Isolation and Characterisation of Procyanidins from Rumex obtusifolius

Abstract

An acetone:water (7:3) extract obtained from the leaves of Rumex obtusifolius was fractionated into procyanidin oligomer and polymer fractions using a linear gradient and a simple step method on Sephadex LH-20. The chemical characteristics of the procyanidin fractions were studied by 13C-NMR spectroscopy, acid-catalysed degradation in the presence of benzyl mercaptan, matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) MS and electrospray ionisation (ESI) MS. The 13C-NMR showed that the polymer fraction consisted predominantly of procyanidin polymers, some with galloyl groups attached. The thiolysis reaction products indicated a mean degree of polymerisation (DP) of 4.3 for the step method, and a range of 2.3-8.2 mean DP for the gradient fractionation, with epicatechin as the most abundant flavan-3-ol extension unit, while the terminal units consisted of equal proportions of catechin, epicatechin and epicatechin gallate. Singly charged ions observed in MALDI-TOF/MS showed a range of oligomeric procyanidins and their polygalloyl derivatives. These species (in the range DP 2-7) were also observed by ESI/MS but the spectra were more complex due to overlapping multiply charged ions. Isolation of oligomers from the Sephadex LH-20 fraction by chromatography on polyamide and C18 yielded B1, B2, B3 and B7 dimers, an A-type trimer and a B2 3,3'-O-digallate.

Deconvolution of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry isotope patterns to determine ratios of A-type to B-type interflavan bonds in cranberry proanthocyanidins

“…Thiolysis and pholoroglucinolysis are widely used to determine monomeric composition and average DP of PAC ( Waters, & Jones, 2001;Spencer et al, 2007;Tarascou et al, 2011) and have also been used to determine the presence of A-type interflavan bonds (Koerner, Hsu, Lee, & Kennedy, 2009;Tarascou et al, 2011). However there are several problems with these techniques that are unresolved.…”

Tannins from Canarium album with potent antioxidant activity

“…show that the polymeric PA fraction of the stem bark is predominantly constituted of procyanidin and prodelphinidin with (−)-epicatechin and (−)-epigallocatechin as main constitutive monomers, some with galloyl groups attached (Spencer et al, 2007).…”

Herbal Drugs Used for Domestic Animals

“…Rumex abyssinicus contains oxalic acid, chrysophanic acid, chrysophanol, emodine and physcion. An acetone:water (7:3) extract obtained from the leaves of Rumex obtusifolius L. (Polygonaceae) contains epicatechin (Getie et al 2003, Spencer et al 2007). …”