Mode of action and anti-Candida activity of Artemisia annua mediated-synthesized silver nanoparticles

Candida albicans is a polymorphic opportunistic commensal that causes both superficial and systemic fungal infections especially in immunocompromised patients. Biologically synthesized silver nano-particles (AgNPs) have emerged as potential antifungal agents. The present work evaluates the antifungal activity of Artemisia annua synthesized AgNPs against three Candida species (C albicans ATCC 90028, C tropicalis ATCC 750 and C glabrata ATCC 90030). The in vitro effect of AgNPs was investigated for fungal growth, sterol content, secretion of hydrolytic enzymes and yeast-to-hyphal transition. The green synthesized AgNPs were effective against all the three species with minimum inhibitory concentration (MIC) in the range 80-120 mu gml(-1). Candida glabrata showed greater sensitivity for AgNPs followed by Candida tropicalis and C. albicans. AgNPs at 4MIC were as effective as fluconazole (FLC) and caused only 5% haemolysis while FLC caused 50% haemolysis at the same concentration. The secretion of hydrolytic enzymes was the lowest in case of AgNP exposed C. glabrata. Yeast-to-hyphal transition was significantly reduced in treated C. albicans cells and showed disfigured morphology in SEM images. The decrease in ergosterol content was slightly higher (94%) in both C. glabrata and C. tropicalis in comparison to C. albicans (69%). Green synthesized AgNPs thus have immense potential as an antifungal and can play a crucial role in the management of Candida infections especially those caused by C. glabrata. (C) 2019 Elsevier Masson SAS. All rights reserved.