Proanthocyanidin Structural Details Revealed by Ultrahigh Resolution FT-ICR MALDI-Mass Spectrometry, 1H-13C HSQC NMR, and Thiolysis-HPLC-DAD.
J Agric Food Chem
; 68(47): 14038-14048, 2020 Nov 25.
Article
em En
| MEDLINE
| ID: mdl-33170695
ABSTRACT
Proanthocyanidins (condensed tannins) are important in food chemistry, agriculture, and health, driving demand for improvements in structure determination. We used ultrahigh resolution Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) methods to determine the exact composition of individual species in heterogeneous mixtures of proanthocyanidin polymers from Sorghum bicolor grain and Neptunia lutea leaves. Fragmentation patterns obtained with FT-ICR ESI MS-MS (electrospray ionization) confirmed structural details from thiolysis-high-performance liquid chromatography (HPLC)-diode array detection (DAD) and 1H-13C heteronuclear single quantum coherence (HSQC) NMR. We found that A-type linkages were characteristic of shorter polymers in predominantly B-linked proanthocyanidin. We suggest that supramolecular complex formation between proanthocyanidins and matrix components such as 2,5-dihydroxybenzoic acid was responsible for anomalous 152 dalton peaks, incorrectly assigned as 3-O-galloylation, when using FT-ICR matrix-assisted laser desorption ionization (MALDI-MS). Our data illustrate the power of the ultrahigh resolution FT-ICR methods but include the caveat that MALDI-MS must be paired with complementary analytical tools to avoid artifacts.
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01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proantocianidinas
/
Fabaceae
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article