| الوصف: |
Five new octapeptide analogues of somatostatin, based on RC-160, D-Phe-c(Cys-Tyr-D-Trp-Lys-Val-Cys)-Thr-NH2, containing N-terminal modifications have been syn-thesized. N-terminal, exocyclic D-Phe was replaced by aromatic unnatural amino acids: D-Nal, D-3(2-naphthyl)alanine; D-Pal, D-3-(3-pyridyI)aIanine; D-Qal, D-3-(3-quino-lyl)alanine; D-Cl-Phe, D-3-(4-chIorophenyl)alanine, and D-Cl2-Phe, D-3-(3,4-dichIoro-phenyl)alanine. The inhibitory effect of these new analogues on growth hormone (GH) release in rats was measured. It was found that the analogues with bicyclic D-Nal and D-Qal were less potent than RC-160 in inhibiting GH release in vivo, while all the analogs with aromatic, monocyclic amino acids in position l were morę potent than RC-160. The best results were obtained for the analogue containing hydrophilic D-Pal in position 1. This analogue was 8.4 times more potent than RC-160. |
