Penifulvin A: a sesquiterpenoid-derived metabolite containing a novel dioxa[5,5,5,6]fenestrane ring system from a fungicolous isolate of Penicillium griseofulvum

[structure: see text] Penifulvin A (1), a new fungal metabolite with a previously undescribed ring system, has been isolated from cultures of an isolate of Penicillium griseofulvum (NRRL 35584) obtained from a white mycelial growth on a dead hardwood branch collected in a Hawaiian forest. The structure was assigned by analysis of NMR data and confirmed by single-crystal X-ray diffraction analysis. Penifulvin A (1) shows significant activity in dietary assays against the fall armyworm Spodoptera frugiperda.     

Citrinadin A, a novel pentacyclic alkaloid from marine-derived fungus Penicillium citrinum

[structure: see text] A novel pentacyclic alkaloid, citrinadin A (1), was isolated from the cultured broth of the fungus Penicillium citrinum, which was separated from a marine red alga, and the structure was elucidated by spectroscopic data. The relative stereochemistry of the pentacyclic core was assigned on the basis of NOESY data and (1)H-(1)H coupling constants, and the presence of an N,N-dimethyl-L-valine residue in 1 was determined by chiral HPLC analysis of the hydrolysate.     

Implementation of radiotelemetry in a lab-in-a-pill format

A miniaturised lab-in-a-pill device has been produced incorporating a temperature and pH sensor with wireless communication using the 433.92 MHz ISM band. The device has been designed in order to enable real time in situ measurements in the gastrointestinal (GI) tract, and accordingly, issues concerning the resolution and accuracy of the data, and the lifetime of the device have been considered. The sensors, which will measure two key parameters reflecting the physiological environment in the GI (as indicators for disease) were both controlled by an application specific integrated circuit (ASIC). The data were sampled at 10-bit resolution prior to communication off chip as a single interleaved data stream. This incorporated a power saving serial bitstream data compression algorithm that was found to extend the service lifetime of the pill by 70%. An integrated on-off keying (OOK) radio transmitter was used to send the signal to a local receiver (base station), prior to acquisition on a computer. A permanent magnet was also incorporated in the device to enable non-visual tracking of the system. We report on the implementation of this device, together with an initial study sampling from within the porcine GI tract, showing that measurements from the lab-on-a-pill, in situ, was within 90% of literature values.     

一种天然产物Wangzaozin A的细胞毒活性

从总序香茶菜Isodon racemosa (Hemsl) Hara植物中分离得到一个对人类肿瘤细胞Bel-7402和HD-8910具有毒活性的对映-贝壳衫烷型二萜Wangzaozin A化合物(1). 应用密度泛函理论(DFT)B3LYP方法, 对该分子的几何构型进行优化, 结果表明用B3LYP/6-31G(d)优化的几何参数与它的X射线衍射结构参数基本一致. 在优化的几何构型基础上, 采用规范不变原子轨道(GIAO)法, 在B3LYP理论水平分别用6-31G(d), 6-31G(d,p), 6-31+G(d,p)和6-31++G(d,p)基组进行核磁共振(NMR)化学位移值计算, 预测的1H和13CNMR化学位移值与实验值吻合; 统计误差分析表明, 用B3LYP/6-31G(d)优化的分子构型接近实际的分子构型. 因此, DFT方法适用这一类型化合物的构型和NMR参数进行预测. 在几何优化的基础上, 在B3LYP/6-31G(d)水平上, 对Wangzaozin A分子的静电位(MEP)进行理论计算. MEP三维图表明, 在Wangzaozin A分子中α-亚甲基环戊酮的羰基和羟基附近出现富电子区域(负电位), 起着供电子作用, 与受体的正电子区域结合. 这些结果从理论上支持了α-亚甲基环戊酮结构是一种抗肿瘤活性中心的看法.     

Nagelamide J, a novel dimeric bromopyrrole alkaloid from a sponge Agelas species

A novel dimeric bromopyrrole alkaloid, nagelamide J (1), with antimicrobial activity has been isolated from an Okinawan marine sponge Agelas species, and the structure and stereochemistry were elucidated from spectroscopic data. Nagelamide J (1) is the first bromopyrrole alkaloid possessing a cyclopentane ring fused to an amino imidazole ring.     

Tamandarins A and B: new cytotoxic depsipeptides from a Brazilian ascidian of the family Didemnidae

The structures of two new, naturally occurring cytotoxic depsipeptides, tamandarins A and B (1 and 2), are presented. The tamandarins were isolated from an unidentified Brazilian marine ascidian of the family Didemnidae. The structures of the new cytotoxins were assigned by interpretation of FABMS data and by extensive 2D NMR analyses. The absolute configurations of the tamandarins were assigned by acid and alkaline hydrolysis to yield their corresponding amino acids, which were then analyzed as their Marfey derivatives. The cytotoxicity of tamandarin A (1) was evaluated against various human cancer cell lines and shown to be slightly more potent than didemnin B. A qualitative discussion of the conformation of tamandarin A (1) in solution, obtained from NMR J-value data, variable temperature experiments, and NOESY/ROESY data, is included.     

Callynormine A, a new marine cyclic peptide of a novel class

[structure: see text] A novel cyclic peptide, callynormine A, was isolated from the Kenyan marine sponge Callyspongia abnormis and its structure elucidated by interpretation of its NMR data and X-ray diffraction analysis. Callynormine A represents a new class of heterodetic cyclic peptides (designated endiamino peptides) possessing an alpha-amido-beta-aminoacrylamide cyclization functionality.     

Neocrocin A: a novel crocetin glycoside with a unique system for binding sugars isolated from gardenia yellow

A novel crocetin glycosyl ester, neocrocin A (2), was isolated from gardenia yellow. The structure of 2 was elucidated as that of an all-trans-crocetin beta-D-gentiobiosyl beta-D-glucopyranosyl-(1-->6)-D-2-deoxy-glucopyranos-2-yl diester based on chemical and spectral data. The findings provide evidence that the binding system of crocetin glycosides is not limited to the anomeric position.     

Neojaponicone A, a bioactive sesquiterpene lactone dimer with an unprecedented carbon skeleton from Inula japonica

Five new dimeric sesquiterpene lactones, neojaponicone A (1) and japonicones M-P (2-5) were isolated from the aerial part of Inula japonica. Neojaponicone A (1) has an unprecedented carbon skeleton with an unusual valerolactone system formed between a guaianolide and an eudesmane. The structure and absolute configuration of 1 were established by extensive analysis of spectroscopic data and computational approaches.     

Application of high-field NMR and cryogenic probe technologies in the structural elucidation of poecillastrin a,a new antitumor macrolide lactam from the sponge poecillastra species

Poecillastrin A (1), a new polyketide-derived macrolide lactam, was isolated from a deep-water collection of the marine sponge Poecillastra species. The structure of poecillastrin A (1) was assigned using NMR data acquired at 500 MHz with an inverse-detection cryogenic probe and at 800 MHz with a room-temperature probe.     

Isolation, structural characterization, and synthesis of a naturally occurring bisfuranopseudopterane ether: biskallolide A. Evidence for a carbocation intermediate during the facile conversion of kallolide A and isokallolide A into various solvolysis products

The West Indian alcyonacean Pseudopterogorgia bipinnata (Verrill, 1864) is shown to contain a novel bisditerpenoid ether: biskallolide A (2). The structural assignment of 2 was mainly based on 1D and 2D NMR and MS spectral data and was further confirmed by synthesis. The 2-C-alkoxylation of furanopseudopteranes kallolide A (1) and isokallolide A (8) occurs spontaneously in some solvents and involves replacement of the C2 hydroxyl with an alkoxyl group to yield solvolysis products that display net retention of configuration. The facile solvolytic 2-C-acyloxylation of kallolide A was achieved readily under similar circumstances to afford kallolide A acetate (4) as the sole product. Mechanistic details in conversion of alcohols 1 and 8 into various solvolysis products, including dimeric ethers 2 and 9, were investigated in this study. Solvolysis of kallolide A and isokallolide A in [(18)O]-labeled solvent demonstrated that the C2 alkoxyl of the solvolysis products originated from the solvent, suggesting that these conversions may proceed through an S(N)1 mechanism with generation of a carbocation intermediate. The chemical structures of kallolide A derivatives 3-7and those of isokallolide A congeners 9-11 were established by detailed analysis of the spectral data.     

Equation of state of aqueous NaCl solutions over a wide range of temperatures, pressures and concentrations

This work describes an equation of state for calculating the density of aqueous, liquid-phase NaCl solutions, based on an analytical equation for a mixture of hard-sphere ions and dipoles in the mean spherical approximation. The equation gives reasonable accuracy at temperatures from 273 to 973 K, pressures from 0.1 to 1000 MPa, concentrations from 0 to 50 wt.%, and densities higher than 650 kg m⁻³. The observed data of Hilbert (1979), Rogers and Pitzer (1982) and Urusova (1975) are fitted with only 10 empirically adjusted parameters plus the two water molecule parameters (diameter and dipole moment) which were determined from the density and dielectric properties of water. A comparison of the calculated and observed density data is presented. Errors in the calculated values vary from 0.5 to 1.5% over the whole range of temperature, pressure and concentration. A table of densities at temperatures from 273 to 973 K, pressures from 0.1 to 1000 MPa and concentrations from 0 to 50 wt.% is presented.     

Determination of trace levels of diosmin in a pharmaceutical preparation by adsorptive stripping voltammetry at a glassy carbon electrode.

A systematic study on the electrochemical behavior of diosmin in Britton-Robinson buffer (pH 2.0-10.0) at a glassy carbon electrode (GCE) was made. The oxidation process of the drug was found to be quasi-reversible with an adsorption-controlled step. The adsorption stripping response was evaluated with respect to various experimental conditions, such as the pH of the supporting electrolyte, the accumulation potential and the accumulation time. The observed anodic peak current at +0.73 V vs. Ag/AgCl reference electrode increased linearly over two orders of magnitude from 5.0x10(-8) M to 9.0x10(-6) M. A limit of detection down to 3.5x10(-8) M of diosmin at the GCE was achieved with a mean recovery of 97+/-2.1%. Based on the electrochemical data, an open-circuit accumulation step in a stirred sample solution of BR at pH 3.0 was developed. The proposed method was successfully applied to the determination of the drug in pharmaceutical formulations. The results compared favorably with the data obtained via spectrophotometric and HPLC methods.     

Ipomoeassin F, a new cytotoxic macrocyclic glycoresin from the leaves of Ipomoea squamosa from the Suriname rainforest

A new cytotoxic macrocyclic glycoresin, ipomoeassin F (6), has been isolated from the leaves of Ipomoea squamosa. The structure was elucidated by the interpretation of spectral data. Compound 6 was strongly active in the A2780 (human ovarian cancer cell line) assay with an IC(50) value of 0.036 microM.     

Nordehydrocyclodercitin, a hexacyclic pyridoacridine alkaloid from the marine ascidian, Aplidium sp

A new hexacyclic pyridoacridine alkaloid, nordehydrocyclodercitin (1), from an ascidian, Aplidium sp., cf. Aplidium cratiferum collected at Arab Reef, Great Barrier Reef, Australia is reported. Nordehydrocyclodercitin is structurally related to stellettamine (2) and cyclodercitin (3), which are sponge metabolites, and cycloshermilamine D (4) which was isolated from the marine tunicate Cystodytes violatinctus. The structure of nordehydrocyclodercitin was determined by interpretation of spectroscopic data, particularly those obtained from HMBC correlations, and by comparison with reported data for known related pyridoacridine alkaloids.     

Iriomoteolide-3a, a cytotoxic 15-membered macrolide from a marine dinoflagellate amphidinium species

A 15-membered macrolide, iriomoteolide-3a (1), with an allyl epoxide has been isolated from a marine benthic dinoflagellate Amphidinium sp. (strain HYA024), and the structure was assigned by detailed analyses of 2D NMR data. Relative and absolute configurations were elucidated on the basis of conformational studies of 1 and its acetonide (2) and modified Mosher's method of 1, respectively. Iriomoteolide-3a (1) and the acetonide (2) exhibited potently cytotoxic activity against antitumor cells.     

Utilizing a constant peak width transform for isothermal gas chromatography

A computational approach to partially address the general elution problem (GEP), and better visualize, isothermal gas chromatograms is reported. The theoretical computational approach is developed and applied experimentally. We report a high speed temporally increasing boxcar summation (TIBS) transform that, when applied to the raw isothermal GC data, converts the chromatographic data from the initial time domain (in which the peak widths in isothermal GC increase as a function of their retention factors, k), to a data point based domain in which all peaks have the same peak width in terms of number of points in the final data vector, which aides in preprocessing and data analysis, while minimizing data storage size. By applying the TIBS transform, the resulting GC chromatogram (initially collected isothermally), appears with an x-axis point scale as if it were instrumentally collected using a suitable temperature program. A high speed GC isothermal separation with a test mixture containing 10 compounds had a run time of ～25 s. The peak at a retention factor k ～0.7 had a peak width of ～55 ms, while the last eluting peak at k ～89 (i.e., retention time of ～22 s) had a peak width of ～2000 ms. Application of the TIBS transform increased the peak height of the last eluting peak 45-fold, and S/N ～20-fold. All peaks in the transformed test mixture chromatogram had the width of an unretained peak, in terms of number of data points. A simulated chromatogram at unit resolution, studied using the TIBS transform, provided additional insight into the benefits of the algorithm.     

Relation between the alpha-relaxation and Johari-Goldstein beta-relaxation of a component in binary miscible mixtures of glass-formers

The coupling model was applied to describe the alpha-relaxation dynamics of each component in perfectly miscible mixtures A(1-x)B(x) of two different glass-formers A and B. An important element of the model is the change of the coupling parameter of each component with the composition, x, of the mixture. However, this change cannot be determined directly from the frequency dispersion of the alpha-relaxation of each component because of the broadening caused by concentration fluctuations in the mixture, except in the limits of low concentrations of either component, x --> 0 and x --> 1. Fortunately, the coupling model has another prediction. The coupling parameter of a component, say A, in the mixture determines tau(alpha)/tau(JG), the ratio of the alpha-relaxation time, tau(alpha), to the Johari-Goldstein (JG) secondary relaxation time, tau(JG), of the same component A. This prediction enables us to obtain the coupling parameter, n(A), of component A from the isothermal frequency spectrum of the mixture that shows both the alpha-relaxation and the JG beta-relaxation of component A. We put this extra prediction into practice by calculating n(A) of 2-picoline in binary mixtures with either tri-styrene or o-terphenyl from recently published broadband dielectric relaxation data of the alpha-relaxation and the JG beta-relaxation of 2-picoline. The results of n(A) obtained from the experimental data show its change with composition, x, follows the same pattern as assumed in previous works that address only the alpha-relaxation dynamics of a component in binary mixtures based on the coupling model. There is an alternative view of the thrust of the present work. If the change of n(A) with composition, x, in considering the alpha-relaxation of component A is justified by other means, the theoretical part of the present work gives a prediction of how the ratio tau(alpha)/tau(JG) of component A changes with composition, x. The data of tau(alpha) and tau(JG) of 2-picoline mixed with tri-styrene or o-terphenyl provide experimental support for the prediction.     

A practical procedure for assigning a reference value and uncertainty in the frame of an interlaboratory comparison

A method is suggested for the calculation of a reference value and its uncertainty to be used in the frame of an interlaboratory comparison (ILC). It is assumed that the reference value of the measurand is determined independently from the ILC round. It is derived from a limited set of measurement results obtained from one or several expert laboratories. The procedure involves three stages: (1) check of the experimental data and possible corrections; (2) check of the consistency of data, and possibly increase of the uncertainties in order to attain internal consistency; (3) choice between fully, partially or un-weighted mean.