Effect of green tea catechins on oxidative DNA damage of hamster pancreas and liver induced by N‐Nitrosobis(2‐oxopropyl)amine and/or oxidized soybean oil

Abstract

It has been indicated that high fat diet is a risk factor of the pancreatic cancer by epidemiological studies. We examined whether the oxidized soybean oil (ox-oil) express the synergistic effect on the formation of 8-oxo-2'-deoxyguanosine (8-oxodG) in nuclear DNA of hamster pancreas induced by N-Nitrosobis(2-oxopropyl)amine (BOP) and whether the green tea catechins (GTC) suppressed it. Ox-oil was prepared by air oxidation, and the content of lipid hydroperoxide was 6.22 mg/ml. Hamsters were administered 0.3 ml of ox-oil/day orally for 4 weeks before BOP treatment. GTC was given ad libitum as a 0.1% aqueous solution. Four hours after subcutaneous administration of BOP, hamsters were sacrificed, and the contents of 8-oxodG were measured in nuclear DNA of pancreas and liver. The 8-oxodG content in the pancreas was increased by BOP and/or ox-oil administration. However, it was not suppressed by an intake of GTC. In the liver, though the content of 8-oxodG was increased by ox-oil, it tended to suppress the rise of 8-oxodG by a GTC intake. These results suggested that the long term intake of ox-oil might have the possibility to induce carcinogenesis in hamster pancreas and liver, and an intake of GTC might have the beneficial effect on liver.