Barceló Sebastián, Peralta Mariana, Calise Maximiliano, Finck Soledad, Ortega Gabriela, Diez Roberto A, Cabrera José Luis, Pérez Cristina
Universidad de Buenos Aires, Facultad de Odontología, Farmacología, M. T. de Alvear 2142, 1122 AAH. Buenos Aires, Argentina.
IMBIV-CONICET. Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende. Ciudad Universitaria, X5000HUA. Córdoba, Argentina.
Phytomedicine. 2017 Aug 15;32:24-29. doi: 10.1016/j.phymed.2017.05.001. Epub 2017 May 10.
The prenylated flavonoid 2', 4'-dihydroxy-5'-(1'″, 1'″-dimethylallyl)-8-prenylpinocembrin (8PP, formerly 6PP) shows antifungal activity, inhibits rhodamine 6G efflux and reverses fluconazole (FCZ) resistance in azole-resistant Candida albicans overexpressing cdr1, cdr2 and mdr1 transporters.
In this paper, we tried to characterize 8PP in vitro interactions on the cell growth and lethality of C. albicans. We also initiated preliminary in vivo toxicological studies on mice.
The effects of 8PP and FCZ on cell growth and viability of C. albicans were evaluated by CLSI guidelines. The checkerboard assay was used to search for interactions on cell growth. The time-kill assay was used to study fungicidal effects. Acute toxicity was evaluated at a single dose schedules.
From the checkerboard design, and using a starting inoculum of 10CFU/ml, the fractional inhibitory concentration (FIC) of FCZ and 8PP could be determined as 0.11 and 0.50, respectively, with a FIC index value (FICI) of 0.61. This FICI and the isobologram showing a concave shape suggests an additive interaction between them. At a higher starting inoculum (10CFU/ml), C. albicans growth and viability were decreased by FCZ, 8PP and their combination in a concentration-dependent way. For FCZ, minimum fungicidal concentration (MFC) and FC (the concentration that kills 50% of the fungal cells) were 4-fold reduced (280-70µM) in combination with 125µM 8PP. A decrease of 3 log units in viable counts with respect to control was reached (3.65 ± 1.05 ‰, p< 0.0001). Thus, both fungistatic compounds when combined achieved an almost complete fungicidal effect at lower concentrations respecting of each of them alone. In preliminary toxicological assessment, lethal dose 50% (LD) for 8PP by the i.p. route was 357 and 245mg/kg, for female and male adult albino mice, respectively. FCZ LD was 785 and 650mg/kg for female and male animals, respectively CONCLUSIONS: In vitro results suggest additive interactions between 8PP and FCZ with respect to C. albicans cell growth. Besides killing per se, 8PP helps FCZ to achieve an almost complete fungicidal effect, which would be crucial to eradicate fungal infections.
异戊烯基黄酮2'，4'-二羟基-5'-(1'″，1'″-二甲基烯丙基)-8-异戊烯基松属素（8PP，原称6PP）具有抗真菌活性，可抑制罗丹明6G外排，并逆转过表达cdr1、cdr2和mdr1转运蛋白的唑类耐药白色念珠菌对氟康唑（FCZ）的耐药性。
本文旨在表征8PP对白色念珠菌细胞生长和致死性的体外相互作用。我们还启动了对小鼠的初步体内毒理学研究。
按照CLSI指南评估8PP和FCZ对白色念珠菌细胞生长和活力的影响。采用棋盘法研究对细胞生长的相互作用。采用时间-杀菌试验研究杀菌效果。通过单次给药方案评估急性毒性。
根据棋盘设计，以10CFU/ml的起始接种量，FCZ和8PP的部分抑菌浓度（FIC）分别为0.11和0.50，FIC指数值（FICI）为0.61。该FICI以及呈凹形的等效线图表明它们之间存在相加相互作用。在较高的起始接种量（10CFU/ml）下，FCZ、8PP及其组合以浓度依赖的方式降低了白色念珠菌的生长和活力。对于FCZ，与125µM 8PP联合使用时，最低杀菌浓度（MFC）和FC（杀死50%真菌细胞的浓度）降低了4倍（280 - 70µM）。相对于对照组，活菌数减少了3个对数单位（3.65±1.05‰，p<0.0001）。因此，两种抑菌化合物联合使用时，在低于各自单独使用的浓度下几乎达到了完全杀菌效果。在初步毒理学评估中，8PP经腹腔注射途径对雌性和雄性成年白化小鼠的半数致死剂量（LD）分别为357和245mg/kg。FCZ对雌性和雄性动物的LD分别为785和650mg/kg。结论：体外结果表明8PP和FCZ在白色念珠菌细胞生长方面存在相加相互作用。除了自身杀菌外，8PP有助于FCZ实现几乎完全的杀菌效果，这对于根除真菌感染至关重要。
