Antifungal activity of several essential oils and major components against wood-rot fungi

Biodegradation of wood by fungi is recognized as one of the most serious problems for wooden structures and forest management. This study evaluated the fungicidal activity of 6 plant essential oils (Origanum vulgare, Cymbopogon citratus, Thymus vulgaris, Pelargonium graveolens, Cinnamomum zeylanicum and Eugenia caryophyllata) against the wood-rot fungi, Trametes hirsuta and Laetiporus sulphureus. Results from antifungal tests revealed that six essential oils showed good antifungal activities, in which, O. vulgare was the most toxic to the wood-rot fungi, with the IC50 values against T. hirsuta and L. sulphureus of 79.1 and 36.9 mu g/mL, respectively. The composition of six essential oils was indentified by using gas chromatographic-mass spectrometry. The six major compounds from 6 essential oils were tested individually for their fungicidal activities against two wood-rot fungi. Results from the antifungal tests demonstrated that the six major compounds exhibited strong fungicidal activity. In addition, carvacrol was the most toxic against the wood-rot fungi, with the IC50 values against T. hirsuta and L. sulphureus of 33.6 and 17.2 mu/mL, respectively. Furthermore, phenol and aldehyde groups were more toxic than alcohol. The results show that the six plant essential oils and their major chemical constituents have potential for the development of natural wood preservatives.