Phytotoxicity of Vulpia Residues: IV. Dynamics of Allelochemicals During Decomposition of Vulpia Residues and Their Corresponding Phytotoxicity

The behavior and dynamics of 20 identified allelochemicals in vulpia residues were both collectively and individually monitored, and their kinetic phytotoxicity was assessed. The total content of the identified allelochemicals in decaying vulpia residues increased from 0.31 to 1.24 mg/g dry residue over a 21-day decomposition period, while the total phenolic content increased from 1.86 to 2.16 mg/g dry residue. This corresponded to a phytotoxicity increase from 42% to 82% of radical inhibition. Allelochemicals changed in composition and quantity over the duration of the residue decomposition. Addition of soil to the residues reduced the total allelochemical contents extracted and altered the dynamic pattern. In the same period, the total content of allelochemicals declined from 0.061 to 0.046 mg/g residue + soil, with the total phenolics reduced from 0.20 to 0.11 mg/g residue + soil, corresponding to a radical length increase from 53% to 109% of control. Only 14 of the identified allelochemicals were detected in the mix of soil and residues, in contrast to 20 present in the residues alone. The implications of these findings are discussed.     

Phytotoxicity of Vulpia Residues: II. Separation, Identification, and Quantitation of Allelochemicals from Vulpia myuros

Phytotoxicity-based extraction and fractionation were employed to separate and purify the allelochemicals from an aqueous extract of vulpia (Vulpia myuros) residues. Further analyses, identification, and quantitation of these allelochemicals were conducted by gas chromatography–mass spectrometry on the most toxic fraction. Twenty-one compounds were identified in the ether fraction from the vulpia residue aqueous extract. They were catechol, hydroquinone, 3,4-dimethoxyphenol, pyrogallol, coniferyl alcohol, and benzoic, succinic, hydrocinnamic, salicylic, protocatechuic, vanillic, gentisic, syringic, p-hydroxybenzoic, -hydroxybenzenepropanoic, p-hydroxyphenylacetic, p-hydroxybenzenepropanoic, hydroferulic, p-coumaric, hydrocaffeic, and ferulic acids. A chromatographic internal standard method with multiple-point calibration graphs was used to quantify the identified compounds. Quantities in the vulpia residues ranged from 1.36 to 81.0 g/g dry residue, in total accounting for 0.05% of the dry weight residue. The combined syringic and hydroferulic acids were present in the largest amount, 140.11 g/g residue. Vanillic, succinic, p-hydroxybenzenepropanoic, and salicylic acids were next in amount, ranging from 37.24 to 81.24 g/g residue. Catechol, hydrocinnamic acid, and hydroquinone were present in the smallest quantities, ranging from 1.36 to 1.82 g/g residue. The remainder of the compounds were intermediate in amount, ranging from 2.33 to 18.1 g/g residue.     

Phytotoxicity of Vulpia Residues: IV. Dynamics of Allelochemicals During Decomposition of Vulpia Residues and Their Corresponding Phytotoxicity

The behavior and dynamics of 20 identified allelochemicals in Vulpia residues were collectively and individually monitored, and their kinetic phytotoxicity was assessed. The total content of the identified allelochemicals in decaying Vulpia residues increased from 0.31 mg/g to 1.24 mg/g dry residue over a 21–day decomposition period, while the total phenolic content increased from 1.86 mg/g to 2.16 mg/g dry residue. This corresponded to a phytotoxicity increase from 42% to 82% of radical inhibition. Allelochemicals changed in composition and quantity over the duration of the residue decomposition. Addition of soil to the residues reduced the total allelochemical contents extracted and altered the dynamic pattern. In the same period, the total content of allelochemicals declined from 0.061 mg/g to 0.046 mg/g residue + soil, with the total phenolics dropped from 0.20 mg/g to 0.11 mg/g residue + soil, corresponding to a radical length increase from 53% to 109% of control. Only 14 of the identified allelochemicals were detected in the mix of soil and residues, in contrast to 20 present in the residues alone. The implications of these findings are discussed.     

Phytotoxicity of Vulpia Residues: I. Investigation of Aqueous Extracts

Phytotoxic properties of vulpia (V. myuros) residue extracts on wheat (Triticum aestivum L. cv. Vulcan) were examined in the laboratory. Vulpia residues contained water-soluble materials that were toxic to germination and to coleoptile and root growth of wheat. There were strong correlations between extract concentration and toxicity, between extraction times and toxicity, and between extract pH and phytotoxicity. The phytotoxicity was residue rate dependent. There was no significant correlation between the phytotoxicity of residue extracts and the electrical conductivity of aqueous extracts. Milled residues were more toxic than chopped residues. The toxicity of vulpia residues increased as their decomposition proceeded, reaching a peak phytotoxicity after decomposition for 40 days and remaining potent for up to 60 days, gradually declining thereafter. Radicle elongation of wheat was the most sensitive indicator, germination was the least sensitive, and coleoptile growth was intermediate. The phytoxic effects of residue extracts on seed germination had two aspects: germination delay and inhibition. The relative magnitude of each aspect depended upon the potency of the extracts. With a strong phytotoxic potential, inhibition of germination was dominant over seed germination, whereas with a weak toxic level, delay was dominant over seed germination.     

Identification and Quantitation of Allelochemicals from the Lichen Lethariella canariensis: Phytotoxicity and Antioxidative Activity

Phytotoxicity-based extraction and fractionation were employed to separate allelochemicals contained in an extract of Lethariella canariensis. Twelve phenolic substances were isolated from the phytotoxic fraction Letharal of the thalli. These were identified by spectroscopic methods, physicochemical constants, and HPLC chemical correlation, and determined to be atranol (2), chloroatranol (3), hematommic acid (4), chlorohematommic acid (5), methyl hematommate (6), methyl chlorohematommate (7) (new compound), ethyl hematommate (8), ethyl chlorohematommate (9), methyl -orsellinate (10), atranorin (11), chloroatranorin (12), and (+)-usnic acid (13). Further identification and quantification of these allelochemicals in the environment were conducted by HPLC. Several phenolic compounds showed moderate antimicrobial activity. The cytostatic activity of the polyphenols was investigated on U937 and HL-60 cells. All compounds were assayed, with the exception of 10. The Letharal mixture decreased cell viability in both cell lines. Protection against lipid peroxidation was investigated using brain homogenates. Compounds 2, 3, 6, 8, 11, and Letharal decreased H₂O₂/Fe⁺² induced lipid peroxidation in a concentration-dependent manner, while 10 and 13 were unable to protect tissue against oxidative stress.     

Correlation Between Phytotoxicity on Annual Ryegrass (Lolium rigidum) and Production Dynamics of Allelochemicals Within Root Exudates of an Allelopathic Wheat

An improved allelopathic correlation between phytotoxicity measured in root growth bioassay upon annual ryegrass (Lolium rigidum Gaud.) and the concentrations of a selection of dynamically produced allelochemicals quantified in the root exudates of cv. Khapli wheat (Triticum turgidum ssp. durum (Desf.) Husn.) monitored during the first 15 days of wheat seedling growth in a sterile, agar–water medium, has been established. Changes over the 15-day growth period in the quantities of five exuded benzoxazinones and seven phenolic acids were measured simultaneously using GC/MS/MS. Substantiating pure compound dose–response measurements were conducted over a range of concentrations for the putative allelochemicals within the wheat exudates. One synergism-based proposal using the monitored compounds to explain the observed low-exudate-concentration phytotoxicity was explored, but was found to be experimentally inadequate.     

木姜子属挥发油成分及其生物活性研究概况

综述了木姜子属植物的分布、挥发油成分、生物活性等方面的研究工作;为木姜子属药用植物的系统分类提供了化学依据,并为评价该属植物的药用价值提供参考。     

Drimane倍半萜类化合物的分布和生理活性研究

文章简要综述了Drimane类倍半萜化合物的结构、来源与分布和生理活性.     

苦参生物碱杀虫生物活性测定

以桃蚜等9种试虫为供试靶标，研究了苦参根提取物和苦参碱、氧化苦参碱、槐果碱、野靛碱的杀虫活性。试验结果表明：苦参生物碱具有一定的杀虫活性，9种试虫中，苦参根提取物对蚜虫的活性最高，其对蚕豆蚜的LC50为20．635mg／L；即使在最高剂量为4000mg/L时，也不能直接杀死粘虫、小菜蛾和棉铃虫。4种生物碱对朱砂叶螨活性均较低，LC50均大于2500mg／L。野靛碱是4种生物碱中杀虫活性最高的，对淡色库蚊、桃蚜、蚕豆蚜、褐飞虱和家蝇的LC50分别为172．431mg/L、207．667mg／L、85．212mg／L、266．179mg／L和763．224mg／L；而且对褐飞虱、桃蚜和家蝇的活性高于苦参根提取物，苦参碱对蚜虫的活性高于氧化苦参碱和槐果碱，槐果碱对淡色库蚊、褐飞虱和家蝇的活性高于苦参碱和氧化苦参碱。     

哌啶类双氨基雄甾烷类化合物的合成及其活性研究

在对双氨基雄甾烷类化合物构效关系研究的基础上,合成了2个哌啶类双氨基雄甾烷类化合物,并对合成的过程和活性测定的结果进行了分析,以期发现更加有效或毒副作用更小的肌松药。化合物的结构均经1H NMR和13C NMR确证。     

巴豆中农药活性物质的提取及其药效初探

本文从巴豆中提取农药活性物质，并进行了药效初探，试验表明，巴豆中的农药活性物质对蚜虫具有触杀效果，致死中量LD50（1小时）＝1769PPM；LD50（6小时）＝502PPM；LD50（24小时）＝302PPM。     

NC-510的合成与生物活性研究

为研究NC-510的生物活性,以硫代苯甲酰胺为起始原料,经环化、取代、酰化等一系列反应合成了(E)-2-氰基-1-(2-甲基-4-三氟甲基噻唑-5-基)-2-(2-苯基噻唑-4-基)新戊酸乙烯酯(NC-510),其结构经过1H NMR和MS确证。室内生物活性测试结果初步表明,NC-510对蚕虫蚜的LC50值为0.661 mg/L;在10 mg/L剂量下药后2 d对蚕虫蚜表现出94.95%的防治效果,优于相同条件下吡蚜酮对蚕虫蚜的活性80.50%。     

甘露聚糖肽生物活性的研究进展

介绍了甘露聚糖肽的结构组成及其特点,简述了甘露聚糖肽的提取方法以及生物活性,探讨了甘露聚糖肽的研究开发进展.     

N-苯并噻唑N′-特丁基酰肼类化合物的合成及生物活性研究

合成了 12个N 苯并噻唑N′ 特丁基酰肼新化合物 ,并经MS和1HNMR结构确证。初步生物活性测定结果表明 :部分化合物具有较好的杀菌和除草活性。     

风吹楠属植物化学成分及活性研究进展

为了全面了解和综合利用风吹楠属植物,本文对风吹楠属植物的化学成分和药理活性研究进展进行了综述。目前风吹楠属植物研究所涉及的种类仅5种,从中共分离到40个化学成分,包括黄酮、色原酮、木脂素、生物碱、芳基酮等结构类型。活性研究表明,一些化学成分具有明显的细胞毒活性和抗疟疾活性。开展风吹楠属植物的研究,对发现新的药用活性成分及资源保护具有重要的意义。     

Biological Activity of Selected Natural and Synthetic Terpenoid Lactones

Terpenoids with lactone moieties have been indicated to possess high bioactivity. Certain terpenoid lactones exist in nature, in plants and animals, but they can also be obtained by chemical synthesis. Terpenoids possessing lactone moieties are known for their cytotoxic, anti-inflammatory, antimicrobial, anticancer, and antimalarial activities. Moreover, one terpenoid lactone, artemisinin, is used as a drug against malaria. Because of these abilities, there is constant interest in new terpenoid lactones that are both isolated and synthesized, and their biological activities have been verified. In some cases, the activity of the terpenoid lactone is specifically connected to the lactone moiety. Recent works have revealed that new terpenoid lactones can demonstrate such functions and are thus considered to be potential active agents against many diseases.     

叶黄素的制备及生物活性研究进展

叶黄素广泛存在于自然界中,属于类胡萝卜素中的一种,是一种安全的天然色素。由于具有多种生物活性,应用前景十分广阔。介绍了近年来叶黄素的制备方法及生物活性研究进展,为叶黄索的进一步研究提供了参考。     

酰基硫脲类化合物的生物活性研究进展

酰基硫脲类化合物具有广泛的生物活性,可作为除草剂、杀菌剂及植物生长调节剂等。本文简要综述了近年来该类化合物生物活性的研究近况。     

Allelochemicals in Wheat (Triticum aestivum L.): Variation of Phenolic Acids in Shoot Tissues

Seven known phenolic acids implicated in wheat allelopathy were analyzed in a worldwide collection of 58 wheat accessions by gas chromatography and tandem mass spectrometry (GC-MS-MS). Chemical analysis showed that accessions differed significantly in the production of p-hydroxybenzoic, vanillic, syringic, trans-p-coumaric, cis-p-coumaric, trans-ferulic, and cis-ferulic acids in the shoots of 17-day-old wheat seedlings. The concentrations of p-hydroxybenzoic, vanillic, cis-p-coumaric, and cis-ferulic acids were normally distributed in the 58 accessions. A binormal distribution was found for syringic and trans-ferulic acids and a skewed normal distribution for trans-p-coumaric acid. The concentration of each compound also varied with phenolic acids. The relative abundance of each phenolic acid was ordered decreasingly as trans-ferulic, vanillic, trans-p-coumaric, p-hydroxybenzoic, syringic, cis-ferulic, and cis-p-coumaric acids. The concentration of total identified phenolic acids varied from 93.2 to 453.8 mg/kg in the shoots of 58 accessions. The content of each phenolic acid or group was highly associated with others in the shoots of wheat seedlings. Wheat accessions with high levels of total identified phenolic acids in the shoots are generally strongly allelopathic to the growth of annual ryegrass.     

牛心朴子生物活性的初步研究

测定了牛心朴子石油醚提取物、乙酸乙酯提取物、甲醇提取物、生物碱、非生物碱5部分杀虫、抑菌、除草活性。结果表明，供试样品中尤以生物碱活性最高，浓度为5％时，生物碱对粘虫3龄幼虫没有明显的触杀和胃毒活性，但有强烈的拒食活性；浓度为500mg／L时，生物碱对烟草赤星病菌、小麦根腐病菌、马铃薯干腐病菌及玉米大斑病菌等8种病菌抑制活性最低也达到了85．6％；浓度为1mg／L时，生物碱对反枝苋主茎及主根生长抑制率分别达到了84．2％和85．4％。