Peptide-based compounds

A compound of general formula (I) having an affinity for the integrin receptors,

• (I) wherein
• G represents glycine, and
• D represents aspartic acid, and
• R1 represents —(CH2)n— or —(CH2)n—C6H4— wherein
• n represents a positive integer 1 to 3, and
• X1 represents a bond or 1 to 2 amino acid residues wherein each amino acid residue independently optionally can be derivatized with a carbohydrate, PEG-containing moiety or alkyl chain in order to modify the pharmacokinetics or blood clearance rates of said agents,
• X2 and X4 represent independently an amino acid residue capable of forming a disulfide bond,
• X3 represents arginine, N-methylarginine or an arginine mimetic,
• X5 represents a hydrophobic amino acid and,
• X6 represents a thiol-containing amino acid residue, and X6 forms a thioether bridge linked to R1,
• and k represents a positive integer 1 to 10, and
• X7 represents a linker (L) moiety comprising a PEG spacer, or
• X7 is absent and
• X8 represents a reporter (R) moiety, or is —NH2 or is absent, and
• pharmaceutical acceptable salts thereof.