白花曼陀罗叶总碱提取物杀线活性及其作用机理研究

为了解白花曼陀罗的杀线活性物质及其作用机理,对白花曼陀罗叶的总生物碱进行了提取鉴定,并通过测定乙酰胆碱酯酶活性及乙酰胆碱含量研究其作用机理,结果表明:生物碱是白花曼陀罗的重要杀线活性物质,可抑制线虫乙酰胆碱酯酶活性,提高线虫乙酰胆碱含量,直接作用于线虫的神经系统。     

微孔过滤对茶叶儿茶素类和生物碱HPLC检测的影响

本试验分别选用4种不同材质[尼龙66（NL66）、聚醚砜（PES）、混合纤维素（MCE）和聚四氟乙烯（PTFE）]滤膜过滤茶样浸提液,考察微孔滤膜过滤对茶叶中没食子酸、儿茶素类和嘌呤碱HPLC分析检测的影响。结果表明同种材质滤膜连续过滤获得3瓶滤液（约1mL/瓶）中的没食子酸和生物碱含量基本相当;尼龙66滤膜过滤液中的儿茶素含量存在较大的瓶间差异,但PES、MCE和PTFE滤膜过滤液并无明显的先后差别。由此可见,PES、MCE和PTFE等是茶样浸提液净化预处理较为适宜的滤膜材质,而吸附作用则可能是引起NL66滤膜过滤液中儿茶素类含量测定结果不一致的主要原因。     

Synthetic Approaches to the Lamellarins—A Comprehensive Review

The present review discusses the known synthetic routes to the lamellarin alkaloids published until 2014. It begins with syntheses of the structurally simpler type-II lamellarins and then focuses on the larger class of the 5,6-saturated and -unsaturated type-I lamellarins. The syntheses are grouped by the strategy employed for the assembly of the central pyrrole ring.     

Six New Tetraprenylated Alkaloids from the South China Sea Gorgonian Echinogorgia pseudossapo

Six new tetraprenylated alkaloids, designated as malonganenones L–Q (1–6), were isolated from the gorgonian Echinogorgia pseudossapo, collected in Daya Bay of Guangdong Province, China. The structures of 1–6 featuring a methyl group at N-3 and a tetraprenyl chain at N-7 in the hypoxanthine core were established by extensive spectroscopic analyses. Compounds 1–6 were tested for their inhibitory activity against the phosphodiesterases (PDEs)-4D, 5A, and 9A, and compounds 1 and 6 exhibited moderate inhibitory activity against PDE4D with IC₅₀ values of 8.5 and 20.3 µM, respectively.     

Seasonal Change of Loline Alkaloids in Endophyte-lnfected Meadow Fescue

Lolines are a group of saturated pyrrolizidine alkaloids that possess broad bioactivity against a wide array of herbivorous insects. However, they do not exhibit toxicity to ruminants such as cattle and sheep. In order to study the direct and potential physiological effects on ruminants and the mechanism of insecticide/insectifuge, the distribution of loline alkaloids in endophyte-infected meadow fescue and the seasonal change of the distribution were analyzed. The crowns, roots and leaves of endophyte-infected meadow fescue at its four different growth periods, i.e., spring, summer, early autumn and late autumn, in New Zealand were colleted. After powdering, organic solvent extraction and purification by column chromatography, all loline alkaloid samples were analyzed by capillary gas chromatography with 4-phenylmorpholine （PM） as an internal standard. The analytic results showed that the loline contents in the roots, crowns and leaves of endophyte-infected meadow fescue vary with seasons. Even within the same season, the distribution of lolines in endophyte-infected meadow fescue varies. During summer, lolines mainly existed in the leaves and roots, but in early autumn, they are produced in the crowns. It was concluded that, lolines were mainly produced in the leaves and roots of endophyte-infected meadow fescue. In gas chromatographic analysis, N-formylloline, the major component of loline alkaloid in the plant, was employed to assay the alkaloids.     

Relevant spatial scales of chemical variation in Aplysina aerophoba

Understanding the scale at which natural products vary the most is critical because it sheds light on the type of factors that regulate their production. The sponge Aplysina aerophoba is a common Mediterranean sponge inhabiting shallow waters in the Mediterranean and its area of influence in Atlantic Ocean. This species contains large concentrations of brominated alkaloids (BAs) that play a number of ecological roles in nature. Our research investigates the ecological variation in BAs of A. aerophoba from a scale of hundred of meters to thousand kilometers. We used a nested design to sample sponges from two geographically distinct regions (Canary Islands and Mediterranean, over 2500 km), with two zones within each region (less than 50 km), two locations within each zone (less than 5 km), and two sites within each location (less than 500 m). We used high-performance liquid chromatography to quantify multiple BAs and a spectrophotometer to quantify chlorophyll a (Chl a). Our results show a striking degree of variation in both natural products and Chl a content. Significant variation in Chl a content occurred at the largest and smallest geographic scales. The variation patterns of BAs also occurred at the largest and smallest scales, but varied depending on which BA was analyzed. Concentrations of Chl a and isofistularin-3 were negatively correlated, suggesting that symbionts may impact the concentration of some of these compounds. Our results underline the complex control of the production of secondary metabolites, with factors acting at both small and large geographic scales affecting the production of multiple secondary metabolites.     

Synthesis and Antiproliferative Activity of 2,5-bis(3′-Indolyl)pyrroles,Analogues of the Marine Alkaloid Nortopsentin

2,5-bis(3′-Indolyl)pyrroles, analogues of the marine alkaloid nortopsentin, were conveniently prepared through a three step procedure in good overall yields. Derivatives 1a and 1b exhibited concentration-dependent antitumor activity towards a panel of 42 human tumor cell lines with mean IC₅₀ values of 1.54 μM and 0.67 μM, respectively. Investigating human tumor xenografts in an ex-vivo clonogenic assay revealed selective antitumor activity, whereas sensitive tumor models were scattered among various tumor histotypes.     

An Aeroplysinin-1 Specific Nitrile Hydratase Isolated from the Marine Sponge Aplysina cavernicola

A nitrile hydratase (NHase) that specifically accepts the nitrile aeroplysinin-1 (1) as a substrate and converts it into the dienone amide verongiaquinol (7) was isolated, partially purified and characterized from the Mediterranean sponge Aplysina cavernicola; although it is currently not known whether the enzyme is of sponge origin or produced by its symbiotic microorganisms. The formation of aeroplysinin-1 and of the corresponding dienone amide is part of the chemical defence system of A. cavernicola. The latter two compounds that show strong antibiotic activity originate from brominated isoxazoline alkaloids that are thought to protect the sponges from invasion of bacterial pathogens. The sponge was shown to contain at least two NHases as two excised protein bands from a non denaturating Blue Native gel showed nitrile hydratase activity, which was not observed for control samples. The enzymes were shown to be manganese dependent, although cobalt and nickel ions were also able to recover the activity of the nitrile hydratases. The temperature and pH optimum of the studied enzymes were found at 41 °C and pH 7.8. The enzymes showed high substrate specificity towards the physiological substrate aeroplysinin-1 (1) since none of the substrate analogues that were prepared either by partial or by total synthesis were converted in an in vitro assay. Moreover de-novo sequencing by mass spectrometry was employed to obtain information about the primary structure of the studied NHases, which did not reveal any homology to known NHases.     

细果角茴香生物碱最低抑菌浓度测定

[目的]研究细果角茴香中总生物碱的抑菌活性,为细果角茴香的合理开发利用提供理论依据。[方法]采用超声辅助提取细果角茴香中总生物碱,以金黄色葡萄球菌、枯草芽孢杆菌和大肠埃希菌为供试菌种,采用琼脂平板稀释法进行MIC的测定。[结果]细果角茴香中总生物碱对供试菌种的最低抑菌浓度分别为：大肠埃希菌0．8mg／ml,金黄色葡萄球菌0．4mg／ml,枯草芽孢杆菌1．6mg／ml。[结论]细果角茴香总生物碱对供试细菌都有一定的抑菌作用。     

Magnificines A and B,Antimicrobial Marine Alkaloids Featuring a Tetrahydrooxazolo[3,2-a]azepine-2,5(3H,6H)-dione Backbone from the Red Sea Sponge Negombata magnifica

Investigation of the Red Sea sponge Negombata magnifica gave two novel alkaloids, magnificines A and B (1 and 2) and a new β-ionone derivative, (±)-negombaionone (3), together with the known latrunculin B (4) and 16-epi-latrunculin B (5). The analysis of the NMR and HRESIMS spectra supported the planar structures and the relative configurations of the compounds. The absolute configurations of magnificines A and B were determined by the analysis of the predicted and experimental ECD spectra. Magnificines A and B possess a previously unreported tetrahydrooxazolo[3,2-a]azepine-2,5(3H,6H)-dione backbone and represent the first natural compounds in this class. (±)-Negombaionone is the first β-ionone of a sponge origin. Compounds 1-3 displayed selective activity against Escherichia coli in a disk diffusion assay with inhibition zones up to 22 mm at a concentration of 50 µg/disc and with MIC values down to 8.0 µM. Latrunculin B and 16-epi-latrunculin B inhibited the growth of HeLa cells with IC₅₀ values down to 1.4 µM.