荷叶总生物碱清除氧自由基作用的研究

应用微弱化学发光法考察荷叶总生物碱对氧自由基的清除作用,并与荷叶水提液、荷叶醇提液及维生素C进行比较.结果表明,荷叶总生物碱对3种氧自由基O-2·、·OH、H2O2的IC50分别为305 μg·mL-1、50 μg·mL-1、3700μg· mL-1,其清除·OH的能力最强,显示了较强的抗氧化活性;荷叶水提液、荷叶醇提...     

生物源杀虫剂的研究进展

从生物中寻找杀虫活性成分是目前杀虫剂研究的热点之一,现将从海洋天然产物及植物源中寻找杀虫活性成分的研究内容作一综述。海洋来源的杀虫剂从结构上讲主要是生物碱和大环内酯类化合物;植物来源的杀虫剂主要包括芳香成分、挥发油、萜类、黄酮类、生物碱类、大环内酯类和乙酸原化合物等。     

荷叶中黄酮抑菌作用的研究进展

黄酮类化合物是荷叶重要的活性成分,具有许多潜在的药用价值,其中抑菌活性是研究热点之一。综述荷叶中黄酮对细菌和真菌的抑制作用,并分析其作用机理,对荷叶中黄酮抑菌的前景进行了展望。     

药用植物中乙酰胆碱酯酶抑制剂研究进展

众多学者对植物中治疗老年性痴呆的化学成分进行了大量研究,发现了一些具有乙酰胆碱酯酶抑制的活性成分,主要为生物碱、萜、黄酮和香豆素等结构类型的化合物。其中生物碱类乙酰胆碱酯酶抑制剂如石杉碱甲、加兰他敏等因活性高、选择性强而受到广泛的关注。进一步开展药用植物中乙酰胆碱酯酶抑制活性成分研究,寻找新作用机制的化合物对发现新的治疗老年性痴呆的药用成分有重要意义。     

生物碱的提取技术研究进展

生物碱是中药中具有生理活性的重要组分,科学高效地从天然产物中提取、纯化其中的生物碱活性成分是生物碱制备的关键环节。文章对生物碱制备常用的提取工艺与新技术的应用进展进行了综述,分析了它们的原理及优缺点并探讨了发展前景。     

超声-酸性乙醇协同提取荷叶生物碱的工艺优化

在单因素实验的基础上,通过正交实验考察了pH值、料液比、超声时间、乙醇体积分数对荷叶生物碱提取率的影响。确定超声-酸性乙醇协同提取荷叶生物碱的最佳工艺为：pH值2、料液比1∶18(g∶mL)、超声时间40 min、乙醇体积分数70%,在此条件下,荷叶生物碱提取率可达3.22%。该工艺具有操作简便、提取率高、耗时短等优点,可应用于荷叶生物碱的提取。     

响应面法优化超声辅助提取荷叶总生物碱

采用超声辅助从荷叶中提取荷叶总生物碱,采用单因素实验考察了提取溶剂、溶剂pH值、料液比(g∶mL)、溶剂体积分数、提取时间和提取温度对荷叶总生物碱提取率的影响,采用响应面法优化了荷叶总生物碱的提取工艺条件。优化的工艺条件为:溶剂pH值2.0、提取温度70℃、料液比1∶32.1(g∶mL)、乙醇体积分数71.1%、提取时间65.31min,在该条件下,总生物碱的提取率达到5.06%。     

刺桐属植物的生物碱成分及其药理作用研究进展

刺桐属（Erythrina）植物的主要成分有黄酮和生物碱。其中生物碱成分的结构类型主要为刺桐生物碱,药理作用主要有增强细胞毒性,抗焦虑,抗痉挛和DPPH自由基清除作用。本文对此属中分离得到的生物碱及其药理活性的研究现状进行综述,为今后对此属植物进一步研究提供参考。     

八仙草生物碱的提取及活性成分分析

为了寻找八仙草中的抗癌活性成分,本实验对八仙草中生物碱成分进行了提取和初步分离,并对各萃取物进行了化学定性分析和体外抗癌活性检测。结果表明:氯仿、乙酸乙酯、正丁醇萃取物都具有抗癌活性,其中正丁醇萃取物活性最高,这说明水溶性生物碱可能是八仙草的抗癌活性成分。     

广东道地药材抗自由基活性组分的快速筛选

采集19种广东道地中药材,通过分类提取法分离了生物碱、多酚、皂苷和多糖组分,测定了其对DPPH自由基的清除活性,并对其主要成分进行分析评价。中药材各组分含量水平和抗自由基活性差异较大,但大部分中药材(13/19)生物碱活性较高,其次为多酚。广陈皮、何首乌、鸡血藤、广佛手和化橘红等活性组分含量和抗自由基活性均较高,具有较好开发前景。此法可快速筛选具有抗氧化活性的中药材,并得到其主要成分的相关信息,有利于中药材的开发利用。     

生物碱类化合物的研究进展

生物碱作为一类广泛存在于自然界中的碱性含氮有机化合物,数目众多,结构类型复杂。依据化学结构不同可分为异喹啉类、喹啉类、咪唑类、哌啶类、莨菪烷类、吲哚类、咔唑类、海洋多环胍类、萜类、manzamine型生物碱等。文章就部分生物碱类化合物结构研究进展进行综述。     

火焰子生物碱对酪氨酸酶的抑制作用

以磷酸缓冲溶液为反应体系、以左旋多巴为底物,采用分光光度法研究了火焰子生物碱对马铃薯酪氨酸酶活性的影响.结果表明,火焰子生物碱对马铃薯酪氨酸酶有抑制作用,抑制作用随着浓度的增大而增强,当火焰子生物碱浓度为1.25 mg·mL-1时,抑制率达最大,为29.27%,导致酶活力下降一半所需的抑制剂浓度(IC50)为0.93 ...     

Colorado Potato Beetle Toxins Revisited: Evidence the Beetle Does Not Sequester Host Plant Glycoalkaloids

The Colorado potato beetle feeds only on glycoalkaloid-laden solanaceous plants, appears to be toxic to predators, and has aposematic coloration, suggesting the beetle may sequester alkaloids from its host plants. This study tested 4th instars and adults, as well as isolated hemolymph and excrement, to determine if the beetles sequester, metabolize, or excrete alkaloids ingested from their host plants. HPLC analysis showed: that neither the larvae nor the adults sequestered either solanine or chaconine from potato foliage; that any alkaloids in the beetles were at concentrations well below 1 ppm; and that alkaloids were found in the excrement of larvae at approximately the same concentrations as in foliage. Analysis of alkaloids in the remains of fed-upon leaflet halves plus excreta during 24 hr feeding by 4th instars, as compared to alkaloids in the uneaten halves of the leaflets, showed that equal amounts of alkaloids were excreted as were ingested. The aposematic coloration probably warns of a previously-identified toxic dipeptide instead of a plant-derived alkaloid, as the Colorado potato beetle appears to excrete, rather than sequester or metabolize, the alkaloids from its host plants.     

Alkaloid Profiles,Concentration, and Pools in Velvet Lupine (<Emphasis Type="Italic">Lupinus leucophyllus</Emphasis>) Over the Growing Season

Lupinus leucophyllus is one of many lupine species known to contain toxic and/or teratogenic alkaloids that can cause congenital birth defects. The concentrations of total alkaloids and the individual major alkaloids were measured in three different years from different plant parts over the phenological development of the plant. All of the alkaloids were found in the different plant tissues throughout the growing season, although their levels varied in different tissues. Concentrations of total alkaloids and the individual alkaloids varied on an annual basis and in their distribution in the different tissues. Anagyrine levels were highest in the floral tissue, lupanine and unknown F accumulated to the greatest level in the vegetative tissue, and 5,6-dehydrolupanine accumulated to the highest level in the stem. These alkaloids appear to be in a metabolically active state with the teratogenic alkaloid anagyrine accumulating to its highest level in the developing seed. The latter is, thus, the phenological stage posing the greatest danger to grazing livestock.     

农药用生物碱的研究进展

综述了杀虫生物碱、灭鼠生物碱及灭菌生物碱的最新研究进展。苦参碱和烟碱在我国已进人工业化开发。黎芦碱、小蘖碱、雷公藤生物碱、甾醇生物碱均显示出良好的杀虫活性，番木鳖碱可用于灭鼠。而吡咯里西啶类生物碱则具有较强的杀菌活性。     

pH梯度萃取-碱性氧化铝柱层析分离长春花中的文多灵和长春质碱

利用生物碱在不同pH值下存在形式不同的性质,采用pH梯度萃取法将长春花总生物碱分为单吲哚生物碱部分（含有文多灵和长春质碱）和双吲哚生物碱部分（含有长春碱）,然后采用碱性氧化铝柱层析对单吲哚生物碱部分进行分离。pH梯度萃取后得到的单吲哚生物碱部分中文多灵和长春质碱的含量分别为18.12%和11.44%,收率分别为80.86% 和88.91%;经碱性氧化铝柱层析分离后,得到文多灵和长春质碱含量分别为85.56%和76.73%,收率分别为85.23%和86.34%;重结晶后文多灵和长春质碱纯度分别达到95.22%和98.46%,收率分别为92.15%和98.24%。此方法适合文多灵和长春质碱的工业化大规模生产。     

Alkaloids in the Mite <Emphasis Type="Italic">Scheloribates laevigatus</Emphasis>: Further Alkaloids Common to Oribatid Mites and Poison Frogs

Poison frogs are chemically defended from predators by diverse alkaloids, almost all of which are sequestered unchanged from alkaloid-containing arthropods in the frog diet. Oribatid mites recently have been proposed as a major dietary source of poison frog alkaloids. Here, we report on alkaloids common to an oribatid mite and poison frogs. Gas chromatographic-mass spectrometric analysis of methanol extracts of adult Scheloribates laevigatus (Oribatida: Scheloribatidae) revealed nine alkaloids. Five of these have been detected previously in the skin glands of poison frogs: two isomers of the pumiliotoxin 291G, two isomers of the 5,6,8-trisubstituted indolizidine 209C, and the 5,6,8-trisubstituted indolizidine 195G. The other four alkaloids, a pumiliotoxin, a tricyclic (coccinelline-like), and two isomers of an izidine, were not previously known, but are similar in structure to alkaloids found in poison frogs. Alkaloids were not detected in immature S. laevigatus, suggesting that they are adult-specific and possibly the result of mite biosynthesis. Although most of the alkaloids detected in S. laevigatus are common to poison frogs, the geographic distributions of these organisms are not sympatric. The findings of this study indicate that oribatid mites, and in particular, members of the genus Scheloribates, represent a relatively unexplored arthropod repository for alkaloids and a significant dietary source of alkaloids in poison frogs.     

Differential Allocation of Seed-Borne Ergot Alkaloids During Early Ontogeny of Morning Glories (Convolvulaceae)

Ergot alkaloids are mycotoxins that can increase host plant resistance to above- and below-ground herbivores. Some morning glories (Convolvulaceae) are infected by clavicipitaceous fungi (Periglandula spp.) that produce high concentrations of ergot alkaloids in seeds—up to 1000-fold greater than endophyte-infected grasses. Here, we evaluated the diversity and distribution of alkaloids in seeds and seedlings and variation in alkaloid distribution among species. We treated half the plants with fungicide to differentiate seed-borne alkaloids from alkaloids produced de novo post-germination and sampled seedling tissues at the cotyledon and first-leaf stages. Seed-borne alkaloids in Ipomoea amnicola, I. argillicola, and I. hildebrandtii remained primarily in the cotyledons, whereas I. tricolor allocated lysergic acid amides to the roots while retaining clavines in the cotyledons. In I. hildebrandtii, almost all festuclavine was found in the cotyledons. These observations suggest differential allocation of individual alkaloids. Intraspecific patterns of alkaloid distribution did not vary between fungicide-treated and control seedlings. Each species contained four to six unique ergot alkaloids and two species had the ergopeptine ergobalansine. De novo production of alkaloids did not begin immediately, as total alkaloids in fungicide-treated and control seedlings did not differ through the first-leaf stage, except in I. argillicola. In an extended time-course experiment with I. tricolor, de novo production was detected after the first-leaf stage. Our results demonstrate that allocation of seed-borne ergot alkaloids varies among species and tissues but is not altered by fungicide treatment. This variation may reflect a response to selection for defense against natural enemies.     

Bioactive Alkaloids from Plants Poisonous to Livestock in North America

Plants produce a multiplicity of chemical compounds which have a variety of uses including flavors, fragrances, insecticides, dyes, poisons, and pharmaceutical agents. In this review, we focus on plant alkaloids from the genera Delphinium, Lupinus, Conium, Nicotiana, Veratrum, and selected plant endophyte derived alkaloids. Alkaloids discussed include norditerpenoid alkaloids which act as antagonists to block the ligand binding sites of nicotinic acetylcholine receptors and cause acute toxicosis in adult animals which can result in death. The inhibition of fetal movement and resulting fetal defects caused by quinolizidine and piperidine alkaloids, the inhibition of the hedgehog (Hh) signaling pathway by Veratrum alkaloids, and compounds derived from fungal endophytes that form symbioses with plant hosts will be also be discussed. The bioactivity of these alkaloids makes them useful tools for research and in human and veterinary medicine or potentially harmful toxins.