title: Effect of two monoterpene phenols on antioxidant defense system in Candida albicans.
abstract: Thymol and carvacrol from the class of monoterpene phenols are one of the most potent plant essential oil components possessing antimicrobial effects. Known for their wide bioactive spectrum, these positional isomers of isopropyl cresol deplete ergosterol content, compromise membrane permeability, block efflux pumps and restore antifungal susceptibility to fluconazole in resistant Candida strains. Exposure to these natural compounds induces a cascade of stress responses, which are important to comprehend their microbicidal mechanisms. This study evaluates the antioxidant defense response to lower concentrations of thymol and carvacrol in Candida albicans. The antioxidant defense responses in C. albicans are important for developmental mechanisms pertaining to resistance against the immune system, infection establishment and drug resistance. In this view, primary and secondary antioxidant defense enzymes, and oxidative stress markers including glutathione and lipid peroxidation were determined in C. albicans cells exposed to lower concentrations of thymol and carvacrol. These compounds were found to induce oxidative stress and compromised the antioxidant defense system in C. albicans at lower concentrations. This study helps in understanding the 'in cell' antifungal mechanisms of natural monoterpene phenols originating from oxidative stress. Thymol and carvacrol induced membrane deterioration reported earlier, is further explained as a result of a toxic radical cascade mediated by lipid peroxidation. Findings reinforce the observed toxic oxidizing effects of these compounds as a consequence of direct damage to antioxidant components and not to their genetic manipulations.
authors: Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors: Amber
authors: A
authors: Khan
authors: Department of Pharmaceutical Sciences, Tshwane University of Technology, Pretoria SA-0001, South Africa.
authors: Aijaz
authors: A
authors: Ahmad
authors: Medical Mycology Lab, Department of Biosciences, Jamia Millia Islamia, New Delhi, India.
authors: Luqman
authors: L
authors: Ahmad Khan
authors: Department of Chemical Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors: Carolyn J
authors: CJ
authors: Padoa
authors: Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. Electronic address: sandy.vanvuuren@wits.ac.za.
authors: Sandy
authors: S
authors: van Vuuren
authors: Medical Mycology Lab, Department of Biosciences, Jamia Millia Islamia, New Delhi, India. Electronic address: nikhatmanzoor@yahoo.co.in.
authors: Nikhat
authors: N
authors: Manzoor
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000378:metabolism*; D002176:Candida albicans / Q000187:drug effects* / Q000378:metabolism* / Q000502:physiology; D000081007:Cymenes; D005978:Glutathione / Q000032:analysis; D015227:Lipid Peroxidation; D039821:Monoterpenes / Q000494:pharmacology*; D018384:Oxidative Stress; D013943:Thymol / Q000494:pharmacology*
chemical_list: D000935:Antifungal Agents; D000975:Antioxidants; D000081007:Cymenes; D039821:Monoterpenes; D013943:Thymol; C073316:carvacrol; D005978:Glutathione
keywords: Candida albicans; Carvacrol; Oxidative stress; ROS; Thymol; qRT-PCR