Trop Biomed. 2021 Jun 1;38(2):40-47. doi: 10.47665/tb.38.2.035.
The reduced efficacy of the mainstay antimalarial drugs due to the widespread of drugresistant Plasmodium falciparum has necessitated efforts to discover new antimalarial drugs with new targets. Quercus infectoria (Olivier) has long been used to treat various ailments including fever. The acetone extract of the plant galls has recently been reported to have a promising antimalarial activity in vitro. This study was aimed to determine the effect of the Q. infectoria gall acetone crude extract on pH of the digestive vacuole of Plasmodium falciparum. A ratiometric fluorescent probe, fluorescein isothiocyanate-dextran (FITC-dextran) was used to facilitate a quantitative measurement of the digestive vacuole pH by flow cytometry. Mid trophozoite stage malaria parasites grown in resealed erythrocytes containing FITC-dextran were treated with different concentrations of the acetone extract based on the 50% inhibitory concentration (IC). Saponin-permeabilized parasites were analyzed to obtain the ratio of green/yellow fluorescence intensity (R) plotted as a function of pH in a pH calibration curve of FITC-dextran. Based on the pH calibration curve, the pH of the digestive vacuole of the acetone extract-treated parasites was significantly altered (pH values ranged from 6.35- 6.71) in a concentration-dependent manner compared to the untreated parasites (pH = 5.32) (p < 0.001). This study provides a valuable insight into the potential of the Q. infectoria galls as a promising antimalarial candidate with a novel mechanism of action.
由于耐药性恶性疟原虫的广泛传播，主流抗疟药物的疗效降低，因此有必要努力寻找具有新靶点的新型抗疟药物。没食子树（Olivier）长期以来一直用于治疗包括发烧在内的各种疾病。最近有报道称，该植物虫瘿的丙酮提取物在体外具有良好的抗疟活性。本研究旨在确定没食子树虫瘿丙酮粗提物对恶性疟原虫消化液泡pH值的影响。使用一种比率荧光探针异硫氰酸荧光素-葡聚糖（FITC-葡聚糖），通过流式细胞术对消化液泡pH值进行定量测量。将在含有FITC-葡聚糖的重封红细胞中生长的滋养体中期疟原虫，根据50%抑制浓度（IC）用不同浓度的丙酮提取物进行处理。对皂素通透的疟原虫进行分析，以获得绿色/黄色荧光强度比（R），并将其绘制为FITC-葡聚糖pH校准曲线中pH值的函数。根据pH校准曲线，与未处理的疟原虫（pH = 5.32）相比，丙酮提取物处理的疟原虫消化液泡的pH值发生了显著变化（pH值范围为6.35 - 6.71），且呈浓度依赖性（p < 0.001）。本研究为没食子树虫瘿作为一种具有新作用机制的有前景的抗疟候选药物的潜力提供了有价值的见解。
