Identification and Mode of Action of a Plant Natural Product Targeting Human Fungal Pathogens
- Dorsaz, Stéphane Institute of Microbiology, University of Lausanne, and Lausanne University Hospital, Lausanne, Switzerland
- Snäkä, Tiia Institute of Microbiology, University of Lausanne, and Lausanne University Hospital, Lausanne, Switzerland
- Favre-Godal, Quentin School of Pharmaceutical Sciences, EPGL, University of Geneva-University of Lausanne, Geneva, Switzerland
- Maudens, Pierre School of Pharmaceutical Sciences, EPGL, University of Geneva-University of Lausanne, Geneva, Switzerland
- Boulens, Nathalie School of Pharmaceutical Sciences, EPGL, University of Geneva-University of Lausanne, Geneva, Switzerland
- Furrer, Pascal School of Pharmaceutical Sciences, EPGL, University of Geneva-University of Lausanne, Geneva, Switzerland
- Ebrahimi, Samad Nejad Division of Pharmaceutical Biology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
- Hamburger, Matthias Division of Pharmaceutical Biology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
- Allémann, Eric School of Pharmaceutical Sciences, EPGL, University of Geneva-University of Lausanne, Geneva, Switzerland
- Gindro, Katia Agroscope, Strategic Research Division Plant Protection, Mycology, and Biotechnology, Nyon, Switzerland
- Queiroz, Emerson Ferreira School of Pharmaceutical Sciences, EPGL, University of Geneva-University of Lausanne, Geneva, Switzerland
- Riezman, Howard Department of Biochemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
- Wolfender, Jean-Luc School of Pharmaceutical Sciences, EPGL, University of Geneva-University of Lausanne, Geneva, Switzerland
- Sanglard, Dominique ORCID Institute of Microbiology, University of Lausanne, and Lausanne University Hospital, Lausanne, Switzerland
- 2017-8-24
Published in:
- Antimicrobial Agents and Chemotherapy. - American Society for Microbiology. - 2017, vol. 61, no. 9
English
ABSTRACT
Candida albicans is a major cause of fungal diseases in humans, and its resistance to available drugs is of concern. In an attempt to identify novel antifungal agents, we initiated a small-scale screening of a library of 199 natural plant compounds (i.e., natural products [NPs]). In vitro susceptibility profiling experiments identified 33 NPs with activity against C. albicans (MIC50 s ≤ 32 μg/ml). Among the selected NPs, the sterol alkaloid tomatidine was further investigated. Tomatidine originates from the tomato (Solanum lycopersicum ) and exhibited high levels of fungistatic activity against Candida species (MIC50 s ≤ 1 μg/ml) but no cytotoxicity against mammalian cells. Genome-wide transcriptional analysis of tomatidine-treated C. albicans cells revealed a major alteration (upregulation) in the expression of ergosterol genes, suggesting that the ergosterol pathway is targeted by this NP. Consistent with this transcriptional response, analysis of the sterol content of tomatidine-treated cells showed not only inhibition of Erg6 (C-24 sterol methyltransferase) activity but also of Erg4 (C-24 sterol reductase) activity. A forward genetic approach in Saccharomyces cerevisiae coupled with whole-genome sequencing identified 2 nonsynonymous mutations in ERG6 (amino acids D249G and G132D) responsible for tomatidine resistance. Our results therefore unambiguously identified Erg6, a C-24 sterol methyltransferase absent in mammals, to be the main direct target of tomatidine. We tested the in vivo efficacy of tomatidine in a mouse model of C. albicans systemic infection. Treatment with a nanocrystal pharmacological formulation successfully decreased the fungal burden in infected kidneys compared to the fungal burden achieved by the use of placebo and thus confirmed the potential of tomatidine as a therapeutic agent.
- Language
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- English
- Open access status
- hybrid
- Identifiers
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- DOI 10.1128/aac.00829-17
- ISSN 0066-4804
- Persistent URL
- https://folia.unifr.ch/global/documents/51286
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