imidazolidin-4-one. The kinetically determined pKa values are ca. 3.6–4.0, i.e., 4 pKa units lower than those of amino acidamides, thus implying that hydrolysis of imidazolidin-4-ones at pH 7.4 involves the unionized form. Reactivity of this form decreases with the steric crowding of the amino acid α-substituent. In contrast, the rate constant for the spontaneous decomposition of the unionized form increases
与基于肽的咪唑啉丁-4-酮相比,由抗疟疾药物的N-(α-氨基酰基)衍生物,伯氨喹和酮合成的那些在37°C的pH 7.4中出乎意料地稳定。在60°C的pH范围0.3–13.5下,研究了基于伯氨喹的咪唑啉丁-4-酮的水解动力学。水解成母体α-氨基酰基伯氨喹的特征是S形的pH速率分布,反映了咪唑烷二-4-酮的结合形式和质子化形式(在N-1下)的自发分解。动力学确定的p K a值为ca。3.6–4.0,即4 p K a单元比氨基酸酰胺的单元低,因此暗示在pH 7.4的咪唑烷基-4-酮的水解涉及联合形式。该形式的反应性随氨基酸α-取代基的空间拥挤而降低。与此相反,速率常数的非离子化形式急剧增加用于从环酮衍生的咪唑烷-4-酮,可由解释的观察自发分解余应变(内应变)的影响。这些结果与水解的涉及一个S的机制一致Ñ酰胺基离去后,咪唑啉丁-4-一C2-N3键的1型单分子裂解。在计算研究的支持下,质子化咪唑啉丁
Imidazolidin-4-one Derivatives of Primaquine as Novel Transmission-Blocking Antimalarials
作者:Maria João Araújo、Joana Bom、Rita Capela、Catarina Casimiro、Paula Chambel、Paula Gomes、Jim Iley、Francisca Lopes、José Morais、Rui Moreira、Eliandre de Oliveira、Virgílio do Rosário、Nuno Vale
DOI:10.1021/jm0494624
日期:2005.2.1
Imidazolidin-4-one derivatives of primaquine were synthesized as potential double prodrugs of the parent drug. The title compounds inhibit the development of the sporogonic cycle of Plasmodium berghei, affecting the appearance of oocysts in the midguts of the mosquitoes. The imidazolidin-4-ones are very stable, both in human plasma and in pH 7.4 buffer, indicating that they are active per se. Thus
The synthesis of imidazolidin-4-one derivatives of primaquine as potential antimalarial agents is described. The target compounds were synthesized in three steps: (i) condensation of (±)-primaquine with Nα-protected amino acids, (ii) removal of the Nα-protecting group, and (iii) reaction of the N-acylprimaquine with a carbonyl compound: acetone, three cyclic ketones and veratraldehyde. Using 2-formylbenzoic
Anti-Pneumocystis carinii and antiplasmodial activities of primaquine-derived imidazolidin-4-ones
作者:Nuno Vale、Margaret S. Collins、Jiri Gut、Ricardo Ferraz、Philip J. Rosenthal、Melanie T. Cushion、Rui Moreira、Paula Gomes
DOI:10.1016/j.bmcl.2007.11.105
日期:2008.1
A series of primaquine-derived imidazolidin-4-ones were screened for their in vitro activity against Pneumocystis carinii and Plasmodium falciparum W2 strain. Most compounds were active against P. carinii above 10 mu g/mL and displayed slight to marked activity. The imidazolidin-4-ones most active against P. carinii were also those most active antiplasmodial agents, in the mu M range. One of the tested imidazolidin-4-ones was slightly more active than the parent primaquine and may represent a lead compound for the development of novel anti-P. carinii 8-aminoquinolines with increased stability and resistance to metabolic inactivation. (c) 2007 Elsevier Ltd. All rights reserved.