[Study on detection method of 8-OH-dG in DNA extracted from HepG2 cells in vitro by capillary zone electrophoresis]

To establish an optimized method to detect 8-OH-dG after DNA oxidation damage by capillary zone electrophoresis.

HepG2 cell was used as target cell and conditions for the separation and detection were obtained by studying the influence of pH of the running buffer, temperature, running voltage on the separation. 0 and 15 mmol/L H2O2 were added into two groups of HepG2 cells (5 x 10(7)) respectively for 24h. DNA was extracted by saturated salting out method to avoid the formation of additional 8-OH-dG by the method of phenol/chloroform extraction. DNA samples were digested to free nucleotides by incubation overnight at 37 degrees C with a mixture of DNase I, snake venom phosphoatase and alkaline phosphate. Proteins were removed and the supernatant was neutralized and then extracted with diethyl ether. The residue was evaporated to dryness and reconstituted and then analyzed under the optimized conditions by capillary zone electrophoresis.

The optimized conditions were: uncoated silica capillary (47 cm x 50 microm i.d.), 20 mmol/L borate buffer (pH 9.5), 25 degrees C, 25kV. The sample was injected by hydrostatic method for 20s. In either of H2O2-treated group and H2O2-untreated group, the peak of 8-OH-dG was detected. The 8-OH-dG content of H2O2-untreated DNA increased.

The method is convenient, rapid, sensitive and cheap and safe. It provides an experimental platform to the application of 8-OH-dG in the biological monitoring of population.