黄連解毒湯の苦味に対する構成生薬の影響

抄録

Orengedokuto (OGT) is a Kampo prescription characterized by a strong bitter taste, consisting of Coptidis Rhizoma (CR), Phellodendori Cortex (PC), Scutellariae Radix (SR), and Gardeniae Fructus (GF). OGT is a multicomponent drug and one of the constituents contained is the alkaloid berberine, which is widely recognized for its bitter taste. Berberine is known to bond with baicalin, one of the constituents of SR, in the decoction to form a precipitate. However, the extent to which this precipitation is responsible for the bitter taste of OGT is unknown. In this study, we quantitatively evaluated the bitter taste of OGT extracts utilizing a taste-sensing system that can objectively measure taste intensity and investigated the effects of the constituents of OGT on bitter taste.

Eight samples (OGT, CR, PC, SR, GF, CR + SR, PC + SR, and OGT without SR (OGT－SR)) were tested, and the content of free berberine in each extract was then determined. The response values to the bitter taste sensor were OGT－SR >> CR ≥ PC > OGT > CR + SR and PC + SR, in agreement with the previous reports. A strong positive correlation was observed between the response value of each sample to the bitter taste sensor and the content of free berberine. Therefore, when decocted with SR, the berberine-baicalin complex formed and precipitated, reducing the bitter taste values attributed to berberine as detected by the taste-sensing system.

This study quantitatively evaluated the bitter taste of OGTs and objectively validated the results of human sensory tests.