Background: Acanthamoeba is an opportunistic pathogen widely spread in the environment. Acanthamoeba causes excruciating keratitis which can lead to blindness. The lack of effective drugs and its ability to form highly resistant cyst are one of the foremost limitations against successful prognosis. Current treatment involves mixture of drugs at high doses but still recurrence of infection can occur due to ineffectiveness of drugs against the cyst form. Pyridine and its natural and synthetic derivatives are potential chemotherapeutic agents due to their diverse biological activities.

Objective: To study the antiamoebic effects of four novel synthetic dihydropyridine (DHP) compounds against Acanthamoeba castellanii belonging to the T4 genotype. Furthermore, to evaluate their activity against amoeba-mediated host cells cytopathogenicity as well as their cytotoxicity against human cells.

Methods: Dihydropyridines were synthesized by cyclic dimerization of alkylidene malononitrile derivatives. Four analogues of functionally diverse DHPs were tested against Acanthamoeba castellanii by using amoebicidal, encystation and excystation assays. Moreover, Lactate dehydrogenase assays were carried out to study cytopathogenicity and cytotoxicity against human cells.

Results: These compounds showed significant amoebicidal and cysticidal effects at 50 μM concentration, whereas, two of the DHP derivatives also significantly reduced Acanthamoebamediated host cell cytotoxicity. Moreover, these DHPs were found to have low cytotoxicity against human cells suggesting a good safety profile.

Conclusion: The results suggest that DHPs have potential against Acanthamoeba especially against the more resistant cyst stage and can be assessed further for drug development.

背景：棘阿米巴是一种在环境中广泛传播的机会病原体。棘阿米巴引起严重的角膜炎，可能导致失明。缺乏有效的药物及其形成高度耐药的囊肿的能力是成功预后的首要限制之一。当前的治疗涉及高剂量药物的混合，但是由于药物对囊肿形式的无效，仍然可能发生感染复发。吡啶及其天然和合成衍生物由于其多种生物活性而成为潜在的化学治疗剂。

目的：研究四种新型合成二氢吡啶（DHP）化合物对属于T4基因型的卡氏棘阿米巴的抗厌氧作用。此外，为了评估它们对变形虫介导的宿主细胞的细胞致病性以及对人细胞的细胞毒性的活性。

方法：通过亚烷基丙二腈衍生物的循环二聚反应合成二氢吡啶。通过杀虫，侵入和兴奋分析，对功能多样的DHP的四个类似物进行了抗卡氏棘阿米巴测试。此外，进行了乳酸脱氢酶测定以研究针对人类细胞的细胞致病性和细胞毒性。

结果：这些化合物在浓度为50μM时显示出显着的杀菌和杀囊作用，而两种DHP衍生物也显着降低了棘阿米巴介导的宿主细胞的细胞毒性。此外，发现这些DHP对人细胞的细胞毒性低，表明其安全性良好。

结论：结果表明，DHPs具有对抗棘阿米巴的潜力，尤其是对更具抵抗力的囊肿阶段具有潜力，可以进一步评估其开发药物的能力。