X-Message-Number: 31838
Date: Fri, 31 Jul 2009 23:11:25 -0700 (PDT)
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Subject: could choline dihydrogen phosphate be useful in cryopreservat...

J Biomech Eng. 2009 Jul;131(7):074514.

Biocompatible ionic liquids: a new approach for stabilizing proteins in liquid 
formulation.

    Vrikkis RM, Fraser KJ, Fujita K, Macfarlane DR, Elliott GD.    Department of
    Mechanical Engineering, University of North Carolina at Charlotte, 9201 
    University City Boulevard, Charlotte, NC 28223.

    Ionic liquids (ILs) have shown excellent promise as both solutes and 
    solvents for stabilizing proteins at room temperature. Because many modern 
    drugs are protein-based, these stabilizing characteristics have great 
    potential to provide advances in the field of liquid formulation of 
    therapeutic proteins. However, before these developments can be translated 
    into clinical solutions it is essential to establish data related to the 
    biocompatibility of these ILs. The current work investigates the 
    cytotoxicity of several ILs that were rationally synthesized from natural 
    biomolecules and compounds that have already been approved as excipients for
    drug formulations. The effect of choline dihydrogen phosphate (choline 
    dhp), choline saccharinate, and 1-butyl 3-methyl imidazolium lactate (bmim 
    lactate) on the metabolic activity of a mouse macrophage cell line (J774) 
    was assessed using the reduction in resazurin as an indicator of activity 
    and, by extension, viability. Two formulations of lysozyme (10 mg/ml and 100
    mg/ml) in 80 wt % choline dhp (aq) were prepared and the proteins were 
    evaluated for structural stability immediately following formulation and 
    again at 1 month. Equivalent formulations in 0.1 M Na acetate aqueous buffer
    were evaluated as controls. A differential scanning microcalorimeter (DSC) 
    was used to evaluate the structural stability on the basis of the unfolding 
    temperature and the enthalpy of unfolding, and a micrococcus lysodiekticus 
    activity test was used to evaluate functional activity. All compounds were 
    found to be relatively benign, with toxicity increasing in the order choline
    dhp<choline saccharinate<bmim lactate. At 1 month lysozyme that had been 
    stored in choline dhp had a higher activity and folded fraction than 
    lysozyme that had been stored in aqueous buffer. These results suggest that 
    biocompatibility and protein stabilization characteristics can be rationally
    designed into ionic liquids.
PMID: 19640150

Biomacromolecules. 2007 Jul;8(7):2080-6. Epub 2007 Jun 20.

Solubility and stability of cytochrome c in hydrated ionic liquids: effect of 
oxo acid residues and kosmotropicity.

    Fujita K, MacFarlane DR, Forsyth M, Yoshizawa-Fujita M, Murata K, Nakamura 
    N, Ohno H. Department of Biotechnology, Tokyo University of Agriculture and 
    Technology, Koganei, Tokyo, Japan.

    Hydrated ionic liquids (ILs) were prepared by adding appropriate amounts of 
    water to hydrophilic ILs. Some hydrated ILs show excellent solubilizing 
    ability for proteins, keeping the basic properties of ILs. The solubility of
    cytochrome c (cyt c) depended on the structure of the component ions. When 
    component anions have oxo acid residues, the resulting hydrated ILs 
    solubilize cyt c quite well. In such hydrated ILs, the structure and 
    activity of cyt c is influenced by the kosmotropicity of the component ions.
    We synthesized ILs from various ions having different kosmotropicity, 
    including dihydrogen phosphate (dhp), dibutylphosphate, acetate, lactate, 
    and methanesulfonate as anions. The activity of the dissolved cyt c depends 
    on the permutations of kosmotropicity of the component ions. cyt c shows no 
    structural change and retains its activity when dissolved in the hydrated 
    choline dhp, which is an excellent combination of chaotropic cation and 
    kosmotropic anion. Furthermore, cyt c dissolved in the hydrated choline dhp 
    remained in a native state and was active after 18 months of storage at room
    temperature.
PMID: 17580947

J Chromatogr A. 2009 Aug 7;1216(32):6020-3. Epub 2009 Jun 18. L

Ionic liquids as superior solvents for headspace gas chromatography of residual 
solvents with very low vapor pressure, relevant for pharmaceutical final dosage 
forms.

    Laus G, Andre M, Bentivoglio G, Schottenberger H. Faculty of Chemistry and 
    Pharmacy, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria.

    1-n-Butyl-3-methylimidazolium dimethyl phosphate (BMIM DMP) was identified 
    as the most suitable ionic liquid as solvent for the headspace gas 
    chromatographic analysis of solvents with very low vapor pressure such as 
    dimethylsulfoxide, N-methylpyrrolidone, sulfolane, tetralin, and ethylene 
    glycol in a realistic matrix of commonly used excipients 
    (carboxymethylcellulose, magnesium stearate, guar flour, and corn starch) in
    pharmaceutical products. Limits of quantification and limits of detection 
    were in the low microgram per gram range. The detection of traces of 
    sulfolane in a real sample of tablets containing the drug cefpodoxim 
    proxetil demonstrated the applicability of the method.
PMID: 19560778

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