Abstract：
Safrole oxide (SAFO), a metabolite of naturally occurring hepatocarcinogen safrole, is implicated in causing DNA adduct formation. Our previous study first detected the most abundant SAFO-induced DNA adduct, N7-(3-benzo[1,3] dioxol-5-yl-2-hydroxypropyl)guanine (N7γ-SAFO-G), in mouse urine using a well-developed isotope-dilution high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (ID-HPLC-ESI-MS/MS) method. This study further elucidated the genotoxic mode of action of SAFO in mice treated with SAFO 30, 60, 90, or 120 mg/kg for 28 days. The ID-HPLC-ESI-MS/MS method detected N7γ-SAFO-G with excellent sensitivity and specificity in mouse liver and urine of SAFO-treated mice. Our data provide the first direct evidence of SAFO-DNA adduct formation in rodent tissues. N7γ-SAFO-G levels in liver were significantly increased by SAFO 120 mg/kg compared with SAFO 30 mg/kg, suggesting rapid spontaneous or enzymatic depurination of N7γ-SAFO-G in tissue DNA. Urinary N7γ-SAFO-G exhibited a sublinear dose response. Moreover, the micronucleated peripheral reticulocyte frequencies increased dose-dependently and significantly correlated with N7γ-SAFO-G levels in liver (r = 0.8647; p < 0.0001) and urine (r = 0.846; p < 0.0001). Our study suggests that safrole-mediated genotoxicity may be caused partly by its metabolic activation to SAFO and that urinary N7γ-SAFO-G may serve as a chemically-specific cancer risk biomarker for safrole exposure.
摘要：
黄樟素氧化物(SAFO),天然存在的肝癌黄樟素的代谢产物，与导致DNA加合物形成有关。我们之前的研究首次检测到最丰富的SAFO诱导的DNA加合物，N7-(3-苯并[1,3]二氧杂环戊烯-5-基-2-羟丙基)鸟嘌呤(N7γ-SAFO-G),在小鼠尿液中使用完善的同位素稀释高效液相色谱-电喷雾电离串联质谱（ID-HPLC-ESI-MS/MS）方法。该研究进一步阐明了SAFO在用SAFO30、60、90或120mg/kg治疗28天的小鼠中的基因毒性作用模式。ID-HPLC-ESI-MS/MS方法在SAFO处理小鼠的小鼠肝脏和尿液中检测N7γ-SAFO-G具有优异的灵敏度和特异性。我们的数据提供了啮齿动物组织中SAFO-DNA加合物形成的第一个直接证据。SAFO120mg/kg与SAFO30mg/kg相比，肝脏中的N7γ-SAFO-G水平显着增加。提示组织DNA中N7γ-SAFO-G的快速自发或酶促脱嘌呤。尿N7γ-SAFO-G表现出亚线性剂量反应。此外，外周网织红细胞微核频率呈剂量依赖性增加，并与肝脏（r=0.8647；p<0.0001）和尿液（r=0.846；p<0.0001）中的N7γ-SAFO-G水平显着相关。我们的研究表明，黄樟素介导的遗传毒性可能部分由其对SAFO的代谢激活引起，尿N7γ-SAFO-G可能作为黄樟素暴露的化学特异性癌症风险生物标志物。
