Safrole is a natural product present in many plants and plant products, including spices and essential oils. During cellular metabolism, it converts to a highly reactive trans-isosafrole (SF) intermediate that reacts with genomic DNA and forms N²-SF-dG and N⁶-SF-dA DNA adducts, which are detected in the oral tissue of cancer patients with betel quid chewing history. To study the SF-induced carcinogenesis and to probe the role of low fidelity translesion synthesis (TLS) polymerases in bypassing SF adducts, herein, we report the synthesis of N²-SF-dG modified DNAs using phosphoramidite chemistry. The N²-SF-dG modification in the duplex DNA does not affect the thermal stability and retains the B-form of helical conformation, indicating that this adduct may escape the radar of common DNA repair mechanisms. Primer extension studies showed that the N²-SF-dG adduct is bypassed by human TLS polymerases hpolκ and hpolη, which perform error-free replication across this adduct. Furthermore, molecular modeling and dynamics studies revealed that the adduct reorients to pair with the incoming nucleotide, thus allowing the effective bypass. Overall, the results indicate that hpolκ and hpolη do not distinguish the N²-SF-dG adduct, suggesting that they may not be involved in the safrole-induced carcinogenicity.

中文翻译：

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带有 DNA 的 N2-反式-异黄樟素-dG 加合物的合成以及使用人 TLS 聚合酶 κ 和 η 的旁路研究

黄樟素是一种天然产物，存在于许多植物和植物产品中，包括香料和精油。在细胞代谢过程中，它转化为高反应性反式异黄樟素 (SF) 中间体，与基因组 DNA 发生反应，形成N ² -SF-dG 和N ⁶ -SF-dA DNA 加合物，可在癌症患者的口腔组织中检测到有咀嚼槟榔的历史。为了研究 SF 诱导的致癌作用并探讨低保真跨损伤合成 (TLS) 聚合酶在绕过 SF 加合物中的作用，本文报告了使用亚磷酰胺化学合成N ² -SF-dG 修饰的 DNA。双链体DNA中的N ^{2 -SF-dG修饰不影响热稳定性并保留了螺旋构}象的B型，表明该加合物可能逃脱了常见DNA修复机制的雷达。引物延伸研究表明，N ² -SF-dG 加合物被人 TLS 聚合酶 hpolκ 和 hpolη 绕过，它们在该加合物上进行无差错复制。此外，分子模型和动力学研究表明，加合物重新定向以与传入的核苷酸配对，从而实现有效的旁路。总体而言，结果表明hpolκ和hpolη不能区分N ² -SF-dG加合物，表明它们可能不参与黄樟素诱导的致癌性。