title: Diallyl disulphide depletes glutathione in Candida albicans: oxidative stress-mediated cell death studied by two-photon microscopy.
abstract: Using two-photon scanning laser microscopy, we investigated the effect of an Allium sativum (garlic) constituent, diallyl disulphide (DADS), on key physiological functions of the opportunistic pathogen Candida albicans. A short 30 min exposure to 0.5 mM DADS followed by removal induced 70% cell death (50% necrotic, 20% apoptotic) within 2 h, increasing to 75% after 4 h. The early intracellular events associated with DADS-induced cell death were monitored with two-photon fluorescence microscopy to track mitochondrial membrane potential (Deltapsi(m)), reactive oxygen species (ROS) and NADH or reduced glutathione (GSH) under aerobic conditions. DADS treatment decreased intracellular GSH and elevated intracellular ROS levels. Additionally, DADS induced a marked decrease of Deltapsi(m) and lowered respiration in cell suspensions and isolated mitochondria. In vitro kinetic experiments in cell-free extracts suggest that glutathione-S-transferase (GST) is one of the intracellular targets of DADS. Additional targets were also identified, including inhibition of a site or sites between complexes II-IV in the electron transport chain, as well as the mitochondrial ATP-synthase. The results indicate that DADS is an effective antifungal agent able to trigger cell death in Candida, most probably by eliciting oxidative stress as a consequence of thiol depletion and impaired mitochondrial function.
authors.affiliation: Microbiology (BIOSI 1), Main Building, Cardiff University, PO Box 915, Cardiff CF10 3TL, UK.
authors.forename: Katey M
authors.initials: KM
authors.lastname: Lemar
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Aon
authors.forename: Sonia
authors.initials: S
authors.lastname: Cortassa
authors.forename: Brian
authors.initials: B
authors.lastname: O'Rourke
authors.forename: Carsten T
authors.initials: CT
authors.lastname: Müller
authors.forename: David
authors.initials: D
authors.lastname: Lloyd
mesh_terms: D000498:Allyl Compounds / Q000737:chemistry / Q000494:pharmacology*; D002176:Candida albicans / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D004220:Disulfides / Q000737:chemistry / Q000494:pharmacology*; D005737:Garlic / Q000737:chemistry; D005978:Glutathione / Q000378:metabolism*; D033401:Microscopy, Acoustic; D018384:Oxidative Stress / Q000187:drug effects
chemical_list: D000498:Allyl Compounds; D004220:Disulfides; C028009:diallyl disulfide; D005978:Glutathione