Weng J H, Blommaert A G, Moizo L, Bado A, Ducos B, Böhme A, Garbay C, Roques B P
Département de Pharmacochimie Moléculaire et Structurale, U266 INSERM-URA D 1500 CNRS, UFR des Sciences Pharmaceutiques et Biologiques, Faculté de Pharmacie, Paris, France.
Bioorg Med Chem. 1996 Apr;4(4):563-73. doi: 10.1016/0968-0896(96)00050-8.
Among the CCK derivatives, the tetrapeptide Boc-Trp-Phg-Asp-Nal-NH2 (1) behaves as a short potent CCK-B agonist which led to the development of an efficient peptidase-resistant CCK-B antagonist by bismethylation of its terminal CONH2 group. Further modifications of the N- and C-terminal moieties of 1 have been performed and are described in this paper, together with the pharmacological profile of the novel synthetized compounds. Introduction of more bulky substituents than NalNH2 on the C-terminal part decreased the CCK-B receptor binding affinity. In the series of N-protected tetrapeptides X30-Phg31-Asp32-Nal33-N(CH3)2, the Boc-substituent was shown to be optimal among the N-protecting groups Boc, 2Adoc, propionyl or acetyl when X = Trp. On the other hand, when X = alpha MeTrp, its optimal N-protecting group was 2Adoc and its configuration was preferentially D. In the newly synthesized compounds, 13: 2Adoc-D-alpha MeTrp-Phg-Asp-NalN(CH3)2 and 16: 2Adoc-D-alpha MeTrp-Phg-Asp-NalNH2 had the best CCK-B receptor affinities (KI = 3.5 and 3.4 nM, respectively) and were selected for further biological evaluation. Interestingly, when tested for their capacity to influence inositol phosphate formation, induced by CCK8 in CHO cells transfected with the rat CCK-B receptor, compound 13 behaved as a full CCK-B antagonist with an IC50 value of 18 +/- 1 nM, being as potent as the antagonist L-365,260 and PD-134,308 (IC50 values respectively, 39 +/- 17 and 30 +/- 2 nM), whereas compound 16 was found to behave as a partial CCK-B agonist. Indeed 16 behaved as an antagonist on the firing rate of rat CA1 hippocampal neurons and acted as an agonist in the pentagastrin stimulated gastric acid secretion (EC50 = 12 nmol/kg) in anesthetized rats. Compound 13 in contrast, was found to inhibit the pentagastrin action at a dose (ID50 = 0.56 mumol/kg) similar to the potent antagonist PD-134,308 (ID50 = 0.4 mumol/kg). The antagonist/agonist properties of compounds 13 and 16 show that both N- and C-terminal substituents modulate the pharmacological properties in the Boc-CCK4 derivatives presented here.
在胆囊收缩素（CCK）衍生物中，四肽Boc-Trp-Phg-Asp-Nal-NH2（1）表现为一种强效的短效CCK-B激动剂，通过对其末端CONH2基团进行双甲基化，促使开发出一种高效的抗肽酶CCK-B拮抗剂。本文对化合物1的N端和C端部分进行了进一步修饰，并对新合成化合物的药理特性进行了描述。在C端引入比NalNH2体积更大的取代基会降低CCK-B受体结合亲和力。在N-保护四肽系列X30-Phg31-Asp32-Nal33-N(CH3)2中，当X = Trp时，Boc取代基在N-保护基团Boc、2Adoc、丙酰基或乙酰基中显示为最佳。另一方面，当X = αMeTrp时，其最佳N-保护基团为2Adoc，且其构型优先为D型。在新合成的化合物中，13: 2Adoc-D-αMeTrp-Phg-Asp-NalN(CH3)2和16: 2Adoc-D-αMeTrp-Phg-Asp-NalNH2具有最佳的CCK-B受体亲和力（KI分别为3.5和3.4 nM），并被选用于进一步的生物学评估。有趣的是，在用大鼠CCK-B受体转染的CHO细胞中，测试它们影响由CCK8诱导的肌醇磷酸形成的能力时，化合物13表现为完全CCK-B拮抗剂，IC50值为18±1 nM，与拮抗剂L-365,260和PD-134,308（IC50值分别为39±17和30±2 nM）效力相当，而化合物16表现为部分CCK-B激动剂。实际上，16在大鼠CA1海马神经元放电频率上表现为拮抗剂，在麻醉大鼠的五肽胃泌素刺激胃酸分泌中（EC50 = 12 nmol/kg）表现为激动剂。相比之下，化合物13在与强效拮抗剂PD-134,308（ID50 = 0.4 μmol/kg）相似的剂量（ID50 = 0.56 μmol/kg）下抑制五肽胃泌素的作用。化合物13和16的拮抗剂/激动剂特性表明，N端和C端取代基均调节此处呈现的Boc-CCK4衍生物的药理特性。
