Effects of ginger and its pungent constituents on transient receptor potential channels

Ginger extract is used as an analeptic in herbal medicine and has been reported to exert antioxidant effects. Transient receptor potential (TRP) canonical 5 (TRPC5), TRP cation channel, subfamily M, member 7 (TRPM7; melastatin 7), and TRP cation channel, subfamily A, member 1 (TRPA1; ankyrin 1) are non-selective cation channels that are modulated by reactive oxygen/nitrogen species (ROS/RNS) and subsequently control various cellular processes. The aim of this study was to evaluate whether ginger and its pungent constituents modulate these channels and exert antioxidant effects. It was found that TRPC5 and TRPA1 currents were modulated by ginger extract and by its pungent constituents, [6]-gingerol, zingerone and [6]-shogaol. In particular, [6]-shogaol markedly and dose-dependently inhibited TRPC5 currents with an IC50 of value of ~18.3 μM. Furthermore, the strong dose-dependent activation of TRPA1 currents by [6]-shogaol was abolished by A-967079 (a selective TRPA1 inhibitor). However, ginger extract and its pungent constituents had no effect on TRPM7 currents. These results suggest the antioxidant effects of ginger extract and its pungent constituents are mediated through TRPC5 and TRPA1, and that [6]-shogaol is predominantly responsible for the regulation of TRPC5 and TRPA1 currents by ginger extract.