The strong hemolytic toxicity of pulsatilla saponin D (1, HD₅₀ 6.3 μM) has hampered its clinical development as an injectable anticancer agent. To combat this challenge, 17 new derivatives of 1 with ring C, C-28, or C-3 modifications were synthesized and evaluated for cytotoxicity against several selected human tumor lines, as well as for hemolytic toxicity against rabbit erythrocytes. Structure–activity relationship (SAR) and structure–toxicity relationship (STR) correlations were also elucidated. Compared to the lead compound 1, the hemolytic activity of all 17 derivatives dropped dramatically. Notably, compound 14 exhibited significant cytotoxicity toward A549 human lung cancer cells (IC₅₀ 2.8 μM) in a dose-dependent manner without hemolytic toxicity (HD₅₀ > 500 μM). Molecular studies indicated that 14 induced typical G₁ cell cycle arrest and apoptosis in A549 cells, and Western blot assays suggested that both intrinsic and extrinsic apoptosis pathways were activated by 14. Collectively, compound 14 may merit further development as a potential anti-lung cancer agent.

中文翻译：

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白头翁皂苷D及其合成衍生物的细胞毒性、溶血毒性及作用机制

白头翁皂苷D ( 1 , HD ₅₀ 6.3 μM)的强溶血毒性阻碍了其作为注射抗癌药物的临床开发。为了应对这一挑战，合成了 17 种带有 C、C-28 或 C-3 环修饰的 1 新衍生物，并评估了其针对几种选定的人类肿瘤系的细胞毒性，以及针对兔红细胞的溶血毒性。还阐明了结构-活性关系（SAR）和结构-毒性关系（STR）相关性。与先导化合物1相比，所有17种衍生物的溶血活性均急剧下降。值得注意的是，化合物14以剂量依赖性方式对A549人肺癌细胞表现出显着的细胞毒性(IC _{50 2.8 μM)，且没有溶血毒性(HD 50} > 500 μM)。分子研究表明14诱导 A549 细胞中典型的 G _{1细胞周期停滞和细胞凋亡，Western blot 分析表明}14激活了内在和外在的细胞凋亡途径。总的来说，化合物14作为潜在的抗肺癌药物值得进一步开发。