title: Evidence for synergistic activity of plant-derived essential oils against fungal pathogens of food.
abstract: The antifungal activities of eight essential oils (EOs) namely basil, cinnamon, eucalyptus, mandarin, oregano, peppermint, tea tree and thyme were evaluated for their ability to inhibit growth of Aspergillus niger, Aspergillus flavus, Aspergillus parasiticus and Penicillium chrysogenum. The antifungal activity of the EOs was assessed by the minimum inhibitory concentration (MIC) using 96-well microplate analysis. The interactions between different EO combinations were done by the checkerboard technique. The highest antifungal activity was exhibited by oregano and thyme which showed lower MIC values amongst all the tested fungi. The antifungal activity of the other EOs could be appropriately ranked in a descending sequence of cinnamon, peppermint, tea tree and basil. Eucalyptus and mandarin showed the least efficiency as they could not inhibit any of the fungal growth at 10,000 ppm. The interaction between these two EOs also showed no interaction on the tested species. A combined formulation of oregano and thyme resulted in a synergistic effect, showing enhanced efficiency against A. flavus and A. parasiticus and P. chrysogenum. Mixtures of peppermint and tea tree produced synergistic effect against A. niger. Application of a modified Gompertz model considering fungal growth parameters like maximum colony diameter, maximum growth rate and lag time periods, under the various EO treatment scenarios, showed that the model could adequately describe and predict the growth of the tested fungi under these conditions.
authors.affiliation: Research Laboratories in Sciences Applied to Food, Canadian Irradiation Centre, INRS-Institute Armand-Frappier, 531 boulevard des Prairies., Laval, Québec H7V 1B7, Canada.
authors.forename: Farah
authors.initials: F
authors.lastname: Hossain
authors.affiliation: USDA-ARS, U.S. Pacific Basin Agricultural Research Center, 64 Nowelo Street, Hilo, HI 96720, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Follett
authors.affiliation: Research Laboratories in Sciences Applied to Food, Canadian Irradiation Centre, INRS-Institute Armand-Frappier, 531 boulevard des Prairies., Laval, Québec H7V 1B7, Canada.
authors.forename: Khang
authors.initials: K
authors.lastname: Dang Vu
authors.affiliation: Research Laboratories in Sciences Applied to Food, Canadian Irradiation Centre, INRS-Institute Armand-Frappier, 531 boulevard des Prairies., Laval, Québec H7V 1B7, Canada.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Harich
authors.affiliation: Research Laboratories in Sciences Applied to Food, Canadian Irradiation Centre, INRS-Institute Armand-Frappier, 531 boulevard des Prairies., Laval, Québec H7V 1B7, Canada.
authors.forename: Stephane
authors.initials: S
authors.lastname: Salmieri
authors.affiliation: Research Laboratories in Sciences Applied to Food, Canadian Irradiation Centre, INRS-Institute Armand-Frappier, 531 boulevard des Prairies., Laval, Québec H7V 1B7, Canada. Electronic address: monique.lacroix@iaf.inrs.ca.
authors.forename: Monique
authors.initials: M
authors.lastname: Lacroix
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D001231:Aspergillus flavus / Q000187:drug effects / Q000254:growth & development; D001234:Aspergillus niger / Q000187:drug effects / Q000254:growth & development; D004357:Drug Synergism; D008826:Microbial Sensitivity Tests; D009822:Oils, Volatile / Q000494:pharmacology*; D031341:Origanum / Q000737:chemistry; D010938:Plant Oils / Q000494:pharmacology*; D046930:Thymus Plant / Q000737:chemistry
chemical_list: D000935:Antifungal Agents; D009822:Oils, Volatile; D010938:Plant Oils
keywords: Essential oil; Fractional inhibitory concentration (FIC); Fungal growth parameter; Minimum inhibitory concentration (MIC)