Personal Care March 2012

SKIN WHITENING colour space called CIE L* a* b* . This three-

dimensional method estimates the skin lightening or, conversely, darkening via the luminosity, the hue and the saturation. Those two last parameters are characterised by chromatic axis such as the red-green axis and the yellow-blue axis, respectively for a*

and for b*

they have developed a connection which combines the coordinates L*

. Afterwards, and a*

and

describes at best the lightening effect: the ITA˚ (Individual Typological Angle). The parameter enables the standardisation of the pigmentation and the development of the classifications called phototypes. Degrees determine the frontiers between each skin category: radiant, luminous, intermediate and matte (Fig. 8). In the study, the measurements of L*

and ITA˚ are considered to evaluate the lightening power of the fruit active. Results are gathered from the chromameter CR- 300 and are expressed with L*

a* b* to be

transposed into chromatic values, basis to calculate the ITA˚ angle (pigmentation degree). This colorimetric method highlights the

significant efficacy of the lightening fruit active ingredient formula (at 4%) regarding luminance and brightening at 28 and 56 days, whereas the placebo formula only showed a slight increase after 56 days. Indeed, at 28 days the analysis shows an enhancement of both parameters (L*

:+0.9 % and ITA˚:+4.6%) confirmed

after 56 days of single daily application (L*

:+1.4% and ITA˚:+4.7%) of the active formula. Overall, we notice a significant

improvement of the skin luminance and pigmentation degree compared to the placebo (Fig. 9).

Conclusion The pigmentary aspect of skin and its tone can be distinct between two persons but even also for one person depending on the studied areas. This topic is covered more and more frequently so as to better understand the mechanisms and all the interactions existing within the skin. At the same time, studies in the cosmetic industry have indicated the importance of natural ingredients (as opposed to chemically synthesised) derived from plants and fruits. Known for its exfoliating action, lactic

*

Melan’oWhite at 4% +1% solution

Kojic acid at 4% +250 µM solution

Placebo

Significant: (Student t-test; p<0.05)

85 90 Figure 7: Significant inhibition of melanin synthesis against placebo.

acid plays a major role in cellular renewal and in keratinocyte desquamation and it is assumed that exfoliating helps to have a lighter skin and a more even complexion. Indeed, this component accelerates the transit of epidermis epithelial cells, where the majority of melanin is located as mentioned in the introduction. Lactic acid also has the ability to inhibit tyrosinase during the synthesis into dopaquinone, independently from its acid nature. The phenomenon is confirmed by a report4 whose study shows that the acid directly acts on the enzyme but also on the tyrosinase gene expression without being cytotoxic to cells. At the same time, a recent report has

shown a synergetic activity coupled with ascorbic acid5

and inducing a skin

lightening effect together with an improvement of skin texture and luminosity. Those effects are proved in ID bio’s studies

Table 3: Skin pigmentation degrees. ITA˚ >55

Radiant

55 ≥ITA˚ >41 41 ≥ITA˚ >28 28 ≥ITA˚ >10

Table 4: Comparison of Melan’oWhite in vivo action against placebo. ITA˚ (pigmentation degree) J+28

L* J+56

Melan’oWhite Placebo

+4.6 %* –1.3 %

*Significant: (Student t-test; p <0.01) 60 PERSONAL CARE March 2012

+6.7 %* +1.2 %

J+28

+0.9 %* –0.2 %

Luminous

Intermediate Matte

and are clinically and statistically significant, as shown by the melanin assays in the monolayer and RHTE models. Thus, fruits are rich in active components and Melan’oWhite, derived from mango, directly acts on skin pigmentary disorder. Thanks to its natural content in lactic and ascorbic acid, this ingredient brings an efficient solution to uneven complexions that need to be lightened.

PC

References 1 Gillbro JM, Olsson MJ. The melanogenesis and mechanisms of skin-lightening agents – existing and new approaches. Int J Cosmet Sci 2011; 33: 210-21.

2 Yamamoto Y, Uede K, Yonei N, Kishioka A, Htani T, Furukawa F. Effects of alpha-hydroxy acids on the human skin of Japanese subjects: The rationale for chemical peeling. J Dermatol 2006; 1: 16-22.

3 Usuki A, Ohashi A, Sato H, Ochiai Y, Ichihashi M, Funasaka Y. The inhibitory effect of glycolic acid and lactic acid on melanin synthesis in melanoma cells. Exp Dermatol 2003; 12 (Suppl 2): 43-50.

4 Ando S, Ando O, Suemoto Y, Mishima Y. Tyrosinase gene transcription and its control by melanogenic inhibitors. The Society for Investigative Dermatology 1993; 100 (2): 150-5S.

(luminance) J+56

+1.4 %* +0.3 %

5 Smith WP. The effects of topical L(+) lactic acid and ascorbic acid on skin whitening. Int J Cosmet Sci 1999; 21: 33-40.

6 Hsiao YP, Huang HL, Lai WW, Chung JG, Yang JH. Antiproliferative effects of lactic acid via the induction of apoptosis and cell cycle arrest in a human keratinocyte cell line (HaCaT). J Dermatol Sci 2009; 54: 175-84.

95 Melanin content (%) 100 –13%*

Figure 5: Phototype VI of a human skin epidermis (left). Figure 6: Reconstructed epidermis – non-melanised, phototype II, IV and VI.

–5%

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