TITLE:
Depigmentory Effects of Keishibukuryogankayokuinin in Human Epidermal Melanocytes
AUTHORS:
Kaho Akimoto, Takuji Yamaguchi, Yuna Naraoka, Ailing Hu, Hiroyuki Kobayashi
KEYWORDS:
Keishibukuryogankayokuinin, Coix Seed, UVB, Tyrosinase, Melanocytes
JOURNAL NAME:
Health,
Vol.11 No.7,
July
11,
2019
ABSTRACT: Keishibukuryogankayokuinin (KBY) is a traditional
Japanese herbal medicine widely used to treat skin pigmentation. The scientific
basis for its use is, however, unclear, and studies evaluating its mechanism
and effectiveness are sparse. In this study, we compared the tyrosinase inhibitory
effects of KBY and Keishibukuryogan (KB, which has the same composition of KBY,
except Coix Seed [CS]) and CS under exposure to UV radiation as well as under
non-exposure conditions. Neonatal human epidermal melanocytes obtained from a
darkly pigmented donor were used. These cells were cultured in a final
concentration of 500 μg/ml or 1000 μg/ml, to which KBY, KB, and CS were added.
After incubation for 72 h, cells were stained with Fontana-Masson stain and
counted. Tyrosinase activity was measured by its dopa oxidase activity, and
tyrosinase expression was estimated using real-time PCR. For UV radiation,
cells were exposed to UVB radiation for 90 s per day for 3 days. Under
non-exposure conditions, tyrosinase activity significantly increased with both
KBY and KB but significantly decreased with CS, regardless of the concentration.
In addition, tyrosinase expression significantly decreased but only with KBY at
both concentrations. Under UV radiation exposure, tyrosinase activity
significantly increased with KBY and KB at both concentrations while tyrosinase
expression significantly decreased with KBY and KB; a significant increase was,
however, observed with CS at both concentrations. These results suggest that
taking KBY after sunburn is effective against skin pigmentation, and the
combination of KB and CS is useful for skin depigmentation.