Synthesis, G-Quadruplex DNA binding and cytotoxic properties of naphthalimide substituted styryl dyes

G-Quadruplex DNAs, formed by G-rich DNA sequences in human genes, are promising targets for design of cancer drugs. In this study, two naphthalimide substituted styryl dyes with different sizes of aromatic groups were synthesized. The spectral analysis showed that the dye X-2 with a large aromatic group formed aggregates in buffer solution displaying very weak fluorescence intensity, and disaggregated in the presence of G-Quadruplex DNAs with large intensity enhancements (up to similar to 1800 fold). Moreover, X-2 displayed good selectivity to G-Quadruplex DNAs. In contrast, dye X-3 with the smaller aromatic group had much lower fluorescence enhancements and poor selectivity to G-Quadruplex DNAs, suggesting that the suitably sized aromatic ring was essential for the interaction with G-Quadruplex. Further binding studies suggested that X-2 mainly bound on G-quartet surface through end-stacking mode. Cytotoxicity assay showed that both of the two dyes showed good anti-proliferative activities against the cancer cell lines and less cytotoxicity in non-malignant cell lines, which were better than a standard drug 5-fluorouracil. In addition, living cell imaging was also studied and demonstrated the potential applications of the new dye X-2 in bioassays and cell imaging.

由人类基因中富含鸟嘌呤（G）的DNA序列形成的G - 四链体DNA是癌症药物设计的有前景的靶点。在本研究中，合成了两种具有不同大小芳香基团的萘酰亚胺取代的苯乙烯基染料。光谱分析表明，具有大芳香基团的染料X - 2在缓冲溶液中形成聚集体，荧光强度非常弱，而在G - 四链体DNA存在时解聚，荧光强度大幅增强（高达约1800倍）。此外，X - 2对G - 四链体DNA显示出良好的选择性。相比之下，具有较小芳香基团的染料X - 3荧光增强低得多，且对G - 四链体DNA选择性差，这表明大小合适的芳香环对于与G - 四链体的相互作用至关重要。进一步的结合研究表明，X - 2主要通过末端堆积模式结合在G - 四分体表面。细胞毒性测定显示，这两种染料对癌细胞系均显示出良好的抗增殖活性，对非恶性细胞系的细胞毒性较小，优于标准药物5 - 氟尿嘧啶。此外，还研究了活细胞成像，证明了新型染料X - 2在生物测定和细胞成像中的潜在应用。