In this study, we investigated the absorption of apple procyanidins, namely, apple condensed tannins (ACTs), in rats using the Porter method and high-performance liquid chromatography/tandem mass spectrometry. The apple procyanidin concentrations in the rat plasma reached a maximum 2 h after administration and decreased thereafter. To investigate the limits of the absorption of apple procyanidins in the polymerization degree, we administered the procyanidin oligomer fraction, which was separated from ACT using normal-phase chromatography according to the degree of polymerization. Procyanidins from each dimer to pentamer group were detected in the plasma by the Porter method. Moreover, by the study using reconstituted procyanidins, polymeric procyanidins influenced the absorption of procyanidin oligomers. These results suggest that ACTs are absorbed and directly involved in physiological functions in the rats.
"Lower-molecularweight components and metabolites are more easily absorbed (Fernandes et al., 2012; Kosi nska and Andlauer, 2012). Most in vivo studies suggest that procyanidin dimers can be absorbed (Baba et al., 2002; Tsang et al., 2005; Shoji et al., 2006; Prasain et al., 2009). The gut is the predominant location for absorption, a large percentage of the parent compound may be transformed by gut microflora, and the resulting metabolites may constitute the predominant form of absorption (Stoupi et al., 2010). "
[Show abstract][Hide abstract] ABSTRACT: Proanthocyanidins are among the most abundant constituents in pine bark extracts (PBEs). This review summarizes medical research on PBEs from Pinus pinaster, Pinus radiata, Pinus massoniana, and other less well-characterized species. The precise mechanisms of the important physiological functions of PBE components remain to be elucidated, but there is evidently great potential for the identification and development of novel antioxidant, anti-inflammatory, cardiovascular, neuroprotective, and anti-cancer medicines. Although toxicological data for PBEs are limited, no serious adverse effects have been reported. PBEs may therefore have potential as nutraceuticals and pharmaceuticals and should be safe for use as food ingredients.
Journal of Pharmacology and Experimental Therapeutics 01/2015; 353(1):9-16. DOI:10.1124/jpet.114.220277 · 3.97 Impact Factor
"Using a mass spectrometer and the Porter method, they also detected free nonconjugated procyanidin dimers to tetramers in rat plasma after oral administration of purified oligomers to rats at a dose of 1 g/kg (Shoji et al., 2006). Pentamers were detected using the Porter method only (Shoji et al., 2006), but these data should be interpreted cautiously because Porter method lacks the specificity and accuracy to detect procyanidins in blood (Gu, 2012). The concentration of procyanidin B1 [epicatechin-(4b!8)- catechin] in human serum was 10.6 nmol/L 2 h after intake of 2.0 g of grape seed extract (Sano et al., 2003). "
[Show abstract][Hide abstract] ABSTRACT: Proanthocyanidins are found in fruits, tree nuts, cereals, legumes, wine, and chocolate. They affect nutritional value, appearance, taste, and texture of these foods and promote better health by preventing cardiovascular diseases, cancers, urinary tract infections, and other aging-related metabolic complications. The bioavailability of proanthocyanidins is largely influenced by their degree of polymerization. The absorption rate of proanthocyanidin dimers is 5–10% of that of (−)-epicatechin. Trimers and tetramers had lower absorption rates than dimers. Absorbed intact dimers, trimers, and tetramers undergo limited phase II metabolism in the intestine and liver in rats compared with (−)-epicatechin. Proanthocyanidins with a degree of polymerization over 4 (DP > 4) are not absorbable because of their large molecular size and gut barrier. Depolymerization of proanthocyanidins in the gastrointestinal tract was negligible. The majority of proanthocyanidins reaches the colon intact and is degraded into phenylvalerolactones and phenolic acids by colon microbiota. These microbial metabolites may contribute to the health promoting properties of proanthocyanidins in vivo. Future research of proanthocyanidin bioavailability will likely focus on identification of new microbial metabolites and investigation of how proanthocyanidins influence human health by affecting the composition of human gut microbiota.
"Ratio of total excretion to administrated amounts for CT is about 1%, respectively, 3% (only CT, respectively, CT and methyl derivatives, both after hydrolysis ) for pigs of control group. These results underline the different absorption rates between flavan-3-ols and procyanidins in connection with the degree of polymerization as observed in former studies  . This was also confirmed by experiments with an in situ perfusion model of the small intestine of rats. "
[Show abstract][Hide abstract] ABSTRACT: Aim of this study was to investigate urinary excretion and metabolism of procyanidins a group of secondary plant metabolites with many beneficial health effects described in literature.
To investigate the metabolism of procyanidins in the absence of flavan-3-ols, centrifugal partition chromatography was used for their reduction in a grape seed extract to a level of almost zero. After administration of the monomer reduced grape seed extract (mredGSE) containing procyanidins B1, B2, B3, B4, C1 to pigs flavan-3-ols, their methyl derivatives, dimeric and trimeric procyanidins were determined in urine by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Maximal concentrations of procyanidins 6 h after administration vary from 5 to 30 ng/mg creatinine. Total excretion of flavan-3-ols and their methyl derivatives indicates an increasing trend for pigs given mredGSE in comparison to pigs of the control group. Flavan-3-ols were conjugated and methylated to a great extent in comparison to dimeric and trimeric procyanidins. In the case of low molecular weight metabolites, an increasing trend was observed for hippuric acid, not for phenolic acids.
Ratios of total excretion of procyanidins to administrated amounts between 0.004% (C1) and 0.019% (B4) suggest a poor urinary excretion by pigs. A transfer of these results to humans is possible due to their similar gastrointestinal tract.
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