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.

黄樟素氧化物 (SAFO) 是天然存在的肝癌黄樟素的代谢产物，与 DNA 加合物的形成有关。我们之前的研究首先使用孔在小鼠尿液中检测到最丰富的 SAFO 诱导的 DNA 加合物 N7-(3-苯并[1,3]二氧杂环戊醇-5-基-2-羟丙基)鸟嘌呤 (N7γ-SAFO-G) -开发了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。这项研究进一步阐明了 SAFO 在用 SAFO 30、60、90 或 120 mg/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 处理小鼠的肝脏和尿液中检测 N7γ-SAFO-G，具有出色的敏感性和特异性。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。与 SAFO 30 mg/kg 相比，SAFO 120 mg/kg 显着增加肝脏中的 N7γ-SAFO-G 水平，表明组织 DNA 中 N7γ-SAFO-G 快速自发或酶促脱嘌呤。尿液 N7γ-SAFO-G 表现出亚线性剂量反应。此外，微核外周网织红细胞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是由其对 SAFO 的代谢激活引起的，并且尿液 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。