Pungent qualities of sanshool-related compounds evaluated by a sensory test and activation of rat TRPV1.

The detection threshold and taste characteristics of sanshools were examined by sensory evaluation, after isolating four sanshools (alpha-, beta-, gamma-, and delta-), and two hydroxy sanshools (alpha- and beta-) from the pericarp of Japanese pepper. The Scoville unit (SU) values of the four sanshools were in the range of 80,000-110,000, while those of hydroxy sanshools were 3-5 fold lower than corresponding sanshools. The pungent qualities of each sanshool were different. Burning and tingling were predominantly perceived and lasted for the longest time with alpha-sanshool. Burning and fresh for gamma-sanshool, and tingling and numbing for hydroxy alpha-sanshool were perceived. Tests on the activation of rat TRPV1 were also performed. All of them were weak agonists. Among them, gamma-sanshool was the most potent agonist, although its EC50 value of 5.3 microM was 230 fold higher than that of capsaicin. These results indicate that it would be difficult to explain the pungent quality of each sanshool simply in terms of TRPV1 activation.