Yu-Chang Su

Antifungal activity of essential oil and its constituents from Calocedrus macrolepis var. formosana Florin leaf against plant pathogenic fungi.

Resistance to conventional fungicides causes the poor disease control of agriculture. Natural products from plants have great potential as novel fungicide sources for controlling pathogenic fungi. In this study antipathogenic activity of the leaf essential oil and its constituents from Calocedrus macrolepis var. formosana Florin were evaluated in vitro against six plant pathogenic fungi. Chemical analysis of leaf oil by GC/MS allowed identification of alpha-pinene (44.2%), limonene (21.6%), beta-myrcene (8.9%), beta-caryophyllene (8.2%), caryophyllene oxide (2.4%), alpha-cadinol (1.6%), beta-pinene (1.2%), and T-muurolol (1.1%) as main components. Sesquiterpenoid components of the oil were more effective than monoterpenoid components of the oil. In particular, T-muurolol and alpha-cadinol strongly inhibited the growth of Rhizoctonia solani and Fusarium oxysporum, with the IC(50) values < 50 microg ml(-1). These compounds also efficiently inhibited the mycelial growths of Colletotrichum gloeosporioides, P. funerea, Ganoderma australe and F. solani. These results showed that T-muurolol and alpha-cadinol possess antifungal activities against a broad spectrum of tested plant pathogenic fungi and could be used as potential antifungal agents for the control of fungal diseases in plants.

Antifungal compounds in the ethyl acetate soluble fraction of the extractives of Taiwania (Taiwania cryptomerioides Hayata) heartwood

Summary This study was to isolate and identify the antifungal compounds in the ethyl acetate soluble fraction of the methanol extractives of Taiwania (Taiwania cryptomerioides Hayata) heartwood and to examine their antifungal activity. Five compounds were obtained by open column chromatography and HPLC and based upon the results from Mass, 1H-NMR, and 13C-NMR analyses. Their structures were identified, namely ferruginol, helioxanthin, savinin, taiwanin C, and hinokiol. According to the results of antifungal test, the order of antifungal index of these compounds for Coriolus versicolor (L. ex Fr.) Quel. was ferruginol > taiwanin C > savinin > hinokiol. For Laetiporus sulphureus (B. ex Fr.) Bond. it was taiwanin C > savinin > ferruginol > hinokiol.

Antifungal Activities and Chemical Compositions of Essential Oils from Leaves of Four Eucalypts

Essential oils from the leaves of 4 eucalypts species, i.e., Eucalyptus urophylla, E. grandis, E. camaldulensis, and E. citriodora, were extracted by hydrodistillation. Compositions of the essential oils were analyzed and identified. Their biological activities with respect to antifungal activity were examined. Yields of the essential oils in descending order were E. camaldulensis (3.48 mL 100 gm^(-1)), E. urophylla (3.14 mL 100 gm^(-1)), E. grandis (3.01 mL 100 gm^(-1)), and E. citriodora (1.89 mL 100 g^(-1)). Components of individual essential oils identified that 51 compounds were present in E. urophylla, with γ-terpinene predominant: E. grandis had 65 identified compounds with 1, 8-cineole being the richest fraction; there were 62 compounds identified from the essential oil of E. camaldulensis with 1, 8-cineole as the main component; and for E. citriodora, 35 compounds were identified with citrionellal as the dominant components. Anti-mildew tests of the 4 eucalypt essential oils indicated that E. citriodora had the best efficacy, and was extensively effective against all tested mildew species. E. urophylla, on the other hand, had the poorest efficacy. On the wood decay fungus tests, the same was observed for E. citriodora essential oil, and this indicated that it might be an excellent choice as a wood preservative. The main reason for its effectiveness was the presence of citronellal and citronellal which had obvious benefits in fighting mildew and fungi.

Chemical composition and potential for utilization of the marine alga Rhizoclonium sp.

This paper reports on the feasibility of utilizing the abundant marine alga Rhizoclonium as a substitute for wood fiber, based on studies on its morphology and chemical composition. The alga appears as wood fiber-like filaments consisting of tubular end-to-end connections of individual cells. In the population studied, each cell averaged 82 μm long, 76 μm wide and had cell wall 7.4 μm thick. The composition was 15.9% ash, 9.72% extractable by 90% acetone, 9.43% extractable by alcohol-benzene, 3.8% acid insoluble fraction, 17.8% pentosan, 36.3% 1% NaOH soluble fraction and 57.4% carbohydrate. The composition of its carbohydrates is similar to that of wood fiber. After hydrolysis, reduction, and acetylation of the sugars, and GC-MS analysis the components showed glucose (65.8%), xylose (19.8%), galactose (12.5%) and mannose (1.3%). There were high contents of cold- and hot-water extractables, 31.1% and 34.6%, respectively. These consisted of xylose, galactose and glucose. The crystallinity index (CI%) of its holocellulose was as high as 86.5%, close to the 90.5% value of wood fiber. The 1091 cm-1 peak intensity increased with reaction cycles, suggesting decreasing absorptivity and increasing crystallinity. This corresponds to terrestrial plant fibers. Taken together, these features suggest that Rhizoclonium has good potential as a raw material for pulp.

Chemical constituents and mechanisms of discoloration of taiwania (Taiwania cryptomerioides Hayata) heartwood. I. The structure reconfirmation and conversion mechanism of taiwanin A.

Summary One of the color substances, taiwanin A, was isolated from Taiwania (Taiwania cryptomerioides Hayata) heartwood. According to the 13C-NMR, 1H-NMR, HSQC, HMBC, and NOE difference spectroscopy analyses, the diene structure of taiwanin A was reconfirmed to be the trans-trans formulation. In addition, it was proven that deep orange crystalline taiwanin A changed to white and pale yellow compounds, taiwanin C and taiwanin E, after light irradiation. The conversion mechanism of taiwanin A into taiwanin C and taiwanin E is also proposed and discussed in this study.

Composition and Bioactivities of the Leaf Essential Oils of Cinnamomum subavenium Miq. from Taiwan

Abstract Leaves of Cinnamomum subavenium Miq. were collected from two sites in Taiwan. Leaf essential oils of C. sub-avenium were isolated using hydrodistillation and headspace-GC methods to determine their composition and yield. Antioxidant and antimicrobial activities of various oils obtained were also evaluated. Forty-four and 88 compounds were identified in the leaf oils obtained. Whereas 26 and 65 compounds were identified by headspace-GC method, respectively. The main headspace components were comparable to those of the oil. The main components of one of the oils were methyl eugenol (75.9%), linalool (7.3%), and eugenol (6.6%); while those from the other oil were p-cymene (21.6%), 1,8-cineole (16.5%), and linalool (11.9%). Both leaf oils had excellent antioxidant and antimicrobial activities.

Aquacultural characteristics of Rhizoclonium riparium and an evaluation of its biomass growth potential

A study was made of environmental factors affecting the growth of Rhizoclonium riparium in order to evaluate its suitability for large-scale culturing. The results indicate that under the natural conditions prevailing at Taishi, Taiwan, this species can grow year-round, with a monthly biomass production (oven-dried) of 945–1540 kg ha−1 pond surface (assuming a pond depth of 1 m). The specific growth rate ranged from –2.1 to 10.4% per day. Salinity and temperature, both influenced the rate significantly, with optimal values at 20% and 25 °C, respectively. Short (2-mm) lengths of filaments had a higher specific growth rate than longer (20 mm) filaments. Under rotational culturing conditions, the specific growth rate was reduced when flow was increased.

Feasibility of utilizing Rhizoclonium in pulping and papermaking

Material of Rhizoclonium from brackish water in Taiwan was investigated for its possible use in pulping and papermaking. After beating, this filamentous alga produced a pulp with a length to width ratio of about 10, much less than that of a typical wood pulp. Handsheets made from this pulp had a moderate breaking length of 4.02 km. Cooking pre-beaten pulp with a low chemical charge (5–25%NaOH) at a low cooking temperature (100 °C), and for a short time (30–120 min) gave high algal pulp yields (70–80%). This cooking process was sulfur-free, but the water requirement was high. After cooking and further caustic soda and bleaching treatments, wide-angle X-ray diffraction and FTIR spectroscopy showed that the crystallinity of the algal pulp increased substantially, but type I cellulose conformation was retained. The best pulp mechanical strengths (breaking length 5.23 km,zero-span tensile strength 79.2 Nm g-1, bursting index of 2.2 kpa m2 g-1) were obtained after cooking for 1 h with 20% NaOH. Because of the morphological characteristics of the algal strands, the pulp generally lacked bursting, tearing and folding strengths, but proper blending with softwood pulp increased the tensile breaking length to8.40 km, the tearing index to 14.5 mNm2 g-1, the bursting index to 6.42 kpam2 g-1 and the folding endurance to 4299 double folds, i.e. levels comparable to a typical kraft pulp. The algal pulp thus showed clear potential as a supplement for traditional medium strength wood pulps.

Retention of Red Color in Taiwania (Taiwania cryptomeriodes Hay.) Heartwood

Taiwania (Taiwania cryptomenodes Hay.) is one of economically important tree species indigenous to Taiwan. The heartwood of Taiwania is yellowish red with distinguished purplish pink streaks. Unfortunately, the red color is susceptible to change to dull black after exposure the heartwood to natural environment. This discoloration is a serious defect that decreases the value of Taiwania products. In order to preserve the red color of Taiwania heartwood, aliphatic polyurethane (PU) clear coatings containing Tinuvin photostabilizer coupled with pretreatment using photostabilizers, polyethylene glycol (PEG), semicarbazide (SCB) and acetic acid, were used. The experimental results demonstrated that discoloration on the surface of Taiwania heartwood could be prevented by pretreating it with photostabilizers (Tinuvin-1130 and Tinuvin-292) or PEG or SCB, followed by finishing it with a PU coating containing Tinuvin-1130 photostabilizer. The discoloration could be reduced to 30% of that of the untreated specimen by treating it with photostabilizers pretreatment or PEG pretreatment followed by finishing it with a PU coating containing Tinuvin-1130 photostabilizer. Furthermore, the discoloration was proven to reduce to 10% of that of the untreated specimen by treating it with SCB pretreatment followed by finishing it with a PU coating containing Tinuvin-1130 photostabilizer.

Composition and antimicrobial activities of the leaf essential oil of Machilus zuihoensis from Taiwan

This study investigated the chemical composition, and antimicrobial and anti-wood-decay fungal activities of the essential oil isolated from the leaf of endemic Machilus zuihoensis Hayata, Lauraceae, of Taiwan. The essential oil from the fresh leaves of M. zuihoensis was isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC-FID and GC-MS. A total of 104 compounds were identified, representing 100% of the oil. The main components identified were n-dodecanal (23.8%) and (E)-nerolidol (10.5%). The antimicrobial activity of the oil was tested by the disc diffusion method and micro-broth dilution method against ten microbial species (Bacillus cereus, Staphylococcus aureus, S. epidermidis, Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa, Vibrio parahaemolyticus, Aspergillus niger, and Candida albicans), respectively. The oil exhibited strong growth suppression against Gram-positive bacteria and yeast with inhibition zones of 35~43 mm to MIC values of 125 µg mL-1, respectively. The anti-wood-decay fungal activity of the oil was also evaluated. Results showed that the oil demonstrated excellent activity against four wood-decay-fungi species (Trametes versicolor, Phaneochaete chrysosporium, Phaeolus schweintizii, and Lenzites sulphureu). For the antimicrobial and anti-wooddecay fungal activities of the oil, the active source compounds were determined to be τ-cadinol, β-eudesmol, and n-dodecanal.