Genotoxic and antigenotoxic effects of catechin and tannins from the bark of Hamamelis virginiana L. in metabolically competent, human hepatoma cells (Hep G2) using single cell gel electrophoresis

• Published in: Phytochemistry (Oxford) Vol. 63; no. 2; pp. 199 - 207
• Main Authors: Dauer, Andreas, Hensel, Andreas, Lhoste, Evelyne, Knasmüller, Siegfried, Mersch-Sundermann, Volker
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01-05-2003; Elsevier
• Subjects: Anthocyanins - isolation & purification; Anthocyanins - pharmacology; Anthocyanins - toxicity; Antigenotoxicity; Antineoplastic Agents, Phytogenic - isolation & purification; Antineoplastic Agents, Phytogenic - pharmacology; Antineoplastic Agents, Phytogenic - toxicity; Benzo(a)pyrene - metabolism; Benzo(a)pyrene - toxicity; Biological and medical sciences; Carcinoma, Hepatocellular - genetics; Catechin; Catechin - isolation & purification; Catechin - pharmacology; Catechin - toxicity; Chemical constitution; Cytochrome P-450 CYP1A1 - metabolism; DNA Damage; Electrophoresis, Agar Gel - methods; Fundamental and applied biological sciences. Psychology; Gallic Acid - analogs & derivatives; Gallic Acid - isolation & purification; Gallic Acid - pharmacology; Gallic Acid - toxicity; General pharmacology; Genotoxicity; Hamamelidaceae; Hamamelis - chemistry; Hamamelis virginiana; Hamamelis virginiana L; Hep G2 cells; Hexoses - isolation & purification; Hexoses - pharmacology; Hexoses - toxicity; Humans; Life Sciences; Liver Neoplasms - genetics; Medical sciences; Mutagens - isolation & purification; Mutagens - pharmacology; Mutagens - toxicity; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Plant Bark - chemistry; Plant physiology and development; Proanthocyanidins; SCGE assay; Tannins; Tumor Cells, Cultured; Hep G2 cells; Hamamelis virginiana L; Catechin; Tannins; SCGE assay; Genotoxicity; Hamamelidaceae; Antigenotoxicity; Proanthocyanidins; Human; Bioassay; Benzopyrene; Essential oil plant; Toxicity; Bark; Biological activity; Cell line; Hepatocyte; Dicotyledones; Angiospermae; Plant origin; Isolation; Spermatophyta; Vegetal tannin
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/S0031-9422(03)00104-3

The genotoxic and antigenotoxic activities of catechin, hamamelitannin and two proanthocyanidin fractions prepared from the bark of
Hamamelis virginiana L. were investigated in a human derived, metabolically competent hepatoma cell line (Hep G2) using single cell gel electrophoresis (SCGE) for the detection of DNA-damage. DNA-migration was calculated as Olive tail moment (OTM). Catechin and a low-molecular weight proanthocyandin fraction (
W
M) caused only slight increases of OTM up to concentrations of 166 μg/ml whereas hamamelitannin and the proanthocyandin fraction with higher molecular weight (
W
A) led to a two-fold enhancement of OTM at the same concentrations. These effects were dose-independent. Treatment of the cells with the test compounds in a dose-range of 2–166 μg/ml prior to the exposure to benzo(a)pyrene (B(a)P, 10 μM, 2.5 μg/ml) led to a significant reduction of induced DNA damage which was dose-dependent for all test compounds, except for hamamelitannin. The inhibitory effects of proanthocyanidins were stronger than those of catechin and hamamelitannin; the lowest effective concentrations were about 2 μg/ml. In order to clarify the mechanisms of protection, possible effects of the test compounds on enzymes involved in toxification and detoxification of B(a)P were investigated. While B(a)P toxification by cytochrome P450 was not inhibited by the test compounds, detoxification by glutathion-
S-transferase (GST) was induced by catechin and W
M. Combination experiments with the ultimate metabolite of B(a)P, (±)-
anti-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE; 5 μM, 1.5 μg/ml), revealed strong inhibitory effects, indicating that the observed protective effects were caused by scavenging of the ultimate mutagen by the test compounds. Exposure of Hep G2 cells to the test compounds after B(a)P treatment did not influence B(a)P induced DNA damage, demonstrating that repair mechanisms were not affected.
The genotoxic and antigenotoxic activities of catechin, hamamelitannin and two proanthocyanidin fractions prepared from the bark of
Hamamelis virginiana L. in a human derived hepatoma cell line are reported.