Analysis of commercial proanthocyanidins. Part 1: The chemical composition of quebracho ( Schinopsis lorentzii and Schinopsis balansae) heartwood extract

Established Phyto- and synthetic chemistry perspectives combined with electrospray mass spectrometry proved that quebracho extract contains no robinetinidol, as is often reported, but only oligomers based on catechin as starter unit and fisetinidol as extender units. [Display omitted] ► Mass spectro...

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Veröffentlicht in:Phytochemistry (Oxford) 2012, Vol.73 (1), p.95-105
Hauptverfasser: Venter, Pieter B., Sisa, Mirek, van der Merwe, Marthinus J., Bonnet, Susan L., van der Westhuizen, Jan H.
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Sprache:eng
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Zusammenfassung:Established Phyto- and synthetic chemistry perspectives combined with electrospray mass spectrometry proved that quebracho extract contains no robinetinidol, as is often reported, but only oligomers based on catechin as starter unit and fisetinidol as extender units. [Display omitted] ► Mass spectrometry investigation into the proanthocyanidins in commercial quebracho extract. ► Extract does not contain detectable quantities of robinetinidol as monomer or as part of an oligomer. ► The starter unit in our sample was thus always catechin and the extender units always ent-fisitinedol. ► Quebracho extract consists of 33% dimers, 37% trimers, 21% tetramers, 8% pentamers, and 1% heptamers. ► A degree of polimerization of 3.1 was calculated from the intensity of MS fragments. Quebracho ( Schinopsis lorentzii and Schinopsis balansae) extract is an important source of natural polymers for leather tanning and adhesive manufacturing. We combined established phyto- and synthetic chemistry perspectives with electrospray mass spectrometry experiments to prove that quebracho proanthocyanidin polymers consist of an homologous series of flavan-3-ol based oligomers. The starter unit is always catechin which is angularly bonded to fisetinidol extender units. By comparison of the MS 2 fragmentation spectra of the oligomer with product ion scans of authentic catechin and robinetinidol samples, we proved that quebracho extract contains no robinetinidol, as is often reported. Quebracho proanthocyanidins have acid resistant interflavanyl bonds, due to the absence of 5-OH groups in fisetinidol, and the aDP cannot be determined via conventional thiolysis and phloroglucinolysis. We used the MS data to estimate a conservative (minimum value) aDP of 3.1.
ISSN:0031-9422
1873-3700
DOI:10.1016/j.phytochem.2011.10.006