Stylotelline,a new sesquiterpene isocyanide from the spongeStylotella sp. application of 2D-NMR in structure determination

The sesquiterpene isocyanide stylotelline isolated from the marinesponge Stylotella sp. was assigned the structure 1a (absolute stereochemistry) on the basis of spectral - essentially 2D-NMR - and chemical data.     

Sebiferone,a New Triterpenoid from Stem Bark of Sapium sebiferum （L.）Roxb.

From the stem bark of Sapium sebiferum a new triterpenoid,anmed sebiferone (1),was isolated.The structure of the new compound was clucidated as 3β-acetoxy-D-friedoolen-14-en-1-one-28-oic acid on the basis of spectral and chemical methods.     

Berchemolide, a novel dimeric vanillic acid glucoside from Berchemia racemosa.

A new phenol glycoside named berchemolide was isolated together with (+)-catechin and (-)-epicatechin (as acetates), from the stems of Berchemia racemosa Sieb. et Zucc. (Rhamnaceae). The structure of berchemolide, having a dimeric dilactone structure with a 22-membered ring, was determined on the basis of spectral and chemical investigations. The conformation of berchemolide was calculated by MNDO (modified neglect of diatomic overlap).     

Structure and Activity of a New Sapogenin from Chlorophytum laxum R. Br.

A new steroidal sapogenin named 25-R-spirosta-3,5-dien-12β-ol(1) was isolated from the dried roots of Chlorophytum laxum R. Br. along with five known compounds, namely, diosgenin(2), stigmasterol(3), β-sitosterols(4), estigmasterol-3-O-β-D-glicopyranoside(5) and 3-O-β-authemisol(6). The structure of compound 1 was elucidated by the analysis of IR, HRESI-MS, 1D and 2D NMR spectral data. Compounds 2-5 were isolated from Chlorophytum laxum R. Br. In addition, all the compounds were evaluated for cytotoxicity on the human nasopharyngeal carcinoma cancer cell line 5-8F. Among them, the newly identified 25-R-spirosta-3,5-dien-12β-ol(1) and diosgenin(2) exhibited high cytotoxicity on 5-8F cells, with IC₅₀ values of 24.8 and 41.9 μmol/L, respectively.     

A novel quinoline alkaloid possessing a 7-benzyl group from the centipede, Scolopendra subspinipes.

The novel quinoline alkaloid scolopendrine was isolated from the centipede, Scolopendra subspinipes mutilans L. Koch. The structure was determined to be 2-hydroxy-7-[(4-hydroxy-3-methoxyphenyl)methyl]-3-methoxy-8-quinolyl sulfate on the basis of high-resolution electron-spray ionization mass spectroscopy and two-dimensional NMR spectral data. Unlike quinoline alkaloids so far reported, scolopendrine is unique in having a 7-benzyl moiety in the quinoline ring.     

Optical properties and nondestructive estimation of anthocyanin content in plant leaves.

Absorption and reflectance spectra of maple (Acer platanoides), cotoneaster (Cotoneaster alaunica), dogwood (Cornus alba) and pelargonium (Pelargonium zonale) leaves with a wide range of pigment content and composition were studied in visible and near-infrared spectra in order to reveal specific anthocyanin (Anth) spectral features in leaves. Comparing absorption spectra of Anth-containing and Anth-free leaves with the same chlorophyll (Chl) content, absorption spectra of Anth in leaves were derived. The main spectral feature of Anth absorption in vivo was a peak around 550 nm; the peak magnitude was closely related to Anth content. A quantitative nondestructive technique was developed to subtract Chl contribution to reflectance in this spectral region and retrieve Anth content from reflectance over a wide range of pigment content and composition. Anth reflectance index in the form ARI = (R550)-1 - (R700)-1, where (R550)-1 and (R700)-1 are inverse reflectances at 550 and 700 nm, respectively, allowed an accurate estimation of Anth accumulation, even in minute amounts, in intact senescing and stressed leaves.     

Tambouranolide, a new cytotoxic hydroxybutanolide from a Tambourissa sp. (Monimiaceae)

A new cytotoxic hydroxybutanolide, tambouranolide, has been isolated by solid phase extraction from an ethanol extract of the dried roots of a species of Tambourissa (Monimiaceae) from the Madagascar rainforest. The structure was elucidated through the interpretation of spectral data and its comparison to data reported in the literature for related molecules. The compound showed moderate in vitro cytotoxicity with an IC50 of 8 micro g mL(-1) in the A2780 human ovarian cancer cell line assay.     

Crystalline constituents from euphorbiaceae—XIII : The structure of a new triterpene from Euphorbia nerifolia L.

From the leaves and stems of Euphorbia nerifolia Linn., a new triterpene was isolated besides friedelan-3α- andβ-ols, and taraxerol. From a study of its chemical reactions and spectral data, the new triterpene was shown to be glut-5(10)-en-1-one(3).     

Two new paeciloxocins from a mangrove endophytic fungus Paecilomyces sp.

Paeciloxocins A and B (2-(1-hydroxy-3-methylbutyl)- and 2-(1-acetoxy-3-methylbutyl)- 11-hydroxy-9-methyl-1-methoxy-5H,7H-dibenzo[b,g]-1,5-dioxocin-5-ones), viz., two new metabolites, were isolated from the mangrove fungus Paecilomyces sp. collected from the Taiwan Strait. Their structures were elucidated by spectral methods. Paeciloxocin A exhibited strong cytotoxicity against the hepG2 cell line.     

Isoflavonoids from Heartwood of Maackia amurensis Rupr. et Maxim.

Orobol, tektorigenin, (-)-medicarpin, (±)-vestitol, and a new isoflavanone, the structure of which was established by chemical transformations and spectral data, were isolated from heartwood ofMaackia amurensis     

Analytical characteristics of a continuum-source tungsten coil atomic absorption spectrometer.

A continuum-source tungsten coil electrothermal atomic absorption spectrometer has been assembled, evaluated, and employed in four different applications. The instrument consists of a xenon arc lamp light source, a tungsten coil atomizer, a Czerny-Turner high resolution monochromator, and a linear photodiode array detector. This instrument provides simultaneous multi-element analyses across a 4 nm spectral window with a resolution of 0.024 nm. Such a device might be useful in many different types of analyses. To demonstrate this broad appeal, four very different applications have been evaluated. First of all, the temperature of the gas phase was measured during the atomization cycle of the tungsten coil, using tin as a thermometric element. Secondly, a summation approach for two absorption lines for aluminum falling within the same spectral window (305.5-309.5 nm) was evaluated. This approach improves the sensitivity without requiring any additional preconcentration steps. The third application describes a background subtraction technique, as it is applied to the analysis of an oil emulsion sample. Finally, interference effects caused by Na on the atomization of Pb were studied. The simultaneous measurements of Pb and Na suggests that negative interference arises at least partially from competition between Pb and Na atoms for H2 in the gas phase.     

Self-association of acetic acid in dilute deuterated chloroform. Wide-range spectral reconstructions and analysis using FTIR spectroscopy, BTEM, and DFT

The binary solution of acetic acid in CDCl(3) was studied at room pressure on the interval T = 293-313 K with a series of acetic acid concentrations up to 0.16 M. In-situ Fourier transform infrared (FTIR) spectroscopy measurements on the interval of 400-3800 cm(-1) were utilized as the analytical method to monitor the spectral changes due to self-association of acetic acid. The band-target entropy minimization (BTEM) algorithm was employed to reconstruct the underlying pure component spectra. Analysis successfully provided two major spectral estimates of acetic acid, namely, the monomer (primarily in the form of monomer-CDCl(3) complex) and the centrosymmetric cyclic dimer. In addition, analysis provided one minor spectral estimate containing signals from both noncyclic dimers and higher aggregates. Also, spectral estimates were obtained for phosgene and water which were present at trace levels even though considerable precaution was taken to conduct the experiments under anhydrous and anaerobic conditions. Density functional theory (DFT) calculation was performed to assign the acetic acid structures corresponding to the BTEM spectral estimates. Since the structure of dilute acetic acid has been the subject of numerous studies, the present investigation helps to resolve some issues concerning the speciation of acetic acid at low concentrations in low polarity solvents. In particular, the present study provides for the first time, wide-range spectral reconstructions of the species present.     

Tomographic Spectral Imaging with Multivariate Statistical Analysis: Comprehensive 3D Microanalysis.

A comprehensive three-dimensional (3D) microanalysis procedure using a combined scanning electron microscope (SEM)/focused ion beam (FIB) system equipped with an energy-dispersive X-ray spectrometer (EDS) has been developed. The FIB system was used first to prepare a site-specific region for X-ray microanalysis followed by the acquisition of an electron-beam generated X-ray spectral image. A small section of material was then removed by the FIB, followed by the acquisition of another X-ray spectral image. This serial sectioning procedure was repeated 10-12 times to sample a volume of material. The series of two-spatial-dimension spectral images were then concatenated into a single data set consisting of a series of volume elements or voxels each with an entire X-ray spectrum. This four-dimensional (three real space and one spectral dimension) spectral image was then comprehensively analyzed with Sandia's automated X-ray spectral image analysis software. This technique was applied to a simple Cu-Ag eutectic and a more complicated localized corrosion study where the powerful site-specific comprehensive analysis capability of tomographic spectral imaging (TSI) combined with multivariate statistical analysis is demonstrated.     

Chemistry of thienopyridines. XIII. Selective formation of sulfones in Bi- and tricyclic Systems. Thieno[2,3-b]pyridine 1,1-dioxide as a dienophile

Bicyclic and tricyclic thienopyridines are converted into sulfones in 13-73% yield by means of acid-hypochlorite. The sulfone thieno[2,3-b]pyridine 1,1-oxide (Ib) undergoes Diels-Alder condensation with furan (both exo and endo products formed), anthracene, and naphthacene. Self-condensation of Ib occurs with elimination of sulfur dioxide to give 8-(3-pyridyl)quinoline (XV). The structure of XV was established by means of pmr and a europium shift reagent. Ultraviolet, pmr, and mass spectral data for various compounds are presented and discussed.     

(-)-Hydroxylindestrenolide, a new sesquiterpenoid from a gorgonian coral Menella sp. (Plexauridae)

(-)-Hydroxylindestrenolide (1), an enantiomer of the known sesquiterpenoid, (+)-hydroxylindestrenolide (2), was isolated from a gorgonian coral identified as Menella sp. The structure, including the relative stereochemistry of 1 was established by spectroscopic methods and by comparison the spectral and physical data with those of 2. Sesquiterpenoid 1 exhibited marginal cytotoxicity toward HL-60 and K562 leukemia tumor cells, and displayed a weak inhibitory effect on superoxide anion generation at a concentration of 10 μg/ml by human neutrophils.     

Chemical Constituents of a Formosan Soft Coral Sinularia sp.

A new marine sterol 7β-hydroperoxy-24-methylenecholesterol ( 1 ) along with five known compounds sarcophytol A ( 2 ), (Z)-N-[2-(4-hydroxyphenyl)ethyl]-3-methyldodec-2-enamide ( 3 ), 5α,7αH-eduesm-11(13)en-4α-ol ( 4 ), 24-methylenecholesterol ( 5 ) and 1β-hydroxy-α-cyperone ( 6 ) have been isolated from a Formosan soft coral Sinularia sp. The structures of the above compounds were determined by spectral analyses. Cytotoxicity of compounds 1–6 toward various cancer cell lines also is reported.     

Dynamics of phase transitions in a liquid crystal probed by Raman spectroscopy

Raman spectra of the Schiff 's base liquid crystalline compound 5O5, N-(4- n-pentyloxybenzylidene)-4'-n-pentylaniline, have been recorded as a function of temperature from 22 to 80°C in the 1140-1220 cm^-1 and 1550-1640 cm^-1 spectral regions. From careful deconvolution of the spectral features using Lorentzian profiles, precise values of peak positions, integrated intensities and linewidths of some selected Raman bands were obtained. The variations of the Raman spectral parameters with temperature are discussed in terms of changes in the molecular alignment and its effect on intra-/inter-molecular interactions at the Cr-G, G-SmF, SmF-SmC and SmA-N phase transitions. From a detailed study, it is inferred that the increased orientational/vibrational freedom of the alkyl chains, as well as the delocalization of the electron clouds, is responsible for the spectral anomalies at the Cr-G transition. Loss of positional ordering and twist around the -C₆H₄-N= bond takes place at the SmF-SmC transition. In the SmA-N transition, some evidence for the formation of cybotactic clusters was obtained.     

Multivariate estimation between mid and near-infrared spectra of hexafluoroisopropanol-water mixtures.

Multivariate regression based on partial least squares (PLS2) was applied to estimating one spectral dataset from another set having an intrinsic relationship with each other. An estimation was successfully carried out between mid-infrared (IR) spectra in the range of 2980 - 3800 cm(-1) and that of near-infrared (NIR) spectra in the range of 6000 - 7500 cm(-1) for hexafluoroisopropanol (HFIP)-water mixtures. The result demonstrates that, after building a suitable regression model, not only NIR spectra, but also well-resolved IR spectra of HFIP-water mixture can be estimated properly in this way. The use of IR and NIR spectroscopy together with PLS2 regression will not only alleviate laborious and costly measurements, but also open a way to provide easier assignments of generally weak and highly overlapped NIR spectral bands.     

Dynamics of phase transitions in a liquid crystal probed by Raman spectroscopy

Raman spectra of the Schiff 's base liquid crystalline compound 5O5, N-(4- n-pentyloxybenzylidene)-4'-n-pentylaniline, have been recorded as a function of temperature from 22 to 80°C in the 1140-1220 cm^-1 and 1550-1640 cm^-1 spectral regions. From careful deconvolution of the spectral features using Lorentzian profiles, precise values of peak positions, integrated intensities and linewidths of some selected Raman bands were obtained. The variations of the Raman spectral parameters with temperature are discussed in terms of changes in the molecular alignment and its effect on intra-/inter-molecular interactions at the Cr-G, G-SmF, SmF-SmC and SmA-N phase transitions. From a detailed study, it is inferred that the increased orientational/vibrational freedom of the alkyl chains, as well as the delocalization of the electron clouds, is responsible for the spectral anomalies at the Cr-G transition. Loss of positional ordering and twist around the -C₆H₄-N= bond takes place at the SmF-SmC transition. In the SmA-N transition, some evidence for the formation of cybotactic clusters was obtained.     

WA, a new Antifungal Antibiotic from a Soil Fungus Strain 38

Inthecourseofourscreeningnewantifungalandanticancercompoundsusingthebioassaysystembasedonmorphologicaldeformationorgrowthinhibiti0n0fPyriculariaoryzae,anovelactivecomPoundWAwasobtainedfromthemetab0litesofthefungusstrain38isolatedfromasoilsample'.ItSminimalinhibitionc0ncentrationwas288.4pglml.InthispaPer,wedescribethephysic0-chemicalpr0pertiesandstructureelucidationofWA.Comp0undWAwasobtainedaswhitep0wderhavingmeltingpointl2ful28"C.Itsm0lecularformula,Cl1HIo04,wasdeterminedbyCI-MS[Inlz20…