryl, -NH 2, -NHR 9, -NR 9 R' 9, -OH, -OR 9, aryloxy, benzyloxy (-OCH 2 C 6 H 5); a 5-membered or 6-membered aromatic or nonaromatic heterocycle comprising one or more heteroatoms chosen from N, O or S, said 5-membered or 6-membered heterocycle also possibly being substituted with a substituent R 4, with: R 4 representing hydrogen, alkyl, alkenyl, alkynyl, aryl, -COR 9, -(CH 2) n- OR 5, -(CH 2) n1 -O-(CH 2) n2 R 5, -(CH 2) n' -COOR 5 or -(CH 2) n -P(=O)(OR 6 R 7), R 3 being bonded to Ar in the ortho, meta or para position, X being bonded to Ar in the ortho, meta or para position, with the exception of the compound 9 H -purin-6-yl-[1,1'-biphenyl]-4-carboxamide. R 1 and R 2, which may be identical or different, represent, independently of one another, hydrogen, alkyl, alkenyl, alkynyl, aryl, acyl (-COR 9), amino (-NH 2), alkylamino (-NHR 9), dialkylamino (-NR 9 R' 9), acylamino (-NHCOR 9), diacylamino (-N(COR 9)(COR' 9)), trifluoromethyl (-CF 3), halogen, hydroxyl (-OH), alkoxy (-OR 9), thio (-SH) or thioalkyl (-SR 9), with R 9 and R' 9, which may be identical or different, representing, independently of one another, alkyl, alkenyl, alkynyl or aryl, with R 9 and R' 9, which may be identical or different, representing, independently of one another, alkyl, alkenyl, alkynyl or aryl, Z is on either of the positions N 7 and N 9 of the purine, and represents hydrogen, alkyl, alkenyl, alkynyl, aryl, -COR 9, halogen, -(CH 2) n -OR 5, -(CH 2) n1 -O-(CH 2) n2 R 5, -(CH 2) n' -COOR 5 or -(CH 2) n -P(=O)(OR 6)(OR 7), with: n, n 1 and n 2, which may be identical or different, representing, independently of one another, an integer ranging from 1 to 10 and n' an integer ranging from 0 to 10, R 5 representing hydrogen, alkyl, alkenyl, alkynyl, aryl or -COR 9, R 6 and R 7, which may be identical or different, representing, independently of one another, hydrogen, alkyl, alkenyl, alkynyl, aryl, -COR 9, an organic cation or a metal cation, n, n 1 and n 2, which may be identical or different, representing, independently of one another, an integer ranging from 1 to 10 and n' an integer ranging from 0 to 10, R 5 representing hydrogen, alkyl, alkenyl, alkynyl, aryl or -COR 9, R 6 and R 7, which may be identical or different, representing, independently of one another, hydrogen, alkyl, alkenyl, alkynyl, aryl, -COR 9, an organic cation or a metal cation, X representi a divalent radical chosen from C=O, C=S, C=NR 8 or SO 2, with: R 8 representing hydrogen, alkyl, alkenyl, alkynyl, -OH or -OR 9, R 8 representing hydrogen, alkyl, alkenyl, alkynyl, -OH or -OR 9, Y has the same meaning as R 5, Ar represents a biphenyl which may be substituted with a substituent R 3, R 3 represents hydrogen, alkyl, alkenyl, alkynyl, aryl, -NH 2, -NHR 9, -NR 9 R' 9, -OH, -OR 9, aryloxy, benzyloxy (-OCH 2 C 6 H 5); a 5-membered or 6-membered aromatic or nonaromatic heterocycle comprising one or more heteroatoms chosen from N, O or S, said 5-membered or 6-membered heterocycle also possibly being substituted with a substituent R 4, with: R 4 representing hydrogen, alkyl, alkenyl, alkynyl, aryl, -COR 9, -(CH 2) n- OR 5, -(CH 2) n1 -O-(CH 2) n2 R 5, -(CH 2) n' -COOR 5 or -(CH 2) n -P(=O)(OR 6 R 7), R 4 representing hydrogen, alkyl, alkenyl, alkynyl, aryl, -COR 9, -(CH 2) n- OR 5, -(CH 2) n1 -O-(CH 2) n2 R 5, -(CH 2) n' -COOR 5 or -(CH 2) n -P(=O)(OR 6 R 7), R 3 being bonded to Ar in the ortho, meta or para position, X being bonded to Ar in the ortho, meta or para position, with the exception of the compound 9 H -purin-6-yl-[1,1'-biphenyl]-4-carboxamide.