238 JOURNAL OF COSMETIC SCIENCE
(P 0.01) on day 28. The content of melanin (Figure 5D) in the experiment group was
significantly decreased on days 14, 28, and 56 (P 0.01), and there was a significant
difference (P 0.01) between the experiment group and the control group on day 56.
These results suggested that the whitening serum containing glabridin is also effective for
brightening nonmelasma areas.
VISIA-CR ANALYSIS
The visual changes of two subjects (NO.12 and NO.16) treated with the whitening serum
for different periods are observed in Figure 6. The application of whitening serum caused
a remarkable improvement of skin color for both subjects. A significantly reduced area of
skin stain and increased skin lightening were observed after day 56 treatments. At the
same time, the area of melasma in the facial skin was significantly reduced and the color
became lighter.
DISCUSSION
Melasma is a pigmentary disorder that typically appears on the face, forehead, and cheeks.
Although the effectiveness of depigmenting agents (containing hydroquinone) or chemical
peels (lactic acid, glycolic acid, ascorbic acid, etc.) was confirmed, the potential side effects
caused the rising concerns over their safety.15,16 Glabridin, as the main hydrophobic
component of the flavonoid extract, uralensis, was confirmed to prevent the formation of
melanogenesis by decreasing tyrosinase activity (IC 50: 0.43 µmol/L).17,11
In this study, the efficacy of this formula containing glabridin was evaluated in the treatment
of epidermal melasma and nonmelasma areas in Chinese women utilizing a bilateral
(split-face) model. After 56 days, the clinical experiment results show that glabridin can
effectively improve the skin glossiness and ITA value in melasma and nonmelasma areas.
Meanwhile, there are significant reductions of melasma area proportion in melasma areas
Figure 6. Images obtained by VISIA-CR.

239 IMPROVEMENT OF MELASMA WITH GLABRIDIN
and the melanin content in nonmelasma areas. However, no clear differences in the melanin
content were found between the two groups. The uneven color of melasma may contribute
to this finding, as subtle differences in the test values may not be accurately reflected in the
treatment outcome. At the same time, it was relatively difficult to remove melanin, due
to its deep location in the epidermis. It seemed that only addition of glabridin displayed
limited effects. The combination with other whitening ingredients was recommend to
achieve better whitening effects.
The skin color modulated by the transfer of melanin synthesized by melanocytes was
embedded by the melanosome to neighboring keratinocytes. The 3D reconstructed
pigmented skin model composed of human melanocytes in the basal layer of multilayered
epidermal keratinocytes was used to detect the changes of melanin content. Hence, the
distribution of melanin in the different skin layers can be well recognized by its brown-
colored pigmentation for the 3D pigmented skin model. The inhibitory effects on
melanogenesis of the whitening serum containing glabridin was also evaluated by 3D skin
model. The whitening serum effectively improved the apparent chromaticity of the melanin
model, increased the L* value, and regulated the content and distribution of melanin.
CONCLUSION
The whitening serum containing glabridin effectively improved the apparent chromaticity
of the melanin model, increased the L* value, and regulated the content and distribution
of melanin. A 56-day clinical experiment showed that glabridin effectively improved
the skin glossiness and ITA value in both melasma and nonmelasma areas. Meanwhile,
a remarkably reduced melasma area proportion and melanin content was observed in
melasma areas and nonmelasma areas, respectively. In summary, these results suggest that
a formula containing glabridin could effectively improve pigmentation in 3D skin models
and volunteers with epidermal melasma.
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding
author upon reasonable request.
ACKNOWLEDGMENTS
The study was supported by the Zhejiang Osmum Biological Co., Ltd, Huzhou, China.
CONFLICT OF INTEREST
The authors declare that they have no competing interests.
AUTHOR CONTRIBUTIONS
Gang Huo, Liping Du, and Ping Ma designed the experiments and wrote the paper. Ying
Zhou performed the experiments. Xinfen Cai analyzed the data.