Quantitative Fractionation of Grape Proanthocyanidins According to Their Degree of Polymerization

Abstract

A method was developed for the fractionation of grape (seed or skin) proanthocyanidins according to their degree of polymerization. After precipitation in chloroform/methanol (75:25, v/v), the grape proanthocyanidins were deposited onto an inert glass powder column and sequentially dissolved in several fractions by increasing proportions of methanol in the solvent. Each fraction from each proanthocyanidin source was quantified and characterized after acidic degradation with phenylmethanethiol (i.e., thiolysis). The comparison of data from total extract and successive fractions showed that a quantitative separation was achieved so that estimation of polymer size distribution in relation to other compositional characteristics (proportions of prodelphinidin units, galloylation rate) was thus possible. Mean degree of polymerization of separated proanthocyanidins ranged increasingly from 4.7 to 17.4 in seed (8.1 for total extract) and from 9.3 to 73.8 in skin (34.9 for total extract). The method proposed is very interesting for the study of grape proanthocyanidins according to their degree of polymerization because it gives both qualitative and quantitative information especially on the highly polymerized forms, which were not fractionated by previous techniques.

Hypoglycaemic and Hypolipidaemic Effects of an Ethylacetate Fraction of Artocarpus heterophyllus Leaves

“…Reductions in blood glucose levels were statistically significant between the control curve and test curves at all time intervals. In similar experiments a higher dose of 150mg/kg of the ethylacetate fraction had resulted in a 36.9% reduction in blood glucose at 2 hr post glucose administration [28].…”

“…An in vivo study using Sprague Dawley rats carried out by Fernando and Thabrew [58] has demonstrated that an aqueous extract of mature leaves of A. heterophyllus exerted no adverse effects even after daily administration for 30 days, as assessed by effects on (a) liver function, (b) haematological parameters such as haemoglobin concentration, red blood cell count, white blood cell count and packed cell volume, (c) reproductive ability of experimental animals and (d) histology of body organs (heart, liver, lung,kidney, intestine and pancreas). Investigations carried out by Chandrika et al [28] also have revealed that the chronic administration of the ethylacetate fraction of A. heterophyllus leaves to normoglycaemic rats over a period of twelve weeks at a dose of 50 mg/kg body weight failed to bring any overt signs of toxicity such as salivation, diarrhea, lacrymation, postural abnormalities or behavioural changes. No significant differences had been observed in the liver function tests and the histology of various body organs between the test and the control groups.…”

“…In recent studies, the phytochemical screening of the ethylactate fraction of A. heterophyllus leaves and bark has revealed the presence of flavanoids in high content. [28,29]. All fractions were evaporated to dryness and the residues stored at -4 0 C until use.…”

“…Further, purification and fractionation results in an enhancement of bioactivity by eliminating the unwanted material which could exert inhibitory effects on the bioactivity of interest. Since the ethylacetate fraction has been shown to contain a high content of flavanoids by phyotochemical screening [19,28,29], the hypoglycaemic activity of this fraction could be attributed to a high molecular weight flavanoid which has a higher solubility in ethylacetate than in water. …”

Proanthocyanidin in Red Rice Inhibits MDA-MB-231 Breast Cancer Cell Invasion <i>via</i> the Expression Control of Invasive Proteins

“…11) Whereas, the proanthocyanidin in grape seed is procyanidin type and represents major oligomer with DP4 (60%). 17) Based on Sephadex LH gel filtration column chromatography, the PRFR was co-eluted at the same fractions (fraction numbers 27 to 29) as the proanthocyanidin from grape seed extract as shown in the supplement data 1. Therefore, we propose that the majority of proanthocyanidin in the PRFR are the oligomer with the same DP of proanthocyanidin found in the grape seed extract as the structure was proposed in Fig.…”