Searching for synergistic calcium antagonists and novel therapeutic regimens for coronary heart disease therapy from a Traditional Chinese Medicine, Suxiao Jiuxin Pill.

Coronary heart disease is a vital cause of morbidity and mortality worldwide, and calcium channel blockers (CCBs) are important drugs that can be used to treat cardiovascular diseases. Suxiao Jiuxin Pill (SX), a traditional Chinese medicine, is widely used as an emergency drug for coronary heart disease therapy. However, understanding its potential mechanism in intracellular calcium concentration ([Ca2+]i) modulation remains a challenge. To identify the active pharmacological ingredients (APIs) and reveal a novel combination therapy for ameliorating cardiovascular diseases, the ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) combined with a dual-luciferase reporter [Ca2+]i assay system was applied. Ligustrazine, ferulic acid, senkyunolide I, senkyunolide A and ligustilide were identified as potential calcium antagonists in SX, and the combination of ligustrazine and senkyunolide A showed synergetic calcium antagonistic activity. Additionally, the synergetic mechanism was further investigated by live-imaging analysis with the Ca2+ indicator fluo-4/AM by monitoring fluorescence changes. Our results indicated that ligustrazine can block voltage-operated Ca2+ channels (VDCCs) effectively and senkyunolide A can exert an inhibition effect mostly on ryanodine receptors (RYRs) and partly on VDCCs. Finally, an arterial ring assay showed that the combination of ligustrazine and senkyunolide A exerted a better vasodilatation function than using any components alone. In this study, we first revealed that a pair of natural APIs in combination acting on VDCCs and RYRs was more effective on vasodilatation by regulating [Ca2+]i.