title: LC-MS metabolic study on quercetin and taxifolin galloyl esters using human hepatocytes as toxicity and biotransformation in vitro cell model.
abstract: Galloyl esters of quercetin and taxifolin have been recently prepared semisynthetically as part of work towards modifying the solubility and modulating the biological activity of these natural flavonoids. In this paper we focused on the liquid chromatography-mass spectrometry (LC-MS) profiling of metabolites of 3-O-galloylquercetin and 7-O-galloyltaxifolin using human hepatocytes as the in vitro cell model. A subtoxic concentration (50μM) was used for both compounds and the formation of metabolites was monitored for 2h in hepatocytes and cultivation medium separately. Using negative electrospray ionization-quadrupole time-of-flight mass spectrometry (ESI-QqTOF MS), we identified different biotransformation patterns for the studied compounds. 3-O-Galloylquercetin is metabolized directly to glucuronides and methyl derivatives. In contrast, 7-O-galloyltaxifolin is oxidized to 7-O-galloylquercetin or cleaved to taxifolin, and consequently the products formed are sulfated or glucuronidated. The oxidative biotransformation of 3-O-galloylquercetin and 7-O-galloyltaxifolin is also accompanied by ester bond cleavage presumably by cellular enzymes (esterases) in a nonspecific manner. Our results provide fundamental insights into the biotransformation of monogalloyl esters of flavonoids and can be applied in investigations of the pharmaceutical potential of other galloylated polyphenolic substances.
authors.affiliation: Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 3, CZ 775 15 Olomouc, Czech Republic. Electronic address: jan.vacek@upol.cz.
authors.forename: Jan
authors.initials: J
authors.lastname: Vacek
authors.forename: Barbora
authors.initials: B
authors.lastname: Papoušková
authors.forename: Jiří
authors.initials: J
authors.lastname: Vrba
authors.forename: Martina
authors.initials: M
authors.lastname: Zatloukalová
authors.forename: Vladimír
authors.initials: V
authors.lastname: Křen
authors.forename: Jitka
authors.initials: J
authors.lastname: Ulrichová
mesh_terms: D000293:Adolescent; D000818:Animals; D001711:Biotransformation; D002478:Cells, Cultured; D002853:Chromatography, Liquid / Q000379:methods; D004952:Esters; D005260:Female; D005707:Gallic Acid / Q000737:chemistry / Q000493:pharmacokinetics / Q000633:toxicity*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D041681:NIH 3T3 Cells; D011794:Quercetin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics / Q000633:toxicity; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D004952:Esters; C012526:quercitrin; D005707:Gallic Acid; D011794:Quercetin; C003377:taxifolin
keywords: 3-O-galloylquercetin; 3-O-galloylquercetin glucuronide; 3-O-galloylquercetin methyl derivative; 3GQ; 3GQG; 3GQM; 7-O-galloylquercetin; 7-O-galloyltaxifolin; 7GQ; 7GT; Cytotoxicity; ESI-QqTOF MS; GA; HPLC; LC–MS; Mass spectrometry; Metabolic transformation; PHE; Quercetin-3-O-gallate; SIM; TG; TS; Taxifolin-7-O-gallate; electrospray ionization-quadrupole time-of-flight mass spectrometry; gallic acid (gallate); high-performance liquid chromatography; liquid chromatography–mass spectrometry; phenyl; selected-ion monitoring; taxifolin glucuronide; taxifolin sulfate