Search

Indigenous cinnamon (Cinnamomum osmophloeum) is an endemic tree in Taiwan. The leaf essential oil is rich in trans-cinnamaldehyde, and its excellent antifungal activity has been reported. Since trans-cinnamaldehyde is a volatile compound, it is here evaluated for whether it is more effective via fumigant action. This study illustrates the antifungal action of trans-cinnamaldehyde against wood-decay fungi. Two ways that trans-cinnamaldehyde inhibits the growth of fungi, namely direct contact and fumigation, were examined using the agar dilution method (AD) and the inverted paper disc method (IPD). In addition, the amount of trans-cinnamaldehyde vapor in the headspace of the Petri dish was quantified using solid-phase microextraction and GC–MS. Antifungal results showed that the antifungal indices observed in the IPD method were clearly higher than those in the AD method, indicating that trans-cinnamaldehyde vapor had stronger antifungal activity. Results from the quantitative analysis also revealed that the amounts of trans-cinnamaldehyde vapor measured by the IPD method were significantly greater than those by the AD method. Accordingly, with higher amount of trans-cinnamaldehyde evaporated, stronger antifungal activity was observed. It is clear that the antifungal action of trans-cinnamaldehyde was primarily attributed to fumigation instead of direct contact.

Taiwania (Taiwania cryptomerioides Hayata) is a native and plantation species in Taiwan, and its heartwood has demonstrated excellent decay resistance. Brown root rot fungus Phellinus noxius has caused severe damage to more than 100 tree species in Taiwan. The aims of this study were to investigate the antifungal activities of Taiwania heartwood extracts against P. noxius and to identify the antifungal compounds. Antifungal activities were examined using the agar dilution method (a direct contact assay) and the inverted lid method (a vapor contact assay). Active compounds were purified using liquid–liquid partition, open-column chromatography and HPLC. Among four soluble fractions (n-hexane, ethyl acetate, n-butanol and water soluble fractions), results showed that n-hexane soluble fraction (HSF) can significantly inhibit the growth of P. noxius via the agar dilution method. Moreover, active compounds present in HSF were obtained using antifungal assay-guided fractionation. Results showed that ferruginol, T-cadinol, α-cadinol and T-muurolol were found to exhibit excellent antifungal activities against P. noxius, and their IC50 values were 16.9, 25.8, 33.8 and 50.6 μg/mL, respectively. According to the current findings, phytochemicals (ferruginol, T-cadinol, α-cadinol and T-muurolol) of Taiwania heartwood had the potential to be used as environmentally benign antifungal agents against P. noxius in place of synthetic or inorganic fungicides.

Chamaecyparis formosensis is a species indigenous to Taiwan. Its timber is renowned for excellent durability. The aim of this study was to investigate the antitermitic activities of wood essential oil of C. formosensis and its constituents. Results showed that wood essential oil of C. formosensis had powerful antitermitic activity, with LD50 values of 0.76 mg/g after 7 days of testing. Among the nine fractions of wood essential oil, Fraction 5 showed the strongest antitermitic activity, with LD50 value of