ABSTRACT
Giardia intestinalis
is the most frequent protozoan agent of intestinal diseases worldwide. Though commonly regarded as an anaerobic pathogen, it preferentially colonizes the fairly oxygen-rich mucosa of the proximal small intestine. Therefore, when testing new potential antigiardial drugs, O
2
should be taken into account, since it also reduces the efficacy of metronidazole, the gold standard drug against giardiasis. In this study, 46 novel chalcones were synthesized by microwave-assisted Claisen-Schmidt condensation, purified, characterized by high-resolution mass spectrometry,
1
H and
13
C nuclear magnetic resonance, and infrared spectroscopy, and tested for their toxicity against
G. intestinalis
under standard anaerobic conditions. As a novel approach, compounds showing antigiardial activity under anaerobiosis were also assayed under microaerobic conditions, and their selectivity against parasitic cells was assessed in a counterscreen on human epithelial colorectal adenocarcinoma cells. Among the tested compounds, three [30(a), 31(e), and 33] were more effective in the presence of O
2
than under anaerobic conditions and killed the parasite 2 to 4 times more efficiently than metronidazole under anaerobiosis. Two of them [30(a) and 31(e)] proved to be selective against parasitic cells, thus representing potential candidates for the design of novel antigiardial drugs. This study highlights the importance of testing new potential antigiardial agents not only under anaerobic conditions but also at low, more physiological O
2
concentrations.
摘要
肠贾第虫
是全球最常见的肠道疾病原生动物病原体。虽然它通常被认为是厌氧病原体,但它更喜欢在氧气相当丰富的近端小肠粘膜上定植。因此,在测试新的潜在抗寄生虫药物时,O
2
也会降低甲硝唑的药效,而甲硝唑是治疗贾第虫病的金标准药物。本研究采用微波辅助克莱森-施密特缩合法合成了 46 种新型查耳酮,并通过高分辨质谱进行了纯化和表征、
1
H 和
13
C 核磁共振和红外光谱对其进行了表征,并测试了它们对
肠杆菌
的毒性。作为一种新方法,在厌氧条件下显示出抗寄生虫活性的化合物也在微氧条件下进行了检测,并在人上皮结直肠腺癌细胞的反筛选中评估了它们对寄生虫细胞的选择性。在测试的化合物中,有三种 [30(a)、31(e) 和 33] 在有 O
2
在厌氧条件下杀死寄生虫的效率是甲硝唑的 2 至 4 倍。其中两种[30(a)和 31(e)]被证明对寄生虫细胞具有选择性,因此是设计新型抗寄生虫药物的潜在候选药物。这项研究强调了不仅在厌氧条件下,而且在低浓度、更生理的 O
2
浓度下进行测试的重要性。