8-hydroxypinoresinol-4-O-β-D-glucoside from Valeriana officinalis L. Is a Novel Kv1.5 Channel Blocker

ABSTRACT Ethnopharmacology relevance In folkloric medicine of many cultures, one of the medical uses of Valeriana officinalis Linn is to treat heart-related disease. Recently, it was shown that the ethanol extracts from V. officinalis could effectively prevent auricular fibrillation, and 8-hydroxypinoresinol-4-O-β-D-glucoside (HPG) from the extracts is one of the two active compounds showing antiarrhythmia activities. Aim of the study: The human Kv1.5 channel (hKv1.5) has potential antiarrhythmia activities, and this study arms at investigating the current blocking effects of HPG on hKv1.5 channel. Material and methods HPG was obtained from V. officinalis extracts, and hKv1.5 channels were expressed in HEK 293 cells. HPG was perfused while recording the current through hKv1.5 channels. Patch-clamp recording techniques were used to study the effects of HPG at various concentrations (10 μM, 30 μM, and 50 μM) on hKv1.5 channels. Results The present study demonstrated that HPG inhibited hKv1.5 channel current in a concentration-dependent manner; the higher the concentration, the greater is the inhibition at each depolarization potential. During washout, the channels did not full recover indicating that the un-coupling between HPG and hKv1.5 channels is a slow process. Conclusion HPG may be an effective and safe active ingredient for AF having translational potential.