A practical method for preparing fluorescent-labeled glycans with a 9-fluorenylmethyl derivative to simplify a fluorimetric HPLC-based analysis.

Analysis of glycans in glycoproteins is often performed by liquid chromatography (LC) separation coupled with fluorescence detection and/or mass spectrometric detection. Enzymatically or chemically released glycans from glycoproteins are usually labeled by reductive amination with a fluorophore reagent. Although labeling techniques based on reductive amination have been well-established as sample preparation methods for fluorometric HPLC-based glycan analysis, they often include time-consuming and tedious purification steps. Here, we reported an alternative fluorescent labeling method based on the synthesis of hydrazone and its reduction using 9-fluorenylmethyl carbazate (Fmoc-hydrazine) as a fluorophore reagent. Using isomaltopentaose and N-glycans from human IgG, we optimized the Fmoc-labeling conditions and purification procedure of Fmoc-labeled N-glycans and applied the optimized method for the analysis of N-glycans released from four glycoproteins (bovine RNase B, human fibrinogen, human α1-acid glycoprotein, and bovine fetuin). The complete workflow for preparation of fluorescent-labeled N-glycans takes a total of 3.5 h and is simple to implement. The method presented here lowers the overall cost of a fluorescently labeled N-glycan and will be practically useful for the screening of disease-related glycans or routine analysis at an early stage of development of biopharmaceuticals.

Synthesis and Properties of a Bay-Annulated-Indigo Tetramer Based on Low-Cost Spiro[Fluorene-9,9'-Xanthene] Core.

A three-dimensional bay-annulated-indigo (BAI) tetramer has been prepared by appending BAI units onto a low-cost spiro[fluorene-9,9'-xanthene] (SFX) core. The target compound 4BAI-SFX exhibits strong and broad absorption in the visible region covering the range of 450~700 nm. The electrochemical measurement illuminates the characteristics of a deep lowest unoccupied molecular orbital (LUMO) level and multiple redox states of 4BAI-SFX. These results suggest that 4BAI-SFX should be a selectable electron-transporting material for eco-friendly organic semiconductors.

Determination of 1-Deoxynojirimycin by a developed and validated HPLC-FLD method and assessment of In-vitro antioxidant, α-Amylase and α-Glucosidase inhibitory activity in mulberry varieties from Turkey.

BACKGROUND: Morus alba and Morus nigra leaves which have been widely used as herbal teas in Anatolian region of Turkey, were extracted twice by 50 mM HCI solution, derivatized with 9-fluorenylmethyl chloroformate and analyzed by reversed phase HPLC equipped with a fluorescence detector. HYPOTHESIS/PURPOSE: This study was performed to determine the main antidiabetic active compounds 1-deoxynojirimycin by HPLC method and evaluate the in-vitro antioxidant and antidiabetic activity of ethanol extracts prepared from Morus alba L. and Morus nigra leaves. STUDY DESIGN: A reliable simple, and rapid high-performance liquid chromatographic (HPLC) method for the determination of 1-deoxynojirimycin in M. alba L. and M. nigra leaves with fluorimetric detection after pre-column derivatization with 9-fluorenylmethyl chloroformate was developed. In addition, the chemical composition of ethanol extract of mulberry leaves was analyzed with GC-MS. METHODS: Separation and quantitation were performed on C18, 250 × 4.6 mm, 5 µm analytical column. Mobile phase consisted of acetonitrile and 0.1% acetic acid solution (1:1, v/v) was performed applied to the column 1.0 ml/min flow rate at 26 °C. Potential antioxidant activity of ethanol extract of different mulberry varieties were evaluated by DPPH, and ABTS radical scavenging assay as well as total phenol and flavonoid content were determined. In addition, α-amylase and α-glucosidase activity was determined by 96-well plate method to evaluate the probable antidiabetic potential use of Turkish mulberry leaves. RESULTS: The isocratic HPLC method showed excellent correlation coefficient (r2 = 0.9985) between 0.3 and 30 µg/ml calibration points. The method was specific and sensitive with detection and quantification limits of 1.07 and 3.27 ng/ml, respectively. Intraday and interday method precision (n = 5) were < 7.3 (RSD%). Intraday and interday method accuracy (n = 5) were between 3.77 and (-8.35) (RE%). The average method recovery (n = 3) was 102.5%. The results showed that the content of 1-deoxynojirimycin in leaves of Morus alba L. was 0.103% (n = 3), and in leaves of M. nigra L. was 0.102%. 2-hexadecen-1-ol, oleamide, 2-propenoic acid, and cyclododecane were identified as the major compounds by GC-MS in the ethanol extract of mulberry leaves. CONCLUSION: The obtained robustness values from emission and excitation detection, mobile phase ingredients and flow rates changes showed that method was very strong. This work contributes to the knowledge of antioxidant and antidiabetic properties of Morus species, thus may be provide useful data in evaluation of food products and pharmaceutical preparations produced from Morus species.

Comparing the selectivity and chiral separation of d- and l- fluorenylmethyloxycarbonyl chloride protected amino acids in analytical high performance liquid chromatography and supercritical fluid chromatography; evaluating throughput, economic and environmental impact.

The chiral separation of d- and l- FMOC amino acids was undertaken using the Lux Cellulose-1 polysaccharide based chiral column in HPLC (normal phase and reverse phase) and SFC conditions. This was done to compare the relative selectivity and separation between the three separation modes and to evaluate the potential benefits of SFC separations with regards to resolution, throughput, economic and environmental impact. It was established that the separation of d- and l- FMOC amino acids in SFC displayed behaviours that were similar to both normal phase and reversed phase, rather than distinctly one or the other. Additionally, although reversed phase conditions yielded significantly higher resolution values between enantiomers across the range of amino acids studied, improvements in selectivity in SFC via the introduction of higher concentrations of formic acid in the mobile phase allowed for better resolution per unit of time. Moreover since the SFC mobile phase is composed mostly of recyclable CO2, there is a reduction in organic solvent consumption, which minimises the economic and environmental costs.

Fast and Facile Synthesis of 4-Nitrophenyl 2-Azidoethylcarbamate Derivatives from N-Fmoc-Protected α-Amino Acids as Activated Building Blocks for Urea Moiety-Containing Compound Library.

A fast and facile synthesis of a series of 4-nitrophenyl 2-azidoethylcarbamate derivatives as activated urea building blocks was developed. The N-Fmoc-protected 2-aminoethyl mesylates derived from various commercially available N-Fmoc-protected α-amino acids, including those having functionalized side chains with acid-labile protective groups, were directly transformed into 4-nitrophenyl 2-azidoethylcarbamate derivatives in 1 h via a one-pot two-step reaction. These urea building blocks were utilized for the preparation of a series of urea moiety-containing mitoxantrone-amino acid conjugates in 75-92% yields and parallel solution-phase synthesis of a urea compound library consisted of 30 members in 38-70% total yields.

Low-Cost Peptide Microarrays for Mapping Continuous Antibody Epitopes.

With the increasing need for understanding antibody specificity in antibody and vaccine research, pepscan assays provide a rapid method for mapping and profiling antibody responses to continuous epitopes. We have developed a relatively low-cost method to generate peptide microarray slides for studying antibody binding. Using a setup of an IntavisAG MultiPep RS peptide synthesizer, a Digilab MicroGrid II 600 microarray printer robot, and an InnoScan 1100 AL scanner, the method allows the interrogation of up to 1536 overlapping, alanine-scanning, and mutant peptides derived from the target antigens. Each peptide is tagged with a polyethylene glycol aminooxy terminus to improve peptide solubility, orientation, and conjugation efficiency to the slide surface.

Assessment of pharmacokinetic compatibility of short acting CDRI candidate trioxane derivative, 99-411, with long acting prescription antimalarials, lumefantrine and piperaquine.

The pharmacokinetic compatibility of short-acting CDRI candidate antimalarial trioxane derivative, 99-411, was tested with long-acting prescription antimalarials, lumefantrine and piperaquine. LC-ESI-MS/MS methods were validated for simultaneous bioanalysis of lumefantrine and 99-411 and of piperaquine and 99-411 combinations. The interaction studies were performed in rats using these validated methods. The total systemic exposure of 99-411 increased when administered with either lumefantrine or piperaquine. However, co-administration of 99-411 significantly decreased the systemic exposure of piperaquine by half-fold while it had no effect on the kinetics of lumefantrine. 99-411, thus, seemed to be a good alternative to artemisinin derivatives for combination treatment with lumefantrine. To explore the reason for increased plasma levels of 99-411, an in situ permeability study was performed by co-perfusing lumefantrine and 99-411. In presence of lumefantrine, the absorption of 99-411 was significantly increased by 1.37 times than when given alone. Lumefantrine did not affect the metabolism of 99-411 when tested in vitro in human liver microsomes. Additionally, ATPase assay suggest that 99-411 was a substrate of human P-gp, thus, indicating the probability of interaction at the absorption level in humans as well.

Rapid determination of 1-deoxynojirimycin in Morus alba L. leaves by direct analysis in real time (DART) mass spectrometry.

A new method based on a Direct Analysis in Real Time (DART) ionization source coupled with triple quadrupole tandem mass spectrometry has been developed for rapid qualitative and quantitative analyses of 1-deoxynojirimycin (DNJ) in mulberry leaves. Two ions produced from DNJ, [M+H](+) (m/z 164) and [M-2H+H](+) (m/z 162), are observed using DART-MS in the positive ion mode. The peak areas of the two selected ions monitoring (SIM) signals of ([M+H](+) (m/z 164) and [M-2H+H](+) (m/z 162)) are integrated to determine the peak area for quantitative analyses. A reasonable linear regression equation is obtained in the range of 1.01 to 40.50 µg/mL, with a linear coefficient (R(2)) of 0.996. The limits of detection (LOD) and quantification (LOQ) of the method are 0.25 and 0.80 µg/mL, respectively. The range of recovery is shown to be 87.73-95.61%. The results derived from the developed DART-MS method are in good agreement with those from the conventional HPLC-FLD method. By contrast, DART-MS in SIM mode is a simple, rapid and high-throughput approach for the determination of the DNJ content in mulberry leaves. The present method is advantageous for the rapid screening of mulberry leaves containing high DNJ contents.

Integration of novel low-cost colorimetric, laser photometric, and visual fluorescent techniques for rapid identification of falsified medicines in resource-poor areas: application to artemether-lumefantrine.

The availability of falsified antimalarial drugs can be reduced with effective drug regulatory agencies and proper enforcement. Fundamental to these agencies taking action, rapid identification must be made as soon as they appear in the market place. Since falsified antimalarials occur mostly in developing countries, performing drug analysis presents itself with unique challenges. A fundamental factor in choosing a useful technique is affordability and simplicity. Therefore, we suggest a three-tiered drug evaluation strategy for identifying a falsified drug in resource-poor areas. Tier I is a simple comparison of a tablet's weight and dimensions with official specifications. Tier II uses inexpensive photometric devices (laser and fluorescence) to evaluate a tablet. Suspicious samples from Tier I and II assessments are then subjected to a colorimetric assay for active ingredients identification and quantification. In this article, we evaluate a novel colorimetric assay for the simultaneous assessment of both lumefantrine and artemether in co-formulated Coartem™ tablets, and integrate the method with two novel, low-cost, fluorescence and laser photometric devices. Image analysis software is used for the assessments. Although artemether-lumefantrine is used as an example, the strategy may be adapted to other medicines.

Solution-phase synthesis and evaluation of tetraproline chiral stationary phases.

A protocol was developed for the solution-phase synthesis of multigram amounts of two 9-fluorenylmethoxycarbonyl (Fmoc)-protected tetraproline peptides. These tetraproline peptides were then attached to amino derivatized silica gel. The replacement of the Fmoc group with the trimethylacetyl group lead to two tetraproline chiral stationary phases (CSPs). A comparison of the chromatographic behavior of these two solution-phase-synthesized tetraproline CSPs with that prepared by stepwise solid-phase synthesis revealed that all three had similar chromatographic performance for resolving 53 model analytes. This suggests that the solution-phase synthesis of oligoprolines, which allows for the specific benefits of good batch reproducibility, selector homogeneity, and possibly low cost, is a feasible alternative to the solid-phase synthesis of oligoproline CSPs.

Industrial-scale manufacturing of a possible oligonucleotide cargo CPP-based drug.

This chapter describes the manufacturing process to a certain level for a possible oligonucleotide cargo and a peptide API in a multi-kilogram scale from a manufacture's point of view. In the concluding remarks, possible conjugation methods will be discussed from an industrial-scale perspective.

Analyzing the molecular weight distribution in supramolecular polymers.

We have investigated the formation process of supramolecular linear polymer chains and its influence on the resulting chain length distribution function. For this purpose, we explored the migration of excitation energy between oligofluorene units coupled together through quadruple hydrogen-bonding groups to form linear chains that are terminated by oligophenylene vinylene end-caps acting as energy traps. The energy transfer dynamics from the main chain to the chain end was monitored experimentally using time-resolved PL spectroscopy and compared to an equivalent Monte Carlo simulation incorporating information on the structure of the chains, the transition transfer rates, and various weight distribution trial functions. We find that the assumption of a Flory distribution of chain lengths leads to excellent agreement between experimental and simulated data for a wide range of end-cap concentrations. On the other hand, both a Poisson function and a simplified assumption of a monodisperse distribution significantly underestimate the presence of long chains in the ensemble. Our results therefore show that supramolecular polymerization is a steplike process equivalent to polycondensation reactions in linear covalent polymers. These findings emphasize that equal reactivity of the supramolecular building blocks leads to a dynamic growth process for the supramolecular chain involving all chain components at all times.

Solvation oscillations and excited-state dynamics of 2-amino- and 2-hydroxy-7-nitrofluorene and its 2'-deoxyriboside.

Push-pull substituted fluorenes are considered for use as dynamic solvation probes in polynucleotides. Their fluorescence band is predicted (by simulations) to show weak spectral oscillations on the subpicosecond time scale depending on the nucleotide sequence. The oscillations reflect the local far-infrared spectrum of the environment around the probe molecule. A connection is provided by the continuum theory of polar solvation which, however, neglects molecular aspects. We examine the latter using acetonitrile solution as a test case. A collective librational solvent mode at 100 cm(-1) is observed with 2-amino-7-nitrofluorene, 2-dimethylamino-7-nitrofluorene, 2-hydroxy-7-nitrofluorene, and its 2'-deoxyriboside. Different strengths of the oscillation indicate that rotational friction of nearby acetonitrile molecules depends on the solute structure or that H bonding is involved in launching the librational coherence. Polar solvation in methanol is used for comparison. With hydroxynitrofluorenes, the observation window is limited by intersystem crossing for which rates are reported. A prominent excited-state absorption band of nitrofluorenes at 430 nm can be used to monitor polar solvation. Structural and electronic relaxation pathways are discussed with the help of quantum chemical calculations.

A simple and economical method for the production of 13C,18O-labeled Fmoc-amino acids with high levels of enrichment: applications to isotope-edited IR studies of proteins.

Isotope-edited IR of proteins has generated considerable interest. Double labeling with 13C and 18O with high levels of isotopic enrichment is required for residue-specific resolution. Current methods for the preparation of doubly labeled amino acids give modest 18O enrichment, limiting the utility of the approach. We report a simple and economical method for preparing 13C,18O-doubly labeled N-(9-fluorenylmethoxycarbonyl)amino acids with high levels of enrichment for residues that do not require acid-labile side-chain protecting groups.

Synthesis and supramolecular properties of molecular clips with anthracene sidewalls.

Novel molecular clips with anthracene sidewalls (1 a-c) were synthesized; they form stable host-guest complexes with a variety of electron-deficient aromatic and quinoid molecules. According to single-crystal structure analyses of clip 1 c and 1,2,4,5-tetracyanobenzene (TCNB) complex 14@1 b, the clips' anthracene sidewalls have to be compressed substantially during the complex formation to provide attractive pi-pi interactions between the aromatic guest molecule and the two anthracene sidewalls in the complex. The compression and expansion of aromatic sidewalls are calculated by molecular mechanics to be low-energy processes, so the energy required for compression of the anthracene sidewalls during complex formation is apparently overcompensated by the gain in energy resulting from the attractive pi-pi interactions. The finding that complexes of the clips 1 a-c are more stable than those of the corresponding clips 2 a-c can be explained in terms of the larger van der Waals contact surfaces of the anthracene sidewalls in 1 a-c (relative to the naphthalene sidewalls in 2 a-c). Color changes resulting from charge-transfer (CT) bands are observed in complex formation by 1 a-c: from colorless to red or purple with TCNB (14), and from yellow to green with 2,4,7-trinitro-9-fluorenone TNF (17). Independently, the host 1 b and guest 14 fluoresce from their respective excited singlet states, whilst in the complex 14@1 b the charge-transfer state quenches the higher-energy singlet states of the two components, and as a result luminescence is only observed from this new CT state. To the best of our knowledge, complex 14@1 b is the first example of CT luminescence from a host-guest complex. The binding constant determined for the formation of the TCNB complex 14@1 b from a UV/Vis titration experiment (Ka = 12 400 m(-1)) agrees well with the value (K(a) = 12 800 m(-1)) obtained by 1H NMR titration.

Large-scale synthesis of peptides.

Recent advances in the areas of formulation and delivery have rekindled the interest of the pharmaceutical community in peptides as drug candidates, which, in turn, has provided a challenge to the peptide industry to develop efficient methods for the manufacture of relatively complex peptides on scales of up to metric tons per year. This article focuses on chemical synthesis approaches for peptides, and presents an overview of the methods available and in use currently, together with a discussion of scale-up strategies. Examples of the different methods are discussed, together with solutions to some specific problems encountered during scale-up development. Finally, an overview is presented of issues common to all manufacturing methods, i.e., methods used for the large-scale purification and isolation of final bulk products and regulatory considerations to be addressed during scale-up of processes to commercial levels.

Positioning, labelling, and medical information control of co-artemether tablets (CPG 56697): a fixed novel combination of artemether and benflumetol. Novartis Co-Artemether International Development Team.

Coartemether is a fixed 1:6 ratio of artemether and lumefantrine (benflumetol), a joint development between Novartis Pharma and the Academy of Military Medical Sciences (Beijing, China). It is well tolerated and has a high efficacy against uncomplicated and drug resistant falciparum malaria by oral administration. The preclinical profile of coartemether revealed no prohibitive toxicological, teratogenic or mutagenic findings. No evidence of neurotoxicity was seen in oral preclinical studies. It shows a negative response to the induction of resistance and prevents recrudescence. Clinically, coartemether shows a rapid onset of antiparasitic action, resolution of symptoms, no clinical neurotoxicity and excellent parasite clearance.

1H NMR studies on mutagenic nitrofluoranthenes and exposure risk assessment.

The 1H NMR spectra of the nitrofluoranthene isomers are presented to allow gas chromatographic analysis of environmental samples suspected of containing nitrofluoranthenes. The mutagenic isomers 1-, 2-, 3-, 7-, and 8-nitrofluoranthene and 1,2- and 1,3-dinitrofluoranthene and a nonmutagenic analogue, 1-phenyl-4-nitronaphthalene, have been studied by using nuclear Overhauser effects and 2D shift-correlated 1H NMR spectroscopy. The X-ray crystal structure of 1-phenyl-4-nitronaphthalene is also reported. Reduction potentials and coplanarity of the nitro group have been used to correlate the mutagenicity of nitrated polycyclic aromatic hydrocarbons (nitro-PAH) measured by the Ames assay, but our data suggest that these parameters are not sufficient for the prediction of mutagenic potency in the nitrofluoranthene series.