ABSTRACT
The growth and proliferation of the human malaria parasite
Plasmodium falciparum
are dependent on the parasite's ability to obtain essential nutrients. One nutrient for which the parasite has an absolute requirement is the water-soluble vitamin pantothenic acid (vitamin B
5
). In this study, a series of pantothenic acid analogs which retain the 2,4-dihydroxy-3,3-dimethylbutyramide core of pantothenic acid but deviate in structure from one another and from pantothenic acid in the nature of the substituent attached to the amide nitrogen were synthesized using an efficient single-step synthetic route. Eight of 10 analogs tested inhibited the proliferation of intraerythrocytic
P. falciparum
parasites in vitro, doing so with 50% inhibitory concentrations between 15 and 200 μM. The compounds were generally selective, inhibiting the proliferation of a human cell line (the Jurkat cell line) only at concentrations severalfold higher than those required for inhibition of parasite growth. It was demonstrated that compounds in this series inhibited the phosphorylation of pantothenic acid by pantothenate kinase, the first step in the parasite's biosynthesis of the essential enzyme cofactor coenzyme A, doing so competitively, with
K
i
values in the nanomolar range.
摘要
人类疟原虫的生长和增殖
恶性疟原虫
的生长和增殖取决于寄生虫获取必需营养物质的能力。寄生虫绝对需要的一种营养物质是水溶性维生素泛酸(维生素 B
5
).本研究采用高效的单步合成路线合成了一系列泛酸类似物,这些类似物保留了泛酸的 2,4- 二羟基-3,3-二甲基丁酰胺核心,但在结构上彼此不同,在酰胺氮上连接的取代基的性质上也与泛酸不同。在测试的 10 种类似物中,有 8 种抑制了红细胞内恶性疟原虫的增殖。
恶性疟原虫
在体外对红细胞内恶性疟原虫寄生虫的增殖有抑制作用,50% 的抑制浓度在 15 至 200 μM 之间。这些化合物一般都具有选择性,只有在抑制寄生虫生长所需的浓度高出数倍时,才能抑制人细胞系(Jurkat 细胞系)的增殖。研究表明,该系列化合物可抑制泛酸激酶对泛酸的磷酸化,这是寄生虫生物合成必需酶辅因子辅酶 A 的第一步。
K
i
值在纳摩尔范围内。