The bark of Prunus jamasakura Siebold (Pruni Cortex) has long been used in Japan as a folk remedy and is one of ingredients of the Kampo formula, Jumi-haidoku-to (JHT). JHT is used for treatment of skin diseases such as acne (acne vulgaris). According to Kampo medicinal sources, Quercus Cortex can be used in place of Pruni Cortex. In this study, we found that water extracts of Pruni Cortex, not Quercus Cortex showed a binding effect on estrogen receptor β (ERβ). Thus, their chemical analysis was carried out by GC-MS and found that five unique constituents (i.e., sakuranetin, naringenin, genistein, genkwanin and arctigenin) were detected in Pruni Cortex. The ERβ binding capacity of these constituents was examined using 70 ng/ml 17β-estradiol, as the positive control with 100% ERβ binding. Among them, genistein (60% at 10 ng/ml) showed the strongest binding capacity than naringenin (60% at 1000 ng/ml) and sakuranetin (40% at 1000 ng/ml). These results suggested that Pruni Cortex in JHT could play an important role in treatment of acne. In addition, those of Pruni Cortex from different harvest places were also examined in their chemical contents and ERβ binding capacity. The extracts of Pruni Cortex from Kyushu in Japan and Anhui Province in China showed higher contents of genistein and stronger ERβ binding capacity than that of Pruni Cortex from Tokushima Prefecture in Japan.
