Department of Organic Chemistry, University of Chemical Technology and Metallurgy, 1756, Sofia, Bulgaria.
Institute of Mineralogy and Crystallography, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria.
Amino Acids. 2020 Apr;52(4):567-585. doi: 10.1007/s00726-020-02836-1. Epub 2020 Mar 24.
Herein, some new analogues of VV-hemorphin-7, modified at position 4 and 7 by the unnatural amino acids followed the structure Val-Val-Tyr-Xxx-Trp-Thr-Yyy-Arg-Phe-NH, where Xxx is Ac5c (1-aminocyclopentanecarboxylic acid) or Ac6c (1-aminocyclohexane carboxylic acid) and Yyy is Dap (diaminopropanoic acid) or Dab (diaminobutanoic acid), were synthesized, characterized and investigated for anticonvulsant activity. The new synthetic peptide analogues were prepared by standard solid-phase peptide synthesis-Fmoc chemistry. A single intracerebroventricular (i.c.v.) injection at doses of 5, 10, and 20 µg/10 µl, respectively, was given before evaluation with timed intravenous pentylenetetrazole (ivPTZ) infusion test and 6-Hz psychomotor seizure test in mice. The acute neurological toxicity was determined using the rotarod test. To explain the structure-active properties of the modified peptides, some physicochemical characteristic was obtained. The FT-IR spectra and their second derivatives of the amide I, II, and III bands of the peptides show ß-sheet structure conformation. The calculation of isoelectric points, by potentiometric determination of dissociated constants, is in the range from 9.79 to 10.84. This study, for the first time, also reported on the reduction-oxidative potentials of the guanidine at Arg-moiety on such kind of peptides containing arginine and tyrosine residues in different medium and electrode surface. The VV-hemorphin-7 analogues 4 and 5 were the most active against the ivPTZ test, with the effect comparable to that of peptide 1 used as a positive control. Except compound 8, all other tested peptide analogues were ineffective to raise the threshold for the clonic seizures. The peptide analogue 5 showed 100% protection in the 6-Hz test, while the other seven VV-hemorphin-7 analogues have dose-dependent activity against psychomotor seizures comparable to 1. The novel peptides did not show neurotoxicity in the rotarod test.
在此，我们合成了一些 VV-hemorphin-7 的类似物，这些类似物在 4 位和 7 位被非天然氨基酸修饰，结构为 Val-Val-Tyr-Xxx-Trp-Thr-Yyy-Arg-Phe-NH，其中 Xxx 是 Ac5c（1-氨基环戊烷羧酸）或 Ac6c（1-氨基环己烷羧酸），Yyy 是 Dap（二氨基丙氨酸）或 Dab（二氨基丁酸）。我们对这些新的合成肽类似物进行了表征，并研究了它们的抗惊厥活性。新的合成肽类似物通过标准的固相肽合成-Fmoc 化学法制备。在评估之前，通过计时静脉戊四氮（ivPTZ）输注试验和小鼠 6-Hz 运动性惊厥试验，分别在 5、10 和 20μg/10μl 的剂量下单次侧脑室（i.c.v.）注射。使用旋转棒试验确定急性神经毒性。为了解释修饰肽的结构-活性性质，我们获得了一些物理化学特性。肽的酰胺 I、II 和 III 带的傅里叶变换红外（FT-IR）光谱及其二级导数显示 β-折叠结构构象。通过测定离解常数的电位滴定法计算等电点，范围在 9.79 到 10.84 之间。本研究首次报道了这种含有精氨酸和酪氨酸残基的肽中胍基的氧化还原电位在不同介质和电极表面上的变化。VV-hemorphin-7 类似物 4 和 5 在 ivPTZ 试验中对抗作用最活跃，效果可与用作阳性对照的肽 1 相媲美。除化合物 8 外，所有其他测试的肽类似物对提高阵挛性发作的阈值均无效。肽类似物 5 在 6-Hz 试验中显示出 100%的保护作用，而其他七种 VV-hemorphin-7 类似物对运动性惊厥具有剂量依赖性的活性，与 1 相当。新型肽在旋转棒试验中没有表现出神经毒性。
