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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.

Cinnamomum osmophloeum ct. cinnamaldehyde is endemic to Taiwan. It has many bioactivities and is suitable for replacing commercial cinnamons (C. zeylanicum and C. cassia) due to the high content of trans-cinnamaldehyde (CAl) with extremely low content of coumarin. To expand its application, the main bioactive compound, CAl, should be consistent. This study investigates seasonal variations in the relative content (RC) of CAl in essential oil (EO) and the total content (TC) of CAl in leaf. Qualitative and quantitative analyses of EOs obtained monthly over a year were carried out using GC–MS and GC-FID. The RC of CAl in May dropped significantly to 32.2% of those in other months (> 76.3%), an obvious seasonal variation. Meanwhile, trans-cinnamyl acetate (CAc) became the major compound (65.4%) in EO. Moreover, the RC of CAc was complementary to that of CAl over a year. This complementary relation, however, was not observed in terms of the TC in leaf since the TC of CAl + CAc in leaf did not remain constant over a year (14.3–37.7 mg/g leaf). Seasonal levels in the TC of CAl in leaf were relatively stable (17.2–23.2 mg/g) over a year except in May (10.8 mg/g leaf). These results suggest that the trans-cinnamaldehyde-rich leaves of C. osmophloeum ct. cinnamaldehyde can be stably harvested except in May. This plant species consequently would be an ideal and renewable source of commercial cinnamons.

Volatile organic compounds (VOCs) released from Chamaecyparis formosensis, Cryptomeria japonica, Cunninghamia lanceolata, Chamaecyparis obtusa var. formosana, and Taiwania cryptomerioides five major building and interior decoration timbers and their essential oil components were analyzed using GC–MS and TD/GC–MS/FID. Results showed that C. obtusa var. formosana had the highest yield of essential oil (3.42%), followed by C. formosensis (3.14%), while C. japonica had the lowest yield (0.95%). Moreover, oxygenated sesquiterpene was the highest relative content in all five essential oils and their main constituents were trans-myrtanol (18.04%), 1-epi-cubenol (15.99%), cedrol (62.26%), α-cadinol (26.42%), and α-cadinol (27.98%), respectively. In terms of emission quantity of top VOC, the results showed the decreasing order of C. formosensis (myrtenal, 74.21 mg/m2) > T. cryptomerioides (thujopsene, 12.00 mg/m2) > C. lanceolata (α-cedrene, 10.27 mg/m2) > C. obtusa var. formosana (α-pinene, 8.05 mg/m2) > C. japonica (α-cedrene, 4.25 mg/m2). C. formosensis had a greater amount of VOCs emitted and hence gave off more fragrance than C. obtusa var. formosana initially. However, after indoor exposure of 24 weeks, the VOC emission quantity of C. obtusa var. formosana exceeded that of C. formosensis. α-Cedrene and thujopsene were the top two major VOCs of both C. lanceolata and T. cryptomerioides. However, they both showed a trend of decrease in emission with prolonged exposure. All five plantation timbers showed good antifungal, antimicrobial, antibacterial, and antitermitic properties, making them ideal materials for interior decoration. Not only do they have strong bioactivities, they can also provide a fragrant and healthy living environment.

The thermal degradation of linalool-chemotype Cinnamomum osmophloeum leaf essential oil and the stability effect of microencapsulation of leaf essential oil with &beta, cyclodextrin were studied. After thermal degradation of linalool-chemotype leaf essential oil, degraded compounds including &beta, myrcene, cis-ocimene and trans-ocimene, were formed through the dehydroxylation of linalool, and ene cyclization also occurs to linalool and its dehydroxylated products to form the compounds such as limonene, terpinolene and &alpha, terpinene. The optimal microencapsulation conditions of leaf essential oil microcapsules were at a leaf essential oil to the &beta, cyclodextrin ratio of 15:85 and with a solvent ratio (ethanol to water) of 1:5. The maximum yield of leaf essential oil microencapsulated with &beta, cyclodextrin was 96.5%. According to results from the accelerated dry-heat aging test, &beta, cyclodextrin was fairly stable at 105 &deg, C, and microencapsulation with &beta, cyclodextrin can efficiently slow down the emission of linalool-chemotype C. osmophloeum leaf essential oil.

The thermal degradation of linalool-chemotype Cinnamomum osmophloeum leaf essential oil and the stability effect of microencapsulation of leaf essential oil with β-cyclodextrin were studied. After thermal degradation of linalool-chemotype leaf essential oil, degraded compounds including β-myrcene, cis-ocimene and trans-ocimene, were formed through the dehydroxylation of linalool; and ene cyclization also occurs to linalool and its dehydroxylated products to form the compounds such as limonene, terpinolene and α-terpinene. The optimal microencapsulation conditions of leaf essential oil microcapsules were at a leaf essential oil to the β-cyclodextrin ratio of 15:85 and with a solvent ratio (ethanol to water) of 1:5. The maximum yield of leaf essential oil microencapsulated with β-cyclodextrin was 96.5%. According to results from the accelerated dry-heat aging test, β-cyclodextrin was fairly stable at 105 °C, and microencapsulation with β-cyclodextrin can efficiently slow down the emission of linalool-chemotype C. osmophloeum leaf essential oil.

Cinnamomum osmophloeum ct. linalool is one chemotype of indigenous cinnamon in Taiwan. Its leaf essential oil (LEO) and main component S-(+)-linalool both possess great anxiolytic activities. The aim of this study was to establish ultrasound-assisted microextraction (UAME) for extracting LEO from C. osmophloeum ct. linalool. The absolute content of S-(+)-linalool and chemical composition of LEO were analyzed using GC-MS and GC-FID. To obtain the optimal conditions for UAME, four parameters (ultrasonic extraction duration, power of ultrasound, times of extraction, and leaf weight of extraction) were investigated according to the S-(+)-linalool content extracted. Results showed that the optimal condition was 10 mg of leaf extracted using n-hexane in an ultrasonicator with ultrasonic power of 80 W for 1 min. Furthermore, the absolute content of S-(+)-linalool obtained by UAME (28.3 ± 0.5 mg/g leaf) was comparable with that extracted by the 30-min hydrodistillation (HD) (26.9 ± 2.7 mg/g leaf). UAME was then employed to extract S-(+)-linalool from leaves at different stages of maturity (young, semi-mature, and mature). Results indicated that only mature leaf contains large amounts of S-(+)-linalool. Of note is that the LEO extracted by UAME contains coumarin, while that extracted by HD does not. Coumarin is an important ingredient in a number of cosmetic products due to its odor-fixing properties. With UAME, the leaf of C. osmophloeum ct. linalool has potential to be used as an aromatic material for further applications. In conclusion, UAME established in the present study provides a simple and rapid method for the determination of S-(+)-linalool and chemical composition of LEO from C. osmophloeum ct. linalool.

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

Research on biogenic volatile organic compounds (BVOCs) emitted from trees is essential in the world since these BVOCs play an important role in the atmospheric process which may further influence on the air quality. However, little is known about BVOCs emitted from trees in the field in Taiwan. Hence, this study intends to establish an enclosure technique coupled with in situ sampling to facilitate the collection of BVOCs emitted from Cryptomeria japonica leaves. Furthermore, the emission model derived from the relationship between emission rate and temperature was applied to estimate the emission of BVOCs in the field. Results from GC–MS showed that the BVOCs emitted from intact leaves contain 14 monoterpenoids and 4 sesquiterpenoid. The emission rate of the major constituent, sabinene, was 0.42 μg h−1 g−1 around noon on September 11, 2013. Sabinene varies with the changing temperature inside the bag. These findings indicated that the enclosure technique can collect the BVOCs emitted from intact leaves and monitor the dynamic changes in emission. Two determinants, basal emission rate (at 30 °C) and β coefficient, of sabinene were further measured, and they were 1.29 μg h−1 g−1 and 0.18 °C−1, respectively. By using these two determinants and data of meteorology and forest resource, the emission of monoterpenes from C. japonica stand was estimated to be 1.13 mg m−2 h−1 in July in Xitou area. Taken together, the results provide valuable information for estimation of BVOCs from tree species in Taiwan for the first time.

The xanthine oxidase inhibitory activity and thermostability of Cinnamomum osmophloeum leaf oil microencapsulated with β-cyclodextrin were evaluated in this study. The yield of leaf oil microcapsules was 86.3% using the optimal reaction conditions at the leaf oil to β-cyclodextrin ratio of 15:85 and ethanol to water ratio ranging from 1:3 to 1:5. Based on the FTIR analysis, the characteristic absorption bands of major constituent, trans-cinnamaldehyde, were confirmed in the spectra of leaf oil microcapsules. According to the dry-heat aging test, β-cyclodextrin was thermostable under the high temperature conditions, and it was beneficial to reduce the emission of C. osmophloeum leaf oil. Leaf oil microcapsules exhibited high xanthine oxidase inhibitory activity, with an IC50 value of 83.3 µg/mL. It is concluded that the lifetime of C. osmophloeum leaf oil can be effectively improved by microencapsulation, and leaf oil microcapsules possess superior xanthine oxidase inhibitory activity.

Cinnamomum kanehirae Hayata is an endemic tree species in Taiwan. Leaf essential oils from 26 sources of C. kanehirae were obtained by hydrodistillation and their chemical constituents were analyzed by gas chromatography-mass spectrometry (GC-MS). Fifty-eight compounds were identified from C. kanehirae leaf essential oils. The main constituents in leaf essential oils were linalool, 1,8-cineole, β-selinene, 1-hexadecyne, and α-cadinol. According to the chemical compositions of leaf essential oils and their relative contents obtained from GC-MS analyses, cluster analysis, and principal component analysis, the 26 sources examined were classified into five chemotypes: linalool type, linalool/1,8-cineole type, 1,8-cineole type, linalool/α-cadinol type, and mixed type. The biochemical correlations between the major constituents of C. kanehirae were examined and their relationship is discussed.

This study aimed to develop a rapid and accurate analytical method for discriminating three Chamaecyparis species (C. formosensis, C. obtusa, and C. obtusa var. formosana) that could not be easily distinguished by volatile compounds. A total of 23 leaf samples from three species were analyzed by static-headspace (static-HS) coupled with gas chromatography-mass spectrometry (GC-MS). The static-HS procedure, whose experimental parameters were properly optimized, yielded a high Pearson correlation-based similarity between essential oil and VOC composition (r = 0.555-0.999). Thirty-six major constituents were identified; along with the results of cluster analysis (CA), a large variation in contents among the three different species was observed. Principal component analysis (PCA) methods illustrated graphically the relationships between characteristic components and tree species. It was clearly demonstrated that the static-HS-based procedure enhanced greatly the speed of precise analysis of chemical fingerprint in small sample amounts, thus providing a fast and reliable tool for the prediction of constituent characteristics in essential oil, and also offering good opportunities for studying the role of these feature compounds in chemotaxonomy or ecophysiology.

BACKGROUND Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), is a major urban pests in many countries throughout the world. In an attempt to find natural products that could be employed in the effective and environmentally friendly control of the termite, this study investigates, for the first time, the insecticidal activities of the wood and leaf essential oils and ethanolic extracts from Cunninghamia konishii Hayata against C. formosanus according to direct contact application. RESULTS Wood and leaf essential oils and wood ethanolic extract showed the excellent antitermitic activities. Among the four fractions of wood ethanolic extract, the hexane-soluble fraction showed the strongest antitermitic activities. In addition, β-elemol and α-cadinol showed excellent inhibitory action against C. formosanus. CONCLUSION The results clearly reveal that the wood and leaf essential oils and ethanolic extract from C. konishii, and their effective constituents, served as potential, eco-friendly termite-control agents. © 2013 Society of Chemical Industry

The aims of the present study were to isolate and identify the antifungal compounds from the ethanolic extract of Cunninghamia konishii wood and to evaluate their antifungal activities against wood decay fungi. The results showed that the n-Hex soluble fraction of the ethanolic extract from C. konishii wood had an excellent inhibitory effect against Lenzites betulina, Trametes versicolor, Laetiporus sulphureus, and Gloeophyllum trabeum, with IC(50) values of 33, 46, 62, and 49 μg/mL, respectively. By following the bioactivity-guided fractionation procedure, four sesquiterpenes, T-cadinol, cedrol, T-muurolol, and (-)-epi-cedrol, and three diterpenes, 13-epi-manool, cis-abienol, and isoabienol, were identified from the active subfractions. Among the main constituents of the ethanolic extract from C. konishii, T-cadinol, cedrol, and T-muurolol efficiently inhibited the growth of four wood-rot fungi at the concentration of 100 μg/mL, with antifungal indices of 51.4-100.0%, 68.3-100.0%, and 39.5-100.0%, respectively. Results of this study show that the ethanolic extract of C. konishii wood may be considered as a potent source of T-cadinol, cedrol, and T-muurolol as new natural antifungal agents.

In this study antifungal activities of essential oils from wood and leaf and their constituents of Cunninghamia konishii against four wood decay fungi and six plant pathogenic fungi were investigated. GC and GC-MS analyses show that the major compounds of wood essential oil were cedrol and α-pinene, while those of leaf essential oil were α-pinene and p-cymene. Antifungal tests demonstrated the wood oil from C. konishii used against Trametes versicolor, Lenzites betulina, Laetiporus sulphureus, and Gloeophyllum trabeum and leaf oil from C. konishii used against L. sulphureus had strong antifungal activities. Moreover, wood oil used against Rhizoctonia solani, Fusarium solani, Pestalotiopsis funereal, and Ganoderma australe also had strong antifungal activities. Among the seven constituents of wood oil, cedrol displayed the best antifungal properties, indicating that it may be used as potential antifungal agents for the control of fungal diseases in plants.

Cinnamomum osmophloeum Kaneh. (Lauraceae) is one of the indigenous tree species in Taiwan. This tree species has been of interest to researchers because the chemical constituents of its essential oil are similar to those of Cinnamomum cassia Presl. bark oil, known as cinnamon oil, which is commonly used in foods and beverages.The anti-inflammatory activities of the leaf essential oils and their major compounds from seven provenances of C. osmophloeum are investigated here for the first time.Chemical compositions of hydrodistilled essential oils obtained from C. osmophloeum leaves were analyzed by gas chromatography-mass spectrometry (GC-MS), and the effects of essential oils on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages were investigated.The leaf essential oils of cinnamaldehyde type and mixed type strongly inhibited NO production, with IC(50) values ranging from 9.7-15.5 μg/mL. Furthermore, trans-cinnamaldehyde is responsible for the inhibitory activity of cinnamaldehyde type, and T-cadinol and α-cadinol are responsible for the inhibitory activity of mixed type.These findings demonstrate that the leaf essential oils and their constituents of C. osmophloeum have excellent anti-inflammatory activities and thus have great potential as a source for natural health products.

BACKGROUND: The current study investigates, for the first time, the mosquito larvicidal activities of leaf and twig essential oils from Clausena excavata Burm. f. and their individual constituents against Aedes aegypti L. and Aedes albopictus Skuse larvae. The yields of essential oils obtained from hydrodistillation were compared, and their constituents were determined by GC-MS analyses. RESULTS: The LC50 values of leaf and twig essential oils against fourth-instar larvae of Ae. aegypti and Ae. albopictus were 37.1–40.1 µg mL−1 and 41.1–41.2 µg mL−1 respectively. This study demonstrated that C. excavata leaf and twig essential oils possess mosquito larvicidal activity, inhibiting the growth of mosquito larvae for both species at a low concentration. In addition, results of larvicidal assays showed that the effective constituents in leaf and twig essential oils were limonene, γ-terpinene, terpinolene, β-myrcene, 3-carene and p-cymene. The LC50 values of these constituents against both mosquito larvae were below 50 µg mL−1. Among these effective constituents, limonene had the best mosquito larvicidal activity, with LC50 of 19.4 µg mL−1 and 15.0 µg mL−1 against Ae. aegypti and Ae. albopictus larvae respectively. CONCLUSION: The findings suggested that the essential oils from Clausena excavata leaf and twig and their effective constituents may be explored as a potential natural larvicide. Copyright © 2008 Society of Chemical Industry

Eleven compounds from indigenous cinnamon (Cinnamomum osmophloeum) leaf essential oil were identified by GC-MS and the dominant constituent was trans-cinnamaldehyde (79.85%). The toxicity of leaf essential oil and trans-cinnamaldehyde were then determined to study their effectiveness in controlling the red imported fire ant, Solenopsis invicta Buren. The results of the toxicity tests indicated that both the indigenous cinnamon leaf essential oil and trans-cinnamaldehyde had an excellent inhibitory effect in controlling the red imported fire ant. The LT(50) values for both 2% leaf essential oil and 2% trans-cinnamaldehyde after open exposure were 105.0min and 32.2min; after close exposure were 18.5min and 21.2min, respectively.

Cinnamomum kanehirae Hayata is an endemic tree species in Taiwan. Leaf essential oils from 26 sources of C. kanehirae were obtained by hydrodistillation and their chemical constituents were analyzed by gas chromatography-mass spectrometry (GC-MS). Fifty-eight compounds were identified from C. kanehirae leaf essential oils. The main constituents in leaf essential oils were linalool, 1,8-cineole, β-selinene, 1-hexadecyne, and α-cadinol. According to the chemical compositions of leaf essential oils and their relative contents obtained from GC-MS analyses, cluster analysis, and principal component analysis, the 26 sources examined were classified into five chemotypes: linalool type, linalool/1,8-cineole type, 1,8-cineole type, linalool/α-cadinol type, and mixed type. The biochemical correlations between the major constituents of C. kanehirae were examined and their relationship is discussed.

The essential oils from leaves of Taiwan's indigenous cinnamon (Cinnamomum osmophloeum ct. cinnamaldehyde) have similar constituents as compared to that from commercial bark cinnamons. This indigenous cinnamon has been proven to have excellent bioactivities. To understand whether this indigenous cinnamon contains a high level of the hepatotoxic compound, coumarin, as often seen in Cassia cinnamons, current research focused on determining the coumarin content in this indigenous cinnamon and screening the low-coumarin clones. The results demonstrated that the coumarin contents in all tested indigenous cinnamon clones were much lower than that found in Cassia cinnamons. In addition, this indigenous cinnamon contains about 80% (w/w) of cinnamaldehyde and 0.4-2.7% (w/w) of eugenol in its leaf essential oils. This combination could provide this indigenous cinnamon a better shelf life compared to that of regular commercial cinnamons. These results suggested that leaves of this indigenous cinnamon could be a potential resource for a safer cinnamon substitute.

Barringtonia racemosa is a nocturnal flowering plant. Information on its floral volatiles and the dynamic emission profiles was very limited. In this study, the floral volatiles of B. racemosa were monitored hourly during its florescence via detached and in situ collection for the first time. The dynamic odor activity value (OAV) was calculated to elucidate the active aroma components of floral scent. Results of compositional analyses showed that the predominant floral volatiles were linalool and phenylacetaldehyde. Their emission started around 8:00 p.m., and the peak emissions were 20541 and 18234 ng h(-1) flower(-1), respectively, during 10:00 p.m.-2:00 a.m. Results from dynamic OAV profiling revealed that linalool (409 min(-1)) and phenylacetaldehyde (547 min(-1)) had higher OAVs than other components (10 min(-1)), indicating that linalool and phenylacetaldehyde contributed mainly to the floral scent with a strong, sweet, and pleasant aroma.

Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), is a major urban pests in many countries throughout the world. In an attempt to find natural products that could be employed in the effective and environmentally friendly control of the termite, this study investigates, for the first time, the insecticidal activities of the wood and leaf essential oils and ethanolic extracts from Cunninghamia konishii Hayata against C. formosanus according to direct contact application.Wood and leaf essential oils and wood ethanolic extract showed the excellent antitermitic activities. Among the four fractions of wood ethanolic extract, the hexane-soluble fraction showed the strongest antitermitic activities. In addition, β-elemol and α-cadinol showed excellent inhibitory action against C. formosanus.The results clearly reveal that the wood and leaf essential oils and ethanolic extract from C. konishii, and their effective constituents, served as potential, eco-friendly termite-control agents.

Cinnamomum osmophloeum ct. linalool is one of the chemotypes of the indigenous cinnamon in Taiwan. In this study, hydrodistillation was used for extracting the essential oils (EOs) of C. osmophloeum ct. linalool leaves collected from various plants and seasons, and GC-MS and GC-FID were used to examine variations and contents of the chemical composition in EOs. Moreover, the absolute configuration of the main constituent and its EO content were illustrated by GC-FID with a chiral column. In addition, we also investigated the effect of the extraction time (1, 2, 6, and 10 h) on the yield of EO and the contents of the main constituents. Results from this study revealed that the average EO yield of 12 plants was 3.7%, and linalool accounted for more than 90%. The linalool in the EO was proved to be pure S-(+)-linalool, and its content in the leaves ranged from 28.8 ± 0.3 to 35.1 ± 0.2 mg/g. Furthermore, there were no obvious differences in EO yield and S-(+)-linalool content from various plants and seasons. On the other hand, we also demonstrated that EO and S-(+)-linalool from C. osmophloeum ct. linalool leaves can be completely extracted out by 1 h of hydrodistillation.

Cryptomeria japonica D. Don, called 'sugi' in Japanese, is an abundant and renewable potential resource of valuable natural products that may serve as natural biocides in Taiwan. Hydrodistillation (HD) and steam distillation (SD) were used for extracting the essential oils from C. japonica leaves in this study. The chemical constituents of the two leaf essential oils were identified by GC/MS analysis, and their antitermitic activities were evaluated. The results from the antitermitic tests against Coptotermes formosanus Shiraki showed that the leaf essential oils extracted by HD and SD had excellent antitermitic activities, with LD(50) values of 1.57 and 1.72 mg/g after 7 d of testing, respectively. Comparison of the chemical composition of the two leaf essential oils revealed that oxygenated diterpenes (kaur-16-ene) and oxygenated sesquiterpenes (β-elemol) were the dominant constituents. In addition, 13 constituents isolated from the C. japonica leaf essential oils were tested individually against C. formosanus. Among these constituents, β-elemol and α-terpineol achieved 100% termite mortality at the dosage of 1 mg/g after 7 d of testing. These results demonstrated that both C. japonica leaf essential oils as well as β-elemol and α-terpineol possessed commendable antitermitic activity.

This study examined the influence of heating temperature and duration on volatile aromatic components of spring and winter Phyllostachys pubescens shoots using SPME. Results from GC-MS analyses revealed that the main constituents in both bamboo shoots at ambient temperature include methoxy-phenyl oxime, followed by n-hexanol and 3Z-hexenal, which gives a fresh green aroma. Comparing the different compounds, between spring and winter shoots, revealed that spring bamboo shoots at ambient temperature comprise 12.30% methyl salicylate, which provides protection against insect attack, and 9.71% epi-cedrol; while winter bamboo shoots comprise 17.00% 1-octen-3-ol, which produces a distinct mushroom aroma. After heating at 100 °C for 60 min, a marked increase in relative content of benzyl salicylate (43.30%) and a significant decrease in methyl salicylate content in spring bamboo shoots were observed; while the major compound in winter bamboo shoots was n-heneicosane (78.09%) and the content of specific 1-octen-3-ol significantly decreased.

Three Chamaecyparis species (C. formosensis, C. obtusa, and C. obtusa var. formosana) are difficult to distinguish by the naked eye. Therefore, from the chemotaxonomic point of view, it would be valuable to find a simple and rapid method to differentiate these three Chamaecyparis species. In this study, the chemical compositions of biogenic volatile organic compounds (BVOCs) from mature leaves were analyzed using solid-phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS). Then cluster analysis (CA) and principal component analysis (PCA) were conducted for the BVOC constituents to reveal the differences among these three species. Results from SPME-GC/MS showed that the compositions of BVOCs from the three species were distinctly different. Moreover, these species were clearly differentiated according to the results of CA and PCA. In conclusion, the findings of this study suggest that SPME-GC/MS coupled with CA and PCA is a feasible and rapid technique to differentiate Chamaecyparis species with similar morphological characteristics.

The species differentiation between Chamaecyparis formosensis, C. obtusa var. formosana, and C. obtusa, based on the composition of the leaf essential oils, was studied. The characterization of the oils by GC-FID and GC/MS analyses showed remarkable differences between these three essential oils. Cluster analysis (CA) and principal-component analysis (PCA) distinguished three groups of essential oils. The C. formosensis oil was dominated by α-pinene while those isolated from C. obtusa var. formosana and C. obtusa were characterized by high levels of (-)-thujopsene and α-terpinyl acetate, respectively. Moreover, the phylogenetic relationships of the genus Chamaecyparis were in agreement with previous findings based on morphological and molecular evidence. In addition, the essential oils from C. obtusa var. formosana could be classified into three chemical types, according to their different characteristic main compounds (β-elemol, (-)-thujopsene, and cis-thujopsenal). The biochemical correlations between the major constituents of the Chamaecyparis species were examined and their relationship is discussed.

The purpose of this study was to investigate the repellent activities of essential oils from Cryptomeria japonica (sugi) against adults of mosquitoes Aedes aegypti and Aedes albopictus . Comparison of essential oils from four different plant parts of C. japonica revealed that essential oil from its leaf exhibited the best repellent activity against mosquitoes. To understand the relationship between volatile organic compounds and repellent activity, the solid-phase microextraction (SPME) method was employed to analyze volatile organic compounds of leaf essential oil. The SPME fiber was coated with divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS). The major volatile organic compounds in the cage were 3-carene, alpha-terpinene, limonene, gamma-terpinene, and terpinolene at 0 min. Results demonstrated that (-)-terpinen-4-ol was the major volatile organic compound adsorbed by SPME fiber during repellent assays. Furthermore, the repellent activities of six compounds against adults of the mosquitoes were evaluated, and the results revealed that (-)-terpinen-4-ol exhibited the best repellent activity against A. aegypti and A. albopictus.