title: Witch hazel (Hamamelis virginiana) fractions and the importance of gallate moieties--electron transfer capacities in their antitumoral properties.
abstract: Witch hazel (Hamamelis virginia) extracts are used in traditional medicine. They are particularly rich in gallate esters included in proanthocyanidins, hydrolyzable tannins (galloylated sugars), and methyl gallate. This study examines the response of human colon cancer cells to treatment with fractions obtained from a witch hazel polyphenolic extract. The results are compared with those obtained previously with homologous fractions from grape (less galloylated) and pine (nongalloylated). Witch hazel fractions were the most efficient in inhibiting cell proliferation in HT29 and HCT116 human colon cancer cell lines, which clearly shows that the more galloylated the fractions, the more effective they were at inhibiting proliferation of colon cancer cells. Witch hazel fractions were, in addition, more potent in arresting the cell cycle at the S phase and inducing apoptosis; they also induced a significant percentage of necrosis. Interestingly, the apoptosis and cell cycle arrest effects induced were proportional to their galloylation. Moreover, witch hazel fractions with a high degree of galloylation were also the most effective as scavengers of both hydroxyl and superoxide radicals and in protecting against DNA damage triggered by the hydroxyl radical system. These findings provide a better understanding of the structure-bioactivity relationships of polyphenolics, which should be of assistance in choosing an appropriate source and preparing a rational design for formulations of plant polyphenols in nutritional supplements.
authors.affiliation: Department of Biochemistry and Molecular Biology, unit associated with CSIC, Faculty of Biology, University of Barcelona, Biomedicine Institute of the University of Barcelona, Diagonal 645, E-08028 Barcelona, Spain.
authors.forename: Daneida
authors.initials: D
authors.lastname: Lizárraga
authors.forename: Sonia
authors.initials: S
authors.lastname: Touriño
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Reyes-Zurita
authors.forename: Theo M
authors.initials: TM
authors.lastname: de Kok
authors.forename: Joost H
authors.initials: JH
authors.lastname: van Delft
authors.forename: Lou M
authors.initials: LM
authors.lastname: Maas
authors.forename: Jacco J
authors.initials: JJ
authors.lastname: Briedé
authors.forename: Josep J
authors.initials: JJ
authors.lastname: Centelles
authors.forename: Josep L
authors.initials: JL
authors.lastname: Torres
authors.forename: Marta
authors.initials: M
authors.lastname: Cascante
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy*; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000737:chemistry*; D029501:Hamamelis / Q000737:chemistry*; D006801:Humans; D010636:Phenols / Q000737:chemistry / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology*; D059808:Polyphenols; D013329:Structure-Activity Relationship
chemical_list: D000970:Antineoplastic Agents; D005419:Flavonoids; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; D005707:Gallic Acid