title: Antimicrobial properties of Quercus ilex L. proanthocyanidin dimers and simple phenolics: evaluation of their synergistic activity with conventional antimicrobials and prediction of their pharmacokinetic profile.
abstract: The antibacterial and antifungal activities of an ample number of phenolic compounds isolated from Quercus ilex leaves, belonging to the classes of flavonoids, proanthocyanidins, and phenolic acids, are discussed. The isolation of A type proanthocyanidin, (+)-epigallocatechin-(2β→O→7, 4β→8)-(+)-catechin is reported for the first time. Its structure was established by means of highfield NMR (correlation spectroscopy, heteronuclear single quantum correlation, heteronuclear multiple bond correlation, and rotating frame Overhauser effect spectroscopy) and MS spectral analyses, while its absolute configuration was determined by circular dichroism measurements. The isolated compounds were tested for their antimicrobial effects against eight human bacterial species and 14 fungal species. In a second step, the most potent compounds were tested in combination with the conventional fungicides, bifonazole and ketoconazole, to evaluate possible synergistic effects. Results showed that proanthocyanidins 3 and 4 when combined with bifonazole and ketoconazole increase the activity of both of these conventional fungicides. Moreover, the pharmacokinetic profile of the isolated compounds was investigated using computational methods.
authors.affiliation: Department of Pharmacognosy and Chemistry of Natural Products, School of Pharmacy, University of Athens , Panepistimiopolis, Zografou, 15771 Athens, Greece.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Karioti
authors.forename: Marina
authors.initials: M
authors.lastname: Sokovic
authors.forename: Ana
authors.initials: A
authors.lastname: Ciric
authors.forename: Catherine
authors.initials: C
authors.lastname: Koukoulitsa
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Bilia
authors.forename: Helen
authors.initials: H
authors.lastname: Skaltsa
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry / Q000493:pharmacokinetics*; D001419:Bacteria / Q000187:drug effects; D019281:Dimerization; D004357:Drug Synergism; D005658:Fungi / Q000187:drug effects; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry / Q000493:pharmacokinetics*; D010936:Plant Extracts / Q000737:chemistry / Q000493:pharmacokinetics*; D044945:Proanthocyanidins / Q000737:chemistry / Q000493:pharmacokinetics*; D029963:Quercus / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D010636:Phenols; D010936:Plant Extracts; D044945:Proanthocyanidins