Related Experiment Video
Updated: Jul 19, 2026
HPLC Measurement of the DNA Oxidation Biomarker, 8-oxo-7,8-dihydro-2’-deoxyguanosine, in Cultured Cells and Animal Tissues
Published on: August 1, 2015
Bioavailable flavonoids to suppress the formation of 8-OHdG in HepG2 cells
Kazuki Kanazawa1, Mari Uehara, Hiroaki Yanagitani
1Department of Biofunctional Chemistry, Graduate School of Science and Technology, Kobe University, Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan. kazuki@kobe-u.ac.jp
Abstract:
Antioxidative flavonoids, ubiquitously included in vegetables, fruits and teas, are expected to prevent degenerative diseases. It is unclear, however, whether flavonoids can enter the cellular nuclei and suppress the oxidative damage of DNA. Here, several flavonoids at the physiological concentration of 10 microM were dosed to 2.5x10(7) HepG2 cells. The nuclei were isolated and determined in the incorporated flavonoid levels, and simultaneously exposed to reactive oxygen generated from 25 mM of 2,2'-azobis(2-amidinopropane) dihydrochloride. Most of the tested flavonoids were incorporated into the cells in the range between 1000 and 1600 pmol/10(7) cells, and were in the nuclei at 250-450 pmol/10(7) cells at the maximum incorporation after 30min of cell incubation. In the cells, 23% of quercetin (3,5,7,3',4'-OH) and 8% of luteolin (5,7,3',4'-OH) were the original aglycone forms and the others were the methylated and gulucuronide/sulfate conjugates, while 72% of kaempferol (3,5,7,4'-OH) and 85% of apigenin (5,7,4'-OH) were aglycones and located in the nuclei at the similar ratio of metabolites. Quercetin and luteolin significantly suppressed the formation of 8-oxo-7,8-dihydrodeoxyguanosine by 25% and 15%, respectively, compared to those in 0-time incubated cells with the flavonoids. Under such conditions of low level and hydroxyl-masked in the nuclei, the limited flavonoids were bioavailable antioxidants to prevent genetic damage and they were B-ring catechols such as quercetin and luteolin.
Insights
Flavonoids from foods like fruits and teas can enter cell nuclei and protect DNA from oxidative damage. Certain flavonoids, particularly quercetin and luteolin, demonstrated significant antioxidant activity, preventing genetic damage.
Area of Science:
- Biochemistry
- Molecular Biology
- Nutritional Science
Background:
- Flavonoids are plant compounds found in fruits, vegetables, and teas, known for their antioxidant properties.
- Their ability to enter cellular nuclei and protect DNA from oxidative damage remains unclear.
- Understanding flavonoid bioavailability and nuclear localization is crucial for assessing their health benefits.
Purpose of the Study:
- To investigate the cellular uptake and nuclear incorporation of various flavonoids.
- To determine the protective effects of flavonoids against DNA oxidative damage within the cell nucleus.
- To identify specific flavonoid structures that are most effective as nuclear antioxidants.
Main Methods:
- HepG2 cells were incubated with physiological concentrations (10 microM) of different flavonoids.
- Cell nuclei were isolated to quantify incorporated flavonoid levels.
- Oxidative DNA damage was induced using reactive oxygen species, and 8-oxo-7,8-dihydrodeoxyguanosine formation was measured.
Main Results:
- Most tested flavonoids were incorporated into cells (1000–1600 pmol/10(7) cells) and nuclei (250–450 pmol/10(7) cells) within 30 minutes.
- Quercetin and luteolin, B-ring catechols, were found in both aglycone and conjugate forms within the nucleus.
- Quercetin and luteolin significantly reduced DNA oxidative damage by 25% and 15%, respectively.
Conclusions:
- Flavonoids can be incorporated into HepG2 cell nuclei at physiological concentrations.
- Specific flavonoids, notably quercetin and luteolin, act as bioavailable antioxidants within the nucleus.
- These findings suggest a mechanism by which dietary flavonoids may prevent DNA damage and associated degenerative diseases.
