Intestinal Metabolism of Two A-type Procyanidins Using the Pig Cecum Model: Detailed Structure Elucidation of Unknown Catabolites with Fourier Transform Mass Spectrometry (FTMS)
NRW Graduate School of Chemistry, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany.Journal of Agricultural and Food Chemistry (Impact Factor: 2.91). 12/2011; 60(3):749-57. DOI: 10.1021/jf203927g
Procyanidins, as important secondary plant metabolites in fruits, berries, and beverages such as cacao and tea, are supposed to have positive health impacts, although their bioavailability is yet not clear. One important aspect for bioavailability is intestinal metabolism. The investigation of the microbial catabolism of A-type procyanidins is of great importance due to their more complex structure in comparison to B-type procyanidins. A-type procyanidins exhibit an additional ether linkage between the flavan-3-ol monomers. In this study two A-type procyanidins, procyanidin A2 and cinnamtannin B1, were incubated in the pig cecum model to mimic the degradation caused by the microbiota. Both A-type procyanidins were degraded by the microbiota. Procyanidin A2 as a dimer was degraded by about 80% and cinnamtannin B1 as a trimer by about 40% within 8 h of incubation. Hydroxylated phenolic compounds were quantified as degradation products. In addition, two yet unknown catabolites were identified, and the structures were elucidated by Fourier transform mass spectrometry.
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- "Dimers with " A-type " and " B-type " interflavan bonds were degraded between 30–50% and 80%, respectively, using a pig cecum model, yielding hydroxylated low MW phenolic acids as hydroxyphenlyacetic, hydroxyphenlypropionic, and hydroxybenzoic acids[76,77]. Similarly, 40% percent of a PAC trimer with " B-type " interflavan bonds was degraded by intestinal microbiota in a pig cecum model generating hydroxylated low MW phenolic acids. The degradation rate decreases with the increase in PAC DP[56,78]and metabolites of microbial origin as phenylvaleric, phenylpropionic, phenylacetic, and benzoic acid derivatives were identified in mice urine. "
ABSTRACT: Urinary tract infections (UTI) are one of the most frequent extra-intestinal infections caused by Escherichia coli (ExPEC). Cranberry juice has been used for decades to alleviate symptoms and prevent recurrent UTI. The putative compounds in cranberries are proanthocyanidins (PAC), specifically PAC with "A-type" bonds. Since PAC are not absorbed, their health benefits in UTI may occur through interactions at the mucosal surface in the gastrointestinal tract. Recent research showed that higher agglutination of ExPEC and reduced bacterial invasion are correlated with higher number of "A-type" bonds and higher degree of polymerization of PAC. An understanding of PAC structure-activity relationship is becoming feasible due to advancements, not only in obtaining purified PAC fractions that allow accurate estimation, but also in high-resolution mass spectrometry methodologies, specifically, matrix assisted laser/desorption ionization time-of-flight (MALDI-TOF MS). A recent MALDI-TOF MS deconvolution method allows quantification of the ratios of "A-type" to "B-type" bonds enabling characteristic fingerprints. Moreover, the generation of fluorescently labeled PAC allows visualization of the interaction between ExPEC and PAC with microscopy. These tools can be used to establish structure-activity relationships between PAC and UTI and give insight on the mechanism of action of these compounds in the gut without being absorbed This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
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- "In cases where only low amounts of intermediates were secreted by the mutant strains, HPLC, in combination with FTMS/MS fragmentation, was used for unequivocal structure elucidation. Previous studies of Engemann et al. could show that this is a good tool for structure elucidation (Engemann et al., 2012). As expected, Dfus1 and Dfus2-9 deletion mutants that have lost the PKS/NRPS-encoding gene fus1 or all cluster genes except for fus1, respectively, did not produce any fusarin C "
ABSTRACT: In this work, the biosynthesis and regulation of the polyketide synthase/nonribosomal peptide synthetase (PKS/NRPS)-derived mutagenic mycotoxin fusarin C was studied in the fungus Fusarium fujikuroi. The fusarin gene cluster consists of nine genes (fus1-fus9) that are coexpressed under high-nitrogen and acidic pH conditions. Chromatin immunoprecipitation revealed a correlation between high expression and enrichment of activating H3K9-acetylation marks under inducing conditions. We provide evidence that only four genes are sufficient for the biosynthesis. The combination of genetic engineering with nuclear magnetic resonance and mass-spectrometry-based structure elucidation allowed the discovery of the putative fusarin biosynthetic pathway. Surprisingly, we indicate that PKS/NRPS releases its product with an open ring structure, probably as an alcohol. Our data indicate that 2-pyrrolidone ring closure, oxidation at C-20, and, finally, methylation at C-20 are catalyzed by Fus2, Fus8, and Fus9, respectively.
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ABSTRACT: Cranberry (Vaccinium macrocarpon) products have been widely recommended in traditional American medicine for the treatment of urinary tract infection (UTI). A total of 19 different commercial cranberry products from American and European markets have been analyzed by different global phenolic methods and by UPLC-DAD-ESI-TQ MS. In addition, in vitro antioxidant capacity and uropathogenic bacterial antiadhesion activity tests have been performed. Results revealed that products found in the market widely differed in their phenolic content and distribution, including products completely devoid of flavan-3-ols to highly purified ones, either in A-type proanthocyanidins (PACs) or in anthocyanins. The product presentation form and polyphenolic profile widely affected the antiadhesion activity, ranging from a negative (nulel) effect to a MIC = 0.5 mg/mL for cranberry powders and a MIC=112 mg/mL for gel capsule samples. Only 4 of 19 products would provide the recommended dose of intake of 36 mg total PACs/day. Of most importance was the fact that this dose would actually provide as low as 0.00 and up to 205 μg/g of procyanidin A2, indicating the lack of product standardization and incongruence between global and individual compound analysis.
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