The ruthenium-based anticancer agent NAMI-A (ImH[trans-RuCl₄(dmso)(Im)], where Im = imidazole) has been shown to interact with RNA in vivo and in vitro. We hypothesized that the similarly structured drug KP1019 (IndH[trans-RuCl₄(Ind)₂], where Ind = indazole) binds to RNA as well. Fluorescence spectroscopy was employed to assay the interactions between either NAMI-A or KP1019 and tRNA^Phe through an intrinsic fluorophore wybutosine (Y) base and by extrinsic displacement of the intercalating agent ethidium bromide. In both the intrinsic Y-base and extrinsic ethidium bromide studies, KP1019 exhibited tighter binding to phenylalanine-specific tRNA (tRNA^Phe) than NAMI-A. In the ethidium bromide study, reducing both drugs from Ru^III to Ru^II resulted in a significant decrease in binding. Our findings suggest that the relatively large heteroaromatic indazole ligands of KP1019 intercalate in the π-stacks of tRNA^Phe within structurally complex binding pockets. In addition, NAMI-A appears to be sensitive to destabilizing electrostatic interactions with the negative phosphate backbone of tRNA^Phe. Interactions with additional tRNA molecules and other types of RNA require further evaluation to determine the role of RNA in the mechanisms of action for KP1019 and to better understand how Ru drugs fundamentally interact with biomolecules that are more structurally sophisticated than short DNA oligonucleotides. To the best of our knowledge, this is the first study to report KP1019 binding interactions with RNA.

钌基抗癌剂NAMI-A（ImH [反式RuCl ₄（dmso）（Im）]，其中Im =咪唑）已显示在体​​内和体外与RNA相互作用。我们假设类似结构的药物KP1019（IndH [反式RuCl ₄（Ind）₂ ]，其中Ind =吲唑）也与RNA结合。荧光光谱法用于通过固有的荧光基团wybutosine（Y）碱基和非固有置换嵌入剂溴化乙锭来测定NAMI-A或KP1019与tRNA ^Phe之间的相互作用。在固有的Y碱基和外在的溴化乙锭研究中，KP1019都表现出与苯丙氨酸特异性tRNA（tRNA ^Phe）比NAMI-A。在溴化乙锭研究中，将两种药物从Ru ^III还原为Ru ^II都会导致结合力显着降低。我们的发现表明，KP1019的相对较大的杂芳族吲唑配体嵌入结构复杂的结合口袋中的tRNA ^Phe的π堆栈中。另外，NAMI-A似乎对破坏与tRNA ^Phe的负磷酸盐主链的静电相互作用具有敏感性。。与其他tRNA分子和其他类型RNA的相互作用需要进一步评估，以确定RNA在KP1019的作用机制中的作用，并更好地了解Ru药物如何从根本上与比短DNA寡核苷酸结构更复杂的生物分子相互作用。据我们所知，这是第一个报告KP1019与RNA结合相互作用的研究。