title: Comprehensive approach for the detection of antifungal compounds using a susceptible strain of Candida albicans and confirmation of in vivo activity with the Galleria mellonella model.
abstract: An efficient screening strategy for the identification of potentially interesting low-abundance antifungal natural products in crude extracts that combines both a sensitive bioautography assay and high performance liquid chromatography (HPLC) microfractionation was developed. This method relies on high performance thin layer chromatography (HPTLC) bioautography with a hypersusceptible engineered strain of Candida albicans (DSY2621) for bioactivity detection, followed by the evaluation of wild type strains in standard microdilution antifungal assays. Active extracts were microfractionated by HPLC in 96-well plates, and the fractions were subsequently submitted to the bioassay. This procedure enabled precise localisation of the antifungal compounds directly in the HPLC chromatograms of the crude extracts. HPLC-PDA-mass spectrometry (MS) data obtained in parallel to the HPLC antifungal profiles provided a first chemical screening about the bioactive constituents. Transposition of the HPLC analytical conditions to medium-pressure liquid chromatography (MPLC) allowed the efficient isolation of the active constituents in mg amounts for structure confirmation and more extensive characterisation of their biological activities. The antifungal properties of the isolated natural products were evaluated by their minimum inhibitory concentration (MIC) in a dilution assay against both wild type and engineered strains of C. albicans. The biological activity of the most promising agents was further evaluated in vitro by electron microscopy and in vivo in a Galleria mellonella model of C. albicans infection. The overall procedure represents a rational and comprehensive means of evaluating antifungal activity from various perspectives for the selection of initial hits that can be explored in more in-depth mode-of-action studies. This strategy is illustrated by the identification and bioactivity evaluation of a series of antifungal compounds from the methanolic extract of a Rubiaceae plant, Morinda tomentosa, which was used as a model in these studies.
authors.affiliation: School of Pharmaceutical Sciences, EPGL, University of Geneva, University of Lausanne, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Favre-Godal
authors.affiliation: Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Dorsaz
authors.affiliation: School of Pharmaceutical Sciences, EPGL, University of Geneva, University of Lausanne, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland. Electronic address: emerson.ferreira@unige.ch.
authors.forename: Emerson Ferreira
authors.initials: EF
authors.lastname: Queiroz
authors.affiliation: School of Pharmaceutical Sciences, EPGL, University of Geneva, University of Lausanne, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
authors.forename: Céline
authors.initials: C
authors.lastname: Conan
authors.affiliation: School of Pharmaceutical Sciences, EPGL, University of Geneva, University of Lausanne, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
authors.forename: Laurence
authors.initials: L
authors.lastname: Marcourt
authors.affiliation: University of Airlangga, Fak Pascasarjana, 60286 Surabaya, Indonesia.
authors.forename: Bambang Prajogo Eko
authors.initials: BP
authors.lastname: Wardojo
authors.affiliation: Swiss Federal Research Station Agroscope Changins Wädenswil ACW, Route de Duiller 50, P.O. Box 1012, 1260 Nyon, Switzerland.
authors.forename: Francine
authors.initials: F
authors.lastname: Voinesco
authors.affiliation: Swiss Federal Research Station Agroscope Changins Wädenswil ACW, Route de Duiller 50, P.O. Box 1012, 1260 Nyon, Switzerland.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Buchwalder
authors.affiliation: Swiss Federal Research Station Agroscope Changins Wädenswil ACW, Route de Duiller 50, P.O. Box 1012, 1260 Nyon, Switzerland.
authors.forename: Katia
authors.initials: K
authors.lastname: Gindro
authors.affiliation: Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland.
authors.forename: Dominique
authors.initials: D
authors.lastname: Sanglard
authors.affiliation: School of Pharmaceutical Sciences, EPGL, University of Geneva, University of Lausanne, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Wolfender
mesh_terms: D000818:Animals; D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D001688:Biological Products / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D008954:Models, Biological; D015394:Molecular Structure; D009036:Moths / Q000187:drug effects*; D019666:Rubiaceae / Q000737:chemistry*
chemical_list: D000935:Antifungal Agents; D001688:Biological Products
keywords: Antifungal; Bioautography; Biofilms; Candida albicans; Galleria mellonella; Genetic modified strain