Nigella sativa L., commonly called Black cumin, is well-known in folk medicine and numerous studies have shown its various pharmacological activities. In this study, we estimated the cytotoxic effects of N. sativa essential oil (NEO) and its major bioactive component Thymoquinone (TQ) on Leishmania tropica promastigotes that cause cutaneous leishmanias, and also observed the programmed cell death features. The extraction of NEO was done by hydro-distillation and analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). Antileishmanial activity of NEO and TQ was determined using 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyl tetrazolium bromide (MTT) assay and the obtained results are expressed as 50% inhibitory concentration (IC₅₀). The leishmanicidal activity of NEO and TQ was mediated via apoptosis as evidenced by in situ labelling of DNA fragments using terminal deoxyribonucleotidyltransferase-mediated dUTP nick end labelling (TUNEL) and cell cycle arrest at sub G₀/G₁ phase. The IC₅₀ values were 5 µg/mL and 1.3 µg/mL, respectively. We noted a significant increase in DNA fragmentation in treated parasites with IC₅₀ of both NEO and TQ as well as a cell cycle arrest. These results revealed that NEO and TQ possess potential antileishmanial activity that mediated high possibility by programmed cell death.

中文翻译：

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Nigella sativa L.精油和胸腺醌引发剂对热带利什曼原虫的抗leishmanial凋亡活性。

俗称黑小茴香的黑变种（Nigella sativa L.）在民间医学界是众所周知的，许多研究表明其各种药理活性。在这项研究中，我们评估了紫花苜蓿精油（NEO）及其主要生物活性成分胸腺醌（TQ）对引起皮肤利什曼原虫的热带利什曼原虫前鞭毛体的细胞毒性作用，并观察了程序性细胞死亡特征。NEO的提取通过加氢蒸馏进行，并通过气相色谱-质谱法（GC-MS）进行分析。使用3-（4.5-二甲基噻唑-2-基）-2.5-二苯基溴化四唑（MTT）测定法测定NEO和TQ的抗利什曼活性，并将所得结果表示为50％抑制浓度（IC ₅₀）。NEO和TQ的杀菌活性是通过凋亡介导的，如使用末端脱氧核糖核苷酸转移酶介导的dUTP缺口末端标记（TUNEL）原位标记DNA片段和将细胞周期阻滞在sub G ₀ / G ₁期所证明的。IC ₅₀值分别为5 µg / mL和1.3 µg / mL。我们注意到，NEO和TQ的IC ₅₀均使治疗过的寄生虫的DNA片段显着增加，并且细胞周期停滞。这些结果表明，NEO和TQ具有潜在的抗菌活性，可通过程序性细胞死亡介导高可能性。