Dept. Public Health and Pediatrics, Microbiology Division, University of Turin, 10126 Turin, Italy.
Area Servizi Alla Ricerca Polo Agraria e Medicina Veterinaria, University of Turin, 10095 Turin, Italy.
Molecules. 2019 Oct 23;24(21):3824. doi: 10.3390/molecules24213824.
The aim of this study was to evaluate the influence of tea tree oil (TTO) and "Mentha of Pancalieri" essential oil (MPP) on intracellular killing of often resistant to conventional drugs, by polymorphonuclear leucocytes (PMNs). Intracellular killing was investigated by incubating yeasts and PMNs with essential oils (EOs) at 1/4 and 1/8 × MIC (Minimal Inhibitory Concentration), in comparison with anidulafungin, used as a reference drug. Killing values were expressed as Survival Index (SI) values. The cytotoxicity of EOs was evaluated by 3-[4,-5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Both EOs were more efficaceous at 1/8 × MIC than 1/4 × MIC, with killing values higher than observed in EO-free systems and in presence of anidulafungin, indicating that the decreasing concentrations did not cause lower candidacidal activity. This better activity at 1/8 × MIC is probably due to the EOs' toxicity at 1/4 × MIC, suggesting that at higher concentrations EOs might interfere with PMNs functionality. TTO and MPP at 1/8 × MIC significantly increased intracellular killing by PMNs through their direct action on the yeasts (both EOs) or on phagocytic cells (MPP), suggesting a positive interaction between EOs and PMNs to eradicate intracellular . These data showed a promising potential application of TTO and "Mentha of Pancalieri" EO as natural adjuvants in infection management.
本研究旨在评估茶树油（TTO）和“蓬热薄荷”精油（MPP）对多形核白细胞（PMN）内杀伤通常对常规药物具有抗性的酵母的影响。通过将酵母和PMN与精油（EOs）在 1/4 和 1/8 × MIC（最小抑菌浓度）孵育，同时与作为参考药物的安尼达弗林进行比较，研究了细胞内杀伤作用。杀伤值表示为存活指数（SI）值。通过 3-[4，-5-二甲基噻唑-2-基]-2,5-二苯基四唑溴盐（MTT）测定法评估 EO 的细胞毒性。与 1/4 × MIC 相比，两种 EO 在 1/8 × MIC 时均更有效，杀伤值高于无 EO 系统和存在安尼达弗林时观察到的值，表明降低浓度不会导致更低的杀酵母活性。这种在 1/8 × MIC 时更好的活性可能是由于在 1/4 × MIC 时 EO 的毒性，这表明在更高浓度下，EO 可能会干扰 PMN 的功能。在 1/8 × MIC 时，TTO 和 MPP 通过其对酵母（两种 EO）或吞噬细胞（MPP）的直接作用显著增加了 PMN 的细胞内杀伤，表明 EO 与 PMN 之间存在积极的相互作用，以消灭细胞内。这些数据显示了 TTO 和“蓬热薄荷”精油作为天然佐剂在真菌感染管理中的潜在应用前景。
