软珊瑚Nephthea sp.中新生物碱分离与结构鉴定(英文)

一个新的化合物Nephoxaloid(1)具有独特的三环骨架结构和一个已知的化合物蕨藻素Caulerpin(2)从中国国西沙群岛的软珊瑚Nephthea sp.中分离得到。通过NMR和MS对它们的平面结构进行分析,化合物(1)和(2)对少数癌细胞株具有细胞毒性作用也有报道。     

蒙桑叶化学成分研究

运用大孔吸附树脂、离子交换树脂、硅胶和Sephadex LH-20等色谱方法对蒙桑Morus mongolica叶的化学成分进行分离纯化,分离得到了10个化合物。通过NMR等波谱技术确定化合物的结构,分别鉴定为l-脱氧野尻霉素(1)、Fagomine(2)、肌醇c(3)、moracin M(4)、moracin M3-O-β-D-glucopyranoside(5)、umbelliferone(6)、scopoletin(7)、syringaresinol(8)、2,4,2′,4′-tetrahydroxychalcone(9)和胡萝卜苷(10)。其中化合物2、3、5～10为首次从该植物中分离得到的,化合物9为一新天然产物。     

Zebra Mussel Antifouling Activity of the Marine Natural Product Aaptamine and Analogs

Several aaptamine derivatives were selected as potential zebra mussel (Dreissena polymorpha) antifoulants because of the noteworthy absence of fouling observed on Aaptos sponges. Sponges of the genus Aaptos collected in Manado, Indonesia consistently produce aaptamine-type alkaloids. To date, aaptamine and its derivatives have not been carefully evaluated for their antifoulant properties. Structure–activity relationship studies were conducted using several aaptamine derivatives in a zebra mussel antifouling assay. From these data, three analogs have shown significant antifouling activity against zebra mussel attachment. Aaptamine, isoaaptamine, and the demethylated aaptamine compounds used in the zebra mussel assay produced EC₅₀ values of 24.2, 11.6, and 18.6 μM, respectively. In addition, neither aaptamine nor isoaaptamine produced a phytotoxic response (as high as 300 μM) toward a nontarget organism, Lemna pausicostata, in a 7-day exposure. The use of these aaptamine derivatives from Aaptos sp. as potential environmentally benign antifouling alternatives to metal-based paints and preservatives is significant, not only as a possible control of fouling organisms, but also to highlight the ecological importance of these and similar biochemical defenses.     

Purification and Characterization of S-Adenosyl-L-Methionine Nicotinic Acid-N-Methyltransferase from Leaves of Glycine max

Trigonelline (TRG), which act as a cell cycle regulator and a compatible solute in response to salinity and water-stress, is the N-methyl conjugate of nicotinic acid the formation of which is catalyzed by S-adenosyl-L-methionine nicotinic acid-N-methyltransferase. The enzyme was purified 2650-fold from soybean (Glycine max L.) leaves with a recovery of 4 %. The purification procedure included ammonium sulfate (45 – 60 %) precipitation, linear gradient DEAE-Sepharose chromatography, adenosine-agarose affinity chromatography, hydroxyapatite chromatography and gel filtration (Sephacryl-S-200). The purified enzyme preparation showed a major band with a molecular mass of 41.5 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis that is related to the enzyme activity. The native enzyme had a molecular mass of about 85 kDa as estimated by gel filtration. The K_m values for S-adenosyl-L-methionine and nicotinic acid were 31 and 12.5 M, respectively. The purified enzyme showed optimum activity at pH 6.5 and temperature of 40 – 45 °C. High concentration of dithiothreitol (10 mM) and glycerol (20 %) stabilize the enzyme during purification and storage. Hg²⁺ strongly inhibits enzyme activity.     

Bioactive steroidal alkaloid glycosides from Solanum aculeastrum.

Solanum aculeastrum Dunal was investigated for the presence of molluscicidal compounds. This led to the isolation of solaculine A, from the root bark in addition to known steroidal alkaloids; solamargine and beta-solamarine from the berries. The structures were elucidated by spectroscopic techniques. Molluscicidal activity of the aqueous extracts of the berries and root bark, and the isolated compounds were investigated.     

Sesquiterpene pyridine alkaloids from Hippocratea excelsa

Nineteen sesquiterpene pyridine alkaloids including 17 new compounds have been isolated from the 70% aq. EtOH extract of stem barks of Hippocratea excelsa. The structures of these compounds were elucidated by various spectroscopic means.     

A rapid quantitative method for the determination of thebaine in Papaver bracteatum

A rapid method enabling a quantitative analysis of thebaine in capsules and latex of Papaver bracteatum has been devised, based on a TLC technique. This method was compared to the commonly used GLC procedure, and highly significant correlation coefficient (r = 0.90) and linear regression were found between the two methods. Values for concentrations to the nearest ±0.25% of the standard spots can be reached by this simple and rapid thebaine determination.     

Immobilized Coffea arabica cell culture using a bubble-column reactor with controlled light intensity

Coffea arabica cells immobilized by calcium alginate gel were photocultured using a bubble-column reactor under controlled light intensity. This process was carried out after their alkaloid productivity was improved by increasing the cell density in the initial gel matrix and preculturing the immobilized cells in the dark prior to light irradiation. The cells were grown in the form of a biofilm on gel beads, producing 100 mg/L of purine alkaloids in a 24-day batch culture. Alkaloid production was relatively constant with respect to light intensity changes, and also cell growth was not suppressed much at high light intensity, with these behaviors being different from those obtained using suspended cells. These phenomena are explained by estimating the light intensity gradient within the cell-immobilizing particles and by measuring the viable cell distribution within them. It subsequently suggests that the subsurface cells affect both the production and growth behaviors. (c) 1993 John Wiley & Sons, Inc.