Structure elucidation and NMR assignments of new spirosolane alkaloids from Solanum campaniforme

From the leaves of Solanum campaniforme, two new spirosolane alkaloids β‐acetoxyl‐(25S)‐22βN‐spirosol‐4‐en‐3‐one (1) and β‐hydroxyl‐(25S)‐22βN‐spirosol‐4‐en‐3‐one (4) were isolated along with two other known alkaloids of the same class (25S)‐22βN‐spirosol‐1,4‐dien‐3‐one (2) and (25S)‐22βN‐spirosol‐4‐en‐3‐one (3), which are reported for the first time as natural products. The structures of all alkaloids were established after an extensive analysis by 1D and 2D NMR spectroscopy (COSY, HSQC, HMBC and NOESY) as well as HRESIMS. Copyright © 2012 John Wiley & Sons, Ltd.     

Phytochemical study of leaves of Ocotea caudata from Colombia

This first phytochemical study of leaves of Ocotea caudata led to the isolation of ten isoquinoline alkaloids, one of them previously unreported, S-(+)-9-O-demethylnorpreocoteine (1), three known flavonoids, two phenols, two eudesmane type sesquiterpenoids, one proline derivative, one fatty alcohol and a phytosterol. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic analyses including HSQC, HMBC, ¹H–¹H COSY, NOESY, as well as HRESIMS data in addition to comparison with reports in the literature.     

Dereplication of oligostilbenes in dipterocarpaceous plants using LCMS-ESI-Ion trap-database

A method for compound identification based on mass fragmentation patterns was developed to distinguish known oligostilbenes directly in crude plant extracts. Eleven pure oligostilbenes were used as standard compounds, and a pilot database of MS data was established. Seven extracts from Dipterocarpaceous plants; three from Neobalanocarpus heimii, three from Dryobalanops spp. and one from Dipterocarpus semivestitus were used as test materials. Eleven compounds were positively identified in the heartwood extract, nine in the bark, and six in the leaves of Neobalanocarpus heimii, one compound each in Dryobalanops lanceolata, D. rappa and D. aromatica, as well as two in Dipterocarpus semivestitus extract. Identification of all compounds were performed within a short analysis time.     

Cytotoxic Components from the Leaves of Schefflera Taiwaniana

The isolation and identification of eighteen components from the leaves of Schefflera taiwaniana are presented. Their structures were determined on the basis of spectral data as well as direct comparison with authentic samples. These compounds include two polyacetylenes, one carotenoid‐like, three sesquiterpenes, one diterpene, four triterpenes, two tocopherols, and five alkyl 4‐hydroxycinnamate mixtures. Among these, 4‐hydroxy‐trans‐cinnamic acid docosyl ester and 4‐hydroxy‐cis‐cinnamic acid tetracosyl ester are new compounds. Some of these components exhibit cytotoxic activity.     

Chemical Constituents from Strychnos Cathayensis

Secostrychnosin ( 1 ), a new secoiridoid, as well as seven compounds never before isolated from nature: 4‐tert‐butyl‐2‐oxazolidinone ( 2 ), 3‐acetoxyindole ( 3 ), indole‐2‐carboxylic acid ( 4 ), benzocaine ( 5 ), 3‐acetylindole ( 6 ), butylparaben ( 7 ) and 2‐hydroxy‐3‐methoxybenzaldehyde ( 8 ), together with fifty other known compounds, have been isolated from the stem of Strychnos cathayensis. These compounds include twenty‐three alkaloids, twelve benzenoids, four steroids, three flavonoids, three iridoids, two triterpenoids, two secoiridoids, two fatty acids, one lignan, one acetophenone, one coumarin, one chromane, one tetraterpenoid, one tannin, and one organic acid. The structures of these compounds were determined by means of spectralanalyses.     

Novel Tetraindoles and Unexpected Cycloalkane Indoles from the Reaction of Indoles and Aliphatic Dialdehydes

The reaction of indoles with dialdehydes was studied for the first time. Mild reaction conditions using glacial acetic acid led to two novel kinds of reaction products: one designated as alkyl chain‐connected tetraindoles and the other one as bis(indolyl)‐substituted cycloalkane indoles. The suggested reaction pathways are discussed. The indole substituents of the cycloalkane indoles were either trans or cis orientated depending from the alkyl chain length.     

Addition of Nucleophiles to Fragment Ions in Mass Spectrometers under Electrospray-Ionization Conditions

Mass spectra of several aromatic compounds containing an amino or thiol group were recorded under electrospray conditions with a Finnigan TSQ 700, as well as on a Bruker Esquire-LC spectrometer. The MS/MS spectra displayed two main peaks: the first one arising from the cleavage of the amino or thiol group; the second one appeared at 18 Da higher than the first one. It could be shown that the second peak resulted from a nucleophilic addition of one water molecule to the fragment ion.     

Chemical Constituents of Heartwood of Bauhinia purpurea

The isolation and identification of twenty-two components from the heartwood of Bauhinia purpurea are described. Their structures were determined on the basis of spectral evidence as well as direct comparison with authentic samples. Those components included six steroids, two triterpenoids, three fatty alcohol, acid and ester, two glycerols, five flavonoids, two phenols, one chromone, and one sugar. Among these, 6′-(β-sitosteryl-3-O-β-glucopyranosidyl)tetraeicosanoate is a new compound.     

Structural Transformation of Methoxy‐Substituted Benzo[de]benzo[4,5]imidazo[2,1‐a]isoquinolin‐7‐ones

Structural transformation of two methoxy derivatives of benzo[de]benzo[4,5]imidazo[2,1‐a]‐isoquinolin‐7‐one were determined via spectroscopic analysis. The transformation mechanism was proposed as the breakage and reformation of the lactam bond.     

Tetra-CMPO-derivatives of calix[4]arenes fixed in the 1,3-alternate conformation

Calix[4]arene derivatives fixed in the 1,3-alternate conformation and substituted at one side by four carbamoylmethylphosphine oxide (CMPO) residues were synthesised. Two CMPO groups are directly attached to the wide rim, while the second pair is bound to the narrow rim via a tri- or tetramethylene spacer. Similar compounds, in which two CMPO groups at the wide rim are combined with two picolinamide groups or two ionisable carboxylic groups at the narrow rim, were also prepared. Some of these calixarene derivatives were studied as extractants for lanthanides (La³⁺, Eu³⁺, Yb³⁺) and thorium (Th⁴⁺) from acidic solution into methylene chloride. For selected samples, stability constants in methanol were determined by spectrophotometric titrations. Three compounds (1b′, 13, 17) in the 1,3-alternate conformation and one intermediate in the cone conformation (18) were confirmed by a crystal structure.     

Construction of recombinant Bacillus subtilis for production of polyhydroxyalkanoates

Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyalkanoates synthesized by numerous bacteria as intracellular carbon and energy storage compounds and accumulated as granules in the cytoplasm of cells. In this work, we constructed two recombinant plasmids, pBE2C1, and pBE2C1AB, containing one or two PHA synthse, genes, respectively. The two plasmids were inserted into Bacillus subtilis DB104 to generate modified strains, B. subtilis/pBE2C1 and B. subtilis/pBE2C1AB. The two recombinants strains were subjected to fermentation and showed PHA accumulation, the first reported example of mcl-PHA production in B. subtilis. Gas Chromatography analysis identified the compound produced by B. subtilis/pBE2C1 to be a hydroxydecanoate-co-hydroxydodecanoate (HD-co-HDD) polymer whereas that produced by B. subtilis/pBE2C1AB was a hydroxybutyrate-co-hydroxyde-canoate-co-hydroxydodecanoate (HB-HD-HDD) polymer.     

PHOTOREACTION OF 5-METHOXYPSORALEN WITH THYMIDINE and THE THYMINE MOIETY OF ISOLATED and Saccharomyces cerevisiae DNA. CHARACTERIZATION and MEASUREMENT OF THE TWO cis-syn FURAN-SIDE MONOCYCLOADDUCTS

The photoreaction of the furan-side moiety of 5-methoxypsoralen (5-MOP) with thymidine used as a DNA model compound was investigated in the dry state. Under these conditions, two main fluorescent photoadducts were formed and isolated by HPLC. The two modified nucleosides were characterized as the two cis-syn diastereoisomers of furan-side monoadducts of 5-MOP to thymidine on the basis of spectroscopic measurements including UV, fluorescence, ¹H-NMR and circular dichroism analysis. The identification and quantification of the latter photoproducts within naked DNA exposed to photoexcited 5-MOP were achieved by enzymatic digestion completed by HPLC separation and fluorescence detection. Similarly, the two cis-syn furan-side monoadducts were found to be formed in the DNA of Saccharomyces cerevisiae cells after incubation with 5-MOP and subsequent exposure to 365 nm at an incident dose of 38.4 kJ m^?2. Under these conditions, the rate of induction of two diastereoisomeric photoadducts was as low as one modification per 10⁶ and 2 × 10⁵ bases, respectively.     

Novel Synthesis of Some Imidazolyl‐, Benzoxazinyl‐, and Quinazolinyl‐2,4‐dioxothiazolidine Derivatives

2‐(2,4‐Dioxothiazolidin‐5‐yl)acetic acid 1 and its chloride derivative 2 were allowed to react with different aromatic amines such as o‐phenylenediamine, o‐aminothiophenol, p‐aminoacetophenone, and anthranilic acid to give the biologically active nuclei such as imidazoles, thiazoles, benzoxazines, and quinazolines incorporated with the thiazolidindione nucleus. The antimicrobial activity of five of the synthesized compounds was examined against one gram positive bacteria (Staphylococcus aureus), one gram negative bacteria (Escherichia coli), and two fungi (Aspergillus flavus and Candida albicans). Four compounds showed moderate antibacterial and antifungal activities.     

Structural elucidation of N‐oxidized clemastine metabolites by liquid chromatography/tandem mass spectrometry and the use of Cunninghamella elegans to facilitate drug metabolite identification

Cunninghamella elegans is a filamentous fungus that has been shown to biotransform drugs into the same metabolites as mammals. In this paper we describe the use of C. elegans to aid the identification of clemastine metabolites since high concentrations of the metabolites were produced and MSⁿ experiments were facilitated. The combination of liquid chromatography and tandem mass spectrometry with two different ionization techniques and hydrogen/deuterium exchange were used for structural elucidation of the clemastine metabolites. Norclemastine, four isomers of hydroxylated clemastine, and two N‐oxide metabolites were described for the first time in C. elegans incubations. The N‐oxidations were confirmed by hydrogen/deuterium exchange and deoxygenation (?16 Da) upon atmospheric pressure chemical ionization mass spectrometry. By MSⁿ fragmentation it was concluded that two of the hydroxylated metabolites were oxidized on the methylpyrridyl moiety, one on the aromatic ring with the chloro substituent, and one on the aromatic ring without the chlorine. Copyright © 2010 John Wiley & Sons, Ltd.     

Block/segmented polymers. A new method of synthesis of copoly(amide-ester)-ester polymer

A new method of preparation of segmented copolymer amide-ester type is described here starting from two oligomers, one hard crystallizable (A) having a glass transition temperature (T_g) above room temperature and the other soft, amorphous (B) having T_g well below room temperature. A, an oligo amide-ester terminated with hydroxyl groups has been synthesized from bis(hydroxy acylo amide) alkane, a reaction product of a lactone and diamine and dicarboxylic acid. B, an oligoester hydroxyl terminated was synthesized by the conventional method. The two oligomers A and B were transesterified removing diol as by-product to obtain segmented (amide-ester)-ester copolymer. The polymer showed mostly two T_gs one at ?40 to ?50°C and other at +40 to +50°C; and one melting temperature 200°C. Max^m inherent viscosity was recorded at 1.75 dL/gm. © 1993 John Wiley & Sons, Inc.     

Structural and Energetic Behavior of Mixed Samples in the Hexacosane (n-C26H54)/Octacosane (n-C28H58) System; Solid-Solid and Solid-Liquid Equilibria

The combination of the experimental (microcalorimetric and X-ray diffraction) methods and thermodynamic analyses enabled us to determine the phase diagram of the system hexacosane (n-C₂₆H₅₄)/octacosane (n-C₂₈H₅₈). Isothermal X-ray measurements performed on mixed samples at `low temperature' (T 308 K) revealed three crystalline forms: two monoclinic (M<sub>011</sub> and M<sub>dci</sub>) and one orthorhombic (O<sub>p</sub>). Four of the five rotator phases were observed at `high temperature': R_I, R_II, R_IV, and R_V. Fourteen solid-solid and two solid-liquid two-phase regions were observed, as well as one peritectic, one eutectoid, one metatectoid, and five peritectoid three-phase equilibria. The thermodynamic calculations of the phase-equilibrium relations, carried out with the polynomial functions described in a previous paper and new ones given here, showed full consistency with the experimental data, evidencing the reliability of these polynomial functions.     

Rational Design of Fluorescent Phthalazinone Derivatives for One‐ and Two‐Photon Imaging

Phthalazinone derivatives were designed as optical probes for one‐ and two‐photon fluorescence microscopy imaging. The design strategy involves stepwise extension and modification of pyridazinone by 1) expansion of pyridazinone to phthalazinone, a larger conjugated system, as the electron acceptor, 2) coupling of electron‐donating aromatic groups such as N,N‐diethylaminophenyl, thienyl, naphthyl, and quinolyl to the phthalazinone, and 3) anchoring of an alkyl chain to the phthalazinone with various terminal substituents such as triphenylphosphonio, morpholino, triethylammonio, N‐methylimidazolio, pyrrolidino, and piperidino. Theoretical calculations were utilized to verify the initial design. The desired fluorescent probes were synthesized by two different routes in considerable yields. Twenty‐two phthalazinone derivatives were synthesized and their photophysical properties were measured. Selected compounds were applied in cell imaging, and valuable information was obtained. Furthermore, the designed compounds showed excellent performance in two‐photon microscopic imaging of mouse brain slices.     

Excess enthalpies of binary mixtures of <Emphasis Type="Italic">ortho</Emphasis>-, <Emphasis Type="Italic">meta</Emphasis>-, and <Emphasis Type="Italic">para</Emphasis>-structural isomers

The excess molar enthalpies of 8 binary mixtures for the o-, m-, and p-isomers of fluoroiodobenzene, fluoromethoxybenzene, bromofluorobenzene, chlorofluoro-benzene, difluorobenzene, fluoromethylbenzene, fluoronitrobenzene, and aminofluoro-benzene were measured at 298.15 K. The changes of the measured enthalpies were very small. The experimental results revealed that the isomers containing two electron-acceptor groups showed the most positive excess enthalpy change, while isomers containing both one electron donor and one electron acceptor group, such as aminofluorobenzene, showed more stable and always the most negative results.     

Geminal poly(silyl ester)s: Highly labile degradable polymers

Geminal silyl ester linkages were used for the backbone construction of linear polymers, which exhibit rapid cleavage in the presence of atmospheric water. A series of poly(gem-silyl ester)s with two ester groups flanking each silicon atom were synthesized, in order to probe the effects of different silyl-substituted side-chain groups upon the physical and chemical properties. The transsilylation condensation reaction of bis(trimethylsilyl) terephthalate with dichlorodiisopropylsilane, dichlorodicyclohexylsilane, dichloromethyl-n-octadecylsilane, and dichloromethyl-4-methylphenethylsilane gave the four poly(gem-silyl ester)s with two isopropyl, two cyclohexyl, one methyl plus one octadecyl, and one methyl plus one 4-methyl-phenethyl side-chain groups per silicon, respectively. The polymers were characterized by NMR (¹H, ¹³C, and ²⁹Si), infrared spectroscopy (IR), size-exclusion chromatography (SEC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Hydrolytic degradation studies of the polymers solvated in tetrahydrofuran and as bulk samples in the solid state were performed in the presence of atmospheric water as the nucleophilic cleavage agent, and the molecular weight loss was monitored by SEC. Poly(diisopropylsilyl terephthalate) (1a) and poly(dicyclohexylsilyl terephthalate) (1b) were found to be more stable towards nucleophilic degradation in comparison to poly(methyl-n-octadecylsilyl terephthalate) (1c) and poly(methyl-4-methylphenethylsilyl terephthalate) (1d), due to the presence of sterically bulky isopropyl or cyclohexyl groups attached to the silicon atoms. All of the polymers degraded into small molecules upon hydrolysis, with the exception that the degradation products of 1c and 1d self-condensed in the solid state to form the respective polysiloxanes. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3606–3613, 1999