title: Fungal sterol C22-desaturase is not an antimycotic target as shown by selective inhibitors and testing on clinical isolates.
abstract: Inhibition of concise enzymes in ergosterol biosynthesis is one of the most prominent strategies for antifungal chemotherapy. Nevertheless, the enzymes sterol C5-desaturase and sterol C22-desaturase, which introduce double bonds into the sterol core and side chain, have not been fully investigated yet for their potential as antifungal drug targets. Lathosterol side chain amides bearing N-alkyl groups of proper length are known as potent inhibitors of the enzymes sterol C5-desaturase and sterol Δ(24)-reductase in mammalian cholesterol biosynthesis. Here we present the results of our evaluation of these amides for their ability to inhibit enzymes in fungal ergosterol biosynthesis. In the presence of inhibitor(s) an accumulation of sterols lacking a double bond at C22/23 (mainly ergosta-5,7-dien-3β-ol) was observed in Candida glabrata, Saccharomyces cerevisiae, and Yarrowia lipolytica. Hence, the lathosterol side chain amides were identified as selective inhibitors of the fungal sterol C22-desaturase, which was discussed as a specific target for novel antifungals. One representative inhibitor, (3S,20S)-20-N-butylcarbamoylpregn-7-en-3β-ol was subjected to antifungal susceptibility testing on patient isolates according to modified EUCAST guidelines. But, the test organisms showed no significant reduction of cell growth and/or viability up to an inhibitor concentration of 100μg/mL. This leads to the conclusion that sterol C22-desaturase is not an attractive target for the development of antifungals.
authors.affiliation: Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians University of Munich, Butenandtstr. 5-13, 81377 Munich, Germany. Electronic address: christoph.mueller@cup.uni-muenchen.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Müller
authors.affiliation: Department of Hygiene, Microbiology and Social Medicine, Division of Hygiene and Medical Microbiology, Medical University Innsbruck, Schöpfstr. 41, 6020 Innsbruck, Austria.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Binder
authors.affiliation: Department of Hygiene, Microbiology and Social Medicine, Division of Hygiene and Medical Microbiology, Medical University Innsbruck, Schöpfstr. 41, 6020 Innsbruck, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Maurer
authors.affiliation: Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians University of Munich, Butenandtstr. 5-13, 81377 Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Grimm
authors.affiliation: Leiden University Medical Center, Center for Proteomics and Metabolomics, Albinusdreef 2, 2300 RC Leiden, The Netherlands.
authors.forename: Martin
authors.initials: M
authors.lastname: Giera
authors.affiliation: Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians University of Munich, Butenandtstr. 5-13, 81377 Munich, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Bracher
mesh_terms: D000577:Amides / Q000737:chemistry; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology*; D002784:Cholesterol / Q000737:chemistry / Q000494:pharmacology; D065607:Cytochrome P-450 Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005658:Fungi / Q000187:drug effects* / Q000201:enzymology* / Q000302:isolation & purification; D057809:HEK293 Cells; D018922:HL-60 Cells; D006801:Humans; D008826:Microbial Sensitivity Tests
chemical_list: D000577:Amides; D000935:Antifungal Agents; D065607:Cytochrome P-450 Enzyme Inhibitors; C001521:lathosterol; D003577:Cytochrome P-450 Enzyme System; D002784:Cholesterol
keywords: Antifungal susceptibility testing; C22-desaturase; C5-desaturase; Candida; Lathosterol side chain amides