Nuciferine analogs block voltage-gated sodium, calcium and potassium channels to regulate the action potential and treat arrhythmia.

ABSTRACT

Dysfunction of the Nav1.5, Cav1.2, and Kv channels could interfere with the AP and result in arrhythmias and even heart failure. We herein present a novel library of nuciferine analogs that target ion channels for the treatment of arrhythmias. Patch clamp measurements of ventricular myocytes revealed that 6a dramatically blocked both the INa and ICa without altering the currentvoltage relationship (including the activation potential and peak potential), accelerated the inactivation of Nav and Cav channels and delayed the resurrection of these channels after inactivation. Additionally, 6a significantly decreased the APA and RMP without affecting the APD30 or APD50. The IC50 values of 6a against Nav1.5 and Cav1.2 were 4.98 µM and 4.62 µM, respectively. Furthermore, 6a (10 µM) blocked IKs, IK1, and Ito with values of 17.01 %±2.54 %, 9.09 %±2.78 %, and 11.15 %±3.52 %, respectively. Surprisingly, 6a weakly inhibited hERG channels, suggesting a low risk of proarrhythmia. The cytotoxicity evaluation of 6a with the H9c2 cell line indicated that this compound was noncytotoxic. In vivo studies suggested that these novel nuciferine analogs could shorten the time of arrhythmia continuum induced by BaCl2 and normalize the HR, QRS, QT and QTc interval and the R wave amplitude. Moreover, 6a dose-dependently affected aconitine-induced arrhythmias and notably improved the cumulative dosage of aconitine required to evoke VP, VT, VF and CA in rats with aconitine-induced arrhythmia. In conclusion, nuciferine analogs could be promising ion channel blockers that could be further developed into antiarrhythmic agents.