Lanthionine bridged peptides

Lanthionine-bridged peptides of the formula:

• wherein R1 is a tetrapeptide selected from the group consisting of
• Tyr-Phe-Gln-Asn, Phe-D-Trp-Lys-Thr, Phe-D-Trp-Lys-Val, Tyr-lleu-Gln-Asn, and Tyr-D-Trp-Lys-Val;
• R2 represents en amino acid selected from the group consisting of D-Phe, D-β-Nal, Tyr, TrpNH2, Thr NH2, Thr(ol), or represents H, acyl or aracyl with 2 to 12 carbon atoms;
• or an amino acid sequence selected from the group consisting of Pro-Arg-Gly and Pro-u-Gly
• R3 is selected from the group consisting of —OH, NH3;
• TrpNH2, ThrNH2, Thr(ol), Leu, Arg, where the -C terminal —COOH is present or is replaced by —CONH2 or —CH2OH;
• and
• may be replaced by CH2OH;
• and with the proviso that when R1 is Phe-Trp-Lys-Thr R2 is not Phe and/or R3 is not Thr;
• R4, R5, R7 and R8 independently represent hydrogen, a methyl group or a C1-10 alkyl group,