超临界萃取技术在生物碱提取中的应用进展

超临界流体萃取技术具有选择性好、收率高、工艺简单、操作条件温和、绿色环保等优点,已被广泛应用于中草药的提取分离中。以生物碱的生物活性分类,综述了超临界萃取技术在各种天然生物碱提取中的应用研究现况及其特点。针对超临界萃取技术在提取生物碱中的发展前景及目前所存在的问题进行分析讨论。结果表明,它能够有效地从植物中提取或分离出生物碱,且与其它的分离手段相结合将是天然药物生物碱今后的提取分离发展方向。     

响应面法优化管萼山豆根总生物碱提取工艺

采用微波控温辅助超声波的方法提取管萼山豆根茎中总生物碱,通过单因素法和响应面法优化了提取工艺,考察了管萼山豆根茎中总生物碱对1, 1-二苯基-2-三硝基苯肼自由基(DPPH·)、2, 2-联氮-二-3-乙基-苯并噻唑-6-磺酸自由基(ABTS·)和超氧阴离子自由基(O2?·)的清除作用。结果表明,模型优化并修正的最佳工艺条件为:提取时间37.8 min,微波加热温度64.5℃,超声功率575 W,乙醇体积分数95%,在该条件下总生物碱得率为0.5418%,高于不采用微波超声辅助的0.2436%、超声辅助的0.4538%、乙醇回流的0.3884%。管萼山豆根茎中总生物碱在DPPH·、ABTS·、邻苯三酚浓度分别为0.1、7.0、8.0 mmol/L条件下,其半数抑制质量浓度(IC50)分别为0.891、0.552和0.390 g/L。     

黄柏化学成分研究

对黄柏树皮Phellodendron chinese Schneid的化学成分进行研究,从中寻找有重要生物活性及药用前景的天然化合物.采用硅胶柱色谱法结合制备高效液相进行分离和纯化,根据理化性质和波谱数据进行结构鉴定.从黄柏树皮的乙醇提取物中分离得到6个化合物,分别为异阔果芸香碱(Ⅰ),γ-花椒碱(Ⅱ),茵芋碱(Ⅲ),铁屎米酮(Ⅳ),阿魏酸(Ⅳ),5-O-阿魏酰基奎宁酸(Ⅵ).化合物Ⅰ为首次从该属植物中分离得到.     

无叶假木贼杀虫有效部位的研究

依次通过酸水煮沸、煤油萃取和不同酸碱度下氯仿萃取煤油层，从无叶假木贼中得到两个提取部位。田间杀虫试验证明其中一部位有良好的杀虫效果。对该杀虫有效部位进行化学成分分析．通过薄层层析和气相色谱-质谱方法，证明有效部位的主要成分是毒藜碱和羽扇豆碱。     

Simultaneous Microwave Extraction and Separation of Volatile and Non-Volatile Organic Compounds of Boldo Leaves. From Lab to Industrial Scale

Microwave extraction and separation has been used to increase the concentration of the extract compared to the conventional method with the same solid/liquid ratio, reducing extraction time and separate at the same time Volatile Organic Compounds (VOC) from non-Volatile Organic Compounds (NVOC) of boldo leaves. As preliminary study, a response surface method has been used to optimize the extraction of soluble material and the separation of VOC from the plant in laboratory scale. The results from the statistical analysis revealed that the optimized conditions were: microwave power 200 W, extraction time 56 min and solid liquid ratio of 7.5% of plants in water. Lab scale optimized microwave method is compared to conventional distillation, and requires a power/mass ratio of 0.4 W/g of water engaged. This power/mass ratio is kept in order to upscale from lab to pilot plant.     

Gene Discovery in Gelsemium Highlights Conserved Gene Clusters in Monoterpene Indole Alkaloid Biosynthesis

Genome mining is a routine technique in microbes for discovering biosynthetic pathways. In plants, however, genomic information is not commonly used to identify novel biosynthesis genes. Here, we present the genome of the medicinal plant and oxindole monoterpene indole alkaloid (MIA) producer Gelsemium sempervirens (Gelsemiaceae). A gene cluster from Catharanthus roseus, which is utilized at least six enzymatic steps downstream from the last common intermediate shared between the two plant alkaloid types, is found in G. sempervirens, although the corresponding enzymes act on entirely different substrates. This study provides insights into the common genomic context of MIA pathways and is an important milestone in the further elucidation of the Gelsemium oxindole alkaloid pathway.     

嘌呤生物碱~（13）C－NMR化学位移的研究（Ⅰ）──化学位移加合和降阶模型

运用数学模型对天然嘌呤生物碱￣（１３）Ｃ－ＮＭＲ化学位移数据进行系统研究表明化学位移相对于未取代母体的增量具有良好的加合性和降解性，并对某些未知物的￣（１３）Ｃ－ＮＭＲ化学位移进行了预测。     

Acquired and Partially De Novo Synthesized Pyrrolizidine Alkaloids in Two Polyphagous Arctiids and the Alkaloid Profiles of Their Larval Food-Plants

The profiles of pyrrolizidine alkaloids (PAs) in the two highly polyphagous arctiids Estigmene acrea and Grammia geneura and their potential PA sources in southeastern Arizona were compiled. One of four species of Boraginaceae, Plagiobothrys arizonicus, contained PAs; this is the first PA record for this plant species. The principle PA sources are Senecio longilobus (Asteraceae) and Crotalaria pumila (Fabaceae). The known PA pattern of S. longilobus was extended; the species was found to contain six closely related PAs of the senecionine type. Three novel PAs of the monocrotaline type, named pumilines A-C, were isolated and characterized from C. pumila, a species not studied before. The pumilines are the major PAs in the seeds, while in the vegetative organs they are accompanied by the simple necine derivatives supinidine and as the dominant compound subulacine (1beta,2beta-epoxytrachelanthamidine). In both plant species, the PAs are stored as N-oxides, except C. pumila seeds, which accumulate the free bases. Great variation in PA composition was observed between local populations of C. pumila. The PA profiles were established for larvae and adults of E. acrea that as larvae had fed on an artificial diet supplemented with crotalaria-powder and of G. geneura fed with S. longilobus. In both experiments, the larvae had a free choice between the respective PA source and diet or food plants free of PAs. The profiles compiled for the two species reflect the alkaloid profiles of their PA sources with one exception, subulacine could never be detected in E. acrea. Besides acquired PAs, insect PAs synthesized from acquired necine bases and necic acids of insect origin were detected in the two arctiid species. These insect PAs that do not occur in the larval food sources accounted for some 40-70% (E. acrea) and 17-37% (G. geneura) of total PAs extracted from the insects. A number of novel insect PAs were identified. Plant-acquired and insect PAs were found to accumulate as N-oxides. The results are discussed in relation to specific biochemical, electrophysiological, and behavioral mechanisms involved in PA sequestration by arctiids.     

Distribution of Norditerpene Alkaloids in Tall Larkspur Plant Parts Through the Growing Season

Previous research showed that toxic and total alkaloid pools in tall larkspur (Delphinium barbeyi) increased during early growth, then declined precipitously during the late flower and pod stage of growth. The objective of this study was to measure the concentration and pools of toxic and total alkaloids in tall larkspur plant parts, including roots, and to evaluate the changes in these pools over the growing season as an estimate of diterpenoid alkaloid kinetics in tall larkspur. Twenty entire plants were harvested at each phenological stage: beginning of growth in the spring, early flower, early pod, late pod, and senescence. The plants were separated into their respective parts, freeze-dried, extracted, and analyzed for toxic and total alkaloid concentration, and alkaloid pools were calculated. Concentration of toxic and total alkaloids in leaves and stems declined as the plants matured, while concentration in flowers and pods increased (P < 0.004). Concentration of alkaloids in the root declined in the early growth, then increased at the end of the season (P = 0.002). Alkaloid pools in the root decreased during early growth, with a corresponding increase of pools in foliar parts. In the late flower and pod stage, alkaloid pools in the leaves and stems declined rapidly, while the pool in the crown and roots tended to increase.     

Response of the Ladybird Parasitoid Dinocampus coccinellae to Toxic Alkaloids from the Seven-spot Ladybird, Coccinella septempunctata

Electrophysiological and behavioral responses of the ladybird parasitoid Dinocampus coccinellae to volatiles from the seven-spot ladybird, Coccinella septempunctata, were investigated to identify semiochemicals involved in host location. Coupled gas chromatography–electroantennography (GC-EAG) with D. coccinellae located a small peak of prominent activity in an extract of volatiles from adult C. septempunctata. The active compound was identified by coupled GC-mass spectrometry and by comparison with an authentic sample as the free-base alkaloid precoccinelline, which forms part of the toxic defense of this ladybird. Behavioral studies in an olfactometer showed that D. coccinellae was significantly attracted to the volatile extract and also to the alkaloid. Myrrhine, a stereoisomer of precoccinelline found in low amounts in C. septempunctata and in other ladybird species, was shown to be electrophysiologically active and significantly attractive. Perception of ladybird alkaloids by D. coccinellae is a rare example of toxicants acting as aerially transmitted cues for interactions between the third and fourth trophic levels.