Department of Biology, Fairfield University, CT 06824, USA.
Can J Microbiol. 2009 Sep;55(9):1033-9. doi: 10.1139/w09-058.
The adherence of Candida albicans to one another and to various host and biomaterial surfaces is an important prerequisite for the colonization and pathogenesis of this organism. Cells in established biofilms exhibit different phenotypic traits and are inordinately resistant to antimicrobial agents. Recent studies have shown that black and green tea polyphenols exhibit both antimicrobial and strong cancer-preventive properties. Experiments were conducted to determine the effects of these polyphenols on C. albicans. Standard growth curves demonstrated a 40% reduction in the growth rate constant (K) with a 2 mg/mL concentration of Polyphenon 60, a green tea extract containing a mixture of polyphenolic compounds. Cultures treated with 1.0 micromol/L -(-)epigallocatechin-3-gallate (EGCG), the most abundant polyphenol, displayed a 75% reduction of viable cells during biofilm formation. Established biofilms treated with EGCG were also reduced, by 80%, as determined through XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) colorimetric assays. Identical concentrations of epigallocatechin and epicatechin-3-gallate demonstrated similar biofilm inhibition. Further investigations regarding the possible mechanism of polyphenol action indicate that in vivo proteasome activity was significantly decreased when catechin-treated yeast cells were incubated with a fluorogenic peptide substrate that measured proteasomal chymotrypsin-like and peptidyl-glutamyl peptide-hydrolyzing activities. Impairment of proteasomal activity by tea polyphenols contributes to cellular metabolic and structural disruptions that expedite the inhibition of biofilm formation and maintenance by C. albicans.
白色念珠菌彼此之间以及与各种宿主和生物材料表面的黏附是该生物定植和发病的重要前提。已建立的生物膜中的细胞表现出不同的表型特征，并且对抗菌剂具有极强的抵抗力。最近的研究表明，黑茶和绿茶中的多酚具有抗菌和强烈的防癌特性。进行了实验以确定这些多酚对白色念珠菌的影响。标准生长曲线表明，用含有多酚混合物的绿茶提取物 Polyphenon 60 处理时，在 2mg/mL 浓度下，生长率常数（K）降低了 40％。用 1.0µmol/L 的（-）表没食子儿茶素-3-没食子酸酯（EGCG）处理的培养物在生物膜形成过程中显示出 75％的活细胞减少。通过 XTT（2,3-双（2-甲氧基-4-硝基-5-磺基苯基）-2H-四唑-5-羧基苯胺）比色法测定，用 EGCG 处理的已建立的生物膜也减少了 80％。表没食子儿茶素和表儿茶素-3-没食子酸酯的相同浓度显示出类似的生物膜抑制作用。关于多酚作用的可能机制的进一步研究表明，当用测量蛋白酶体糜蛋白酶样和肽基-谷氨酰肽水解活性的荧光肽底物孵育用儿茶素处理的酵母细胞时，体内蛋白酶体活性显着降低。茶多酚对蛋白酶体活性的损害导致细胞代谢和结构破坏，从而加速白色念珠菌生物膜形成和维持的抑制。
