Tri- and Tetrameric Proanthocyanidins with Dentin Bioactivities from Pinus massoniana

Guided by dentin biomechanical bioactivity, this phytochemical study led to the elucidation of an extended set of structurally demanding proanthocyanidins (PACs). Unambiguous structure determination involved detailed spectroscopic and chemical characterization of four A-type dimers (2 and 4–6), seve...

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Bibliographic Details
Published in:Journal of organic chemistry 2020-07, Vol.85 (13), p.8462-8479
Main Authors: Zhou, Bin, Alania, Yvette, Reis, Mariana, Phansalkar, Rasika S, Nam, Joo-Won, McAlpine, James B, Chen, Shao-Nong, Bedran-Russo, Ana K, Pauli, Guido F
Format: Article
Language:English
Subjects:
Chromatography, High Pressure Liquid
Dentin
Mass Spectrometry
Pinus
Proanthocyanidins
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Summary:Guided by dentin biomechanical bioactivity, this phytochemical study led to the elucidation of an extended set of structurally demanding proanthocyanidins (PACs). Unambiguous structure determination involved detailed spectroscopic and chemical characterization of four A-type dimers (2 and 4–6), seven trimers (10–16), and six tetramers (17–22). New outcomes confirm the feasibility of determining the absolute configuration of the catechol monomers in oligomeric PACs by one-dimensional (1D) and two-dimensional (2D) NMR. Electronic circular dichroism as well as phloroglucinolysis followed by mass spectrometry and chiral phase high-performance liquid chromatography (HPLC) analysis generated the necessary chiral reference data. In the context of previously reported dentin-bioactive PACs, accurately and precisely assigned 13C NMR resonances enabled absolute stereochemical assignments of PAC monomers via (i) inclusion of the 13C NMR γ-gauche effect and (ii) determination of differential 13C chemical shift values (ΔδC) in comparison with those of the terminal monomer (unit II) in the dimers 2 and 4–6. Among the 13 fully elucidated PACs, eight were identified as new, and one structure (11) was revised based on new knowledge gained regarding the subtle, stereospecific spectroscopic properties of PACs.
ISSN:0022-3263
1520-6904
DOI:10.1021/acs.joc.0c00783