Geraniol eradicates Candida glabrata biofilm by targeting multiple cellular pathways.

Abstract

Global burden of fungal infections and associated health risk has accelerated at an incredible pace and needs to be attended at the earliest with an unbeatable therapeutic intervention. Candida glabrata is clinically the most relevant and least drug susceptible Candida species. In the pursuit of mining alternative novel drug candidates, the antifungal activity of a monoterpene phytoactive molecule geraniol (GR) against C. glabrata biofilm was evaluated. Biofilm inhibitory and eradication ability of GR evaluated against C. glabrata along with its clinical isolates. Impact of GR on various cellular pathways was evaluated to delineate its antifungal mode of action. GR has inhibited both planktonic and sessile growth of all the studied C. glabrata strains and eradicated the mature biofilm. GR reduced the carbohydrate and eDNA content, as well as hydrolytic enzyme activity in extracellular matrix of C. glabrata. The chemical profiling, microscopic, and spectroscopic studies revealed that GR targets chitin and β-glucan in cell wall. Further, results highlighted the reduction of cell membrane ergosterol content, and blocking of ABC drug efflux pump by GR which was also confirmed by RT-PCR where expression of CDR1 and ERG4 was downregulated in GR exposed C. glabrata cells. The fluorescence microscopy and flow cytometry results emphasized the alteration in mitochondrial activity, increased Ca+2 uptake, thus changing the membrane permeability ensuing increased cytochrome C release from mitochondria to cytoplasm. Indeed, GR also has arrested cell cycle in G1/S phase and interfered with DNA replication. These observations suggest GR targets multiple cellular pathways and mediated killing of C. glabrata cells via apoptosis. In conclusion, the present study strengthens the candidacy of GR as novel antifungal therapeutic. Key points • GR inhibits growth and eradicates biofilm of C. glabrata and its clinical isolates. • GR inactivates the hydrolytic enzymes in extracellular matrix. • GR mediates C. glabrata apoptosis by interfering with multiple signaling pathways.