A New Samarium(III) Complex of Liriodenine: Synthesis, Crystal Structure, Antitumor Activity, and DNA Binding Study

A novel Sm-III complex [Sm-III(LA)(2)(pic)(3)] (Hpic = picric acid), in which LA is a natural-derived alkaloid, liriodenine, was synthesized and characterized by IR, elemental analysis, and single-crystal X-ray diffraction analysis. This complex showed enhanced solubility compared with liriodenine and its metal complexes that have been previously reported. The interaction of the Sm-III complex with ct-DNA was further investigated by various spectroscopic techniques, such as UV/Vis spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy (CD), and viscosity measurement. The results showed that the intrinsic binding constant K-b of the Sm-III complex with ct-DNA was calculated to be 5.03 x 10(3) L center dot mol(-1) by UV/Vis absorption spectral analysis. The thermodynamic fluorescent spectral analysis suggested that the fluorescence intensity of the Sm-III complex was weakened by ct-DNA mainly through a dynamic quenching mechanism. The presence of Sm complex could increase the viscosity of DNA solution, so it was concluded that the complex bound with ct-DNA via a moderate intercalative mode. Furthermore, this Sm-III complex exhibited significant growth inhibition on the three typical tumor cell lines, HepG2, T-24, and SK-OV-3, with the corresponding IC50 values, 10.76 +/- 0.19, 8.85 +/- 1.12, and 10.01 +/- 0.55 mu M, respectively. The in vitro antitumor activity was comparable with LA and cisplatin, which suggested that it might be a new broad spectrum antitumor agent with more satisfying solubility.

一种新型的钐（III）配合物[Sm - III(LA)(2)(pic)(3)]（Hpic = 苦味酸）被合成出来，其中LA是一种天然来源的生物碱——鹅掌楸碱。通过红外光谱、元素分析和单晶X射线衍射分析对其进行了表征。与先前报道的鹅掌楸碱及其金属配合物相比，该配合物显示出更高的溶解性。通过多种光谱技术，如紫外 - 可见光谱、荧光光谱、圆二色光谱（CD）和黏度测量，进一步研究了钐（III）配合物与小牛胸腺DNA（ct - DNA）的相互作用。结果表明，通过紫外 - 可见吸收光谱分析计算出钐（III）配合物与ct - DNA的内在结合常数Kb为5.03×10³ L·mol⁻¹。热力学荧光光谱分析表明，ct - DNA主要通过动态猝灭机制使钐（III）配合物的荧光强度减弱。钐配合物的存在会增加DNA溶液的黏度，因此得出结论：该配合物通过一种适度的嵌入模式与ct - DNA结合。此外，这种钐（III）配合物对三种典型的肿瘤细胞系HepG2、T - 24和SK - OV - 3表现出显著的生长抑制作用，相应的半数抑制浓度（IC₅₀）值分别为10.76 ± 0.19、8.85 ± 1.12和10.01 ± 0.55 μM。其体外抗肿瘤活性与鹅掌楸碱和顺铂相当，这表明它可能是一种溶解性更令人满意的新型广谱抗肿瘤药物。