West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana.
Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana.
PLoS Negl Trop Dis. 2019 Feb 25;13(2):e0007206. doi: 10.1371/journal.pntd.0007206. eCollection 2019 Feb.
Leishmaniasis is a disease caused by the protozoan parasite, Leishmania. The disease remains a global threat to public health requiring effective chemotherapy for control and treatment. In this study, the effect of some selected phenolic compounds on Leishmania donovani was investigated. The compounds were screened for their anti-leishmanial activities against promastigote and intracellular amastigote forms of Leishmania donovani.
METHODOLOGY/PRINCIPAL FINDINGS: The dose dependent effect and cytotoxicity of the compounds were determined by the MTT assay. Flow cytometry was used to determine the effect of the compounds on the cell cycle. Parasite morphological analysis was done by microscopy and growth kinetic studies were conducted by culturing cells and counting at 24 hours intervals over 120 hours. The cellular levels of iron in promastigotes treated with compounds was determined by atomic absorption spectroscopy and the effect of compounds on the expression of iron dependent enzymes was investigated using RT-qPCR. The IC50 of the compounds ranged from 16.34 μM to 198 μM compared to amphotericin B and deferoxamine controls. Rosmarinic acid and apigenin were the most effective against the promastigote and the intracellular amastigote forms. Selectivity indexes (SI) of rosmarinic acid and apigenin were 15.03 and 10.45 respectively for promastigotes while the SI of 12.70 and 5.21 respectively was obtained for intracellular amastigotes. Morphologically, 70% of rosmarinic acid treated promastigotes showed rounded morphology similar to the deferoxamine control. About 30% of cells treated with apigenin showed distorted cell membrane. Rosmarinic acid and apigenin induced cell arrest in the G0/G1 phase in promastigotes. Elevated intracellular iron levels were observed in promastigotes when parasites were treated with rosmarinic acid and this correlated with the level of expression of iron dependent genes.
CONCLUSIONS/SIGNIFICANCE: The data suggests that rosmarinic acid exerts its anti-leishmanial effect via iron chelation resulting in variable morphological changes and cell cycle arrest.
利什曼病是一种由原生动物寄生虫利什曼原虫引起的疾病。这种疾病仍然对全球公共卫生构成威胁，需要有效的化疗来控制和治疗。在这项研究中，研究了一些选定的酚类化合物对杜氏利什曼原虫的影响。这些化合物被筛选出对杜氏利什曼原虫的前鞭毛体和内阿米巴体形式的抗利什曼原虫活性。
方法/主要发现：通过 MTT 测定法测定了化合物的剂量依赖性效应和细胞毒性。流式细胞术用于确定化合物对细胞周期的影响。通过显微镜进行寄生虫形态分析，并通过在 120 小时内每隔 24 小时培养细胞和计数来进行生长动力学研究。通过原子吸收光谱法测定用化合物处理的前鞭毛体中的细胞铁含量，并通过 RT-qPCR 研究化合物对铁依赖性酶表达的影响。与两性霉素 B 和去铁胺对照物相比，化合物的 IC50 范围为 16.34 μM 至 198 μM。迷迭香酸和芹菜素对前鞭毛体和内阿米巴体形式最有效。迷迭香酸和芹菜素的选择性指数（SI）分别为 15.03 和 10.45，用于前鞭毛体，而内阿米巴体的 SI 分别为 12.70 和 5.21。形态学上，70％的迷迭香酸处理的前鞭毛体显示出类似于去铁胺对照物的圆形形态。用芹菜素处理的约 30％的细胞显示出细胞膜扭曲。迷迭香酸和芹菜素在前鞭毛体中诱导细胞停滞在 G0/G1 期。在用迷迭香酸处理寄生虫时，观察到前鞭毛体中的细胞内铁水平升高，这与铁依赖性基因的表达水平相关。
结论/意义：数据表明，迷迭香酸通过螯合铁发挥其抗利什曼原虫作用，导致形态发生变化和细胞周期停滞。
