Lanthionine bridged peptides

Biologically active peptides having improved biological activity selected from the group consisting of lanthionine-bridged biologically active peptides of the formula

• 37
• wherein
• R1 is selected from the group consisting of a sequence of 2 to 7 amino acids selected from naturally occurring amino acids and the D- enantiomers thereof and
• peptidomimetrics;
• R2 is selected from the group consisting of —H, C1-8 alkyl, C7-12 aralkyl, —HCO, C2-18 acyl or C2-18 aracyl,
• a naturally occurring amino acid or sequence of up to 25 amino acids where the —N terminal —NH2 group is present or is replaced by C1-8 alkyl, C7-12 aralkyl, —HCO, or C2-18 acyl —OH, —H or —NHCOR6, and
• peptidomimetics;
• R3 is selected from the group consisting of —OH, NH2;
• a naturally occurring amino acid or a sequence of up to 25 amino acids where the —C terminal —COOH is present or is replaced by —CONH2 or —CH2OH;
• and
• peptidomimetics;
• and
• 38
• with the proviso that R1 is not Phe-Trp-Lys-Thr when R2 is Phe and R3 is Thr[ol];
• R4 is hydrogen, cyclohexyl or a substituted or unsubstituted C1-10 alkyl;
• R5 is hydrogen, cyclohexyl or a substituted or unsubstituted C1-10 alkyl;
• R6 is an alkyl or aralkyl residue;
• R7 is hydrogen, cyclohexyl or a substituted or unsubstituted C1-10 alkyl;
• and
• R8 is hydrogen, cyclohexyl or a substituted or unsubstituted C1-10 alkyl.