Antioxidant small molecules confer variable protection against oxidative damage in yeast mutants.
To assess the capacity of small molecules to function as antioxidants in pathologic conditions, a set of yeast assays utilizing strains deficient in the antioxidant machinery was applied with measurements of reactive oxygen species (ROS), glutathione (GSH/GSSG), and induction of the stress responsive proteins oye2 and oye3. Yeast strains deficient in superoxide dismutase (Delta sod1), catalase A (Delta cta1), and double-deficient in Old Yellow enzyme 2 and glutathione reductase 1 (Delta oye2 glr1) were supplemented with ascorbic acid, beta-carotene, caffeic acid, or quercetin, subjected to pro-oxidant insult, and monitored for growth recovery. Ascorbic acid and caffeic acid protected cells under most circumstances, whereas beta-carotene and quercetin protection was highly context dependent, exhibiting protection in some cases and inhibition in others. Beta-carotene and quercetin elevated substantially endogenous levels of ROS in some yeast mutants. Quercetin supplementation increased significantly GSH and GSSG levels but could not maintain GSH levels in H(2)O(2)-exposed cells. Induction of the stress response machinery was manifested by the strong up-regulation of a chromosomally encoded OYE2-GFP fusion. In the case of quercetin, there was simultaneous induction of OYE3-GFP, which was previously shown to sensitize cells to H(2)O(2)-induced programmed cell death (PCD). Taken together, the results show that mutations in the antioxidant machinery affect significantly the capacity of dietary antioxidants to protect cells.
Amari
Foued
F
Department of Natural Products, Mediterranean Agronomic Institute of Chania, P.O. Box 85, Chania 73100, Greece.
Fettouche
Abdelmadjid
A
Samra
Mario Abou
MA
Kefalas
Panagiotis
P
Kampranis
Sotirios C
SC
Makris
Antonios M
AM
D000975:Antioxidants / Q000494:pharmacology*; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D050296:Microbial Viability / Q000187:drug effects; D009154:Mutation; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism
D000975:Antioxidants; D017382:Reactive Oxygen Species; D029701:Saccharomyces cerevisiae Proteins; D002374:Catalase; D013482:Superoxide Dismutase; D005978:Glutathione