Analysis of DNA adducts in mice treated with safrole 2'',3''-oxide

• Main Authors: Yu-Tzu Wei, 魏宇孜
• Other Authors: Kuen-Yuh Wu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/51006534287461857491

碩士 === 國立臺灣大學 === 職業醫學與工業衛生研究所 === 102 === Safrole (1-allyl-3,4-methylenedioxybenzene), the main component of the sassafras oil, is commonly present in plants such as anise, cinnamon, basil, nutmeg, and pepper. People could be exposed to safrole in their daily life. Safrole-2’,3’- oxide (SFO), an active metabolite and an electrophile of safrole, is suspected to be responsible for genotoxicity and mutagenicity in Salmonella typhimurium strains TA1535 and TA100. In a previous study, scientists tried to analyze SFO-induced DNA adducts by using 32P-postlabeling method. Nevertheless, they failed to analyze any SFO-induced DNA adducts in liver tissue of mice. Therefore, SFO was not considered as a genotoxic carcinogen. However, the structure of SFO is similar with that of styrene-7,8-oxide, an animal carcinogen, and recent studies have shown that SFO can induce cytotoxicity, DNA strand breaks, micronuclei formation both in vitro and in vivo. Recently, our lab verified that SFO could cause in vivo formation of N7γ-SFO-Gua, which might then be rapidly depurinated from the DNA backbone and excreted through urine. In the present study, we aimed to further investigate SFO-induced DNA adducts in animal tissue and in HepG2 cells. Analysis of SFO-induced DNA adducts not only confirms SFO genotoxicity, but also serves as risk-associated biomarkers for cancers. Therefore, the objective of this study was to determine the SFO-induced DNA adducts in HepG2 cell and tissues of mice-treated with SFO by using an solid-phase extraction liquid chromatography/tandem mass spectrometry method. N7-(3-benzo[1,3]dioxol-5-yl-2-hydroxypropyl)guanine(N7γ-SFO-Gua), N1-(3-benzo[1,3]dioxol-5-yl-2-hydroxypropyl)adenine(N1γ-SFO-dAdo) were first measured in HepG2 cells treated with 250 and 375 μM SFO. Female CD-1 mice were repeatedly treated with 150 and 300 mg/kg/day of safrole and 30, 60, 90, and 120 mg/kg/day of SFO through ip injection for continuous 28 days. N7γ-SFO-Gua in liver DNA and urine samples were further analyzed. Results show dose-dependent increases in N7γ-SFO-Gua contents in liver and urine and demonstrate that SFO indeed caused formation of DNA adducts, which probably depurinated from DNA backbone and suggested the genotoxicity of SFO in mice.