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Polymorphic forms of valinomycin investigated by NMR crystallography

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    0525568 - ÚMCH 2021 RIV CH eng J - Journal Article
    Czernek, Jiří - Brus, Jiří
    Polymorphic forms of valinomycin investigated by NMR crystallography.
    International Journal of Molecular Sciences. Roč. 21, č. 14 (2020), s. 1-13, č. článku 4907. E-ISSN 1422-0067
    R&D Projects: GA MŠk(CZ) LTAUSA18011
    Research Infrastructure: CESNET II - 90042; CERIT-SC - 90085
    Institutional support: RVO:61389013
    Keywords : valinomycin * antiviral * 2019-nCoV
    Subject RIV: CF - Physical ; Theoretical Chemistry
    OBOR OECD: Physical chemistry
    Impact factor: 4.556, year: 2019

    A dodecadepsipeptide valinomycin (VLM) has been most recently reported to be a potential anti-coronavirus drug that could be efficiently produced on a large scale. It is thus of importance to study solid-phase forms of VLM in order to be able to ensure its polymorphic purity in drug formulations. The previously available solid-state NMR (SSNMR) data are combined with the plane-wave DFT computations in the NMR crystallography framework. Structural/spectroscopical predictions (the PBE functional/GIPAW method) are obtained to characterize four polymorphs of VLM. Interactions which confer a conformational stability to VLM molecules in these crystalline forms are described in detail. The way how various structural factors affect the values of SSNMR parameters is thoroughly analyzed, and several SSNMR markers of the respective VLM polymorphs are identified. The markers are connected to hydrogen bonding effects upon the corresponding (13C/15N/1H) isotropic chemical shifts of (CO, Namid, Hamid, Hα) VLM backbone nuclei. These results are expected to be crucial for polymorph control of VLM and in probing its interactions in dosage forms.
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