Comprehensive Metabolite Identification of Genipin in Rats Using Ultra-High-Performance Liquid Chromatography Coupled with High Resolution Mass Spectrometry.

Genipin, an aglycone of geniposide, is a rich iridoid component in the fruit of Gardenia jasminoides Ellis and has numerous biological activities. However, its metabolic profiles in vivo and vitro remain unclear. In this study, an effective analytical strategy based on ultra-high-performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) in positive and negative ion modes was developed to analyze and identify genipin metabolites in rat urine, blood, feces, and fecal fermentation in combination with many methods including post-collection data mining methods, high-resolution extracted ion chromatography (HREIC), and multiple mass defect filtering (MMDF). Simultaneously, the metabolites of genipin in vivo were verified by fecal fermentation of SD rats at different times. Finally, based on information such as reference substances, chromatographic retention behavior, and accurate mass determination, a total of 50 metabolites (including prototypes) were identified in vivo. Among them, 7, 31 and 28 metabolites in vivo were identified in blood, urine, and feces, respectively. Our results showed that genipin could generate different metabolites that underwent multiple metabolic reactions in vivo including methylation, hydroxylation, dehydroxylation, hydrogenation, sulfonation, glucuronidation, demethylation, and their superimposed reactions. Forty-six metabolites were verified in vitro. Meanwhile, 2 and 19 metabolites identified in blood and urine were also verified in fecal fermentation at different times. These results demonstrated that metabolites were produced in feces and reabsorbed into the body. In conclusion, the newly discovered metabolites of genipin can provide a new perspective for understanding its pharmacological effects and build the foundation for thee toxicity and safety evaluations of genipin.

Properties of Gaseous Deprotonated L-Cysteine S-Sulfate Anion [cysS-SO3]-: Intramolecular H-Bond Network, Electron Affinity, Chemically Active Site, and Vibrational Fingerprints.

L-cysteine S-sulfate, Cys-SSO3H, and their derivatives play essential roles in biological chemistry and pharmaceutical synthesis, yet their intrinsic molecular properties have not been studied to date. In this contribution, the deprotonated anion [cysS-SO3]- was introduced in the gas phase by electrospray and characterized by size-selected, cryogenic, negative ion photoelectron spectroscopy. The electron affinity of the [cysS-SO3]• radical was determined to be 4.95 ± 0.10 eV. In combination with theoretical calculations, it was found that the most stable structure of [cysS-SO3]- (S1) is stabilized via three intramolecular hydrogen bonds (HBs); i.e., one O-H⋯⋯N between the -COOH and -NH2 groups, and two N-H⋯⋯O HBs between -NH2 and -SO3, in which the amino group serves as both HB acceptor and donor. In addition, a nearly iso-energetic conformer (S2) with the formation of an O-H⋯⋯N-H⋯⋯O-S chain-type binding motif competes with S1 in the source. The most reactive site of the molecule susceptible for electrophilic attacks is the linkage S atom. Theoretically predicted infrared spectra indicate that O-H and N-H stretching modes are the fingerprint region (2800 to 3600 cm-1) to distinguish different isomers. The obtained information lays out a foundation to better understand the transformation and structure-reactivity correlation of Cys-SSO3H in biologic settings.

Excited-State Dynamics of Crossing-Controlled Energy Transfer in Europium Complexes.

Photosensitized energy transfer (EnT) phenomena occur frequently in a variety of photophysical and photochemical processes and have traditionally been treated with the donor-acceptor distance-dependent Förster and Dexter models. However, incorrect arguments and formulae were employed by ignoring energy resonance conditions and the selection rules of the state-to-state transition in special cases, especially for the sensitive intramolecular EnT of lanthanide complexes. Herein, we proposed an innovative model of energy-degeneracy-crossing-controlled EnT, which can be experimentally confirmed by time-resolved two-dimensional photoluminescence measurements. The computationally determined energy resonance region provides the most effective channel to achieve metal-to-ligand EnT beyond the distance-dependent model and sensitively bifurcates into symmetry-allowed or -forbidden channels for some representative europium antenna complexes. The outcomes of the multidisciplinary treatment contribute to a complementary EnT model that can be tuned by introducing a phosphorescence modulator and altering the antenna-related parameters of the ligand-centered energy level of the 3ππ* state and its spin-orbit coupling for the 3ππ* → S0 * transition through mechanism-guided crystal engineering and should motivate further development of mechanistic models and applications.

Quantitative analysis of nitrogen in ammonium phosphate fertilizers using laser-induced breakdown spectroscopy.

Laser-induced breakdown spectroscopy (LIBS) coupled with the linear multivariate calibration method was applied to analyze nitrogen (N) quantitatively in ammonium phosphate fertilizers. The intensity of lines N (NI:742.4, 744.2, 746.8, 856.7, 859.4, 862.9, 870.3, 871.2, 871.8 nm) and O (OI:777.2, 844.6, 882.0 nm) were used as independent variables for the models. To verify the accuracy of the models, the unary, binary, ternary, and quaternary variables were chosen to establish the linear regression equations. The results of the linear models showed that the quaternary model was better than the other three models. The correlation coefficient of the quaternary linear model was 0.981 and the maximum relative error of the validation samples was 4.32%.

Univariate and Multivariate Analysis of Phosphorus Element in Fertilizers Using Laser-Induced Breakdown Spectroscopy.

Rapid detection of phosphorus (P) element is beneficial to the control of compound fertilizer production process and is of great significance in the fertilizer industry. The aim of this work was to compare the univariate and multivariate analysis of phosphorus element in compound fertilizers and obtain a reliable and accurate method for rapid detection of phosphorus element. A total of 47 fertilizer samples were collected from the production line; 36 samples were used as a calibration set, and 11 samples were used as a prediction set. The univariate calibration curve was constructed by the intensity of characteristic line and the concentration of P. The linear correlation coefficient was 0.854 as the existence of the matrix effect. In order to eliminate the matrix effect, the internal standardization as the appropriate methodology was used to increase the accuracy. Using silicon (Si) element as an internal element, a linear correlation coefficient of 0.932 was obtained. Furthermore, the chemometrics model of partial least-squares regression (PLSR) was used to analysis the concentration of P in fertilizer. The correlation coefficient was 0.977 and 0.976 for the calibration set and prediction set, respectively. The results indicated that the LIBS technique coupled with PLSR could be a reliable and accurate method in the quantitative determination of P element in complex matrices like compound fertilizers.

Spectroscopic identification of the low-lying electronic states of S2 molecule.

As is well-known, the S2 molecule is a ubiquitous intermediate in the combustion, atmosphere, and interstellar space. The six low-lying bound states of S2 have been characterized via photoelectron velocity map imaging and a high-level multi-reference configuration interaction method with the Davidson correction. Spectroscopic constants have been extracted by fitting the potential energy curves extrapolated to the complete basis set limit with a series of Dunning's correlation-consistent basis sets: aug-cc-pV(Q, 5)Z. The calculated spectroscopic parameters well reproduce the experimental results in this work. On the basis of the theoretical calculations, Franck-Condon simulations are performed to assign six adjacent electronic states, especially for three higher overlapping electronic states (c1Σu -, A'3Δu, and A3Σu +). The dissociation energy De of the S2 - is evaluated to be 4.111 (4) eV in this work, in agreement with the theoretical prediction (4.056 eV).

A comparative study on the bond features in CO, CS, and PbS.

Covalent and noncovalent interactions dominate most compounds in the condensed phase and gas phase. For a classical diatomic molecule CO, it is usually regarded as a triple-bond system with one dative bond. In this work, the photoelectron velocity-map imaging spectra of the CS and PbS anions were first measured. The two interactions have been intuitively understood by a comparative investigation of electrostatic potential (ESP) and bond features in CO, CS, and PbS. It is suggested that both electrostatic and dative covalent interactions compete in CO molecules, while dative covalent interaction prevails in CS molecules and electrostatic interaction dominates in PbS molecules. As a consequence, CO has a very small dipole moment (∼0.1 D) compared to the large dipole moment in CS (>1.8 D) and PbS (>4 D). It is indicated that the electron affinity value increases with the increasing dipole moment in the order of CO < CS < PbS. In addition, intriguing ESP with negative bond-ends and positive bond-cylindrical-surface in CO is also revealed by comparing with that in CS and PbS. In the latter, the two molecules present opposite ESP maps. Molecular orbital analyses indicate surprising participation of Pb 5d orbitals in the Pb-S chemical bonding although Pb belongs to main-group elements. Further bond analyses using electron localization function, natural resonance theory, and bond order methods suggest that covalence is dominant in CS and ionicity is a major component in PbS, but somewhere in between for CO molecules. By a comparative study in this work, the CS molecule is also revealed as a promising ligand molecule for the transition-metal coordination chemical synthesis.

Spreading a water droplet through filter paper on the metal substrate for surface-enhanced laser-induced breakdown spectroscopy.

To improve the quantitative analysis accuracy of an aqueous solution using surface-enhanced laser-induced breakdown spectroscopy (SENLIBS), the filter paper was used as a transmission medium by placing it onto the surface of a metallic substrate to make the microdroplet spreading more uniform in a fixed region of the substrate surface. The trace elements (Cu, Pb, Cd, and Cr) in an aqueous solution were detected successfully using this method. The results showed that the sample preparation repeatability of SENLIBS was noticeably improved with the aid of filter paper. Moreover, the limit of detection (LoD) values was similar to those without filter paper. Furthermore, the R2 values were improved from 0.6192~0.9321 to 0.9481~0.9766, the RMSECV values were decreased from 0.53~1.95 µg/mL to 0.33~1.06 µg/mL, and the average relative error (ARE) values were decreased from 8.96~22.31% to 4.28~14.37% with the aid of filter paper. This demonstrated that the use of filter paper could improve the quantitative analysis accuracy of SENLIBS by increasing the sample preparation repeatability.

Analytical-performance improvement of aqueous solution by chemical replacement combined with surface-enhanced laser-induced breakdown spectroscopy.

In this study, chemical replacement combined with surface-enhanced laser-induced breakdown spectroscopy (CR-SENLIBS) was introduced for detecting the trace chromium (Cr) element in an aqueous solution, which could use chemical replacement to change the sample from liquid to solid. In order to illustrate the analytical-performance of the CR-SENLIBS, the direct analysis of the liquid surface by LIBS (LSLIBS) was investigated for comparison. The results show that the spectral intensity of Cr I 357.86 nm, plasma lifetime, and spectral stability were improved. Moreover, the limit of detection of Cr I 357.86 nm was 0.018 µg/mL, which was lower than 1.814 µg/mL for LSLIBS. Furthermore, the accuracy and precision were improved more than 60% and 80%, respectively; for example, the root-mean-square error of cross-validation was improved from 1.09 to 0.75 µg/mL, and the average relative standard deviation of the predicted concentration of Cr was reduced from 22.89% to 4.53% by using CR-SENLIBS. These results suggest that CR-SENLIBS has good analytical-performance, which exhibits great potential in water quality monitoring.

Identifying and Modulating Accidental Fermi Resonance: 2D IR and DFT Study of 4-Azido-l-phenylalanine.

Azido-modified aromatic amino acids have been used as powerful infrared probes for the site-specific detection of proteins because of their large transition dipole strengths. However, their complex absorption profiles hinder their wider application. The complicated absorption profile of 4-azido-l-phenylalanine (pN3Phe) in isopropanol was identified and attributed to accidental Fermi resonances (FRs) by means of linear absorption and two-dimensional (2D) IR spectroscopies. The 2D IR results of pN3Phe in H2O and D2O further demonstrate that the FRs are distinctively influenced by the hydrogen-bonding environment. Under the influence of FRs, the 2D IR shape is distorted, indicating that pN3Phe is not a good candidate in spectral diffusion studies. A three-state model and first-principles calculations were used to analyze unperturbed energy levels, unveiling the FRs between the azide asymmetric stretching band and two combination bands. Furthermore, the anharmonic frequency calculations suggest that changing the substitution position of the azide group from para to meta can effectively modulate the FRs by reducing the coupling strength. This work provides a deep understanding of the FRs in azido-modified aromatic amino acids and sheds light on the modification of azido-modified amino acids for wider utilization as vibrational probes.

Electron velocity map imaging and theoretical study on CuXH (X=O and S) anions.

Vibrationally resolved photoelectron spectra of CuOH- and CuSH- have been determined via velocity map imaging method to investigate the transitions of X1A'←X2A' at 532nm. Adiabatic detachment energies of CuOH- and CuSH- are assigned to 0.995(12) and 1.098(12) eV, respectively. Combined theoretical calculations with Franck-Condon simulations, it allows extracting the vibrational frequencies in neutral, which yields 629(32) cm-1 with CuO stretching mode and 387(24) cm-1 with CuS stretching mode for CuXH (X=O and S). Parallel transition properties of photoelectron angular distributions (PADs) for both species are correlated to the photodetachment of SOMO orbitals, which mainly involved in the Cu atom s orbital and partial s orbital in other atoms. Based on chemical bonding analyses (Wiberg, NAO, Mayer, NRT, and ELF), it is suggested that a trend is observed with a subtle variation of covalent component from weak covalent behavior between CuO in CuOH-1/0 to stronger covalent bonding between CuS in CuSH-1/0 (especially for non-ignorable covalent component in CuSH species) though ionic bonding dominates both in CuO and CuS bonds for the two systems.

Slow-electron velocity-map imaging study of aniline via resonance-enhanced two-photon ionization method.

Slow electron velocity-map imaging (SEVI) of aniline has been investigated via two-color resonant-enhanced two-photo (1+1') ionization (2C-R2PI) method. A number of vibrational frequencies in the first excited state of neutral (S1) and 2B1 ground electronic state of cation (D0) have been accurately determined. In addition, photoelectron angular distributions (PADs) in the two-step transitions are presented and reveal a near threshold shape resonance in the ionization of aniline. The SEVI spectra taken via various S1 intermediate states provide the detailed vibrational structures of D0 state and directly deduce the accurate adiabatic ionization potential (IP) of 62,271±6cm-1. Ab initio calculations excellently reproduce the experimental IP value (Theo. 62,242cm-1). For most vibrational modes, good agreement between theoretical and experimental frequencies in the S0 and D0 states of aniline is obtained to aid us to clearly assign vibrational modes. Especially, the vibrational frequencies calculated at the CASSCF level are much better consistent with experimental data than that obtained using the TDDFT and CIS methods.

Ag-Ag2S Hybrid Nanoprisms: Structural versus Plasmonic Evolution.

Recently, Ag-Ag2S hybrid nanostructures have attracted a great deal of attention due to their enhanced chemical and thermal stability, in addition to their morphology- and composition-dependent tunable local surface plasmon resonances. Although Ag-Ag2S nanostructures can be synthesized via sulfidation of as-prepared anisotropic Ag nanoparticles, this process is poorly understood, often leading to materials with anomalous compositions, sizes, and shapes and, consequently, optical properties. In this work, we use theory and experiment to investigate the structural and plasmonic evolution of Ag-Ag2S nanoprisms during the sulfidation of Ag precursors. The previously observed red-shifted extinction of the Ag-Ag2S hybrid nanoprism as sulfidation occurs contradicts theoretical predictions, indicating that the reaction does not just occur at the prism tips as previously speculated. Our experiments show that sulfidation can induce either blue or red shifts in the extinction of the dipole plasmon mode, depending on reaction conditions. By elucidating the correlation with the final structure and morphology of the synthesized Ag-Ag2S nanoprisms, we find that, depending on the reaction conditions, sulfidation occurs on the prism tips and/or the (111) surfaces, leading to a core(Ag)-anisotropic shell(Ag2S) prism nanostructure. Additionally, we demonstrate that the direction of the shift in the dipole plasmon is a function of the relative amounts of Ag2S at the prism tips and Ag2S shell thickness around the prism.

[Quantitative Analysis of Mn in Soil Samples Using LIBS].

The trace element of Manganese element in the agricultural farm (Anhui Huaiyuan Nongkang) soil was quantitatively analyzed by Laser-induced breakdown spectroscopy. The line of 403.1 nm was selected as the analysis line of Mn. The matrix element of Fe in soil was chosen as the internal calibration element and the analysis line was 407.2 nm. Ten soil samples were used to construct calibration curves with traditional method and internal standard method, and four soil samples were selected as test samples. The experimental results showed that the fitting correlation coefficient (r) is 0.954 when using the traditional method, the maximum relative error of the measurement samples is 5.72%, and the detection limit of Mn in soil is 93 mg x kg(-1). While using the internal standard method to construct the calibration curve, the fitting correlation coefficient (r) is 0.983, the relative error of measurement samples is reduced to 4.1%, and the detection limit of Mn in soil is 71 mg x kg(-1). The result indicates that LIBS technique can be used to detect trace element Mn in soil. In a certain extent, the internal standard method can improve the accuracy of measurement.

The design of double electrostatic-lens optics for resonance enhanced multiphoton ionization and photoelectron imaging experiments.

Compared to single ion/electron-optics for velocity-map imaging, a double-focusing lens assembly designed not only allows for mapping velocity imaging of photoelectrons but also allows for investigating the vibrational structure of the intermediate states of neutral species in resonance enhanced multiphoton ionization (REMPI) spectra. In this presentation, in order to record REMPI and photoelectron spectra separately, we have constructed a compact photoelectron velocity-map imaging (VMI) apparatus combined with an opposite linear Wiley-Mclaren time-of-flight mass spectrometer (TOFMS). A mass resolution (m/Δm) of ∼1300 for TOFMS and electron energy resolution (ΔE/E) of 2.4% for VMI have been achieved upon three-photon ionization of Xe atom at 258.00 nm laser wavelength. As a benchmark, in combination of one-color (1 + 1) REMPI and photoelectron imaging of benzene via 6(1) and 6(1)1(1) vibronic levels in the S1 state, the vibrational structures of the cation and photoelectron angular anisotropy are unraveled. In addition, two-color (1 + 1') REMPI and photoelectron imaging of aniline was used to complete the accurate measurement of ionization potential (62,271 ± 3 cm(-1)). The results suggest that the apparatus is a powerful tool for studying photoionization dynamics in the photoelectron imaging using vibrational-state selected excitation to the intermediate states of neutrals based on REMPI technique.

[Quantitative analysis of thiram by surface-enhanced raman spectroscopy combined with feature extraction Algorithms].

Three feature extraction algorithms, such as the principal component analysis (PCA), the discrete cosine transform (DCT) and the non-negative factorization (NMF), were used to extract the main information of the spectral data in order to weaken the influence of the spectral fluctuation on the subsequent quantitative analysis results based on the SERS spectra of the pesticide thiram. Then the extracted components were respectively combined with the linear regression algorithm--the partial least square regression (PLSR) and the non-linear regression algorithm--the support vector machine regression (SVR) to develop the quantitative analysis models. Finally, the effect of the different feature extraction algorithms on the different kinds of the regression algorithms was evaluated by using 5-fold cross-validation method. The experiments demonstrate that the analysis results of SVR are better than PLSR for the non-linear relationship between the intensity of the SERS spectrum and the concentration of the analyte. Further, the feature extraction algorithms can significantly improve the analysis results regardless of the regression algorithms which mainly due to extracting the main information of the source spectral data and eliminating the fluctuation. Additionally, PCA performs best on the linear regression model and NMF is best on the non-linear model, and the predictive error can be reduced nearly three times in the best case. The root mean square error of cross-validation of the best regression model (NMF+SVR) is 0.0455 micormol x L(-1) (10(-6) mol x L(-1)), and it attains the national detection limit of thiram, so the method in this study provides a novel method for the fast detection of thiram. In conclusion, the study provides the experimental references the selecting the feature extraction algorithms on the analysis of the SERS spectrum, and some common findings of feature extraction can also help processing of other kinds of spectroscopy.

Ginkgolide A reduces inflammatory response in high-glucose-stimulated human umbilical vein endothelial cells through STAT3-mediated pathway.

High-glucose-induced low-grade inflammation has been regarded as a key event in the onset and progression of endothelial dysfunction in diabetic vascular complications. Ginkgolide A (GA), a major compound from Ginkgo biloba extract, is widely used for the treatment of cardiovascular diseases and diabetic vascular complications. Here, its effect on high-glucose-stimulated vascular inflammation in human umbilical vein endothelial cells (HUVECs) was investigated. In the present study, the optimal stimulation conditions for HUVECs were screened for inducing endothelial inflammation, namely, high glucose at the concentration of 30mM for continuous 8h. The endothelial production of high-glucose-induced interleukin (IL)-4, IL-6, IL-13 and signal transducer and activator of transcription-3 (STAT-3) phosphorylation were significantly inhibited by the pretreatment with GA at concentrations of 10, 15 and 20µM based on enzyme-linked immunosorbent assay (ELISA), western blot or/and RT-PCR experiments. These senescent alterations induced by high glucose were significantly attenuated by the specific STAT3 inhibitor S3I-201 at the concentration of 20µM. Furthermore, the phosphorylation of STAT3, IL-4, IL-6, IL-13 and intercellular cell adhesion molecule-1 (ICAM-1) protein as well as mRNA levels were attenuated by the pretreatment of cells with STAT3 siRNA. Our results demonstrated that GA improved high-glucose-caused low-grade vascular inflammation, which might be achieved through regulating the STAT3-mediated pathway. These findings indicated that GA might be a promising candidate for attenuating vascular inflammation in diabetic vascular complications.

BcMctA, a putative monocarboxylate transporter, is required for pathogenicity in Botrytis cinerea.

Monocarboxylate transporters have a central role in mammalian metabolism, but rarely reported in phytopathogenic fungi. In this study, a putative monocarboxylate transporter gene in Botrytis cinerea [B. cinerea MctA (BcMctA)] was identified in the research of a B. cinerea transfer DNA (T-DNA) insertional mutant (74). Disruption of the gene decreased the growth rate on the medium with monocarboxylate (acetate or pyruvate) as the sole carbon sources, but not affected on lactate. The pyruvate contents in BcmctA deletion mutants decreased about 35 % compared with the wild strain. Besides, the conidial yield was increased about two times in BcmctA disruption mutant. The pathogenicity assay indicated that disruption of BcmctA significantly reduced the virulence of B. cinerea on cucumber and tomato leaves. Our results demonstrated that BcMctA is related to pyruvate uptake and pathogenicity of B. cinerea on cucumber and tomato leaves.

Photoinduced electron transfer between 2-methylanthraquinone and triethylamine in an ionic liquid: time-resolved EPR and transient absorption spectroscopy study.

Photoinduced electron transfer between 2-methylanthraquinone (MeAQ) and triethylamine (TEA) in a room-temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), was investigated by comparing the time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy and the transient absorption spectroscopy. The results of TR-EPR spectroscopy, in which MeAQ was 8 mmol L(-1) and TEA was 150 mmol L(-1), indicated that the transient radical would exist longer time in [bmim][PF6] than in acetonitrile. At the delay time of 8 µs after laser excitation, the TR-EPR signal transformed from an emissive peak into an absorptive peak when the experiment was performed in [bmim][PF6]. The results of the transient absorption spectroscopy, in which MeAQ was 0.1 mmol L(-1) and TEA was 2.2 mmol L(-1), showed that the efficiency and the rate of the photoinduced electron transfer reaction in [bmim][PF6] were obviously lower than that in acetonitrile. It was concluded that various factors, such as concentration, viscosity and local structural transformation of the solution, have an influence on the process of photoinduced electron transfer in [bmim][PF6].

Enhanced production of lipstatin from Streptomyces toxytricini by optimizing fermentation conditions and medium.

This paper is concerned with optimization of fermentation conditions for lipstatin production with Streptomyces toxytricini zjut011 by the single factor and orthogonal tests. Five single factors of important effects on lipstatin production were explored. L-Leucine was identified to be the most suitable precursor for lipstatin biosynthesis and for the first time the divalent cations Mg(2+), Co(2+) and Zn(2+) were found to have significant effect on enhancing lipstatin fermentation titer. The effects of the additives on the lipstatin production were in the order of L-leucine ＞ Mg(2+) ＞ Co(2+) ＞ Zn(2+) ＞ octanoic acid. The optimized conditions for lipstatin production were determined as 45.72 mmol/L of L-leucine (added on the 4 th day), 31.1985 mmol/L of octanoic acid (added on the 6th day), 12 mmol/L of Mg(2+), 1 mmol/L of Co(2+) and 0.25 mmol/L of Zn(2+). Under these conditions, a maximum lipstatin of 4.208 g/ml was achieved in verification experiments in 500 ml shake flasks.