Allelopathic effects of water extracts ofArtemisia princeps var.orientalis on selected plant species

The allelopathic effects of wormwood plants (Artemisia princeps var.orientalis) and their possible phytotoxicity on receptor species were investigated. The aqueous extracts of mature leaf, stem, and root of wormwood plants caused significant inhibition in germination and decreased seedling elongation of receptor plants, whereas germination of some species was not inhibited by extracts of stems and roots. Dry weight growth was slightly increased at lower concentrations of the extract, whereas it was proportionally inhibited at higher concentrations. The calorie value of the organic matter in receptor plants measured by bomb calorimeter was reduced proportionally to the extract concentration. However, results with extracts of juvenile leaf did not correlate with inhibition or promotion of elongation and dry weight.     

Phytotoxic and antimicrobial activity of volatile constituents ofArtemisia princeps var.orientalis

The volatile constituents ofArtemisia princeps var.orientalis (wormwood) were investigated for phytotoxic and antimicrobial activities. The germination and radicle elongation of receptor plants were inhibited by volatile substances emitted from wormwood leaf and effects were concentration-dependent. Essential oil of the plant extracted by Karlsruker's apparatus suppressed seed germination and seedling elongation of the receptor plants at a threshold concentration of 4.8l/100 ml.Escherichia coli was not susceptible to the wormwood essential oil, but the growth ofBacillus subtilis, Aspergillus nidulans, Fusarium solani, andPleurotus ostreatus was inhibited severely.     

Assessment of allelopathic potential inArtemisia princeps var.Orientalis residues

Field and laboratory studies were conducted to examine the differential phytotoxicity of residues ofArtemisia princeps var.orientalis (wormwood) using various plants as test species. Seedling elongation and dry weights of receptor plants were inversely proportional to the concentration and incubation time of dry leaves ofA. princeps var.orientalis in vermiculite. In seedling growth tests with abandoned field soils (control) and soil underneath wormwood plants (test), the elongation, dry weight, and caloric content of seedlings grown in the soil from under wormwood plants were severely inhibited, thereby suggesting that certain growth inhibitors were released from wormwood and the inhibitor remained in the soil.     

Mycorrhizal Colonization and Plant Growth Affected by Aqueous Extract of Artemisia princeps var. orientalis and Two Phenolic Compounds

The effects of an aqueous extract of Artemisia princeps var. orientalis and two phenolic compounds on mycorrhizal colonization and plant growth have been investigated. Greenhouse studies showed that the inhibitory effect of the extract on mycorrhizal colonization and plant growth increased in proportion to the concentration of the extract. When the mycorrhizal test plants were treated with an increasing concentration of phenolic compounds, the mycorrhizal colonization in roots of the test plant and the plant growth were decreased. There were strong indications that mycorrhizal fungi mitigated the inhibitory influence of shoot extract of A. princeps var. orientalis and phenolic compounds.     

Extraction and purification of eupatilin fromArtemisia princeps PAMPAN recycling preparative HPLC

A recycling preparative HPLC was used to extract and separate the eupatilin contained inArtemisia princeps PAMPAN, and the optimum operating condition was experimentally determined. Eupatilin was extracted by ethanol solvent from the leaf and trunkof Artemisia princeps PAMPAN. The resulting solution was further partitioned with n-hexane, chloroform and ethyl acetate. The solution containing eupatilin was collected using a preparative as well as analytical column, and it was identified by LC-CE-MS. In the experiment, the mobile phase consisted of water/aceto-nitrile/TFA=50/50/0.5 (vol%), and UV wavelength measured was 370 nm. For analytical chromatography, the injection volume was 20 μL and the flow rate was fixed at 1.0 mL/min. The measured retention time for eupatilin was approximately 8.6 min in the above operating condition. For recycling preparative HPLC with commercially available GSA 310A column at 1.5 mL/min of the flow rate and 2 mL of injection volume, the purity of the eupatilin was almost 100% after recycling twice.     

Inhibition of growth ofPhytophthora parasitica var.nicotianae by aromatic acids and coumarins in a laboratory bioassay

Hydroxy-, dihydroxy-, trihydroxy-, methoxy-, dimethoxy-, hydroxy-+methoxy-, amino-, chloro-, and nitro-substituted benzoic, phenylacetic, phenylpropanoic, and phenylpropenoic (cinnamic) acids were evaluated for activity against the growth ofPhytophthora parasitica var.Nicotianae, Races 0 and 1, in a laboratory bioassay. Several substituted coumarins were also tested. In general, for Race 0, the phenylpropenoic acids were more active (on a millimolar basis), than the corresponding benzoic, phenylacetic, or phenylpropionic acids (9 of 14 series). Among the most active acids wereo-hydroxycinnamic and the chloro- and methoxycinnamic acids. The activities of unsubstituted benzoic and phenylpropionic acids were comparable to the most active compounds tested. Monohydroxyaromatic acids were more active than most dihydroxy acids of the same chain length. Dihydro-3,4-dihydroxycinnamic acid was slightly more active than the corresponding cinnamic acid, while the reverse was true for the mono-p-hydroxycinnamic acid versusp-hydroxyphenylpropionic acid. Coumarin was more active than its hydroxy, methyl, hydroxymethyl, or methoxy derivatives. In general, Race 1 was even more significantly affected by the aromatic acids. Glycosylated coumarins were inactive in the bioassay, compared to their aglycones.     

香叶天竺葵精油和纯露的挥发性成分分析及抗氧化活性评价

分别采用水蒸气蒸馏和同时蒸馏萃取法对香叶天竺葵精油和纯露的挥发性成分进行提取,通过气相色谱-质谱联用技术结合保留指数分析鉴定其化学组成,用峰面积归一化法确定各成分的相对含量。结果表明,香叶天竺葵精油中鉴定出71种化合物,主要成分有香茅醇、甲酸香茅酯、香叶醇、异薄荷酮、β-古芸烯、芳樟醇和惕各酸苯乙酯等;香叶天竺葵纯露中鉴定出39种化合物,主要成分有香茅醇、芳樟醇、香叶醇、异薄荷酮、α-松油醇、顺式芳樟醇氧化物和反式芳樟醇氧化物等。其中香叶天竺葵纯露中的挥发性成分大多存在于香叶天竺葵精油中,但含量存在较大的差异。采用DPPH自由基和羟基自由基清除试验对香叶天竺葵精油和纯露的抗氧化活性进行评价。结果表明,香叶天竺葵精油和纯露均对DPPH自由基和羟基自由基具有一定的清除作用,香叶天竺葵纯露对DPPH自由基和羟基自由基的清除能力稍强于香叶天竺葵精油。     

Olfactory responses of a specialist and a generalist grasshopper to volatiles ofArtemisia ludoviciana nutt. (Asteraceae)

Hypochlora alba is a specialist grasshopper that lives and feeds almost exclusively onArtemisia ludoviciana, a plant that produces large amounts of allelochemics including a variety of monoterpenes. This plant is not a host for generalist grasshoppers such asMelanoplus sanguinipes. The role of olfaction in the grasshopper-plant relationship was investigated by comparing electroantennograms (EAGs) of males and females of both species generated by solvent-extracted volatiles from plant leaves and by major individual components. Volatiles ofA. ludoviciana were identified by gas chromatography-mass spectrometry. The major components were 1,8-cineole, camphor, camphene, and borneol, while minor identified compounds were - and -pinene, -thujene, myrcene,p-cymene, Artemisia ketone, -thujone, and bornyl acetate. The EAGs (mV) ofH. alba males to a range of concentrations of individual volatiles or the total plant extract were nearly double those of conspecific females or both sexes ofM. sanguinipes. However, both sexes ofM. sanguinipes were more sensitive than either sex ofH, alba to geraniol, a monoterpene that commonly occurs in many plant species but is absent or is present in only trace amounts inA. ludoviciana. The increased sensitivity ofH. alba males to the odor components of their host plant appears to be related to the greater number of certain olfactory chemoreceptors on male versus female antennae. The significance of this phenomenon is discussed.     

Sorption of boron by invasive marine seaweed: Caulerpa racemosa var. cylindracea

The sorption of boron from aqueous solution onto Caulerpa racemosa var. cylindracea (CRC), collected from Seferihisar/Izmir region in Turkey, was investigated as a function of pH, temperature, initial boron concentration, adsorbent dosage, contact time and ionic strength. Optimum conditions for the sorption of boron were obtained at pH 7.5, 318 K, 8 mg L⁻¹ initial boron concentration, 0.2 g of CRC, 2.5 h contact time and greater ionic strength (10⁻¹ M NaCl). As the temperature was increased the boron removal took place with higher percentages. In experiments conducted at optimum conditions, maximum boron sorption was determined to be about 63%. The experimental data were analyzed by Freundlich, Langmuir and Dubinin–Radusckevich (DR) equations. Freundlich and DR models provide best conformity with the experimental data. In order to describe kinetics of boron sorption onto CRC, first-order Lagergren equation, pseudo-second-order kinetic model and intraparticle diffusion model were used. It was seen that the first order Lagergren equation was better described than the pseudo-second-order kinetic model. Thermodynamic parameters of sorption process were also calculated. It was obtained that sorption process was not spontaneous. The characterization of CRC was carried out by Fourier transform infrared spectroscopy (FTIR) analysis.     

Antignawing factor of crude oil derived fromThujopsis dolabrata S. et Z. var.hondai sawdust against mice

The antignawing activity of the steam distillate ofThujopsis dolabrata S. et. Z. var.hondai sawdust against mice was evaluated using a wire-dipping method. This method is suitable for measuring repellent activities of chemicals and plant-derived materials. The steam distillate of theThujopsis sawdust was shown to have potent antignawing activity. Three terpenoid compounds with antignawing activity were isolated from the steam distillate of theThujopsis sawdust: thujopsene, carvacrol, and-thujaplicine. Carvacrol exhibited the most potent repellent activity. As a naturally occurring repellent, carvacrol could be useful as new preventive agent against various kinds of damage caused by rodents.     

Caste-dependent reactions to soldier defensive secretion and chiral alarm/recruitment pheromone inNasutitermes princeps

The soldier frontal gland secretion ofNasutitermes princeps induces strong short-range caste-specific alarm and attraction in both soldiers and workers. Soldiers are excited and patrol the surroundings of the source. The secretion per se does not induce ejection of additional secretion. Large workers of the second stage or older are massively attracted when tested in homogeneous groups. They focus their activities much more accurately than the soldiers around the source. The workers' reaction is less intense in the presence of soldiers. Large and small workers of stage 1 scarcely react at all to the secretion, whether tested in homogeneous or mixed groups. These results suggest the following complementary roles of soldiers and workers in defense. The first line of defense is provided by soldiers, which immobilize and incapacitate mobile enemies with their sticky secretion. Defense then is completed by older large workers as they eliminate the source of disturbance. The absence of reaction of young workers, small or large, confirms previous reports on age polyethism inNasutitermes observed in other contexts: young workers tend to stay in the nest. Alarm reactions are elicited by a source of (+)--pinene, the major monoterpene in the secretion, while its enantiomer, almost absent from the secretion, induces a much weaker reaction.     

Allelopathy on Bark of Downed Logs of <Emphasis Type="Italic">Chamaecyparis Obtusa</Emphasis> sieb. and Zucc. var. <Emphasis Type="Italic">formosana</Emphasis> (Hayata) Rehder

Chamaecyparis obtusa Sieb. and Zucc. var. formosana (Hayata) Rehder is the dominant species in the temperate forest of Yuanyang Lake Nature Reserve (YYL), Taiwan. Although downed logs of C. obstusa var. formosana occupy only a small percentage of the forest floor area in YYL, they are important regeneration substrates. Seedlings of this species often grow without competition on the new downed logs, and a few broadleaf trees grow with them. We hypothesized that the bark of the newly fallen logs possesses allelopathic potential that provides a habitat especially suitable for seedling establishment. Eight different seeds including those from Lactuca sativa L. (lettuce), Bidens pilosa (an invasive weed), and six species in YYL were planted on the bark of the downed logs in an incubator for germination tests. Two dominant species in the forest of YYL, C. obtusa var. formosana and Rhododendron formosanum, were able to grow normally, but the others, Pieris taiwanensis, Barthea formosana, Chamaecyparis formosensis, Miscanthus transmorrisonensis, lettuce, and B. pilosa were growth inhibited. A bioactivity-guided isolation was designed to isolate allelochemicals from the bark. Salicylic acid, one of the inhibiting substances, was isolated and identified by gas chromatography/mass spectroscopy (GC/MS), proton nuclear magnetic resonance (¹H NMR), and infrared (IR). Bioassay of salicylic acid confirmed a phytotoxic effect. The results suggest that the dominance of C. obtusa var. formosana seedlings on bark could be partly due to allelopathy.     

Chemotypes ofCyperus rotundus in Pacific Rim and Basin: Distribution and inhibitory activities of their essential oils

Four major chemotypes ofCyperus rotundus L. (purple nutsedge) have been reported based on the composition of essential oils in mature tubers. Distribution of the H, M, K, and O type in countries of the Pacific Rim and Basin was investigated. In general, the H type dominates on the islands of Japan, and the O type has the widest range of distribution. The O type also dominates the Pacific Basin islands except for Hawaii, where the K-type is dominant. Inhibitory activity of the essential oils fromC. rotundus tubers against the seedling growth of lettuce and oats was in the order of H > M > K > O. Seven major sesquiterpenes were isolated from the oils and their inhibitory activities determined. Results suggest thatC. rotundus of different chemotypes may have different allelopathic activity in the crop-weed interaction.On leave from the Department of Agricultural Biochemistry.     

铁箍散根茎挥发油成分的GC-MS分析

铁箍散是贵州民间治疗风湿麻木、跌打损伤的常用药材,主要有效成分为挥发油。采用水蒸气蒸馏法提取铁箍散根茎部位的挥发油,气相色谱-质谱联用技术对相对质量分数大于0.02%的挥发油成分进行了鉴定,共鉴定出54个成分,相对质量分数之和为94.02%,其中相对质量分数较高的有4-萜烯醇(20.22%)、γ-杜松烯(12.33%)、1,2,3,4,4a,7-六氢-1,6-二甲基-4-(1-甲基乙基)-萘(13.25%)、T-依兰油醇(11.85%)。该文报道工作的新颖性已为遵义医学院图书馆信息部2009年9月14日出具的第2009K043号《科技查新报告》所证实。     

Effects of phenolic acids on germination and early growth of herbaceous woodland plants

Four herbaceous plant species from woodland (clearings),Deschampsia flexuosa, Scrophularia nodosa, Senecio sylvaticus, andChamaenerion angustifolium, were tested for their sensitivity to phenolic acids. Seven commonly occurring phenolic compounds were used in a germination experiment in concentrations ranging from 0.01 to 10 mM, i.e., salicylic,p-hydroxybenzoic, syringic, caffeic, vanillic,p-coumaric, and ferulic acids. Germination was delayed rather than inhibited. Radicle elongation was strongly affected; at lower concentrations stimulatory effects were observed, whereas at high concentrations radicle elongation was severely reduced. Salicylic acid was the most effective phenolic compound, whereas caffeic acid caused no effects. Early growth was studied in more detail in a second experiment withDeschampsia flexuosa andSenecio sylvaticus and the phenolic acids, ferulic and p-coumaric acid. Primary root length, number and length of secondary roots, and dry weight were stimulated at 0.01 mM but were inhibited at 10 mM of both compounds. The results are discussed in view of the allelopathic relations between trees and herbaceous understory vegetation.     

荆条等8种植物提取物除草活性初探

[方法]筛选具有除草活性的植物材料是开发植物源除草剂的基础.采用平皿法,以反枝苋、黄瓜、生菜和稗草为供试植物,测定了8种植物乙醇提取物的除草活性,并对除草活性最好的荆条花乙醇提取物进行初步研究.[结果]质量浓度为10 g/L时,荆条花乙醇提取物对反枝苋、黄瓜、生菜和稗草幼苗幼根的抑制率分别为94.76％、34.56％、84.17％和94.50％.对幼茎的抑制率分别为85.21％、6.44％、80.70％和46.60％.荆条花石油醚和乙酸乙酯萃取物在质量浓度为10 g/L时,对反枝苋、生菜和稗草幼苗幼根生长的抑制率均大于70％;对反枝苋幼苗幼茎生长的抑制率都为100％.[结论]荆条花具有潜在的除草活性,值得进一步研究.     

Activation of soil respiration and shift of the microbial population balance in soil as a response to Lavandula stoechas essential oil

Lavandula stoechas, a native plant of Greece, is rich in essential oil and fenchone is its major constituent. We examined the effect of the essential oil and its main constituents on soil metabolism and microbial growth. Addition of the essential oil or fenchone to soil samples induced a remarkable increase in soil respiration. This was accompanied by an increase in the soil bacterial population of three orders of magnitude. This sizable population was not qualitatively similar to that of the control soil samples. One bacterial strain dominated soil samples treated with L. stoechas essential oil or fenchone. By use of the disk diffusion assay, we evaluated the capacity of three bacterial strains that we isolated from the soil samples, as well as Escherichia coli and Bacillus subtilis (reference strains), to grow in the presence of the essential oil and three of its main constituents (fenchone, cineol, -pinene). The substances tested did not inhibit the growth of the strain found to dominate the bacterial populations of treated soil samples; they severely inhibited B. subtilis. The other two isolated strains could also grow in liquid cultures in the presence of different quantities of essential oil or fenchone. Addition of fenchone at the end of the exponential phase increased the cell numbers of the strain that dominated the bacterial populations of treated soil samples, indicating use of the substrate added. On the basis of these results, we propose a scheme of successional stages during the decomposition process of the rich-in-essential-oil litter of aromatic plants that abound in the Mediterranean environment.     

Influence of corrosion and mechanical loads on advanced ceramic components

Advanced oxide ceramics are prospective materials for severe application conditions, including corrosion, particularly, in oxygen-rich environments, combined with the action of mechanical loads. The corrosion behavior and mechanical strength decrease of oxide ceramics, such as high alumina, alumina–mullite and zirconia-based ceramics, were studied in water steam supercritical conditions (elevated temperatures and pressures). The strength decrease under the action of the studied aggressive environment is mostly dealt with the glassy phase dissolution and intergranular corrosion for alumina–mullite and high alumina ceramics, while degradation of zirconia-based ceramics is also dealt with the phase transformation. The influence of structure defects related to processing of the ceramics on corrosion is considered.     

Effects of juglone on growth,photosynthesis, and respiration

The impacts of juglone on plant growth and several other physiological functions were evaluated in this study. Juglone inhibitedLemna minor growth, chlorophyll content, and net photosynthesis at treatments between 10 and 40M. Soybean leaf disks vacuum infiltrated with as little as 10M juglone had reduced photosynthesis. Oxygen evolution by chloroplasts isolated fromPisum sativum was inhibited by juglone with an I₅₀ of 2M. Micromolar treatments of juglone stimulated oxygen uptake in mitochondria isolated fromGlycine max. These data suggest perturbations of chloroplast and mitochondrial functions may contribute to plant growth reductions observed in juglone-mediated allelopathy.This study was supported by National Science Foundation grant STI-8902066.     

Chemical constituents and inhibitory activities of essential oils fromCyperus brevifolius andC. kyllingia

Cyperus brevifolius andC. kyllingia are two common weeds in Hawaii. The underground parts, including the rhizomes and roots, contain allelopathic essential oils, which may contribute to the aggressive spread of these weeds in grasslands and lawns. Although morphologically similar,C. kyllingia contains more essential oils thanC. brevifolius. Also, the former is rich in terpenes, including -cyperone, -selinene, and -humulene, while the latter is rich in C₁₇ to C₂₅ n-paraffins. These chemical differences agree with their inhibitory activities against indicator species and the general observation thatC. kyllingia is the more prevalent weed of the two.On leave from the Department of Agricultural Chemistry, Kinki University, Osaka, Japan.