Characterization Of Proanthocyanidins Research Articles

Study on the extraction, purification, stability, free radical scavenging kinetics, polymerization degree and characterization of proanthocyanidins from Pinus koraiensis seed scales

To efficiently harness resources from Pinus koraiensis seed scales, a type of forestry waste, rigorous studies on the extraction, purification, stability, and free radical scavenging capacity of the proanthocyanidins derived from these seed scales were conducted. Kinetic models showed that under ultrasonic conditions, the proanthocyanidins content reached 2.66 mg/g within 0.5 h. The optimal storage parameters include darkness, 4 °C, and pH 4. The degrees of polymerization of the mixture and the high- and low-polymer components were 4.89, 7.42 and 3.07, respectively, with the low-polymer component exhibiting the highest radical scavenging activity. Through HPLC–QE-MS/MS, 1H NMR, and FT-IR analyses, we identified proanthocyanidin B1, proanthocyanidin B2, (−)-epicatechin, and polymeric trimer esters. The Pinus koraiensis proanthocyanidins exhibited a high molecular weight, a complex internal molecular structure, and commendable stability, with crystallization requiring elevated temperatures. Therefore, the proanthocyanidins from Pinus koraiensis seed scales have emerged as highly promising novel natural antioxidants.

Variability between organs of proanthocyanidins in Geranium sylvaticum analyzed by off-line 2-dimensional HPLC-MS

Proanthocyanidins have been characterized in the different organs of Geranium sylvaticum by using an off-line 2-dimensional chromatographic method. In the first dimension, proanthocyanidins were separated according to their increasing degree of polymerization by hydrophilic interaction liquid chromatography. In the second dimension, reversed-phase liquid chromatography was used to separate the same size isomers based on their hydrophobicity. Ultraviolet detection and high-resolution electrospray ionization time-of-flight mass spectrometry were used for the identification and characterization of proanthocyanidins. The method was proven to be suitable for the analysis of plant organ fractions of G. sylvaticum that contained complex mixtures of phenolic compounds and proanthocyanidins from several classes. Procyanidins, prodelphinidins and mixed proanthocyanidins composed of both (epi)catechin and (epi)gallocatechin units including monomers, oligomers and polymers up to the degree of polymerization of 20 were identified. The type and size of proanthocyanidins varied between eight studied organs of G. sylvaticum. The 2-dimensional analysis revealed that each proanthocyanidin type occur in the equally complex isomeric pattern. The mean degree of polymerization of different proanthocyanidins in the eight plant organs of G. sylvaticum was 5 and it varied only slightly between plant organs.

Characterisation of proanthocyanidins from Schisandra chinensis seed coats by UPLC-QTOF/MS

In this article, an ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry method was developed to detect the chemical structures of proanthocyanidins (PAs) from seed coats of Schisandra chinensis. The cleavage pathways of the compounds were revealed. The structures of S. chinensis PAs, including two monomers, two B-type procyanidin dimers, three B-type procyanidin trimers, one mixed trimer and one B-type procyanidin tetramer, were confirmed. These nine compounds were detected in seed coats for the first time. The structures were identified by comparing their maximum absorption wavelengths, HPLC retention times and ESI-MS with those of authentic standards, or tentatively identified by MS/MS determination along with MetaboLynxTM software.

Characterization of Proanthocyanidins in Stems of Polygonum multiflorum Thunb as Strong Starch Hydrolase Inhibitors

Characterzation of polyphenolic compounds in the stems of P. multiflorum was conducted using HPLC, high resolution LC-MS and LC-MSn. Proanthocyanidins in particular were isolated in 4.8% yield using solvent extraction followed by Sephadex LH-20 fractionation. HPLC analysis using a diol column revealed oligomers (from dimer to nonamer) as minor components, with (epi)catechin monomeric units predominating, and oligomers with higher degree of polymerization being dominant. Thiolysis treatment of the proanthocyanidins using mercaptoacetic acid produced thioether derivatives of (epi)catechin as the major product and a mean value of the degree of polymerization of 32.6 was estimated from the ratio of terminal and extension units of the (epi)catechin. The isolated proanthocyanidins were shown to strongly inhibit α-amylase with an acarbose equivalence (AE) value of 1,954.7 µmol AE/g and inhibit α-glucosidase with an AE value of 211.1 µmol AE/g.

Extraction and Characterization of Proanthocyanidins from Grape Seeds

Grape seed contains many polyphenolic compounds that have potential health-promoting benefits. Among the- se compounds are proanthocyanidins, also known as condensed tannins, which is a class of flavanols. The basic structural building blocks of flavanols are polyhydroxyflavan-3-ol units linked together by C-C bonds. They are widely distributed in plants but grape seed has very high contents. This study examined extraction and purification technologies for obtain- ing proanthocyanidins from grape seeds and analytical methods and tools for characterizing them. Proanthocyanidins are polyphenolic compounds that can be found in the plant physiology of several plant species, are mainly concentrated in tree barks and outer skins of seeds. Grape seeds are one of the richest sources of proanthocyanidins (2). Public awareness of the antioxidant and free radical-scavenging abilities of these phenolic com- pounds results largely from the potential of these compounds to increase human health in many ways. Reductions in cardi- ovascular disease, cerebrovascular diseases, and cancer mor- tality are just some of the noticeable examples associated with these phenolic compounds (3-5). Recent advances in the field of nutraceuticals have shown that the compounds found in grapes exhibit even more benefits than initially be- lieved. This paper aims at reviewing these compounds found in the anatomy of the grape seeds and current methods of separation and characterization of proanthocyandins.

Separation and characterisation of proanthocyanidins in Virginia type peanut skins by LC–MS n

Proanthocyanidins were extracted from peanut skins, an agricultural waste product of Virginia. Proanthocyanidin composition of single solvent and multistep extraction procedures of peanut skins were compared by HPLC–UV–vis absorbance. The multistep extraction procedure yielded more proanthocyanidin peaks and larger peak areas. Thus this extraction procedure was chosen for subsequent fractionation. Fractionation was performed by size exclusion (Toyopearl HW-40S) and normal phase (NP) (porous silica) high performance liquid chromatography (HPLC) before reversed phase (RP) electrospray ionisation liquid chromatography–mass spectrometry analysis (ESI–LC–MS n ). Proanthocyanidin separation on the NP column was better overall, compared to size exclusion chromatography, and thus was chosen for characterisation by MS. Peanut skin procyanidins were found to separate in order of increasing molecular weight on the NP column. The ESI-MS generated positive and negative molecular-type ions and their dissociation product ions were used to identify specific proanthocyanidins and procyanidins. New proanthocyanidin dimeric and trimeric species were identified. These species consisted of one or two (epi)catechin units bound to luteolin or kaempferol. Monomers through nonamers of flavan-3-ols were identified by retention time and their multistep (MS n ) dissociation pathway. Hexamers were identified as both singly and doubly charged negative ions, [M− zH] z−, z = 1 or 2. Species of greater than pentamers were tentatively identified due to their low ionisation efficiency and significant overlap of species both chromatographically and in the MS spectra.

Characterisation and biological activities of proanthocyanidins from the barks of Pinus massonian and Acacia mearnsii

The biological activities and characterisation of proanthocyanidins (PAs) from the barks of Pinus massonian and Acacia mearnsii have been studied in our research. The free-radical scavenging activity of the PAs was measured by means of the DPPH method, and it was clear that the PA product had a strong radical scavenging ability. Furthermore, anti-tumour activities of PAs on different human cancer cells were investigated. The results indicated that PAs from the bark of A. mearnsii had better anti-tumour activities than those from the bark of P. massonian, and the PAs extracted from the ethyl acetate fraction had better anti-tumour activities than those from the water fraction. PAs from the bark of A. mearnsii in an ethyl acetate fraction (PAE) had an effective inhibition on human mammary cancer cells (MDA- MB-231) and human liver cancer cells (BEL-7402), a weak effect on human cervical cancer cells (Hela), but no effect on human lung cancer cells (A549); while the PAs from the bark of A. mearnsii in a water fraction (PAW) had weak effect on MDA- MB-231, Hela and A549, but no effect on BEL-7402. PAs from the bark of P. massonian in ethyl acetate fraction (PPE) had weak effect on Hela and BEL-7402; whereas the PAs from the bark of P. massonian in a water fraction (PPW) had a weak effect on Hela, but no effect on the other cells. PAs were characterised by HPLC- ESI-MS analysis and the PA dimers and trimers were identified, respectively.

LC-ESI-MS with monolithic stationary phase and ESI-MS/MS characterization of proanthocyanidins from selected antinflammatory plants

LC-ESI-MS with monolithic stationary phase and ESI-MS/MS characterization of proanthocyanidins from selected antinflammatory plants

Condensed tannins from steamed Acacia mearnsii bark

Abstract The optimum steaming conditions for extraction of condensed tannins from Acacia mearnsii bark were explored, after which characterization of proanthocyanidins from bark steamed under optimum conditions was carried out. The optimum conditions were as follows: steaming time, 30 min; steaming temperature, 140°C; and water volume, 75 ml. The total phenolics content obtained under these conditions amounted to 25.31%, which was much higher than the 21.70% obtained by conventional hot water extraction. Six proanthocyanidin dimers were isolated from the steamed bark. Analysis revealed them to be fisetinidol-(4β-8)-catechin, fisetinidol-(4α-8)-catechin, robinetinidol-(4β-8)-catechin, robinetinidol-(4α-8)-catechin, robinetinidol-(4β-8)-gallocatechin, and robinetinidol-(4α-8)-gallocatechin. Proanthocyanidin polymers were found to consist mainly of prorobinetinidin extender units, similar to those obtained from the same bark by conventional extraction with 70% acetone aqueous solution. However, nuclear magnetic resonance and gel permeation chromatography analyses suggested that during steaming the polymers undergo condensation reactions, as well as inversion of the configuration of interflavanoid bonds.

Optimising Beer Stabilisation by the Selective Removal of Tannoids and Sensitive Proteins

Colloidal stabilisation of all malt and adjunct lager beers through selective removal of haze sensitive glycoproteins using silica gel and tannoid polyphenols using polyvinylpolypyrrolidone (PVPP) or a polyvinylpyrrolidone (PVP)-modified silica gel has been demonstrated during full brewery production. At this scale PVPP and the PVP-modified silica gel exhibited equivalent binding capability for tannoid polyphenols although PVPP removed additional polyphenolic species. Characterisation of proanthocyanidins following treatment at 4°C with PVPP and the PVP-modified silica gel silica co-product confirmed that PVPP removes a wider range of polyphenolics. Both products exhibited poorer polyphenolic binding capability at 4°C as would be expected for a physical adsorption process.

Characterization of proanthocyanidins in grape seeds using electrospray mass spectrometry.

Two proanthocyanidin (PA) fractions, one (Sdp3) with the mean degree of polymerization (mDP) of 3 and the other (Sdp9) with mDP of 9, were obtained from a Vitis vinifera cv. Shiraz grape seed extract. The PA fractions were directly analyzed by electrospray ionization mass spectrometry (ES-MS) and negative ion mass spectra were recorded. The mass spectrum of Sdp3 exhibited only singly charged ions corresponding to the molecular mass of PA with a degree of polymerization (DP) up to 9 (nonamers). In contrast, Sdp9 yielded rather complex mass spectra featuring ions with single [M - H](-), double [M - 2H](2-) and triple [M - 3H](3-) charge representing the molecular masses of PAs up to a DP of 28. In addition, the degree of galloylation per procyanidin (DG) was observed to be up to 5 (pentagallates) in Sdp3 and 8 (octagallates) in the Sdp9. This is the first evidence obtained by mass spectrometry for the distribution of grape seed PAs with such a high degree of polymerization and a broad diversity of galloylation. ES-MS data together with the complementary information provided by acid hydrolysis provides a detailed picture of the composition of grape seed PAs.

Interactions of grape seed tannins with salivary proteins.

To evaluate the amount and type of condensed tannins binding salivary proteins, which are supposed to be involved in astringent sensation, model systems allowing further analyses of proteins and condensed tannins were developed. The precipitates formed after addition of grape seed tannins to salivary proteins indicate that a binding interaction occurs. Dissociation of insoluble complexes was achieved by sodium dodecyl sulfate treatment. Thiolysis reaction allowed the quantification and characterization of proanthocyanidins on both the resulting pellet and the supernatant. Binding proteins were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The higher polymerized tannins predominantly precipitated together with the salivary proteins. The condensed tannins remaining in solution were low molecular weight polymers.

Tannins and related compounds. XCI. Isolation and characterization of proanthocyanidins with an intramolecularly doubly-linked unit from the fern, Dicranopteris pedata Houtt.

A chemical examination of the polyphenolic constituents of the fern, Dicranopteris pedata HOUTT., has led to the isolation of eight new proanthocyanidins possessing a doubly-linked (A-type) unit, together with known flavan-3-ols and proanthocyanidins. On the basis of chemical and spectroscopic evidence, they are characterized as epiafzelechin-(4β→8, 2β→O→7)-eniafzelechin-(4α→8)-epiafzelechin(8), epicatechin-(4β→8, 2β→O→7)-epiafzelechin-(4α→8)-epiafzelechin(9), epiafzelechin-(4β→8, 2β→O→7)-epizfzelechin-(4α→8)-epicatechin(10), epiafzelechin-(4β→8, 2β→O→7)-epicatechin-(4α→8)-epicatechin (11), epicatechin-(4β→8, 2β→O→7)-epiafzelechin-(4α→8)-epicatechin (12), epicatechin-(4β→8, 2β→O→7)-epicatechin-(4α→8)-epiafzelechin (13), epicatechin-(4β→8, 2β→O→7)-epicatechin-(4α→8)-epigallocatechin (14) and epiafzelechin-(4β→8)epicatechin-(4β→8, 2β→O→β→7)-epicatechin-(4α→8)-epicatechin (15).

Tannins and related compounds. LX. Isolation and characterization of proanthocyanidins with a doubly-linked unit from Vaccinium vitis-idaea L.

New proanthocyanidin trimers (14 and 15) and tetramers (16 and 17) have been isolated from the whole body of Vaccinium vitis-idaea L. (Ericaceae). The structures of these proanthocyanidins were established by thiolytic degradation and by analyses of the proton and carbon-13 nuclear magnetic resonance spectra. In addition, the presence of (-)-epicatechin (1), (+)-catechin (2), (-)-epigallocatechin (3), (+)-gallocatechin (4), procyanidins B-1 (5), B-3 (6), A-1 (8), and A-2 (9), and cinnamtannins B1 (10), D1 (11), B2 (12), D2(13) in this plant was demonstrated.

Tannins and related compounds. XXXI. Isolation and characterization of proanthocyanidins in Kandelia candel (L.) Druce.

Tannins and related compounds. XXXI. Isolation and characterization of proanthocyanidins in Kandelia candel (L.) Druce.