抑制麦角甾醇生物合成的杀菌剂抗性研究

七十年代开发的许多杀菌剂,已知是麦角甾醇(固醇)生物合成抑制剂。从结构上可以分为六种类型,即吗啉类、哌嗪类、咪唑类、三唑类、吡啶类和嘧啶类。它们的生物活性范围虽然有所不同,但是它们都是防治各种白粉病的特效药剂,对那些生物膜中缺乏甾醇的真菌,如卵菌,都没有好的活性作用;其中有些化合物对多种子囊菌、担子菌和半知菌具有广谱的生物活性,也有的只对白粉病有效。绝大多数化合物能被植物吸收,并且能在植物体内输导。因此,它们也是内吸性杀菌剂。上述六种类型杀菌剂并不都是在同一位点抑制甾醇的生物合成。已知嘧啶类、哌嗪类、     

Koenigs-Knorr糖基化反应的研究进展

糖苷化合物广泛存在于药物分子和天然产物中,且具有重要的生物活性.Koenigs-Knorr糖基化反应作为构筑糖苷键的经典反应,被广泛应用于糖苷化合物的合成,已成为当今糖化学领域的一个研究热点.本文简单介绍Koenigs-Knorr糖基化反应及其特点,重点介绍近年来发展的一系列Koenigs-Knorr糖基化反应进展.     

烟草化学成分农用生物活性研究进展

烟草次生代谢产物丰富,是传统的植物源农药资源。综述了烟草生物碱类、酚类、糖酯类、萜类、糖苷类化合物抗虫、抑菌、抗病毒等农用生物活性研究进展,重点总结了烟碱、绿原酸、东莨菪内酯以及西柏三烯二醇等主要化合物的农业应用研究情况。提出了烟草作为植物源农药资源开发与利用存在的问题,展望了其开发利用前景,以期为开发烟草在植物源农药方向的利用价值提供研究思路。     

具除草活性的新颖平板霉素衍生物

<正>生物活性次级代谢产物还没有被有效地用于新农药的开发。这些天然产品为新产品的开发提供着灵感,如倍半萜内酯具有消炎、抗发芽、植物毒性和抗癌等多种生物活性。倍半萜烯主要由菊科植物生物合成,但也可从真菌Biscogniauxia nummularia分离得到,是新的一类具有发展前景的生物活性物质。天然倍半萜烯化合物去氢木香烃内酯(1)、木香烃内酯(2)、α-山道年(3),合成衍生物α-亚甲基-α-山     

大孔吸附树脂分离纯化黄酮类化合物的研究进展

黄酮类化合物是在植物中分布非常广泛的一类天然产物,具有多种生物活性。大孔吸附树脂纯化是一项不需复杂设备、操作条件温和的新型分离技术。综述了大孔吸附树脂分离纯化黄酮类化合物的研究进展。     

国外植物源杀虫剂研究进展

综述了近几年国外植物源杀虫活性天然产物的研究进展.主要介绍了生物碱类、萜烯类、酯类、酮和醌类以及其它种类的植物源杀虫剂对各种害虫的效果.特别介绍了一些新颖化学结构的生物活性化合物及其构效关系,并探讨了害虫化学防治的新途径以及植物源杀虫剂的应用前景.     

植物精油及化合物对埃及伊蚊幼虫的生物活性

植物精油及化合物对登革热的主要媒介埃及伊蚊幼虫具有杀幼虫活性。从269种植物中提取的361个植物精油中,超过60%具有较高的生物活性(LC_(50)100 mg/L),这些植物主要为桃金娘科、唇形科和芸香科。精油中富含苯丙烷类、倍半萜烯类和单萜烯类物质具有最高的活性。着重介绍了植物精油对埃及伊蚊幼虫的活性、影响精油的活性因素、分子结构与活性相关性及精油及化合物的作用机理。     

山药的化学成分及其生物活性研究进展

山药为薯蓣科薯蓣属植物,具有药用和食用价值,其主要化学成分为多糖、环肽类和腺苷类化合物。其中多糖类化合物具有广泛的生物活性和药理作用。文章对近年来山药的化学成分和生物活性的研究进行了综述。     

具有生物活性的异噻唑类化合物研究进展

异噻唑类化合物正逐渐成为农药的一个重要类别。按照化合物结构类型的不同将具有生物活性的异噻唑类化合物归纳为糖精类、胺类、异噻菌胺类似物、磺酰脲类、脲类、酰胺类及其他类共7类化合物。概述了这些类别中具有较好生物活性的化合物,同时介绍了研发此类化合物的创制经纬并对其研究趋势进行了展望,为以后该类化合物的研究提供了思路和依据。     

具有农药活性的哌啶类化合物的研究进展

哌啶类杂环化合物具有广泛的生物活性,如杀虫、杀菌、除草、抗植物病毒活性,具有选择性好、活性高、毒性低等特点,正逐渐成为农药的一个重要类别。将近年来文献报道的哌啶类化合物结构特点进行归类,分为哌啶醇类、肉桂哌啶类、哌啶噻唑类和其他类,并对该类化合物的研究趋势进行了展望。     

Steryl glycoside biosynthesis

The existence of steroid glycosides has been known for many years and, more recently, their derivatives have been described. Steroid glycosides have been isolated from a number of organisms, however, the largest number of these compounds are found in plants. As to glycoside biosynthesis, the sterols are the most extensively studied steroid group. Of the sterols, only the 4-demethyl sterols have been isolated as glycosides. The glycosidic bond formation is mediated through nucleotide sugars, and UDP-glucose appears to be the most active glycosyl donor. In cell-free studies, the pH of the incubation medium is quite critical and depends on the tissue under investigation, but generally the optimum is near pH 7.0. Formation of steryl glycosides is particulate in nature and is stimulated by ATP, Ca²⁺, and Mg²⁺. Similar results are obtained, regardless whether the sterol or the sugar moiety is labeled. Formation of acylsteryl glycosides could occur via two pathways: through the acylation of steryl glycosides or through the transfer of an acylglycosyl unit to a sterol moiety. Results from in vitro experiments suggest that acylsteryl glycoside formation occurs via steryl glycosides. Two acyl transfer reactions have been demonstrated; one is microsomal in nature and involves phosphatidylethanolamine, while the other reaction involves a soluble enzyme and requires galactolipids. In vivo experiments, however, indicate that a second pathway may also exist. If cholesterol-4-¹⁴C is used as substrate, a highly radioactive component can be isolated which is readily converted to acylsteryl glycoside, but not to free sterol or steryl glycoside. It is suggested that this component is an intermediate in acylsteryl glycoside biocynthesis. At present, the nature of the component is unknown. It is quite stable, and acid hydrolysis produces free sterol. Saponification produces two products which in thin layer chromatograms closely resemble acylsteryl glycoside.     

Assembly of naturally occurring glycosides, evolved tactics, and glycosylation methods

Glycosylation of proteins and lipids is critical to many life processes. Secondary metabolites (or natural products), such as flavonoids, steroids, triterpenes, and antibiotics, are also frequently modified with saccharides. The resulting glycosides include diverse structures and functions, and some of them have pharmacological significance. The saccharide portions of the glycosides often have specific structural characteristics that depend on the aglycones. These molecules also form heterogeneous "glycoform" mixtures where molecules have similar glycosidic linkages but the saccharides vary in the length and type of monosaccharide unit. Thus, it is difficult to purify homogeneous glycosides in appreciable amounts from natural sources. Chemical synthesis provides a feasible access to the homogeneous glycosides and their congeners. Synthesis of a glycoside involves the synthesis of the aglycone, the saccharide, the connection of these two parts, and the overall manipulation of protecting groups. However, most synthetic efforts to date have focused on the aglycones, treating the attachment of saccharides onto the aglycones as a dispensable topic. The synthesis of the aglycone and the synthesis of the saccharide belong to two independent categories of chemistry, and different types of the aglycones and saccharides pose as specific synthetic subjects in their own disciplines. The only reaction that integrates the broad chemistry of glycoside synthesis is the glycosidic bond formation between the saccharide and the aglycone. Focusing on this glycosylation reaction in this Account, we string together our experience with the synthesis of the naturally occurring glycosides. We briefly describe the synthesis of 18 glycosides, including glycolipids, phenolic glycosides, steroid glycosides, and triterpene glycosides. Each molecule represents a prototypical structure of a family of the natural glycosides with interesting biological activities, and we emphasize the general tactics for the synthesis of these diverse structures. We provide a rationale for four tactics for the synthesis of glycosides, based on the stage at which the glycosidic bond is formed between the saccharide and the aglycone. This choice of tactic determines the success or failure of a synthesis, and the flexibility and the overall efficiency of the synthesis as well. Toward the synthesis of heterogeneous glycoform mixtures, we discuss successive and random glycosylation reactions. Finally, we have developed two new glycosylation protocols that address the challenges in the glycosylation of aglycones that are poorly nucleophilic, extremely acid labile, or extremely electrophilic. One of these new protocols takes advantage of glycosyl trifluoroacetimidate donors, and a second protocol uses gold(I)-catalyzed glycosylation with glycosyl ortho-alkynylbenzoate donors.     

具有生物活性不饱和酸及其衍生物研究进展

源自天然产物不饱和酸衍生物具有新颖的化学结构和多种生物活性。综述了近年来天然不饱和酸衍生物及仿生合成不饱和酸衍生物的研究进展,初步总结了它们的生物活性。     

Astonishing diversity of natural surfactants: 6. Biologically active marine and terrestrial alkaloid glycosides

This review article presents 209 alkaloid glycosides isolated and identified from plants, microorganisms, and marine invertebrates that demonstrate different biological activities. They are of great interest, especially for the medicinal and/or pharmaceutical industries. These biologically active glycosides have good potential for future chemical preparation of compounds useful as antioxidants, anticancer, antimicrobial, and antibacterial agents. These glycosidic compounds have been subdivided into several groups, including: acridone; aporphine; benzoxazinoid; ergot; indole; enediyne alkaloidal antibiotics; glycosidic lupine alkaloids; piperidine, pyridine, pyrrolidine, and pyrrolizidine alkaloid glycosides; glycosidic quinoline and isoquinoline alkaloids; steroidal glycoalkaloids; and miscellaneous alkaloid glycosides. For the previous article in this series, see Reference 1.     

Astonishing diversity of natural surfactants: 7. Biologically active hemi- and monoterpenoid glycosides

This review article presents 90 hemi- and 188 monoterpenoid glycosides, isolated and identified from plants and microorganisms, that demonstrate different biological activities. These natural bioactive glycosides are good prospects for future chemical preparations from these compounds as antioxidants and as anticancer, antimicrobial, and antibacterial agents. These glycosidic compounds have been subdivided into several groups, including hemiterpenoids; acyclic, monocyclic, and bicyclic monoterpenoids; and iridoid monoterpenoids. For the previous article in this series, see Reference 1.     

Systemic,genotype-specific induction of two herbivore-deterrent iridoid glycosides in Plantago lanceolata L. in response to fungal infection by Diaporthe adunca (Rob.) Niessel

Iridoid glycosides are a group of terpenoid secondary plant compounds known to deter generalist insect herbivores. In ribwort plantain (Plantago lanceolata), the iridoid glycosides aucubin and catalpol can be induced following damage by insect herbivores. In this study, we investigated whether the same compounds can be induced following infection by the fungal pathogen Diaporthe adunca, the causal agent of a stalk disease in P. lanceolata. Significant induction of aucubin and catalpol was observed in two of the three plant genotypes used in this study following inoculation with the pathogen. In one of the genotypes, induction occurred within 6 hr after inoculation, and no decay was observed within 8 days. The highest level of induction was observed in reproductive tissues (spikes and stalks) where infection took place. In these tissues, iridoid glycoside levels in infected plants were, on average, 97% and 37% higher than the constitutive levels in the corresponding control plants, respectively. Significant induction was also observed in leaves (24%) and roots (17%). In addition to significant genotypic variation in the level of induction, we found genetic variation for the tissue-specific pattern of induction, further broadening the scope for evolutionary fine-tuning of induced responses. Recent studies have revealed a negative association between iridoid glycoside levels in P. lanceolata genotypes and the amount of growth and reproduction of D. adunca that these genotypes support. However, for the three genotypes used in the present study, differences in resistance were not related to their constitutive or induced levels of iridoid glycosides, suggesting that additional resistance mechanisms are important in this host-pathogen system. We conclude that iridoid glycosides in P. lanceolata can be induced both by arthropods and pathogenic micro-organisms. Pathogen infection could, therefore, potentially enhance resistance to generalist insect herbivores in this species.     

烷基糖苷衍生物在清洗剂中的发展前景

烷基糖苷是世界一流的可再生绿色非离子型表面活性剂,其衍生物在保留有烷基糖苷(APG)优异性能的基础上,解决了烷基糖苷难溶于水,抗硬水性差等缺点。烷基糖苷衍生物性能温和,在去污性和安全性等方面具有明显优势。论述了烷基糖苷衍生物的合成及其在清洗领域的发展前景。     

Surfactants from fatty esters of polyalkoxylated polyol glycosides

The glycoside raw materials used to prepare the surfactants were mixtures produced directly from low cost starch and the polyols by transglycosidation. After alkoxylation with ethylene oxide and propylene oxide, the glycosides were transesterified by the methyl esters of various fatty acids to yield the final products. Monolaurates of the polyalkoxylated glycosides containing a combination of 8 mol ethylene oxide and 4 mol propylene oxide per mole of glycoside showed detergency in an alkaline formulation comparable to two commercial detergents. An advantage in this application is the potential for complete biodegradation because of the fatty ester carbohydrate structures. The two monolaurates of glycerol glycoside polyethers containing 4.8 and 8 mol propylene oxide, in particular, produced oil-inwater emulsions of high stability. ARS, USDA.     

Iridoid Glycoside Variation in the Invasive Plant Dalmatian Toadflax, <Emphasis Type="Italic">Linaria dalmatica</Emphasis> (Plantaginaceae), and Sequestration by the Biological Control Agent, <Emphasis Type="Italic">Calophasia lunula</Emphasis>

Invasive plant species can have significant ecological and economic impacts. Although numerous hypotheses highlight the importance of the chemical defenses of invasive plant species, the chemical ecology of many invasive plants has not yet been investigated. In this study, we provide the first quantitative investigation of variation in iridoid glycoside concentrations of the invasive plant Dalmatian toadflax (Linaria dalmatica). We examined variation in chemical defenses at three levels: (1) variation within and among populations; (2) variation due to phenology and/or seasonal differences; and (3) variation among plant parts (leaves, flowers, and stems). Further, we examined two biological control agents introduced to control L. dalmatica for the ability to sequester iridoid glycosides from this invasive plant. Results indicate that L. dalmatica plants can contain high concentrations of iridoid glycosides (up to 17.4% dry weight of leaves; mean = 6.28 ± 0.5 SE). We found significant variation in iridoid glycoside concentrations both within and among plant populations, over the course of the growing season, and among plant parts. We also found that one biological control agent, Calophasia lunula (Lepidoptera: Noctuidae), was capable of sequestering antirrhinoside, an iridoid glycoside found in L. dalmatica, at levels ranging from 2.7 to 7.5% dry weight. A second biological control agent, Mecinus janthinus (Coleoptera: Curculionidae), a stem-mining weevil, did not sequester iridoid glycosides. The demonstrated variation in L. dalmatica chemical defenses may have implications for understanding variation in the degree of invasiveness of different populations as well as variation in the efficacy of biological control efforts.