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1.
Evaluation of a Freeze-Concentration Technique for Enrichment of Natural Organic Substances in Water
《Analytical letters》2012,45(6):1035-1045
Abstract A freeze concentration method was tested for its ability to concentrate uncharacterized organic carbon, measured by TOC analyzer, in tap water derived from a surface water reservoir in eastern Massachusetts. Freeze concentration was carried out in polypropylene bottles of 2 liter volume, stirred at either 140 rpm or 400 rpm, and placed in a freezer at either -15°C or -25°C. No effect of stirring speed or freezer temperature on the recovery efficiency was found except possibly at high (>10x) concentration factors. For theoretical concentration factors below approximately ten, measured TOC was reproducible but substantially less than the theoretical value (e.g., for a theoretical value of 10, the measured concentration factor was only 4.3. At higher concentration factors, the ratio of the actual to theoretical concentration decreased further and became variable from experiment to experiment. Lack of quantitative recovery of TOC indicates the likelihood that selective concentration of different components of this material occurred. 相似文献
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New agricultural strategies aim to reduce the use of pesticides due to their damage to the environment and humans, and the caused resistance to pathogens. Therefore, alternative sources of antifungal compounds from plants are under investigation lately. Extracts from plants have a wide composition of chemical compounds which may complicate the development of pathogen resistance. Botrytis cinerea, causing grey mould, is an important horticultural and ornamental pathogen, responsible for the relevant yield and quality losses. B. cinerea isolated from a different plant host may differ in the sensitivity to antifungal substances from plants. Assessing the importance of research covering a wide range of pathogens for the rapid development of biopesticides, this study aims to determine the sensitivity of the B. cinerea isolate complex (10 strains) to plant extracts, describe morphological changes caused by the extract treatment, and detect differences between the sensitivity of different plant host isolates. The results showed the highest sensitivity of the B. cinerea isolates complex to cinnamon extract, and the lowest to laurel extract. In contrast, laurel extract caused the most changes of morphological attributes in the isolates. Five B. cinerea isolates from plant hosts of raspberry, cabbage, apple, bell pepper, and rose were grouped statistically according to their sensitivity to laurel extract. Meanwhile, the bell pepper isolate separated from the isolate complex based on its sensitivity to clove extract, and the strawberry and apple isolates based on their sensitivity to cinnamon extract. 相似文献
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Ana I. F. Lopes Mariana Monteiro Ana R. L. Araújo Ana Rita O. Rodrigues Elisabete M. S. Castanheira David M. Pereira Pedro Olim A. Gil Fortes M. Sameiro T. Gonalves 《Molecules (Basel, Switzerland)》2020,25(24)
The potential of plant extracts as bioinsecticides has been described as a promising field of agricultural development. In this work, the extracts of Punica granatum (pomegranate), Phytolacca americana (American pokeweed), Glandora prostrata (shrubby gromwell), Ulex europaeus (gorce), Tagetes patula (French marigold), Camellia japonica red (camellia), Ruta graveolens (rue or herb-of-grace) were obtained, purified, and their activity against Spodoptera frugiperda (Sf9) insect cells was investigated. From the pool of over twenty extracts obtained, comprising different polarities and vegetable materials, less polar samples were shown to be more toxic towards the insect cell line Sf9. Among these, a dichloromethane extract of R. graveolens was capable of causing a loss of viability of over 50%, exceeding the effect of the commercial insecticide chlorpyrifos. This extract elicited chromatin condensation and the fragmentation in treated cells. Nanoencapsulation assays of the cytotoxic plant extracts in soybean liposomes and chitosan nanostructures were carried out. The nanosystems exhibited sizes lower or around 200 nm, low polydispersity, and generally high encapsulation efficiencies. Release assays showed that chitosan nanoemulsions provide a fast and total extract release, while liposome-based systems are suitable for a more delayed release. These results represent a proof-of-concept for the future development of bioinsecticide nanoformulations based on the cytotoxic plant extracts. 相似文献
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Michele Trombin de Souza Mireli Trombin de Souza Maíra Chagas Morais Daiana da Costa Oliveira Douglas Jos de Melo Leonardo Figueiredo Paulo Henrique Gorgatti Zarbin Maria Aparecida Cassilha Zawadneak Daniel Bernardi 《Molecules (Basel, Switzerland)》2022,27(19)
The spotted wing drosophila (Drosophila suzukii) is one of the main invasive pests of small fruits in the world. Thus, 19 essential oils (EOs) were selected to analyze the effects through toxicity and repellency on oviposition and D. suzukii adults. In addition, their lethal and sublethal effects on the pupal endoparasitoid Trichopria anastrephae were evaluated. The EOs of C. flexuosus and Mentha spp. had the highest toxicity observed in the topical application bioassay for D. suzukii. In contrast, the EOs of C. verum, C. citratus QT citratus, and C. winterianus showed the highest toxicity in the ingestion bioassay for D. suzukii. The dry residues of C. verum and C. citratus QT citratus reduced the oviposition of D. suzukii. In the repellency bioassays, the 19 EOs analyzed repelled ≅ 90% of the D. suzukii females. All EOs evaluated using the LC90 values of the products provided mortality of less than 20% of T. anastrephae adults and did not cause a reduction in the parasitism of surviving T. anastrephae females. We conclude that the EOs evaluated have the potential to be used in the management of D. suzukii. They can also serve as selective active ingredients for the formulation and synthesis of new biopesticides. 相似文献
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本文由ｐＨ滴定法原理导出多元弱酸及两性物质逐级稳定常数ｋ＿ｉ的计算公式。编辑了由Ｍｏｎｔｅ－Ｃａｒｌｏ法确定初值，Ｈｏｏｋｅ－Ｊｅａｖｅｓ法精解的计算程序。由此算法测定了方酸及其衍生物的各级稳定常数。结果表明，该法实验简便，数值运算效率高，结果可靠 相似文献
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He‐Shui Yu Peng Zou Xin‐Bo Song Li‐Ping Kang Yi‐Xun Liu Xu Pang Jie Zhang Jing Fu Yang Zhao Cheng‐Qi Xiong Da‐Wei Tan Li‐Juan Zhang Bai‐Ping Ma 《Helvetica chimica acta》2011,94(7):1351-1358
A new furostanol saponin, sisalasaponin C ( 1 ), and a new spirostanol saponin, sisalasaponin D ( 2 ), were isolated from the fresh leaves of Agave sisalana, along with three other known steroidal saponins and two stilbenes. Their structures were identified as (3β,5α,6α,22α,25R)‐3,26‐bis[(β‐D ‐glucopyrano‐ syl)oxy]‐22‐hydroxyfurostan‐6‐yl β‐D ‐glucopyranoside ( 1 ), (3β,5α,25R)‐12‐oxospirostan‐3‐yl 6‐deoxy‐α‐L ‐mannopyranosyl‐(1→4)‐β‐D ‐glucopyranosyl‐(1→3)‐[β‐D ‐xylopyranosyl‐(1→3)‐β‐D ‐glucopyranosyl‐(1→2)]‐β‐D ‐glucopyranosyl‐(1→4)‐β‐D ‐galactopyranoside ( 2 ), (3β,5α,6α,22α,25R)‐22‐methoxyfurostane‐3,6,26‐triyl tris‐β‐D ‐glucopyranoside, cantalasaponin‐1, polianthoside D, (E)‐ and (Z)‐2,3,4′,5‐tetrahydroxystilbene 2‐O‐β‐D ‐glucopyranosides. The last three known compounds were isolated from the fresh leaves of Agavaceae for the first time. The structures of the new compounds were elucidated by detailed spectroscopic analysis, including 1D‐ and 2D‐NMR experiments, and chemical techniques. 相似文献
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Isolation and Structure Elucidation of New Glycosides from the Leaves of Oplopanax Elatus Nakai（Ⅱ） 总被引：1，自引：0，他引：1
ＩｓｏｌａｔｉｏｎａｎｄＳｔｒｕｃｔｕｒｅＥｌｕｃｉｄａｔｉｏｎｏｆＮｅｗＧｌｙｃｏｓｉｄｅｓｆｒｏｍｔｈｅＬｅａｖｅｓｏｆＯｐｌｏｐａｎａｘＥｌａｔｕｓＮａｋａｉ（Ⅱ）ＷＡＮＧＧｕａｎｇ－ｓｈｕ，ＺＨＡＯＣｈｕｎ－ｆａｎｇａｎｄＸＵＪｉｎｇ－ｄａ（... 相似文献
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冻地银莲花中三萜皂苷的HPLC/MSn分析 总被引：1，自引：0，他引：1
药用植物冻地银莲花(Anemone rupestris ssp. gelida)的全草中含有丰富的三萜皂苷, 经HPLC-MSn分析, 发现其总皂苷中共含有10余个三萜皂苷成分. 除由总离子流色谱图给出各皂苷成分的相对含量外, 从每个色谱峰的正负离子ESI-MS获得相应皂苷的分子量, 进而由多级质谱给出糖链连接的信息, 结合文献报道, 将11个主要三萜皂苷成分分别鉴定为革叶常春藤皂苷F (1), 牡丹草皂苷D (2), 刺楸皂苷B (3), 革叶常春藤皂苷E (4), 红毛七皂苷D (5), 常春藤皂苷B(6), 刺五加皂苷C3 (7), 牡丹草皂苷B (8), 刺楸皂苷A (9), 木通皂苷D (10)和齐墩果酸-3-鼠李糖基-(12)-[葡萄糖基-(14)]-阿拉伯糖苷(11). 其中微量成分2, 5, 7, 10和11为首次从冻地银莲花中分离鉴定. 最后通过与标准品的HPLC保留时间对照证实了他们的存在. 相似文献
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Prof. John M. Woodley 《ChemSusChem》2022,15(9):e202102683
Abstract : Biocatalysis offers many attractive features for the synthetic chemist. In many cases, the high selectivity and ability to tailor specific enzyme features via protein engineering already make it the catalyst of choice. From the perspective of sustainability, several features such as catalysis under mild conditions and use of a renewable and biodegradable catalyst also look attractive. Nevertheless, to be sustainable at a larger scale it will be essential to develop processes operating at far higher concentrations of product, and which make better use of the enzyme via improved stability. In this Concept, it is argued that a particular emphasis on these specific metrics is of particular importance for the future implementation of biocatalysis in industry, at a level that fulfills its true potential. 相似文献
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Augusto Lopes Souto Muriel Sylvestre Elisabeth Dantas Tlke Josean Fechine Tavares Jos Maria Barbosa-Filho Gerardo Cebrin-Torrejn 《Molecules (Basel, Switzerland)》2021,26(16)
Pests and diseases are responsible for most of the losses related to agricultural crops, either in the field or in storage. Moreover, due to indiscriminate use of synthetic pesticides over the years, several issues have come along, such as pest resistance and contamination of important planet sources, such as water, air and soil. Therefore, in order to improve efficiency of crop production and reduce food crisis in a sustainable manner, while preserving consumer’s health, plant-derived pesticides may be a green alternative to synthetic ones. They are cheap, biodegradable, ecofriendly and act by several mechanisms of action in a more specific way, suggesting that they are less of a hazard to humans and the environment. Natural plant products with bioactivity toward insects include several classes of molecules, for example: terpenes, flavonoids, alkaloids, polyphenols, cyanogenic glucosides, quinones, amides, aldehydes, thiophenes, amino acids, saccharides and polyketides (which is not an exhaustive list of insecticidal substances). In general, those compounds have important ecological activities in nature, such as: antifeedant, attractant, nematicide, fungicide, repellent, insecticide, insect growth regulator and allelopathic agents, acting as a promising source for novel pest control agents or biopesticides. However, several factors appear to limit their commercialization. In this critical review, a compilation of plant-derived metabolites, along with their corresponding toxicology and mechanisms of action, will be approached, as well as the different strategies developed in order to meet the required commercial standards through more efficient methods. 相似文献
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Matheus V. Coste Grahl Fernanda Cortez Lopes Anne H. Souza Martinelli Celia R. Carlini Leonardo L. Fruttero 《Molecules (Basel, Switzerland)》2020,25(22)
Intrinsically disordered proteins (IDPs) and intrinsically disordered regions (IDRs) do not have a stable 3D structure but still have important biological activities. Jaburetox is a recombinant peptide derived from the jack bean (Canavalia ensiformis) urease and presents entomotoxic and antimicrobial actions. The structure of Jaburetox was elucidated using nuclear magnetic resonance which reveals it is an IDP with small amounts of secondary structure. Different approaches have demonstrated that Jaburetox acquires certain folding upon interaction with lipid membranes, a characteristic commonly found in other IDPs and usually important for their biological functions. Soyuretox, a recombinant peptide derived from the soybean (Glycine max) ubiquitous urease and homologous to Jaburetox, was also characterized for its biological activities and structural properties. Soyuretox is also an IDP, presenting more secondary structure in comparison with Jaburetox and similar entomotoxic and fungitoxic effects. Moreover, Soyuretox was found to be nontoxic to zebra fish, while Jaburetox was innocuous to mice and rats. This profile of toxicity affecting detrimental species without damaging mammals or the environment qualified them to be used in biotechnological applications. Both peptides were employed to develop transgenic crops and these plants were active against insects and nematodes, unveiling their immense potentiality for field applications. 相似文献
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The critical micellar concentration (cmc) is a fundamental property of surfactant solutions. Many proposed methods for the definition and determination of the cmc from property-concentration plots yield values, which depend on the studied property, on the specific technique used for its analysis and in many cases on the subjective choice of the chosen type of plot and concentration interval. In this focus review, we revise the application of a surfactant concentration model we proposed earlier that defines the cmc directly based on the surfactant concentration. Known equations for the concentration-dependence of different surfactant properties can then be combined with this concentration model and fitted to experimental data. This modular concept makes it possible to determine the cmc and the transition width in a systematic and unambiguous way. We revise its use in the literature in different contexts: the determination of the cmc of surfactants and their mixtures from different properties (electrical conductivity, NMR chemical shift, self-diffusion, surface tension, UV-Vis absorption, fluorescence intensity and fluorescence correlation). We also revise the dependence of the width of the transition region on composition, detailed studies of the properties of fluorescent probes and the aggregation of non-surfactant systems, namely amyloid peptides. 相似文献
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《应用化学》2011,28(05):565-570
Four kinds of quaternary ammonium salt cationic surfactants(dodecyl benzyl dimethyl ammonium chloride(1227), tetradecyl dimethyl benzyl ammonium(1427), hexadecyl trimethyl ammonium bromide(1631) and octadecyl trimethyl ammonium bromide(1831)) were used to modify sodium bentonite(Na-Ben). The prepared organic bentonites(1227-Ben, 1427-Ben, 1631-Ben, 1831-Ben) were characterized by Fourier transform infrared spectroscopy(FT-IR) and X-ray diffraction(XRD), and used as subsidence-resistance for preparing suspensions containing 5% hexaconazole. The suspension capability of bentonite modified by above four organic additives in water and the effects of these bentonites on the physical stability of suspensions were examined. FT-IR spectra and XRD analysis results showed that these four cationic surfactants were intercalated into the layer of bentonite. Suspension capability results indicated that 1831-Ben has a better suspension than the other three. Subsidence-resistance tests showed that bentonites modified by organic additives could improve the physical stability of suspensions. The water segregation ratio of samples prepared by 1831-Ben was the lowest, while the viscosity, yield value and suspension rate were the highest. So 1831-Ben could be used as a suspension-additive for the preparation of suspensions containing 5% hexaconazole. 相似文献
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《Analytical letters》2012,45(11):841-857
Abstract Isolation of organic constituents from water frequently involves an extraction with a large volume of organic solvent which must be reduced to achieve the desired sensitivity. The objective of this research was to evaluate common solvent evaporation techniques to determine which are acceptable for use in pollutant analysis. Techniques for solvent reduction from 200 to 10 mL (macro) and 8 to 0.2 mL (micro) were evaluated. The macro concentration technques included Kuderna-Danish (K-D) concentration, rotary evaporation, evaporation on a hot plate in an Erlen-meyer flask, and heated nitrogen blowdown in an Erlenmeyer flask. The micro techniques included micro K-D concentration, nitrogen blowdown, and nitrogen blowdown with a modified Snyder column. A series of model compounds covering a wide range of boiling points (108° to 323°C) and polarity was used. Based upon recovery efficiency alone, nitrogen blowdown was significantly superior to the other macro techniques; however, its extreme slowness gave K-D the highest Figure of Merit. With methylene chloride as the solvent, nitrogen blowdown with a column was the superior technique. 相似文献
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Two new triterpenoid saponins named lonimacranthoideⅣ(1) and lonimacranthoideⅤ(2) were isolated from the flower buds of Lonicera macranthoides Hand.-Mazz.(Caprifoliaceae).They have hederagenin as aglycone.LonimacranthoideⅣ(1) is a rare chlorogenic acid ester acylated on the C-23 of hederagenin.LonimacranthoideⅣis a new sulfated triterpenoid saponin.The structures of the saponins were established by chemical and spectral methods. 相似文献
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Angelika Kliszcz Andrzej Danel Joanna Pu&#x;a Beata Barabasz-Krasny Katarzyna Mode&#x; 《Molecules (Basel, Switzerland)》2021,26(9)
This article is devoted to some aspects of the fragrant substances of plant origin applied in the food industry and perfumery as well. Since antiquity many extractive techniques have been developed to obtain essential oils. Some of them are still applied, but new ones, like microwave or ultrasound-assisted extractions, are more and more popular and they save time and cost. Independently of the procedure, the resulting essential oils are the source of many so-called isolates. These can be applied as food additives, medicines, or can be used as starting materials for organic synthesis. Some substances exist in very small amounts in plant material so the extraction is not economically profitable but, after their chemical structures were established and synthetic procedures were developed, in some cases they are prepared on an industrial scale. The substances described below are only a small fraction of the 2000–3000 fragrant molecules used to make our life more enjoyable, either in food or perfumes. Additionally, a few examples of allelopathic fragrant compounds, present in their natural state, will be denoted and some of their biocidal features will be mentioned as an arising “green” knowledge in agriculture. 相似文献