@article{DirimanovHoegger2019,
  author    = {Dirimanov, Stoyan and H{\"o}gger, Petra},
  title     = {Screening of inhibitory effects of polyphenols on Akt-phosphorylation in endothelial cells and determination of structure-activity features},
  series = {Biomolecules},
  volume    = {9},
  journal   = {Biomolecules},
  number    = {6},
  issn      = {2218-273X},
  doi       = {10.3390/biom9060219},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197333},
  pages     = {219},
  year      = {2019},
  abstract  = {Polyphenols exert beneficial effects in type 2 diabetes mellitus (T2DM). However, their mechanism of action remains largely unknown. Endothelial Akt-kinase plays a key role in the pathogenesis of cardiovascular complications in T2DM and therefore the modulation of its activity is of interest. This work aimed to characterize effects of structurally different polyphenols on Akt-phosphorylation (pAkt) in endothelial cells (Ea.hy926) and to describe structure-activity features. A comprehensive screening via ELISA quantified the effects of 44 polyphenols (10 µM) on pAkt Ser473. The most pronounced inhibitors were luteolin (44 ± 18\%), quercetin (36 ± 8\%), urolithin A (35 ± 12\%), apigenin, fisetin, and resveratrol; (p < 0.01). The results were confirmed by Western blotting and complemented with corresponding experiments in HUVEC cells. A strong positive and statistically significant correlation between the mean inhibitory effects of the tested polyphenols on both Akt-residues Ser473 and Thr308 (r = 0.9478, p = 0.0003) was determined by immunoblotting. Interestingly, the structural characteristics favoring pAkt inhibition partially differed from structural features enhancing the compounds' antioxidant activity. The present study is the first to quantitatively compare the influence of polyphenols from nine different structural subclasses on pAkt in endothelial cells. These effects might be advantageous in certain T2DM-complications involving over-activation of the Akt-pathway. The suggested molecular mode of action of polyphenols involving Akt-inhibition contributes to understanding their effects on the cellular level.},
  language  = {en}
}
@article{MuelekSeefriedGenestetal.2017,
  author    = {M{\"u}lek, Melanie and Seefried, Lothar and Genest, Franca and H{\"o}gger, Petra},
  title     = {Distribution of constituents and metabolites of maritime pine bark extract (Pycnogenol\(^{®}\)) into serum, blood cells, and synovial fluid of patients with severe osteoarthritis: a randomized controlled trial},
  series = {Nutrients},
  volume    = {9},
  journal   = {Nutrients},
  number    = {5},
  doi       = {10.3390/nu9050443},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-159862},
  pages     = {443},
  year      = {2017},
  abstract  = {The present randomized controlled study aimed to investigate the in vivo distribution of constituents or metabolites of the standardized maritime pine bark extract Pycnogenol\(^{®}\). Thirty-three patients with severe osteoarthritis scheduled for a knee arthroplasty were randomized to receive either 200 mg per day Pycnogenol\(^{®}\) (P+) or no treatment (Co) over three weeks before surgery. Serum, blood cells, and synovial fluid samples were analyzed using liquid chromatography coupled to tandem mass spectrometry with electrospray ionization (LC-ESI/MS/MS). Considerable interindividual differences were observed indicating pronounced variability of the polyphenol pharmacokinetics. Notably, the highest polyphenol concentrations were not detected in serum. Catechin and taxifolin primarily resided within the blood cells while the microbial catechin metabolite δ-(3,4-dihydroxy-phenyl)-γ-valerolactone, ferulic, and caffeic acid were mainly present in synovial fluid samples. Taxifolin was detected in serum and synovial fluid exclusively in the P+ group. Likewise, no ferulic acid was found in serum samples of the Co group. Calculating ratios of analyte distribution in individual patients revealed a simultaneous presence of some polyphenols in serum, blood cells, and/or synovial fluid only in the P+ group. This is the first evidence that polyphenols distribute into the synovial fluid of patients with osteoarthritis which supports rationalizing the results of clinical efficacy studies.},
  language  = {en}
}
@article{VolppFerianecJežovičovaetal.2020,
  author    = {Volpp, Linda and Ferianec, Vladim{\´i}r and Ježovičov{\´a}, Miriam and Ďuračkov{\´a}, Zdeňka and Scherf-Clavel, Oliver and H{\"o}gger, Petra},
  title     = {Constituents and Metabolites of a French Oak Wood Extract (Robuvit®) in Serum and Blood Cell Samples of Women Undergoing Hysterectomy},
  series = {Frontiers in Pharmacology},
  volume    = {11},
  journal   = {Frontiers in Pharmacology},
  number    = {74},
  issn      = {1663-9812},
  doi       = {10.3389/fphar.2020.00074},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-200105},
  year      = {2020},
  abstract  = {Ellagitannins are signature constituents of oak wood and their consumption has been associated with various health benefits. In vivo, they undergo metabolic degradation including gut microbial metabolism yielding urolithins. Only limited data is available about compounds being present in blood after intake of an extract from French oak wood, Robuvit®. In the course of a randomized, double-blind, controlled clinical investigation, 66 patients undergoing hysterectomy received placebo or 300 mg Robuvit® per day before and over 8 weeks after surgery. Serum and blood cell samples were analyzed by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The number of urolithin producers and the urolithin levels increased after intake of Robuvit®. In serum samples, the median concentration of urolithin A was 14.0 ng/ml [interquartile range (IQR) 57.4] after 8 weeks. Urolithin B was determined at 22.3 ng/ml (IQR 12.6), urolithin C at 2.66 ng/ml (IQR 2.08). In blood cells, lower concentrations and only urolithins A and B were detected. A statistically significant association of lower post-surgical pain scores with metabotype A was detected (p < 0.05). To conclude, supplementation with French oak wood extract raised urolithin generation in patients and suggested health advantages for urolithin-producers.},
  language  = {en}
}