Tracer studies on dinoflagellate luciferin with [N]-glycine and [N]-l-glutamic acid in the dinoflagellate Pyrocystis lunula

The bioluminescence of dinoflagellate is a typical luciferin-luciferase reaction. To clarify the biosynthesis of dinoflagellate luciferin, we performed a feeding experiment with [¹⁵N]-glycine and [¹⁵N]-l-glutamic acid in the dinoflagellate Pyrocystis lunula. In a control experiment, we also examined whether or not chlorophyll a was incorporated with these labeled compounds. We detected by mass spectrometry the incorporation of [¹⁵N]-glycine and [¹⁵N]-l-glutamic acid into the four tetrapyrrole rings of the luciferin. In the control experiment, chlorophyll a was also incorporated with [¹⁵N]-glycine and [¹⁵N]-l-glutamic acid. Our results show that either glycine or glutamic acid could be the original component of dinoflagellate luciferin as well as chlorophyll a in the dinoflagellate P. lunula.     

Microencapsulated Caraway Essential Oil Affects Initial Growth of Maize Cultivars

Caraway (Carum carvi L.) essential oil is a candidate for botanical herbicides. A hypothesis was formulated that the sand-applied maltodextrin-coated caraway oil (MCEO) does not affect the growth of maize (Zea mays L.). In the pot experiment, pre-emergence application of five doses of MCEO was tested on four maize cultivars up to the three-leaf growth stage. The morphological analyses were supported by the measurements of relative chlorophyll content (SPAD), two parameters of chlorophyll a fluorescence, e.g., Fv/Fm and Fv/F0, and fluorescence emission spectra. The analyzed MCEO contained 6.5% caraway EO with carvone and limonene as the main compounds, constituting 95% of the oil. The MCEO caused 7-day delays in maize emergence from the dose of 0.9 g per pot (equal to 96 g m⁻²). Maize development at the three-leaf growth stage, i.e., length of roots, length of leaves, and biomass of shoots and leaves, was significantly impaired already at the lowest dose of MCEO: 0.4 g per pot, equal to 44 g m⁻². A significant drop of both chlorophyll a fluorescence parameters was noted, on average, from the dose of 0.7 g per pot, equal to 69 g m⁻². Among the tested cultivars, cv. Rywal and Pomerania were less susceptible to the MCEO compared to the cv. Kurant and Podole. In summary, maize is susceptible to the pre-emergence, sand-applied MCEO from the dose of 44 g m⁻².     

On the conformational characteristics of the O,O,O-trimethyl selenophosphate molecule

Spectroscopic and theoretical studies were carried out for O,O,O-trimethyl selenophosphate molecule. DFT structural and vibrational calculations were performed at 6-311++G^∗∗ level. Ar/matrix-FTIR spectra were recorded. A coexistence of different conformers with C₃ and C₁ symmetries was detected at different temperatures. Spectral evidence of a lower energy C_s conformer was found. These conclusions are consistent with the results from DFT calculations. A tentative assignment of the features observed in the Ar/matrix-FTIR spectra is proposed.     

西尼地平核磁共振碳谱氢谱的谱峰归属

利用普通1H-NMR，13C-NMR，极化转移谱(DEPT)以及同核相关谱(COSY)、异核相关谱(HSQC)，特别是远程偶合谱(HMBC)等多种核磁研究方法对新型的血管扩张药西尼地平的1H、13C信号进行完全归属。对由于分子结构对称而引起的化学位移相差最小为0．94Hz的两个碳加以区分，解决了由于样品的近似对称性而导致几组谱峰难以归属的问题。     

Anion recognition by N,N′-diarylalkanediamides

The preparation of N,N′-diarylalkanediamides from the respective aliphatic dicarboxylic acids and 4-nitroaniline via microwave-prompted reactions is presented. The most positive effect of microwave irradiation was observed for N,N′-bis(4-nitrophenyl)butanediamide. Anion binding studies on the obtained diamides were carried out in DMSO and acetonitrile using UV-vis and ¹H NMR spectroscopy. A mechanism for selective fluoride recognition by N,N′-bis(4-nitrophenyl)butanediamide in DMSO is proposed.     

Structural characterization of a procyanidin tetramer and pentamer from the apple by low-temperature NMR analysis

The structures of a procyanidin tetramer and pentamer from unripe apple (Malus pumila) were elucidated by low-temperature NMR analysis at −34 °C. These structures were [epicatechin-(4β→6)-epicatechin-(4β→8)-epicatechin-(4β→8)-epicatechin (1)] and [epicatechin-(4β→8)-epicatechin-(4β→8)-epicatechin-(4β→8)-epicatechin-(4β→8)-epicatechin (2)].     

Synthesis of N,N-Ac,Boc laurylthio sialoside and its application to O-sialylation

The combination of the 5-N-tert-butoxycarbonyl (Boc) group of laurylthio sialoside and cyclopentyl methyl ether (CPME) as a solvent enhanced the reactivity and α-selectivity of the sialyl donor during sialylation. Selective deprotection of the N-Boc group of sialoside, including an acid-sensitive isopropylidene function, was successfully achieved by Yb(OTf)₃-SiO₂. Transformation of N,N-Ac,Boc into an N-acetylglycolyl group of sialoglycoside was easily performed via selective N-deacylation of the mixed Ac-N-Boc carbamate, subsequent Boc group removal, and acylation.     

Structure of an anthocyanin-anthocyanin dimer molecule in anthocyanin-producing cells of a carrot suspension culture

A novel anthocyanin, an anthocyanin-anthocyanin dimer, was isolated from the cells of an anthocyanin-producing carrot cell-line culture, and its structure was elucidated using spectroscopic methods. It consists of two molecules of the anthocyanin, cyanidin 3-[xylosyl-(sinapoyl-glucosyl)-galactoside], with a CH-CH₃ linkage at the 8-8 position. This is the first report of the identification and isolation of an anthocyanin-anthocyanin dimer with a CH-CH₃ linkage from intact plant cells.     

Subcellular and molecular localization of rare earth elements and structural characterization of yttrium bound chlorophyll a in naturally grown fern Dicranopteris dichotoma

A rare earth element (REE) hyperaccumulator, Dicranopteris dichotoma, sampled from an REE mining area in South-Jiangxi region, was chosen for analysis of 15 REEs at subcellular and molecular levels by inductively coupled plasma-mass spectrometry (ICP-MS). The sum of the concentrations of 15 REEs (∑REEs) of D. dichotoma leaf was about 0.1% dry mass. Results indicated that the ∑REEs of different subcellular fractions of D. dichotoma leaf were cell walls>organelles>the ‘soluble’ fraction (i.e., cytosol and vacuoles)>cell membranes. ICP-MS results also showed that REEs existed in chlorophylls and lutein, though REE concentrations in carotene and pheophytin were both lower than the procedural blank levels. The ∑REEs of crude lipopolysaccharide and Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) obtained from D. dichotoma leaf were 1200 and 343 mg/kg, respectively. The extended X-ray absorption fine structure (EXAFS) study of D. dichotoma chlorophyll a indicated that yttrium was bound to the porphyrin ring of chlorophyll a, and one yttrium atom was surrounded by four nitrogen atoms with the average yttrium-nitrogen bond length being 0.236 nm. These data might be useful for understanding of the physiological role of REEs in hyperaccumulator D. dichotoma.     

Infrared spectra of p-, m- and o-fluorobenzaldehyde in low temperature argon matrices

Three structural isomers of fluorobenzaldehyde (p-, m- and o-forms) have been investigated in detail with matrix-isolation infrared spectroscopy, in the 700-3000 cm⁻¹ region, combined with the UV photoexcitation and the density functional calculations. Two rotamers (syn and anti) were identified for m- and o-fluorobenzaldehyde upon the photoexcitation and most of the bands of each rotamer were assigned. It is shown that the formation of the intramolecular C-H?F hydrogen bond for the anti rotamer of o-FB results in the shortening of the aldehyde C-H bond length and that the C-F and/or CO bond lengths are shortened for the syn rotamer of o-FB presumably due to the repulsion between the aldehyde O and F atoms.     

Efficient preparation of N′,N″-1H-isoindole-1,3-diylidenedicarbohydrazides via 1,1,3-trichloro-1H-isoindole, and their characterization

N′,N″-1H-Isoindole-1,3-diylidenedialkyl(aryl,heteroaryl)carbohydrazides were prepared in good yields via 1,1,3-trichloro-1H-isoindole, which was shown to be a versatile reagent for their synthesis. Tautomeric structure and conformational behaviour of dicarbohydrazides in solid state as well as in solution have been studied by X-ray crystallography, NMR spectroscopy and quantum calculations. The dependence of Z/E amide-type isomerism upon steric effects and solvent polarity is discussed.     

Synthesis, X-ray crystal structure and vibrational spectroscopy of the acidic pyrophosphate KMg0.5H2P2O7·H2O

The hydrated potassium hemimagnesium dihydrogen pyrophosphate KMg_0.5H₂P₂O₇·H₂O was synthesized. It crystallizes in the triclinic system, space group (n. 2), Z=2, with the following unit-cell parameters: a=6.8565(2) Å, b=7.3621(3) Å, c=7.6202(3) Å, α=81.044(2)°, β=72.248(2)°, γ=83.314(3)°, V=360.90(2) Å³. The structure was obtained by single-crystal X-ray diffractometry, and a full-matrix least-squares refinement based on F² gave a final R index of =0.0368 (wR=0.0975), utilizing 1446 observed reflections with I>2σ(I). The crystal packing consists in a three-dimensional network made by layers parallel to ab plane of PO₄ double tetrahedra and MgO₆ octahedra, linked by hydrogen bonds, while K atoms form complex coordination within cavities between tetrahedra and octahedra. The dihydro-pyrophosphate anion (H₂P₂O₇)²⁻ shows bent eclipsed conformation and the Mg²⁺ ion lies on inversion center. No coincidences observed between most of infrared and Raman spectral bands confirmed the centrosymmetric structure of the title compound; the vibrational spectra point to a bent POP bridge angle.     

Galanthamine analogs: 6H-benzofuro[3a,3,2,-e,f][1]benzazepine and 6H-benzofuro[3a,3,2-e,f][3]benzazepine

The known cholinesterase inhibitory capability of the Amarylidaceae alkaloid galanthamine prompted preparation of analogs in which the position of the nitrogen within the azepine ring is altered. The analogs 6H-benzofuro[3a,3,2-e,f][1]benzazepine and 6H-benzofuro[3a,3,2-e,f][3]benzazepine were prepared in 19 and 2.5%, respectively, following Kametani and Shimizu approaches, respectively. The aniline derivative 6H-benzofuro[3a,3,2-e,f][1]benzazepine failed to undergo most of the reactions typical for galanthamine. Thus, it neither oxidized to the analogous narwedine, nor epimerized to the analogous epigalanthamine, nor reduced to the lycoramine analog, under the conditions used for galanthamine.     

HPLC–MS2 Analysis of Chlorophylls in Green Teas Establishes Differences among Varieties

Green teas are nonfermented teas, the quality of which is measured by the green color. However, this category encompasses a high number of tea varieties that differ in cultivation and processing. For example, leaf or stem/bubble tea, plants cultivated under a light or shadow regime, powdered or unpowdered tea, etc. These variables determine the different qualities among green teas (Matcha, Sencha, Gyokuro, etc.) and consequently their different values on the market. Our purpose is to determine if these variables can exert an influence on the chlorophyll profile and to establish a characteristic profile for specific green teas. With such an aim, we analyzed the chlorophyll profiles of 6 different green tea varieties via HPLC-hr ESI/APCI–MS² and identified up to 17 different chlorophyll compounds. For the first time, 13²-hydroxy-chlorophylls, 13²-hydroxy-pheophytins, and 15¹-hydroxy-lactone-pheophytins have been identified in green teas. Shadow teas (Matcha and Sencha) and light-regimen green teas can be statistically differentiated by the total chlorophyll content and the a/b ratio. However, only Matcha tea contains a higher proportion of chlorophylls a and b among the green tea varieties analyzed, justifying the higher quality and price of this variety. Other chlorophyll metabolites (pheophytins, pyropheophytins, and oxidized chlorophylls) are indicative of the various processing and storage conditions.     

Heavy metal phosphate nanophases in silica: influence of radiolysis probed via f-electron state properties

We have assessed the feasibility of carrying out time- and wavelength-resolved laser-induced fluorescence measurements of radiation damage in glassy silica. The consequences of alpha decay of Es-253 in LaPO₄ nanophases embedded in silica were probed based on excitation of 5f states of Cm³⁺, Bk³⁺, and Es³⁺ ions. The recorded emission spectra and luminescence decays showed that alpha decay of Es-253 ejected Bk-249 decay daughter ions into the surrounding silica and created radiation damage within the LaPO₄ nanophases. This conclusion is consistent with predictions of an ion transport code commonly used to model ion implantation. Luminescence from the ⁶D_7/2 state of Cm³⁺was used as an internal standard. Ion-ion energy transfer dominated the dynamics of the observed emitting 5f states and strongly influenced the intensity of observed spectra. In appropriate sample materials, laser-induced fluorescence provides a powerful method for fundamental investigation of alpha-induced radiation damage in silica.     

Electrostatic forces that determine O,O-trans versus O,S-cis conformers in the aminated porphyrin complexes of Cd(N-NHCO-2-C4H3O-tpp)(OAc) and Cd(N-NHCO-2-C4H3S-tpp)(OAc)

Two new diamagnetic, mononuclear and aminated porphyrin complexes of O,O-trans-Cd (3-trans) and O,S-cis-Cd (4-cis) have been synthesized and characterized by ¹H, ¹³C NMR spectroscopy. The crystal structures of (acetato)(N-2-furancarboxamido-meso-tetraphenylporphyrinato)cadmium(II) [Cd(N-NHCO-2-C₄H₃O-tpp)(OAc); 3-trans] and (acetato)(N-2-thiophenecarboxamido-meso-tetraphenylporphyrinato)cadmium(II) [Cd(N-NHCO-2-C₄H₃S-tpp)(OAc); 4-cis] were determined. The coordination sphere around Cd²⁺ is a distorted square-based pyramid in which the apical site is occupied by a bidentate chelating OAc⁻ group for 3-trans and 4-cis. The plane of three pyrrole nitrogen atoms [i.e., N(1), N(2), N(4) for 3-trans and N(1), N(2), N(3) for 4-cis] strongly bonded to Cd²⁺ is adopted as a reference plane 3N. The N(3) and N(4) pyrrole rings bearing the 2-furancarboxamido (Fr) and 2-thiophenecarboxamido groups in 3-trans and 4-cis, respectively, deviate mostly from the 3N plane, thus orienting separately with a dihedral angle of 33.4° and of 31.0°. In 3-trans, Cd²⁺ and N(5) are located on different sides at 1.06 and −1.49 Å from its 3N plane, while in 4-cis, Cd²⁺ and N(5) are also located on different sides at 1.04 and −1.53 Å from its 3N plane. An attractive electrostatic interaction between the Cd²⁺ and O(4)⁻ atoms in furan stabilizes the O,O-trans conformer of 3. A repulsive electrostatic interaction between Cd²⁺ and S(1)⁺ destabilizes the O,S-trans conformer of 4. Both of these repulsive and the mutually attractive interactions between S(1)⁺ and O(3)⁻ atoms favor the O,S-cis rotamer of 4 both in the vapor phase and in low polarity solvents. NOE difference spectroscopy, HMQC and HMBC were employed for the unambiguous assignment of the ¹H and ¹³C NMR resonances of 3-trans and 4-cis in CDCl₃ at 20 and −50 °C.     

Facile synthesis of N-(benzyl, methyl)-lysine as a building block for site-specifically lysine monomethylated peptides

Facile, mild and efficient one-pot preparation of N^α-Fmoc-N^ε-(benzyl, methyl)-lysine, a building block for monomethylated peptide synthesis, was described. This building block was proved to be efficient for the synthesis of site-specifically monomethylated peptide. Benzyl group, which was incorporated by reductive benzylation and removed via catalytic hydrogenolysis, served as an excellent protecting group.     

Comparative XANES study on the two electron-doped high-Tc superconductor systems, (Sr,La)CuO2 and (Nd,Ce)2CuO4

Here we employ high-quality samples of (Sr_1−xLa_x)CuO₂ and (Nd_2−xCe_x)CuO₄ and XANES spectroscopy at O-K, Cu-L_2,3 and Ce-M_4,5 edges to gain comprehensive understanding of the electronic structure and doping in n-type high-T_c superconductors. Not only common but also slightly different features are revealed for the two systems. From O-K-edge spectra, the UHB is found essentially independent of the electron-doping level for both the systems, in line with our understanding that the doped electrons do not go to the O site in n-type copper-oxide superconductors. Another common observation is that the main Cu^II peak at the Cu-L₃ edge (due to transitions to the Cu^II-3d orbitals) systematically decreases in intensity upon electron doping, hence verifying the fact that the doped electrons go to the Cu site. The difference then between the two systems is that in (Sr_1−xLa_x)CuO₂ the weaker Cu^II peak due to transitions to the Cu^II-4s orbital depends on the degree of doping. Moreover, it was found that with increasing x, electron density increases much faster in (Sr_1−xLa_x)CuO₂ than in (Nd_2−xCe_x)CuO₄. This is a consequence of two phenomena: a tiny increase in oxygen content concomitant to the Ce^IV-for-Nd^III substitution and the somewhat lower Ce-valence value of +3.8 compared to the nominal tetravalent state.     

Terreusinone, a novel UV-A protecting dipyrroloquinone from the marine algicolous fungus Aspergillus terreus

A novel chiral dipyrrolobenzoquinone derivative, terreusinone (1), has been isolated as a potent UV-A protectant from the marine algicolous fungus Aspergillus terreus. The structure and absolute stereochemistry of the new compound was established by spectral interpretation, Horeau's method and quantum chemistry calculations as 2,6-bis[(1R)-1-hydroxyisobutyl]-1H,5H-pyrrolo[2,3-b]indole-4,8-dione (1). Compound 1 exhibited a UV-A absorbing activity with ED₅₀ value of 70 μg/mL.