Patent ID: 8329644

Claim:
A compound of the formula: wherein: X1-X2- represents -Leu-Val-, -Leu-Leu-, -Leu-lle-, -Val-Leu-, Val-lle-, -lle-Leu-, lle-Val- or -lle-lle-; R 1 represents an alkyl or heteroalkyl group, substituted by at least one hydroxyl substituent, and R 2 represents hydrogen, or an alkyl or heteroalkyl group, optionally substituted by at least one hydroxyl substituent, or R 1 and R 2 taken together with the nitrogen atom represent a heterocyclic group having at least one hydroxyl substituent, wherein the heterocyclic group optionally further contains one or more heteroatoms; Z is an amino acid residue, —NR 3 R 4 , —NR 5 COR 6 , —NR 5 C(O)OR 6 ; —NR 5 SOR 6 , —NR 5 SO 2 R 6 ; —NR 5 C(S)NR 6 R 7 , —NR 5 C(NR 8 )NR 6 R 7 , or —N═R 9 , where R 3 , R 4 , R 5 , R 6 , R 7 , R 8 and R 9 are independently hydrogen, or a group, optionally substituted, selected from alkyl, heteroalkyl, aryl, heteroaryl, aralkyl and heteroaralkyl, with the proviso that R 9 is not hydrogen; Y is —S— or —S(O)—; or a pharmaceutically acceptable salt thereof.