title: Effects of Tannic Acid, Green Tea and Red Wine on hERG Channels Expressed in HEK293 Cells.
abstract: Tannic acid presents in varying concentrations in plant foods, and in relatively high concentrations in green teas and red wines. Human ether-à-go-go-related gene (hERG) channels expressed in multiple tissues (e.g. heart, neurons, smooth muscle and cancer cells), and play important roles in modulating cardiac action potential repolarization and tumor cell biology. The present study investigated the effects of tannic acid, green teas and red wines on hERG currents. The effects of tannic acid, teas and red wines on hERG currents stably transfected in HEK293 cells were studied with a perforated patch clamp technique. In this study, we demonstrated that tannic acid inhibited hERG currents with an IC50 of 3.4 μM and ~100% inhibition at higher concentrations, and significantly shifted the voltage dependent activation to more positive potentials (Δ23.2 mV). Remarkably, a 100-fold dilution of multiple types of tea (green tea, oolong tea and black tea) or red wine inhibited hERG currents by ~90%, and significantly shifted the voltage dependent activation to more positive potentials (Δ30.8 mV and Δ26.0 mV, respectively). Green tea Lung Ching and red wine inhibited hERG currents, with IC50 of 0.04% and 0.19%, respectively. The effects of tannic acid, teas and red wine on hERG currents were irreversible. These results suggest tannic acid is a novel hERG channel blocker and consequently provide a new mechanistic evidence for understanding the effects of tannic acid. They also revealed the potential pharmacological basis of tea- and red wine-induced biology activities.
authors.affiliation: Department of Pharmacy, The Fourth Hospital of Hebei Medical University, Shijiazhuang, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Chu
authors.affiliation: Department of Orthopaedic Trauma Dept. 2, The Third Hospital of Shijiazhuang, Shijiazhuang, China.
authors.forename: Yusong
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Department of Biochemistry, Hebei University of Chinese Medicine, Shijiazhuang, China.
authors.forename: Bingyuan
authors.initials: B
authors.lastname: Xu
authors.affiliation: Department of Physiology, Hebei University of Chinese Medicine, Shijiazhuang, China.
authors.forename: Wenya
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, China.
authors.forename: Xiaorun
authors.initials: X
authors.lastname: Sun
authors.affiliation: Arrhythmia Center, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Ding
authors.affiliation: Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000037:antagonists & inhibitors*; D057809:HEK293 Cells; D006801:Humans; D018408:Patch-Clamp Techniques; D013634:Tannins / Q000494:pharmacology*; D013662:Tea / Q000737:chemistry; D014920:Wine
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; D013634:Tannins; D013662:Tea