Figure 6

1,8-cineole inhibits but does not activate hTRPA1-mediated currents in HEK293T cells. (A) A representative AITC (20 μM)-evoked hTRPA1 current that was inhibited by 1,8-cineole in a dose-dependent manner in the absence of extracellular Ca²⁺. (B) Dose-dependent inhibition of AITC (20 μM)-evoked hTRPA1 current by 1,8-cineole. IC₅₀ and Hill’s coefficient values are 3.4 ± 0.6 mM and 1.7 ± 0.4, respectively. Data are shown as the mean ± SEM (n = 5–8). (C) A representative whole-cell menthol (500 μM)-evoked hTRPA1 current that was inhibited by 1,8-cineole (5 mM) in the absence of extracellular Ca²⁺. (D) Dose-dependent inhibition of menthol (500 μM)-evoked hTRPA1 current by 1,8-cineole. IC₅₀ and Hill’s coefficient values are 0.5 ± 0.1 mM and 1.0 ± 0.2, respectively. Data are shown as the mean ± SEM (n = 5–8). (E) A representative whole-cell FFA (100 μM)-evoked hTRPA1 current that was inhibited by 1,8-cineole (5 mM) in the absence of extracellular Ca²⁺. (F) Dose-dependent inhibition of FFA (100 μM)-evoked hTRPA1 current by 1,8-cineole. IC₅₀ and Hill’s coefficient values are 5.3 ± 0.1 mM and 2.4 ± 0.8, respectively. Data are shown as the mean ± SEM (n = 6–8). (G) A representative whole-cell octanol (1 mM)-evoked hTRPA1 current that was inhibited by 1,8-cineole (5 mM) in the presence of extracellular Ca²⁺. (H) 1,8-cineole did not inhibit hTRPV1 (n = 25), hTRPV2 (n = 50) or hTRPV3 (n = 32 responses) by capsaicin, 2-APB or cocktail (2-APB + carvacrol), respectively.