Lycorine is an Amaryllidaceae alkaloid that presents anti-Trichomonas vaginalis activity. T. vaginalis causes trichomoniasis, the most common non-viral sexually transmitted infection. The modulation of T. vaginalis purinergic signaling through the ectonucleotidases, nucleoside triphosphate diphosphohydrolase (NTPDase), and ecto-5′-nucleotidase represents new targets for combating the parasite. With this knowledge, the aim of this study was to investigate whether NTPDase and ecto-5′-nucleotidase inhibition by lycorine could lead to extracellular ATP accumulation. Moreover, the lycorine effect on the reactive oxygen species (ROS) production by neutrophils and parasites was evaluated as well as the alkaloid toxicity. The metabolism of purines was assessed by HPLC. ROS production was measured by flow cytometry. Cytotoxicity against epithelial vaginal cells and fibroblasts was tested, as well as the hemolytic effect of lycorine and its in vivo toxicity in Galleria mellonella larvae. Our findings showed that lycorine caused ATP accumulation due to NTPDase inhibition. The alkaloid did not affect the ROS production by T. vaginalis; however, it increased ROS levels in neutrophils incubated with lycorine-treated trophozoites. Lycorine was cytotoxic against vaginal epithelial cells and fibroblasts; conversely, it was not hemolytic neither exhibited toxicity against the in vivo model of G. mellonella larvae. Overall, besides having anti-T. vaginalis activity, lycorine modulates ectonucleotidases and stimulates neutrophils to secrete ROS. This mechanism of action exerted by the alkaloid could enhance the susceptibility of T. vaginalis to host immune cell, contributing to protozoan clearance.

番石榴碱是一种具有抗阴道滴虫活性的金眼兰生物碱。阴道锥虫可引起滴虫病，最常见的非病毒性传播感染。阴道锥虫的调控通过外切核苷酸酶，三磷酸核苷二磷酸水解酶（NTPDase）和外切5'-核苷酸酶的嘌呤能信号代表了对抗寄生虫的新靶标。以此为基础，本研究的目的是研究赖氨酸对NTPDase和ecto-5′-核苷酸酶的抑制是否会导致细胞外ATP的积累。此外，评估了lycorine对嗜中性粒细胞和寄生虫产生的活性氧（ROS）的影响以及生物碱的毒性。嘌呤的代谢通过HPLC评估。通过流式细胞术测量ROS的产生。对阴道上皮细胞和成纤维细胞的细胞毒性进行了测试，在石蒜碱的以及溶血作用和其在体内的毒性大蜡螟幼虫。我们的研究结果表明，由于NTPDase抑制，蛋氨酸引起ATP积累。生物碱不影响阴道三角杆菌的ROS产生; 然而，它增加了经蛋黄素处理的滋养体培养的中性粒细胞的ROS水平。番石榴碱对阴道上皮细胞和成纤维细胞具有细胞毒性。相反，它既不溶血，也没有表现出对G. mellonella幼虫体内模型的毒性。总体而言，除了具有抗阴道T.活性外，赖氨酸还调节外切核苷酸酶并刺激中性粒细胞分泌ROS。生物碱所产生的这种作用机制可以增强阴道锥虫对宿主免疫细胞的敏感性，从而有助于原生动物的清除。