Antioxidant activities and phytochemical study of leaf extracts from 18 indigenous tree species in taiwan.

The objective of this study is to assess antioxidant activities of methanolic extracts from the leaves of 18 indigenous tree species in Taiwan. Results revealed that, among 18 species, Acer oliverianum exhibited the best free radical scavenging activities. The IC(50) values were 5.8 and 11.8 µg/mL on DPPH radical and superoxide radical scavenging activities, respectively. In addition, A. oliverianum also exhibited the strongest ferrous ion chelating activity. Based on a bioactivity-guided isolation principle, the resulting methanolic crude extracts of A. oliverianum leaves were fractionated to yield soluble fractions of hexane, EtOAc, BuOH, and water. Of these, the EtOAc fraction had the best antioxidant activity. Furthermore, 8 specific phytochemicals were isolated and identified from the EtOAc fraction. Among them, 1,2,3,4,6-O-penta-galloyl-ß-D-glucopyranose had the best free radical scavenging activity. These results demonstrate that methanolic extracts and their derived phytochemicals of A. oliverianum leaves have excellent antioxidant activities and thus they have great potential as sources for natural health products.

Chemical composition and antitermitic activity against Coptotermes formosanus Shiraki of Cryptomeria japonica leaf essential oil.

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 (ß-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, ß-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 ß-elemol and α-terpineol possessed commendable antitermitic activity.

Characteristic Properties of a Bamboo-Based Board Combined with Bamboo Veneers and Vacuum Heat-Treated Round Bamboo Sticks.

In this study, a bamboo stick board with rotary-cut bamboo veneers was successfully fabricated. Additionally, vacuum heat (VH) treatment, which is a popular thermal modification method, was used to modify bamboo sticks. Therefore, the effects of different VH treatment temperatures on the dimensional stability and flexural properties of bamboo stick boards with and without bamboo veneers were investigated. For all boards, as the temperature increased to 220 °C, the thickness change rate and equilibrium moisture content decreased, and the flexural properties increased. The results exhibited that VH treatment improved the dimensional stability and flexural properties of the boards. Furthermore, the board with veneers had lower flexural properties and higher thickness swelling after water absorption than the board without veneers (BSB). The results indicated that bamboo veneer caused low flexural properties and high thickness swelling of the board compared to the BSB. However, the bamboo veneer played an aesthetic role in the appearance of the bamboo stick board.

Insecticidal activities of Cunninghamia konishii Hayata against Formosan subterranean termite, Coptotermes formosanus (Isoptera: Rhinotermitidae).

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, ß-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.

Profiling of volatile compounds of Phyllostachys pubescens shoots in Taiwan.

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.

Phytochemicals from Cunninghamia konishii Hayata act as antifungal agents.

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.