32 SUN CARE Epidermis Basement membrane Dermis Type IV collagen Control 2% ascorbyl glucoside
0.5 0
Control
2% Ascorbyl glucoside
Figure 6: Type IV collagen expression and deposition in a 3D skin model treated, or not treated, with ascorbyl glucoside. A) Immunostaining images of type IV collagen. B) Protein expression level of type IV collagen relative to control. N=1
40 mJ/cm2 UVB radiation, and cultured for an
additional 24 hours without ascorbyl glucoside. The mRNA and protein expression of type IV collagen and MMP-9 were measured. Irradiation by UVB decreased expression
of type IV collagen, and increased the level of MMP-9. However, pre-treatment with ascorbyl glucoside suppressed the effects of UVB; increased expression of type IV collagen and decreased expression of MMP-9 were observed both in mRNA and protein (Figure 7). This study suggests that ascorbyl glucoside
inhibits not only the decreased expression of collagen but also its degradation, which prevents UV-induced damage to the BM that leads to the signs of photoageing.
A 1.5 1 * 0.5 0
Control -UVA
Lightening the colour of age spots In addition to wrinkling and sagging, age spots are also a major sign of photoageing. Many brightening ingredients to treat age spots target the epidermis, specifically keratinocytes, melanocytes, and melanin itself. Recent studies have shown that the BM and dermis situated beneath the epidermis are also important factors in the development of age spots. One report revealed the fragility of the BM and dermal ECM in the area of age spots, which suggests that these structural alternations cause a delay of skin turnover, leading to an accumulation of melanin that accelerates the development of age spots.13 Since it is considered that chronic UV
B 0 + UVB 5
0.8 0.6 0.4 0.2 0
ascorbyl glucoside (mmoI/L
Control -UVA
damage causes structural deterioration of the BM and dermal ECM, the suppression of UV- induced damage to the BM and ECM is a key factor in the treatment of age spots, as well as the approach of targeting the epidermis. It is known that ascorbyl glucoside inhibits
melanin production, and has a reductive effect on existing melanin.3
In the tests mentioned
above, we showed that ascorbyl glucoside has positive effects on the BM and ECM. Hence, it was conjectured that ascorbyl glucoside could improve age spots through a multiple approach targeting the epidermis, BM and dermis. To confirm the effect on age spots, a
randomized double-blind, pre-clinical study was carried out. In this study, Japanese female subjects (37 - 55 years, mean age 47.3 ± 4.8) with age spots were screened, and a dermatologist selected age spots (one spot per subject) for evaluation. The subjects applied a toner containing 2% ascorbyl glucoside or a placebo toner to the entire face twice a day for four weeks. The lightness score was determined by the
0 + UVB 5
ascorbyl glucoside (mmoI/L
dermatologist performing a visual evaluation of spots using a Japan Colour Research Institute lightness scale of skin tone colours, before and after application. In this visual evaluation, an increase of lightness score indicated a lighter colour of age spots. The change in lightness was calculated
C
25 20 15 10 5 0
Control -UVA
# D 0.6 0.4 0.2 0 + UVB 5 0
ascorbyl glucoside (mmoI/L
Control -UVA
from the score before and after four weeks of application, and statistical analysis was performed. A further, stratified analysis was performed by dividing the subjects into two groups based on their initial scores: a group with lighter coloured spots, and another group with darker coloured spots. It was found that the ascorbyl glucoside
0 + UVB 5
ascorbyl glucoside (mmoI/L
Figure 7: Type IV collagen and MMP-9 expression in UVB-irradiated NHEK pre-treated, or not pre-treated, with ascorbyl glucoside. A, C) mRNA expression level (βactin: Endogenous Control ). N=3-4, Mean + SD, *p<0.05, #p<0.1 (Unpaired t-test) B, D) Protein expression level (standardized byβ actin expression ) N=1
PERSONAL CARE April 2025
application tended to increase the amount of change in lightness compared to the placebo (Figure 8A). As a result of the stratified analysis, in the group with lighter spots, no significant difference was observed between treatment with ascorbyl glucoside or placebo (Figure 8B). On the other hand, in the darker group, treatment with ascorbyl glucoside significantly enhanced the increase in lightness compared to placebo, showing improvement of age spots (Figure 8C). Therefore, ascorbyl glucoside is considered
to be effective to make darker age spots appear less visible.
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1.5 1
MMP-9 mRNA expression level
Type IV collagen mRNA expression level
MMP-9 expression level
Type IV collagen expression level
Type IV collagen expression level relative to control
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