Potent compstatin analogs

A compound that inhibits complement activation, comprising a peptide having a sequence:

• (SEQ ID NO:
• 26)
• Xaa1-Cys-Val-Xaa2-Gln-Asp-Xaa3-Gly-Xaa4-His-Arg-
• Cys-Xaa5;
• wherein:
• Xaa1 is Ile, Val, Leu, Ac-Ile, Ac-Val, Ac-Leu or a dipeptide comprising Gly-Ile;
• Xaa2 is Trp or an analog of Trp, wherein the analog of Trp has increased hydrophobic character as compared with Trp, with the proviso that, if Xaa3 is Trp, Xaa2 is the analog of Trp comprising 5-fluoro-l-tryptophan, or 6-fluoro-l-tryptophan, or 5-methoxytryptophan, or 5-methyltryptophan, or 1-methyltryptophan, or 1-formyltryptophan;
• Xaa3 is Trp or an analog of Trp comprising a chemical modification to its indole ring wherein the chemical modification increases the hydrogen bond potential of the indole ring;
• Xaa4 is His, Ala, Phe or Trp;
• Xaa5 is L-Thr, D-Thr, Ile, Val, Gly, a dipeptide comprising Thr-Asn or Thr-Ala, or a tripeptide comprising Thr-Ala-Asn, wherein a carboxy terminal —OH of any of the L-Thr, D-Thr, Ile, Val, Gly or Asn optionally is replaced by —NH2;
• and
• the two Cys residues are joined by a disulfide bond.