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Chamaecyparis formosensis (Cupressaceae) is among the most precious endemic conifers in Taiwan. Field study was conducted on seasonal variations in emission rates and compositions of terpenoids from this tree species of two different ages. A total of 21 terpenoids were detected, of which there were 13 monoterpenoids (MTs), 4 sesquiterpenoids (STs), and 4 diterpenoids (DTs). MTs dominated the emissions in both saplings and adult trees and produced more than 80% of terpene emissions. Contrasting seasonal pattern between saplings and adult trees was found. Total actual emissions from saplings were higher in cold seasons (range, 64.40 ± 13.18 to 140.74 ± 18.90 ng g−1 h−1) than in warm seasons (range, 55.63 ± 15.84 to 63.48 ± 11.85 ng g−1 h−1). Photosynthetically active radiation (PAR) was found to be the most important factor affecting terpene emissions from saplings. On the contrary, higher emissions were found in warm seasons for adult trees (range, 101.49 ± 12.29 to 181.35 ± 80.15 ng g−1 h−1), and the emissions were mainly in response to temperature. Some compounds in C. formosensis of both ages (e.g., β-myrcene, α-terpinene, trans -β-ocimene, terpinen-4-ol, α-cedrene and trans -β-farnesene) showed comparably higher contents in cold seasons. Results presented here provide important fundamental information for better understanding of forest bathing and estimating air quality in Taiwan. Image 1 • BVOCs emitted from Chamaecyparis formosensis were measured over seasons in situ. • An opposite emission pattern was found between saplings and adult trees. • Monoterpenoids with less volatility showed variations in different seasons. • PAR and temperature play critical roles in BVOC emission of this tree species. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Seasonal variation of leaf oils of C. osmophloeum was clearly observed in May. • Cinnamaldehyde and cinnamyl acetate have a complementary relation in leaf oils. • The content of cinnamaldehyde in leaf is high and stable over a year except in May. • For a high quality of leaf, it can be harvested anytime over a year except in May. • C. osmophloeum leaf is a renewable and eco-friendly source of commercial cinnamons. Abstract 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. [ABSTRACT FROM AUTHOR]

Chamaecyparis formosensis Matsumura and C. obtusa var. formosana (Hayata) Rehder are important, precious, and well-known species grown in Asia. Renowned for excellent natural durability, their wood logs are regularly used as quality building materials or furniture. However, these two species have similar appearances, e.g., leaf, twig, wood, hardly distinguishable by the naked eye. The purpose of the present study is to phytochemically differentiate these two species using volatile compounds from the woods. Wood essential oils were obtained by 6-h hydrodistillation. The chemical composition was identified by GC-MS, and semi-quantification was carried out to determine the content of each compound. Furthermore, compounds with a significantly higher content than those of the other species were screened by t -test and principal component analysis (PCA). Results from semi-quantification and t -test showed that C. formosensis contained higher content of cis -myrtanol (ratio 37.1 ± 19.8), chamaecynone (11.0 ± 6.7), and α-eudesmol (8.5 ± 7.9), while C. obtusa var. formosana comprised mainly of α-terpineol (30.2 ± 10.1) and borneol (24.0 ± 16.1). Moreover, PCA results showed that the representative compounds of C. formosensis were cis -myrtanol and chamaecynone, while those of C. obtusa var. formosana were α-terpineol, borneol, and α-cadinol. Taken together, the above-mentioned results suggested significant compositional differences between these two species. For distinguishing the two kinds of wood, C. formosensis should be easily identified by its two characteristic compounds: cis -myrtanol and chamaecynone; while C. obtusa var. formosana could also be distinguished by its characteristic compounds: α-terpineol and borneol. [Display omitted] • Chemical compositions of wood essential oils of the two species are differentiated. • C. formosensis and C. obtusa var. formosana have their own characteristic compounds. • The two species can be distinguished from each other using indicator compounds. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: 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 60min, 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. [Copyright &y& Elsevier]

Abstract: 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 LT50 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. [Copyright &y& Elsevier]