Usnic acid activity on oxidative and nitrosative stress of azole-resistant Candida albicans biofilm

PERALTA, MARIANA ANDREA; DA SILVA, MARIA ANGEL; ORTEGA, MARÍA GABRIELA; CABRERA, JOSE LUIS; PARAJE, MARÍA GABRIELA

PLANTA MEDICA

GEORG THIEME VERLAG KG

Año: 2016

0032-0943

everal studies report that (+)-usnic acid (UA), a lichen secondary metabolite, inhibits growth of different bacteria and fungi; however, mechanism of its antimicrobial activity remains unknown. In this study, we have explored the ability of UA, obtained from Usnea amblyoclada, as an antibiofilm agent against azole-resistant (RCa) and azole-sensitive (SCa) Candida albicans strains by studying the cellular stress and antioxidant response in biofilms. The biofilm inhibitory concentration (BIC) of UA (4 µg/mL) exhibited a significant biofilm inhibition, 71.08% for RCa and 87.84% for SCa. Confocal scanning laser microscopy (CSLM) showed that the morphology of mature biofilm was altered (reduced the biomass and thickness) in the presence of UA. The antifungal effect was mediated by an oxidative and nitrosative stress, with a significant accumulation of intracellular and extracellular ROS detected by CSLM and by nitro blue tetrazolium, respectively. In fact, RCa and SCa biofilms treated at B