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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 IC 50 values against T. hirsuta and L. sulphureus of 79.1 and 36.9 μg/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 IC 50 values against T. hirsuta and L. sulphureus of 33.6 and 17.2 μg/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. [ABSTRACT FROM AUTHOR]

Rhizoctonia solani and Fusarium oxysporum are very well known phytopathogens with worldwide spread that cause one of the most destructive diseases, resulting significant yield losses in crop production. In order to find effective fungicides for controlling phytopathogen, the structure-activity relationships of cinnamaldehyde and eugenol derivatives against R. solani and F. oxysporum were evaluated. Additionally, the composition and fungicidal activity of Cinnamomum cassia and Syzygium aromatica essential oils was assessed. Cinnamaldehyde (49.75%) is the major compound in cinnamon bark oil, and eugenol (89.17%) is most abundant in clove bud oil. The clove bud oil exhibited good antifungal activities against R. solani and F. oxysporum (IC 50 = 106.5 and 149.9 μg/mL, respectively). Cinnamon bark oil showed a lower activity than clove bud oil. The fungicidal activity of cinnamaldehyde (IC 50 = 75.4 and 156.9 μg/mL, respectively) and eugenol (IC 50 = 58.9 and 52.9 μg/mL, respectively) against R. solani and F. oxysporum was also evalutated. Comparisons of the antifungal activities of cinnamaldehyde and eugenol derivatives revealed that α-methylcinnamaldehyde, α-methylcinnamic acid, methyleugenol, acetyleugenol, isoeugenol, methylisoeugenol, and acetylisoeugenol showed good antifungal activities against R. solani and F. oxysporum . In structure-activity relationships, the fungicidal activity of cinnamaldehyde derivatives could be related to conjugated double bond and the length of CH chain outside the ring. In addition, the presence of the lipophilicity may have a considerable influence on the toxicity of phenylpropenes. The present approach may help future work in the search for fungicidal compounds. [ABSTRACT FROM AUTHOR]

Biodegradation of wood by fungi and termites is recognized as one of the most serious problems for wooden structures. In this study, we analyzed the antitermitic and antifungal activities of flower buds essential oil from Syzygium aromaticum and its dominant constituents. Essential oil components were analyzed by gas chromatography and the major compound of essential oil was eugenol (90.6%). The results demonstrated that at the dosage of 50 μg/g, clove essential oil had 100% mortality to Reticulitermes chinensis after testing for 5 d. Furthermore, we found eugenol killed all termites after testing for 3 d, with an LC 50 value of 12.1 μg/g. Meanwhile, we also found clove essential oil and eugenol displayed activity against three fungi, Trametes hirsuta , Schizphylhls commne , and Pycnoporus sanguineus . We found eugenol was principal antifungal constituent of clove oil. The IC 50 values of eugenol against T. hirsuta , S. commne , and P. sanguineus were 83.6, 116.1, and 102.4 μg/mL, respectively. In addition, comparisons of the termite mortality and antifungal indices of eugenol and its congeners proved that eugenol exhibited the strongest antitermitic and antifungal activities. The clove oil and eugenol have potential for the development of natural wood preservatives. [ABSTRACT FROM AUTHOR]