Springer Eric, Heimsch Kim C, Sidiropoulos Niklas, Krijnse Locker Jacomina, Przyborski Jude M
Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen, Germany.
Justus Liebig University, Giessen, Germany.
Antimicrob Agents Chemother. 2025 Aug 6;69(8):e0033225. doi: 10.1128/aac.00332-25. Epub 2025 Jun 23.
The anti-parasitic compound arylmethylamino steroid 1o (1o) is a promising drug candidate with low nanomolar activity against the malaria parasite , but with a so far unknown mode of action. To address this, we applied previously developed live-cell ATP and pH assays to measure effects upon exposure of parasites to 1o. Furthermore, we analyzed the parasites' heme species distribution, the ultrastructural morphology, food vacuole (FV) appearance, and lifecycle development of different parasite stages. We found that 1o increases cytosolic [ATP] level and causes a slight drop in pH, similar to the effects of arylamino alcohols such as mefloquine. The compound also prevents chloroquine (CQ)-mediated proteolysis and limits cytosol acidification within the range of its EC. Additionally, 1o prevents CQ-mediated heme and hemoglobin accumulation, and preserves ultrastructural FV integrity. Furthermore, we can demonstrate that 1o blocks the development of ring and early trophozoite stages, while late trophozoite stages were unaffected. These findings suggest that the mechanism underlying the killing activity of 1o may be the interference of a pathway within or upstream of hemoglobin digestion, particularly during the highly metabolically active earlier parasite stages. Our data open a new perspective on the compound's mode of action, information critically needed for target identification and further drug development.
抗寄生虫化合物芳基甲基氨基甾体1o（1o）是一种很有前景的候选药物，对疟原虫具有低纳摩尔活性，但迄今为止其作用方式尚不清楚。为了解决这个问题，我们应用先前开发的活细胞ATP和pH测定法来测量寄生虫暴露于1o后的影响。此外，我们分析了寄生虫的血红素种类分布、超微结构形态、食物泡（FV）外观以及不同寄生虫阶段的生命周期发育。我们发现1o会增加胞质[ATP]水平并导致pH值略有下降，这与甲氟喹等芳基氨基醇的作用类似。该化合物还能防止氯喹（CQ）介导的蛋白水解，并在其EC范围内限制胞质酸化。此外，1o可防止CQ介导的血红素和血红蛋白积累，并保持超微结构FV的完整性。此外，我们可以证明1o会阻断环状体和早期滋养体阶段的发育，而晚期滋养体阶段则不受影响。这些发现表明，1o杀伤活性的潜在机制可能是干扰血红蛋白消化过程中或其上游的一条途径，特别是在代谢高度活跃的早期寄生虫阶段。我们的数据为该化合物的作用方式开辟了一个新视角，这是靶点识别和进一步药物开发急需的信息。
