Patent ID: 7713935

Claim:
A compounds of Formula I: wherein R 1 is an optionally substituted 4-, 5- or 6-membered heterocyclic ring comprising one or more heteroatoms, in which at least one carbon atom of the ring is substituted with O or S or N; X 1 is —CO— or —CS— or —CH 2 CO— or CH(R 4 ), wherein R 4 is H, or an optionally substituted alkyl, or a —COOH or —COOR 11 , wherein R 11 is an optionally substituted alkyl; X 2 is —CO— or —CS—; Z is —CH 2 — or —S— or —O— or —NH—; R 7 and R 8 are each independently H or an optionally substituted lower alkyl; R 9 and R 10 are each independently H, an optionally substituted alkyl, or an optionally substituted carbocyclic ring; W represents an amino acid residue; X represents a 1 to 20 amino acid, at least a majority of which are in the D-configuration, the C-terminal amino acid residue optionally being substituted with an amino group or 7-amino-4-methyl coumarin; and pharmaceutically acceptable salts thereof.