Antifungal activities of essential oils from some Iranian medicinal plants against various post harvest moulds

Abstract

The potential antifungal effects of the essential oils and components of Thymus vulgaris L.,Thymus migricus Klokov and Desj-Shost., Thymus koschyanus Boiss., Mentha spicata L.,Mentha pulegium L., and Satureja mutica Fisch and C.A. (Lamiaceae) were investigated against four food poisoning and plant pathogens. The essential oils were obtained by hydro distillation of dried plant materials and their composition was determined by gas chromatograph and mass spectrometer (GC-MS) in previous studies. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of the oils and their components were determined by dilution assays. Thymus species showed very strong antifungal activities. Culture Potato Dextrose Agar (PDA) media with all oil-enrichment resulted in significant (P≤0.01) reduction on subsequent colony development of Rhizopus oryzae (up to 28%) at 100 ppm; Botrytis cinerea (up to 100%); Penicillium expansum (up to 69%) at 100 ppm and Rhizopus stolonifer (up to 56%) at 100 ppm. Among studied fungi, B. cinerea and P. expansum were the most sensitive pathogens treated with MICs of 100 and 150 ppm, respectively. Differences between high MICs and MFCs of M. spicata and T. vulgaris and low MICs and MFCs of T. koschyanus and T. migricus inhibiting the growth and colony development of tested fungi correlated with simultaneous high concentration of thymol and carvacrol in species of T. koschyanus, T. migricus, M. pulegium and S. mutica. It is concluded that essential oils of Thymus, Satureja and Mentha species possess great antifungal potential and could be used as natural preservatives and fungicides. Key words: Antifungal activity, plant pathogens, essential oils, fungal growth, Lamiaceae family.