Derengowski Lorena S, De-Souza-Silva Calliandra, Braz Shélida V, Mello-De-Sousa Thiago M, Báo Sônia N, Kyaw Cynthia M, Silva-Pereira Ildinete
Laboratório de Biologia Molecular, CEL/IB, Universidade de Brasília, Brasília, DF, Brasil.
Ann Clin Microbiol Antimicrob. 2009 Apr 29;8:13. doi: 10.1186/1476-0711-8-13.
Farnesol is a sesquiterpene alcohol produced by many organisms, and also found in several essential oils. Its role as a quorum sensing molecule and as a virulence factor of Candida albicans has been well described. Studies revealed that farnesol affect the growth of a number of bacteria and fungi, pointing to a potential role as an antimicrobial agent.
Growth assays of Paracoccidioides brasiliensis cells incubated in the presence of different concentrations of farnesol were performed by measuring the optical density of the cultures. The viability of fungal cells was determined by MTT assay and by counting the colony forming units, after each farnesol treatment. The effects of farnesol on P. brasiliensis dimorphism were also evaluated by optical microscopy. The ultrastructural morphology of farnesol-treated P. brasiliensis yeast cells was evaluated by transmission and scanning electron microscopy.
In this study, the effects of farnesol on Paracoccidioides brasiliensis growth and dimorphism were described. Concentrations of this isoprenoid ranging from 25 to 300 microM strongly inhibited P. brasiliensis growth. We have estimated that the MIC of farnesol for P. brasiliensis is 25 microM, while the MLC is around 30 microM. When employing levels which don't compromise cell viability (5 to 15 microM), it was shown that farnesol also affected the morphogenesis of this fungus. We observed about 60% of inhibition in hyphal development following P. brasiliensis yeast cells treatment with 15 microM of farnesol for 48 h. At these farnesol concentrations we also observed a significant hyphal shortening. Electron microscopy experiments showed that, despite of a remaining intact cell wall, P. brasiliensis cells treated with farnesol concentrations above 25 microM exhibited a fully cytoplasmic degeneration.
Our data indicate that farnesol acts as a potent antimicrobial agent against P. brasiliensis. The fungicide activity of farnesol against this pathogen is probably associated to cytoplasmic degeneration. In concentrations that do not affect fungal viability, farnesol retards the germ-tube formation of P. brasiliensis, suggesting that the morphogenesis of this fungal is controlled by environmental conditions.
法尼醇是一种由多种生物体产生的倍半萜醇，也存在于几种香精油中。其作为群体感应分子和白色念珠菌毒力因子的作用已得到充分描述。研究表明，法尼醇会影响多种细菌和真菌的生长，表明其具有作为抗菌剂的潜在作用。
通过测量培养物的光密度，对在不同浓度法尼醇存在下培养的巴西副球孢子菌细胞进行生长测定。在每次法尼醇处理后，通过MTT法和计数菌落形成单位来确定真菌细胞的活力。还通过光学显微镜评估法尼醇对巴西副球孢子菌二态性的影响。通过透射电子显微镜和扫描电子显微镜评估经法尼醇处理的巴西副球孢子菌酵母细胞的超微结构形态。
在本研究中，描述了法尼醇对巴西副球孢子菌生长和二态性的影响。这种类异戊二烯浓度范围为25至300微摩尔时强烈抑制巴西副球孢子菌的生长。我们估计法尼醇对巴西副球孢子菌的最低抑菌浓度为25微摩尔，而最低杀菌浓度约为30微摩尔。当使用不影响细胞活力的浓度（5至15微摩尔）时，表明法尼醇也会影响这种真菌的形态发生。在用15微摩尔法尼醇处理巴西副球孢子菌酵母细胞48小时后，我们观察到菌丝发育受到约60%的抑制。在这些法尼醇浓度下，我们还观察到菌丝显著缩短。电子显微镜实验表明，尽管细胞壁保持完整，但用高于25微摩尔浓度法尼醇处理的巴西副球孢子菌细胞表现出完全的细胞质变性。
我们的数据表明，法尼醇对巴西副球孢子菌具有强效抗菌作用。法尼醇对这种病原体的杀真菌活性可能与细胞质变性有关。在不影响真菌活力的浓度下，法尼醇会延迟巴西副球孢子菌芽管的形成，表明这种真菌的形态发生受环境条件控制。
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