Table of Contents Author Guidelines Submit a Manuscript
Evidence-Based Complementary and Alternative Medicine
Volume 2015 (2015), Article ID 853846, 9 pages
Research Article

Inhibition of Rat 5α-Reductase Activity and Testosterone-Induced Sebum Synthesis in Hamster Sebocytes by an Extract of Quercus acutissima Cortex

1Tsumura Research Laboratories, Tsumura & Co., 3586 Yoshiwara, Ami-machi, Inashiki-gun, Ibaraki 300-1192, Japan
2Kampo Formulations Development Center, Tsumura & Co., 3586 Yoshiwara, Ami-machi, Inashiki-gun, Ibaraki 300-1192, Japan

Received 29 November 2014; Accepted 6 January 2015

Academic Editor: Alfredo Vannacci

Copyright © 2015 Junichi Koseki et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Objective. Bokusoku (BK) is an extract from the Quercus cortex used in folk medicine for treatment of skin disorders and convergence, and is present in jumihaidokuto, a traditional Japanese medicine that is prescribed for purulent skin diseases like acne vulgaris. The excess of sebum production induced by androgen is involved in the development of acne. Our aim is to examine whether BK and its constituents inhibit testosterone metabolism and testosterone-induced sebum synthesis. Methods. Measurements of 5α-reductase activity and lipogenesis were performed using rat liver microsomes and hamster sebocytes, respectively. Results. BK dose-dependently reduced the conversion of testosterone to a more active androgen, dihydrotestosterone in a 5α-reductase enzymatic reaction. Twenty polyphenols in BK categorized as gallotannin, ellagitannin, and flavonoid were identified by LC-MS/MS. Nine polyphenols with gallate group, tetragalloyl glucose, pentagalloyl glucose, eugeniin, 1-desgalloyl eugeniin, casuarinin, castalagin, stenophyllanin C, (−)-epicatechin gallate, and (−)-epigallocatechin gallate, inhibited testosterone metabolism. In particular, pentagalloyl glucose showed the strongest activity. BK and pentagalloyl glucose suppressed testosterone-induced lipogenesis, whereas they weakly inhibited the lipogenic action of insulin. Conclusions. BK inhibited androgen-related pathogenesis of acne, testosterone conversion, and sebum synthesis, partially through 5α-reductase inhibition, and has potential to be a useful agent in the therapeutic strategy of acne.