Analysis of commercial proanthocyanidins. Part 4: Solid state 13C NMR as a tool for in situ analysis of proanthocyanidin tannins, in heartwood and bark of quebracho and acacia, and related species

Development of methodology for identification the nature of the polyphenolic extracts by FTIR associated with multivariate analysis

“…Tannins are water-soluble, polyphenolic compounds formed by secondary metabolism in plants and can be found in various plant parts, such as roots, twigs, flowers, leaves, fruits, and seeds [1,2].…”

“…This type of tannin can be extracted from the heartwood of the quebracho (Schinopsis lorentzii) and black wattle bark (Acacia mearnsii) [2,23]. These extracts are extracted in an aqueous medium, and the quebracho usually is sulphited to improve the extraction of polyphenols [2].…”

“…These extracts are extracted in an aqueous medium, and the quebracho usually is sulphited to improve the extraction of polyphenols [2]. The chemical characterisation of this class of compounds has been slow, mainly due to the diversity of structures, stereochemistry, and difficulty of purification with chromatographic materials based on silica gels [27].…”

“…With advances in technology, techniques including solid-state carbon nuclear magnetic resonance ( 13 C-NMR), matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS), electrospray ionisation mass spectrometry (ESI-MS), and highperformance liquid chromatography mass spectrometry (HPLC-MS) have been used with significant success [2,[27][28][29]. In 2001, Pasch et al [28] developed a method for determining the chemical structure of tannins by MALDI-TOF-MS.…”

Principal Component Analysis of Commercial Tannin Extracts Using Digital Images on Mobile Devices

“…The black wattle contains, in addition to catechin starter and fisetinidin extender units, gallocatechin starter and robinetinidin extender units as well. 40,41 The valonea and chestnut tannins are compounds mainly formed by pentagalloylglucose clusters linked to each other. The other main constituents of these commercial tannin extract are castalagin and vescalagin derived from the hydrolysis of polypentagalloylglucose chains.…”