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Background Only a few studies have investigated the bioactivity of the essential oils (EOs) of Chamaecyparis formosensisand C. obtusavar. formosana, which are endemic to Taiwan. The wood and leaf EOs extracted from C. obtusavar. formosanahad anti-inflammatory and antitermitic effects, respectively, and the twig EO extracted from C. formosensisinhibited the growth of Fusarium oxysporum, Pestalotiopsis funerea,and Ganoderma australe.Methods A poisoned food technique was used to evaluate the antifungal effects of wood and leaf EOs extracted from C. formosensisand C. obtusavar. formosanaon brown rot fungus, white rot fungus, and mold. A phytatray chamber assay was conducted to investigate the antifungal activities of the EOs in the vapor phase. Gas chromatography-mass spectrometry was used to examine the chemical constituents of both EOs.Results The leaf EO extracted from C. formosensisprimarily contained monoterpene hydrocarbons, whereas the leaf EO extracted from C. obtusavar. formosanaprimarily contained monoterpene and sesquiterpene hydrocarbons. The wood EOs extracted from C. formosensisand C. obtusavar. formosanaprimarily contained sesquiterpene hydrocarbons and oxygenated sesquiterpenes. These results indicated that the wood EOs had higher antifungal activity in the liquid phase, whereas the leaf EOs had higher antifungal activity in the vapor phase.Conclusion Wood EOs extracted from C. formosensisand C. obtusavar. formosanahave strong antifungal effects against Gloeophyllum trabeum, Lenzites betulina, Trametes versicolor, and Trichodermasp. Compared with wood EOs, leaf EOs have a greater inhibitory effect on mycelial growth in the vapor phase. In both the liquid and vapor phases, the EOs extracted from C. formosensisand C. obtusavar. formosanaserve as effective antifungal agents against pathogenic fungi. Further research is required to elucidate the mechanisms underlying the antifungal activities of EOs in different phases and explore their potential applications.

Calocedrus formosanaFlorin (Cupressaceae) is an endemic tree species in Taiwan; its timber is recognized for natural decay resistance. To examine the antitermitic and antifungal activities of leaf essential oil and its main constituents, C. formosanaleaves were extracted and the essential oils analyzed by GC-MS. Bioactivity tests against the termite Coptotermes formosanusdemonstrate that the LC50value of leaf essential oil is 27.6 mg/g. Furthermore, exposure to T-muurolol caused 100% mortality at a dosage of 5 mg/g after 14 d. Leaf oil constituents displayed activity against four fungi, Lenzites betulina, Pycnoporus coccineus, Trametes versicolor, and Laetiporus sulphureus. Two compounds, α-cadinol and T-muurolol, exhibited the strongest antifungal activity. The LC50values of α-cadinol against L. sulphureus, L. betulina, and T. versicolorare 9.9, 28.6, and 30.4 μ g/ml, respectively.

Calocedrus formosanaFlorin (Cupressaceae) is an endemic tree to Taiwan. To evaluate the antioxidant activity of the plant extracts from heartwood, bark, and leaf of C. formosana, assays for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide anion scavenging activities, as well as prevention of DNA strand cleavage were performed in this study. Similar IC50values against the DPPH radical were found for the heartwood and bark extracts at approximately 23 µg/ml. Moreover, the heartwood extract exhibited the highest inhibitory activity against superoxide radicals among the test samples; a 2.3-fold lower value of IC50for superoxide radical inhibition was found in the heartwood extract relative to that of (+)-catechin. Much less effect on inhibition of DPPH and superoxide radicals was found from the leaf extract of C. formosana. More than 70% of superoxide radicals were inhibited in the presence of 10 µg/ml heartwood extract, whereas only 15% inhibition was obtained from the leaf extract. The heartwood extract, at a dose of approximately 0.5 mg/ml, apparently completely prevented the ΦX174 supercoiled DNA cleavage induced by ultraviolet photolysis of H2O2, as judged by agarose gel electrophoresis. This report also suggests that the antioxidant activities of the plant extracts of C. formosanaare in good correlation with their phenolic contents.

SummaryThe heartwood of sugi (Cryptomeria japonicaD. Don), one of the most important planted trees in Taiwan, has a pleasant yellow, yellowish red to red color. Unfortunately, its attractive appearance is susceptible to discoloration after environmental exposure. This degradation is a significant defect that decreases the value of sugi products. The objective of the present study was to evaluate the effects of environmental factors on the color of sugi yellowish heartwood. We found that the color eventually turned to brownish black in the presence of moisture. Under the combined influence of light and oxygen the color of heartwood changed from yellow to reddish blue. The effect of light wavelengths on the discoloration of sugi yellowish heartwood was also investigated. After irradiation with light of wavelengths above 600 nm, the color of sugi yellowish heartwood changed significantly from yellowish to red. Our findings show that red color enhancement, and hence the economic value of sugi yellowish heartwood, can be achieved by irradiating with light of wavelengths above 600 nm.

Antitermitic activity of Taiwania (Taiwania cryptomerioides Hayata) against Coptotermes formosanus Shiraki was demonstrated in laboratory tests. Blocks of sapwood and heartwood from T. cryptomerioides exhibited antitermitic activity. Bioassays revealed that heartwood essential oil exhibited the highest antitermitic activity, followed by sapwood essential oil and then the n-C6H14soluble fraction when tested at 10 mg/g. The order of termite mortality of three compounds purified from n-C6H14soluble extracts of heartwood was cedrol > α-cadinol > ferruginol. The termite resistance of T. cryptomerioides wood can be attributed to the termiticidal activity of cedrol and α-cadinol.

Sugi (Cryptomeria japonicaD. Don) is one of the most important planted trees in Taiwan. The normal heartwood of sugi has a red to pinkish rose color. Unfortunately, this pleasant appearance is susceptible to discoloration after environmental exposures. This discoloration is a serious defect that decreases the value of sugi products. The objective of this study was to investigate the effects of environmental factors such as moisture, oxygen, and lights of different wavelengths on the discoloration of sugi. The results show that under the combined effects of light and oxygen the color of heartwood changes from red (or rosepink) to bluish green. The color further darkens and eventually turns to black with the presence of moisture. As for the effect of light wavelengths on the discoloration of sugi heartwood, it was found that the red color was enhanced after being irradiated with light of wavelengths above 600 nm. Bothδa*andδb*values increased significantly as a result of such exposure.

The in vitroand in vivoantioxidant activities and its potential to protect against amyloid-β toxicity of essential oils from Zelkova serrata(Thunb.) Makino were investigated in the model organism Caenorhabditis elegans. The results revealed that the essential oil of Z. serrataheartwood exhibited great radical scavenging activities and high total phenolic content. In vivoassays showed significant inhibition of oxidative damage in wild-type C. elegansunder juglone-induced oxidative stress and heat shock. Based on results from both in vitroand in vivoassays, the major compound in essential oil of heartwood, (-)-(1S, 4S)-7-hydroxycalamenene (1S, 4S-7HC), may contribute significantly to the observed antioxidant activity. Further evidence showed that 1S, 4S-7HC significantly delayed the paralysis phenotype in amyloid beta-expressing transgenic C. elegans. These findings suggest that 1S, 4S-7HC from the essential oil of Z. serrataheartwood has potential as a source for antioxidant or Alzheimer's disease treatment.