Guerrini R, Caló G, Bigoni R, Rizzi D, Rizzi A, Zucchini M, Varani K, Hashiba E, Lambert D G, Toth G, Borea P A, Salvadori S, Regoli D
Department of Pharmaceutical Sciences and Biotechnology Center, University of Ferrara, 44100 Ferrara, Italy.
J Med Chem. 2001 Nov 8;44(23):3956-64. doi: 10.1021/jm010221v.
A total of 32 compounds was prepared to investigate the functional role of Phe(4) in NC(1-13)-NH(2), the minimal sequence maintaining the same activity as the natural peptide nociceptin. These compounds could be divided into three series in which Phe(4) was replaced with residues that would (i) alter aromaticity or side chain length, (ii) introduce steric constraint, and (iii) modify the phenyl ring. Compounds were tested for biological activity as (a) inhibitors of the electrically stimulated contraction of the mouse vas deferens; (b) competitors of the binding of [(3)H]-NC-NH(2) to mouse brain membranes; and (c) inhibitors of forskolin-stimulated cAMP accumulation in CHO cells expressing the recombinant human OP(4) receptor. Results indicate that all compounds of the first and second series were inactive or very weak with the exception of [N(CH(3))Phe(4)]NC(1-13)-NH(2), which was only 3-fold less potent than NC(1-13)-NH(2). Compounds of the third series showed higher, equal, or lower potencies than NC(1-13)-NH(2). In particular, [(pF)Phe(4)]NC(1-13)-NH(2) (pF) and [(pNO(2))Phe(4)]NC(1-13)-NH(2) (pNO(2)) were more active than NC(1-13)-NH(2) by a factor of 5. In the mVD, these compounds showed the following order of potency: (pF) = (pNO(2)) > or = (pCN) > (pCl) > (pBr) > (pI) = (pCF(3)) = (pOCH(3)) > (pCH(3)) > (pNH(2)) = (pOH). (oF) and especially (mF) maintained high potencies but were less active than (pF). Similar orders of potency were observed in binding competition and cAMP accumulation studies. There was a strong (r(2) > or = 0.66) correlation between data observed in these assays. Biological activity data of compounds of the third series were plotted against some Hansch parameters that are currently used to quantify physicochemical features of the substituents. In the three biological assays agonist potency/affinity positively correlates with the electron withdrawal properties of the groups in the p-position of Phe(4) and inversely with their size.
共制备了32种化合物，以研究苯丙氨酸（Phe）（4）在NC（1 - 13）-NH₂中的功能作用，NC（1 - 13）-NH₂是与天然肽痛敏肽具有相同活性的最小序列。这些化合物可分为三个系列，其中苯丙氨酸（4）被替换为以下残基：（i）改变芳香性或侧链长度；（ii）引入空间位阻；（iii）修饰苯环。对化合物进行了生物活性测试，测试内容包括：（a）作为小鼠输精管电刺激收缩的抑制剂；（b）作为[³H]-NC-NH₂与小鼠脑膜结合的竞争剂；（c）作为福司可林刺激表达重组人OP（4）受体的CHO细胞中cAMP积累的抑制剂。结果表明，除了[N（CH₃）Phe（4）]NC（1 - 13）-NH₂外，第一和第二系列的所有化合物均无活性或活性非常弱，[N（CH₃）Phe（4）]NC（1 - 13）-NH₂的效力仅比NC（1 - 13）-NH₂低3倍。第三系列的化合物显示出比NC（1 - 13）-NH₂更高、相等或更低的效力。特别是，[（pF）Phe（4）]NC（1 - 13）-NH₂（pF）和[（pNO₂）Phe（4）]NC（1 - 13）-NH₂（pNO₂）的活性比NC（1 - 13）-NH₂高5倍。在小鼠输精管中，这些化合物的效力顺序如下：（pF） = （pNO₂） ≥ （pCN） > （pCl） > （pBr） > （pI） = （pCF₃） = （pOCH₃） > （pCH₃） > （pNH₂） = （pOH）。（oF）尤其是（mF）保持了高效力，但比（pF）活性低。在结合竞争和cAMP积累研究中观察到了类似的效力顺序。在这些测定中观察到的数据之间存在很强的（r² ≥ 0.66）相关性。将第三系列化合物的生物活性数据与一些目前用于量化取代基物理化学特征的Hansch参数进行了绘制。在这三种生物测定中，激动剂效力/亲和力与苯丙氨酸（4）对位基团的吸电子性质呈正相关，与它们的大小呈负相关。
