Penta-or tetrapeptide binding to somatostatin receptors and the use of the same

A peptide selected from the general formulae 1, 2, 3, 4, 5, 6, and pharmaceutically acceptable salts thereof:

• y1-An-B—C-Dm-Z-y2 (1) y1-Z-An-B—C-Dm-y2 (2) y1-Dm-Z-An-B—C-y2 (3) —C-Dm-Z-An-B-y2 (4) y1-B—C-Dm-Z-An-y2 (5) 26
• wherein Z is a radical of the general formula (7)
• 27
• wherein the substituents Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, R3, R4, R5, R6, R7, R8 and X have the following meaning:
• X is selected from O, S, Se, NR9, PR9 and CR9R10, wherein R9, R10 are independently selected from H, OH, SH, F, Cl, Br, I, alkyl, alkenyl, alkinyl, aryl, alkylaryl, arylalkyl, alkoxy, alkenyloxy, aryloxy, thioalkyl, thioaryl, selenoalkyl, selenoaryl, which may optionally be substituted with F, OH, SH, SeH, an amino group, an oxo group or a carboxy group;
• Q1 and Q2 are independently selected from a single bond, CH2, CH(OH), CH(OR1), CHR1 and CR1R2;
• wherein R1 and R2 are independently selected from alkyl, alkenyl, aryl, arylalkyl, alkylaryl, which may optionally be substituted with F, OH, an amino group or a carboxy group;
• Q3 to Q8 are independently selected from a single bond, O, S, Se, N2, NR9, PO3;
• R3 to R8 are independently selected from the group consisting of H, OH, SH, N3, CN, NC, SCN, F, Cl, Br, I, SO3, NO2, PR11R12, COOR11, alkyl, alkenyl, alkinyl, aryl, alkylaryl, arylalkyl, alkanoyl, alkenoyl, alkinoyl, aroyl, arylalkanoyl, alkylaroyl, which may optionally be substituted with F, OH, SH, SeH, an amino group, an oxo group or a carboxy group;
• wherein R11 and R12 are independently selected from H, OH, SH, F, Cl, Br, I, CN, NC, SCN, alkyl, alkenyl, alkinyl, aryl, alkylaryl, arylalkyl, alkoxy, alkenyloxy, aryloxy, thioalkyl, thioalkenyl, thioaryl, selenoalkyl, selenoalkenyl, selenoaryl, amidoalkyl, amidoalkenyl, amidoalkinyl, arylalkanoyloxy, alkylaroyloxy, arylalkoxy, alkylaryloxy, which may optionally be substituted with F, OH, SH, SeH, an amino group, an oxo group or a carboxy group;
• wherein two substituents Ri and Rj, with i, j=3 to 8, may optionally be linked, forming a 5- or 6-membered ring, wherein optionally one or more of the ring atoms are independently substituted with one or more groups selected from alkyl, alkenyl and aryl;
• wherein the radicals, A, B, C and D have the following meaning:
• A is an α-, β- or γ-amino carboxylic acid radical having an aromatic side chain or an aliphatic side chain;
• B is an α-, β- or γ-amino carboxylic acid radical having an aromatic side chain;
• C is an α-, β- or γ-amino carboxylic acid radical having a basic side chain or an aliphatic side chain;
• D is an α-, β- or γ-amino carboxylic acid radical which does not have acidic groups or basic groups in the side chain;
• wherein y1 is linked to the amino group of the corresponding amino carboxylic acid and is selected from H, CH3(CH2)rCO, with r=0 to 6, butoxy carbonyl and 9-fluorenyl methyoxy carbonyl;
• wherein y2 is linked to the carboxy group of the corresponding amino acid and is selected from H, NH2, alkoxy, aryloxy, alkyl, aryl, alkenyl, alkinyl, F, Cl, Br, I, CN, NC, SCN, thioalkyl, thioaryl;
• wherein n and m represent integers selected from 0 and 1 such that m+n is 1 or 2;
• and the groups A, B, C, D and Z linked to each other via a peptide linkage each.