Natural Deep Eutectic Solvents for the Extraction of Bioactive Steroidal Saponins from Dioscoreae Nipponicae Rhizoma.

In the present study, a simple and environmentally friendly extraction method based on natural deep eutectic solvents (NADESs) was established to extract four bioactive steroidal saponins from Dioscoreae Nipponicae Rhizoma (DNR). A total of twenty-one types of choline chloride, betaine, and L-proline based NADESs were tailored, and the NADES composed of 1:1 molar ratio of choline chloride and malonic acid showed the best extraction efficiency for the four steroidal saponins compared with other NADESs. Then, the extraction parameters for extraction of steroidal saponins by selected tailor-made NADES were optimized using response surface methodology and the optimal extraction conditions are extraction time, 23.5 min; liquid-solid ratio, 57.5 mL/g; and water content, 54%. The microstructure of the DNR powder before and after ultrasonic extraction by conventional solvents (water and methanol) and the selected NADES were observed using field emission scanning electron microscope. In addition, the four steroidal saponins were recovered from NADESs by D101 macroporous resin with a satisfactory recovery yield between 67.27% and 79.90%. The present research demonstrates that NADESs are a suitable green media for the extraction of the bioactive steroidal saponins from DNR, and have a great potential as possible alternatives to organic solvents for efficiently extracting bioactive compounds from natural products.

Structural Identification and Conversion Analysis of Malonyl Isoflavonoid Glycosides in Astragali Radix by HPLC Coupled with ESI-Q TOF/MS.

In this study, four malonyl isoflavonoid glycosides (MIGs), a type of isoflavonoid with poor structural stability, were efficiently isolated and purified from Astragali Radix by a medium pressure ODS C18 column chromatography. The structures of the four compounds were determined on the basis of NMR and literature analysis. Their major diagnostic fragment ions and fragmentation pathways were proposed in ESI/Q-TOF/MS positive mode. Using a target precursor ions scan, a total of 26 isoflavonoid compounds, including eleven malonyl isoflavonoid glycosides coupled with eight related isoflavonoid glycosides and seven aglycones were characterized from the methanolic extract of Astragali Radix. To clarify the relationship of MIGs and the ratio of transformation in Astragali Radix under different extraction conditions, two MIGs (calycosin-7-O-glycoside-6″-O-malonate and formononetin-7-O-glycoside-6″-O-malonate) coupled with related glycosides (calycosin-7-O-glycoside and formononetin-7-O-glycoside) and aglycones (calycosin and formononetin) were detected by a comprehensive HPLC-UV method. Results showed that MIGs could convert into related glycosides under elevated temperature conditions, which was further confirmed by the conversion experiment of MIGs reference compounds. Moreover, the total contents of MIGs and related glycosides displayed no obvious change during the long-duration extraction. These findings indicated that the quality of Astragali Radix could be evaluated efficiently and accurately by using the total content of MIGs and related glycosides as the quality index.

[Electrochemical fingerprint of traditional Chinese medicines based on BrO⁻3-Ce4⁺-H⁺-malonic acid/tartaric acid chemical oscillating system].

A new composite organic oscillating reaction system based on BrO3-Ce(SO4)2-H2SO4-malonic acid/tartaric acid was proposed in this paper. On the basis of the influence of the concentration of each component on the stability and characteristic parameters of the blank system, the electrochemical fingerprints of 30 kinds of traditional Chinese medicines (TCM) were obtained. The results showed that the electrochemical fingerprint can be used for the identification of TCMs, the distinguishment of different parts and the appraisal of genuineness, which is fast, sensitive and accurate. At the same time, we explored and verified the mechanism of oscillation and the formation mechanism of TCM fingerprint.

One-pot production of chitin with high purity from lobster shells using choline chloride-malonic acid deep eutectic solvent.

For the first time in this study, chitin was solely extracted from lobster shells through a fast, easy and eco-friendly method using deep eutectic solvents (DESs), consisting of mixtures of choline chloride-thiourea (CCT), choline chloride-urea (CCU), choline chloride-glycerol (CCG) and choline chloride-malonic acid (CCMA). The physiochemical properties of the isolated chitins were compared with those of the chemically prepared one and commercial one from shrimp shells. Results showed that CCT, CCU and CCG DESs had no important effect on the elimination of proteins and minerals, while chitin obtained by CCMA DES showed a high purity. The yield (20.63±3.30%) of chitin isolated by CCMA DES was higher than that (16.53±2.35%) of the chemically prepared chitin. The chitin obtained by CCMA DES could be divided into two parts with different crystallinity (67.2% and 80.6%), which also had different thermal stability. Chitin from lobster shells showed porous structure, which is expected to be used for adsorption materials and tissue engineering.

Stepwise pH-responsive nanoparticles for enhanced cellular uptake and on-demand intracellular release of doxorubicin.

Physicochemical properties, including particle size, zeta potential, and drug release behavior, affect targeting efficiency, cellular uptake, and antitumor effect of nanocarriers in a formulated drug-delivery system. In this study, a novel stepwise pH-responsive nanodrug delivery system was developed to efficiently deliver and significantly promote the therapeutic effect of doxorubicin (DOX). The system comprised dimethylmaleic acid-chitosan-urocanic acid and elicited stepwise responses to extracellular and intracellular pH. The nanoparticles (NPs), which possessed negative surface charge under physiological conditions and an appropriate nanosize, exhibited advantageous stability during blood circulation and enhanced accumulation in tumor sites via enhanced permeability and retention effect. The tumor cellular uptake of DOX-loaded NPs was significantly promoted by the first-step pH response, wherein surface charge reversion of NPs from negative to positive was triggered by the slightly acidic tumor extracellular environment. After internalization into tumor cells, the second-step pH response in endo/lysosome acidic environment elicited the on-demand intracellular release of DOX from NPs, thereby increasing cytotoxicity against tumor cells. Furthermore, stepwise pH-responsive NPs showed enhanced antiproliferation effect and reduced systemic side effect in vivo. Hence, the stepwise pH-responsive NPs provide a promising strategy for efficient delivery of antitumor agents.

Neutral Loss Ion Mapping Experiment Combined with Precursor Mass List and Dynamic Exclusion for Screening Unstable Malonyl Glucoside Conjugates.

Malonates are one type of the acylation conjugates and found abundantly in ginseng and soybean. Malonyl conjugates of ginsenosides and isoflavone glycosides were often considered as the characteristic components to evaluate various species and different forms of ginseng and soybean products because of their thermal instability. Another famous isoflavonoid-rich leguminous traditional Chinese medicine (TCM), named Puerarin lobata (Gegen), has also been reported to contain malonyl daidzin and malonyl genistin. However, the conjugates were found to present in very low amount and particularly unstable in the negative ion mode scan using LTQ Orbitrap mass spectrometry with electrospray ionization (ESI). In order to screen and characterize the malonyl conjugates in Gegen, a specific method was designed and developed combining neutral loss ion mapping (NLIM) experiment and precursor mass list (PL) triggered data dependent acquisition (DDA). Along with the activation of dynamic exclusion (DE), the method was proven to be specific and efficient for searching the malonate derivatives from Gegen. Two samples were examined by the established method. A total of 66 compounds were found, and 43 of them were malonates of isoflavone glycoside. Very few compounds were reported previously in Gegen. The results are helpful to understand the constituents of Gegen with more insight. The study not only provided a method for analyzing the malonyl conjugates from complex matrices but also explored a way to trace other low amount components in TCMs.

Development of amino acid derivatization reagents for liquid chromatography electrospray ionization mass spectrometric analysis and ionization efficiency measurements.

Derivatization is one of the most common ways for improving chromatographic separation and sensitivity for LC-ESI-MS analysis. The aim of this work was to design new derivatization reagents for LC-ESI-MS analysis of amino acids which would (1) provide good reversed phase chromatographic separation, (2) most importantly, provide low detection limits, (3) be easily synthesized, (4) produce derivatives which are less susceptible to matrix influences and (5) have convenient derivatization procedure with stable derivatives suitable for automatization. In the current work two new LC-ESI-MS compatible derivatization reagents have been designed and synthesized, dibenzyl ethoxymethylene malonate (DBEMM) and benzyl ethyl ethoxymethylene malonate (EBEMM). The DBEMM meets all the goals set with instrumental detection limits as low as 1 femtomole for amino acids and 40 attomole for selenoamino acids.

Derivatives of mesoxalic acid block translocation of HIV-1 reverse transcriptase.

The pyrophosphate mimic and broad spectrum antiviral phosphonoformic acid (PFA, foscarnet) was shown to freeze the pre-translocational state of the reverse transcriptase (RT) complex of the human immunodeficiency virus type 1 (HIV-1). However, PFA lacks a specificity domain, which is seen as a major reason for toxic side effects associated with the clinical use of this drug. Here, we studied the mechanism of inhibition of HIV-1 RT by the 4-chlorophenylhydrazone of mesoxalic acid (CPHM) and demonstrate that this compound also blocks RT translocation. Hot spots for inhibition with PFA or CPHM occur at template positions with a bias toward pre-translocation. Mutations at active site residue Asp-185 compromise binding of both compounds. Moreover, divalent metal ions are required for the formation of ternary complexes with either of the two compounds. However, CPHM contains both an anchor domain that likely interacts with the catalytic metal ions and a specificity domain. Thus, although the inhibitor binding sites may partly overlap, they are not identical. The K65R mutation in HIV-1 RT, which reduces affinity to PFA, increases affinity to CPHM. Details with respect to the binding sites of the two inhibitors are provided on the basis of mutagenesis studies, structure-activity relationship analyses with newly designed CPHM derivatives, and in silico docking experiments. Together, these findings validate the pre-translocated complex of HIV-1 RT as a specific target for the development of novel classes of RT inhibitors.

Study of the matrix effects and sample dilution influence on the LC-ESI-MS/MS analysis using four derivatization reagents.

For liquid chromatographic analysis of amino acids involving derivatization and mass-spectrometric detection, it becomes more important to evaluate the presence of matrix effects in complex samples. This is somewhat complicated for amino acid analysis where analyte free sample matrix is often unavailable. In this work, matrix effects were investigated using post-column infusion method for 9-fluorenylmethyl chloroformate (FMOC-Cl) derivatives of ß-Ala, Gly and Phe and diethyl ethoxymethylenemalonate (DEEMM) derivative of ß-Ala. While for DEEMM derivatives, the main signal suppression was due to the borate buffer, in case of FMOC-Cl, other FMOC-derivatives caused signal suppression. Analysis of amino acids in tea and honey with DEEMM, FMOC-Cl, p-N,N,N-trimethylammonioanilyl N'-hydroxysuccinimidyl carbamate iodide (TAHS) and dansyl chloride (DNS) showed that amino acid concentrations found with different reagents do not agree well. Sample dilution experiments indicated that the sample matrix affected the analysis results obtained with DEEMM the least, but with FMOC-Cl, TAHS and DNS, sample dilution had an influence on the results. When sample dilution and extrapolative dilution approach were applied on the latter results, an agreement of amino acid concentrations measured with different reagents was achieved within relative standard deviation (RSD) of 22% for most cases.

Structural characterisation of malonyl flavonols in leek (Allium porrum L.) using high-performance liquid chromatography and mass spectrometry.

INTRODUCTION: Vegetables contain a variety of phytochemicals that have the ability to modify enzymatic and chemical reactions, and therefore may have a positive influence on human health. In particular kaempferol is known to possess anti-carcinogenic activity. OBJECTIVE: The purpose of this work was to determine the structure of glycosylated kaempferol derivatives, acylated with malonic acid on the sugar portion. METHODS: A methanolic extract of the leaves of Allium porrum L. was submitted to fractionation procedures through semi-preparative HPLC/UV-MS techniques. The collected fractions were evaluated by accurate tandem mass spectrometry experiments using an electrospray ionisation (ESI) quadrupole time-of-flight instrument. Isolated compounds were hydrolysed in order to obtain information on the ester moieties. RESULTS: The structures of five compounds not previously reported in leek were determined. The molecules are mono-hexose, di-hexose and coumaroyl, feruloyl and caffeoyl acylated di-hexose derivatives of kaempferol. The common characteristic of the structures relies on the presence of the malonyl moiety on the primary alcoholic function of the sugar immediately linked to the aglycone. Accurate tandem MS experiments and basic hydrolysis treatments revealed a sequence of the acylated glycosidic moieties. CONCLUSION: A set of secondary metabolites of the aerial part of Allium porrum L. (leek) was identified and characterised by ESI/MS(2) . Knowledge of the presence of these first-reported compounds in leek could provide the means for fully understanding of the metabolism of this plant in relation to the biosynthesis of the phenolics.

Simplified ultrasonically- and microwave-assisted solvent extractions for the determination of ginsenosides in powdered Panax ginseng rhizomes using liquid chromatography with UV absorbance or electrospray mass spectrometric detection.

New approaches for the recovery of ginsenosides are presented that greatly simplify the liquid chromatographic (LC) determination of the total content of eight ginsenosides (Rb1, Rb2, Rc, Rd, Re, Rf, Rg1 and Rg2) in powdered Panax ginseng rhizomes. The extraction protocols not only recover the neutral ginsenosides, but also simultaneously incorporate base-catalyzed hydrolysis of the malonyl-ginsenosides using dilute potassium hydroxide added to the methanol-water extractant. This eliminates the need for an independent extraction step followed by acid- or base-catalyzed hydrolysis. Both ultrasonically-assisted and microwave-assisted extraction methods are developed. The optimization of these simplified methods to remove pendant malonate esters, while retaining the glycosidic linkages, was determined by LC through variation of the extraction/hydrolysis time, order of hydrolysis reagent addition, and evaluation of multiple extractions. A comparison of the ginsenoside profiles obtained with and without addition of base to the extractant solution was made using LCMS with positive-mode electrospray ionization (ESI(+)) detection. A number of malonyl-ginsenosides were tentatively identified by their mass spectral fragmentation spectra and indicating that they were converted to the free ginsenosides by the new extraction/hydrolysis procedure.

Malonylated glycerolipids from the glandular trichome exudate of Ceratotheca triloba.

Chemical investigation of the glandular trichome exudate from Ceratotheca triloba (Pedaliaceae) led to the identification of nine 1-O-acetyl-2-O-[(R)-3-acetyloxy-fatty acyl]-3-O-malonylglycerols. Among these, 1-O-acetyl-2-O-[(R)-3-acetyloxyicosanoyl]-3-O-malonylglycerol (7) was the most abundant constituent (41%), followed by 1-O-acetyl-2-O-[(R)-(3-acetyloxyoctadecanoyl)-3-O-malonylglycerol (2; 21%). Compounds having iso- and anteiso-type structures in the 3-acetyloxy-fatty acyl groups in the fatty acyl moiety were also characterized as minor constituents. This is the first report of the isolation of malonylated glycerolipids as natural products.

Elemental and metabolite profiling of nickel hyperaccumulators from New Caledonia.

Leaf material from nine Ni hyperaccumulating species was collected in New Caledonia: Homalium kanaliense (Vieill.) Briq., Casearia silvana Schltr, Geissois hirsuta Brongn. & Gris, Hybanthus austrocaledonicus Seem, Psychotria douarrei (G. Beauvis.) Däniker, Pycnandra acuminata (Pierre ex Baill.) Swenson & Munzinger (syn Sebertia acuminata Pierre ex Baill.), Geissois pruinosa Brongn. & Gris, Homalium deplanchei (Viell) Warb. and Geissois bradfordii (H.C. Hopkins). The elemental concentration was determined by inductively-coupled plasma optical emission spectrometry (ICP-OES) and from these results it was found that the species contained Ni concentrations from to 250-28,000 mg/kg dry mass. Gas chromatography mass spectrometry (GC-MS)-based metabolite profiling was then used to analyse leaves of each species. The aim of this study was to target Ni-binding ligands through correlation analysis of the metabolite levels and leaf Ni concentration. Approximately 258 compounds were detected in each sample. As has been observed before, a correlation was found between the citric acid and Ni concentrations in the leaves for all species collected. However, the strongest Ni accumulator, P. douarrei, has been found to contain particularly high concentrations of malonic acid, suggesting an additional storage mechanism for Ni. A size exclusion chromatography separation protocol for the separation of Ni-complexes in P. acuminata sap was also applied to aqueous leaf extracts of each species. A number of metabolites were identified in complexes with Ni including Ni-malonate from P. douarrei. Furthermore, the levels for some metabolites were found to correlate with the leaf Ni concentration. These data show that Ni ions can be bound by a range of small molecules in Ni hyperaccumulation in plants.

Liquid-liquid extraction of Pu(IV), U(VI) and Am(III) using malonamide in room temperature ionic liquid as diluent.

The extraction behavior of U(VI), Pu(IV) and Am(III) from nitric acid medium by a solution of N,N-dimethyl-N,N-dioctyl-2-(2-hexyloxyethyl)malonamide (DMDOHEMA) in the room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C(4)mimNTf(2)), was studied. The distribution ratio of these actinides in DMDOHEMA/C(4)mimNTf(2) was measured as a function of various parameters such as the concentration of nitric acid, DMDOHEMA, NTf(2)(-), alkyl chain length of ionic liquid. The extraction of actinides in the absence of DMDOHEMA was insignificant and the distribution ratio achieved in conjunction with C(4)mimNTf(2), was remarkable. The separation factor of U(VI) and Pu(IV) achieved with the use of DMDOHEMA, ionic liquid was compared with Am(III) and other fission products. The stoichiometry of the metal-solvate was determined to be 1:2 for U(VI) and Pu(IV) and 1:3 for Am(III).

Discovery of novel indane derivatives as liver-selective thyroid hormone receptor ß (TRß) agonists for the treatment of dyslipidemia.

Thyromimetics that specifically target TRß have been shown to reduce plasma cholesterol levels and avoid atherosclerosis through the promotion of reverse cholesterol transport in an animal model. We designed novel thyromimetics with high receptor (TRß) and organ (liver) selectivity based on the structure of eprotirome (3) and molecular modeling. We found that indane derivatives are potent and dual-selective thyromimetics expected to avoid hypothyroidism in some tissues as well as heart toxicity. KTA-439 (29), a representative indane derivative, showed the same high human TRß selectivity in a binding assay as 3 and higher liver selectivity than 3 in a cholesterol-fed rat model.

The effects of dynamic changes of malonyl ginsenosides on evaluation and quality control of Panax ginseng C.A. Meyer.

To clarify the effects of malonyl ginsenosides (MGR) on evaluation and quality control of Panax ginseng, the contents of neutral and malonyl ginsenosides from P. ginseng were examined by high-performance liquid chromatography equipped with UV-VIS detector (HPLC-UV) during extraction, processing and storage. Several solvents, including water, ethanol, methanol, and n-butanol were used in the cold-soaked extraction (CSE). Among the four extraction solvents, methanol was found to be the most efficient. CSE was compared with other extraction methods such as Soxhlet extraction (SE), heat reflux extraction (HRE), ultrasonic-assisted extraction (UAE), and microwave-assisted extraction (MAE). The content of MGR showed significant differences, higher in CSE and UAE; lower in MAE and HRE; no MGR could be detected after SE. However, the total contents of neutral and malonyl ginsenosides were not different. Meanwhile, white ginseng, stored at 25°C in air of low humidity, showed a marked decrease in the concentration of MGR from 1.19% to 0.63% but with an increase in the neutral ginsenosides from 1.12% to 1.53% after 0-9-month storage. The results indicated that MGR changed dynamically in P. ginseng with different extraction solvents, extraction methods and increasing storage time. The total ginsenosides was not only underestimated but also determined imprecisely by ignoring malonyl ginsenosides. On the basis of our results, we suggest that malonyl ginsenosides should be transformed into the corresponding neutral ginsenosides during sample preparation for quality control and evaluation of P. ginseng. Then the content of six neutral ginsenosides in samples was used as the true level of total ginsenosides. The results reported here might provide useful information for accurate evaluation and quality control of P. ginseng.

Analysis of selenomethylselenocysteine and selenomethionine by LC-ESI-MS/MS with diethyl ethoxymethylenemalonate derivatization.

A simple method to identify and determine Selenomethionine (SeMet) and Selenomethylselenocysteine (Se-MeSeCys) with diethyl ethoxymethylenemalonate (DEEMM) derivatization and LC-ESI-MS/MS determination was developed. Separation of SeMet and Se-MeSeCys was achieved in 15.3 minutes. The calibration graph was linear in the range of 0.32 pmol to 49 pmol for SeMet and 0.34 pmol to 40 pmol for Se-MeSeCys. To prevent oxidation of SeMet, 2-mercaptoethanol was introduced to the calibration solutions. Detection limits were 0.1 pmol, which are comparable to LC-ICP-MS analysis. The developed method therefore offers an alternative to LC-ICP-MS offering similar sensitivity and additionally allows identification. The method was used to determine Se-MeSeCys and SeMet in onion samples.

A novel malonamide grafted polystyrene-divinyl benzene resin for extraction, pre-concentration and separation of actinides.

A new chelating polymeric extraction chromatographic resin was prepared by chemical anchoring of N,N'-dimethyl-N,N'-dibutyl malonamide (DMDBMA) with chloromethylated Merrifield resin((R)). The grafted resin exhibited stronger binding for hexavalent and tetravalent actinides such as U(VI), Th(IV) and Pu(IV) over trivalent actinides, viz. Am(III) and Pu(III). Batch studies on solid phase extraction performed over a wide range of acid solution (0.01-6M HNO(3)) revealed that ternary mixer of uranium, americium and plutonium or thorium, americium and plutonium could be separated from each other at 1M HNO(3). Desorption of U(VI), Pu(IV) and Am(III) from the loaded resin was efficiently carried out using 0.1M alpha-HIBA, 0.25M oxalic acid and 0.01M EDTA, respectively. Quantitative pre-concentration of actinide ions such as Th(IV) and U(VI) was possible from 3M HNO(3) solution. The practical utility of the grafted resin was evaluated by uranium sorption measurements in several successive cycles. The sorption efficiency of the resin with respect to uranyl ion remained unchanged even after 30 days of continuous use. The surface morphology of the resin was monitored with the help of scanning electron microscopy (SEM) technique.

Differentiation of isomeric malonylated flavonoid glyconjugates in plant extracts with UPLC-ESI/MS/MS.

INTRODUCTION: Glycosylation at different hydroxyl groups of flavonoids and acylation of sugar moieties are ubiquitous modifications observed in plants. These modifications give rise to simultaneous presence of numerous isomeric and isobaric compounds in tissues and extracts thereof. OBJECTIVE: To develop UPLC-MS method capable for resolution of isomeric malonylated glycoconjugates of flavonoids and recognition of structural differences. METHODOLOGY: Flavonoid glycoconjugates were extracted from leaves of blue lupin (Lupinus angustifolius L.) plants with 80% methanol. Extracts were analysed using ultraperformance liquid chromatography (UPLC) combined with tandem (quadrupole-time of flight, QToF) mass spectrometry. RESULTS: Differentiation of malonylated glycosides of isoflavones and flavones is demonstrated in this paper. The use of UPLC-MS/MS enabled 38 flavonoid conjugates to be distinguished, including the discrimination of five different isomers of a single 3'-O-methylluteolin glycoside. Additionally, pseudo MS(3) experiments (CID spectra registered at high cone voltages) enabled confirmation of the aglycone structures by comparison of their spectra with those obtained from aglycone standards. CONCLUSIONS: Application of UPLC-MS/MS allows separation and identification numerous positional isomers of malonylated glycosides of flavonoids and isoflavonoids in plant material. Provided there is strict control of the MS ionisation parameters, this method may be useful for preparation of a flavonoids spectra database, enabling the inter-laboratory comparison of analytical results.

Chiral bisphosphazides as dual basic enantioselective catalysts.

Chiral bisphosphazides complexed with lithium salts efficiently catalyze the direct enantioselective 1,4-addition of dialkyl malonates to acyclic enones. Spectroscopic studies on the stoichiometry of the bisphosphazide and lithium salt have indicated the formation of a 1:1 species as the active enantioselective catalyst. It is suggested that the catalyst generates a complex of the protonated phosphazide and the chiral nucleophile as the key intermediate. The phosphazide moiety appears to be a promising dual basic functionality for stereo- and chemoselective catalytic transformations.