title: Mechanism of azole antifungal activity as determined by liquid chromatographic/mass spectrometric monitoring of ergosterol biosynthesis.
abstract: A liquid chromatography/mass spectrometry (LC/MS) method for separation and characterization of ergosterol biosynthetic precursors was developed to study the effect of Posaconazole on sterol biosynthesis in fungi. Ergosterol biosynthetic precursors were characterized from their electron ionization mass spectra acquired by a normal-phase chromatography, particle beam LC/MS method. Fragment ions resulting from cleavage across the D-ring and an abundant M - 15 fragment ion were diagnostic for methyl substitution at C-4 and C-14. Comparison of the sterol profile in control and treated Candida albicans incubations showed depletion of ergosterol and accumulation of C-4 and C-14 methyl-substituted sterols following treatment with Posaconazole. These C-4 and C-14 methyl sterols are known to be incapable of sustaining cell growth. The results demonstrate that Posaconazole exerts its antifungal activity by inhibition of ergosterol biosynthesis. Furthermore, Posaconazole appears to disrupt ergosterol biosynthesis by inhibition of lanosterol 14alpha-demethylase.
authors.affiliation: Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, New Jersey 07033, USA. larry.heimark@spcorp.com
authors.forename: Larry
authors.initials: L
authors.lastname: Heimark
authors.forename: Petia
authors.initials: P
authors.lastname: Shipkova
authors.forename: Jonathan
authors.initials: J
authors.lastname: Greene
authors.forename: Hanan
authors.initials: H
authors.lastname: Munayyer
authors.forename: Taisa
authors.initials: T
authors.lastname: Yarosh-Tomaine
authors.forename: Beth
authors.initials: B
authors.lastname: DiDomenico
authors.forename: Roberta
authors.initials: R
authors.lastname: Hare
authors.forename: Birendra N
authors.initials: BN
authors.lastname: Pramanik
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004875:Ergosterol / Q000032:analysis / Q000096:biosynthesis*; D007810:Lanosterol / Q000032:analysis / Q000096:biosynthesis; D021241:Spectrometry, Mass, Electrospray Ionization; D013261:Sterols / Q000096:biosynthesis; D014230:Triazoles / Q000494:pharmacology*
chemical_list: D000935:Antifungal Agents; D001393:Azoles; D013261:Sterols; D014230:Triazoles; D007810:Lanosterol; C101425:posaconazole; D004875:Ergosterol