Study of sunless tanning formulas using molted snake skin as an alternative membrane model

Abstract

Sunless tanning formulas have become increasingly popular in recent years for their ability to give people convincing tans without the dangers of skin cancer. Most sunless tanners currently on the market contain dihydroxyacetone (DHA), a keto sugar with three carbons. The temporary pigment provided by these formulas is designed to resemble a UV-induced tan. This study evaluated the effectiveness of carbomer gels and cold process self emulsifying bases on skin pigmentation, using different concentrations of a chemical system composed of DHA and N-acetyl tyrosine, which are found in moulted snake skins and their effectiveness was tested by Mexameter(®) MX 18. Eight different sunless tanning formulas were developed, four of which were gels and four of which were emulsions (base, base plus 4.0%, 5.0% and 6.0% (w/w) of a system of DHA and N-acetyl tyrosine). Tests to determine the extent of artificial tanning were done by applying 30 mg cm(-2) of each formula onto standard sizes of moulted snake skin (2.0 cm × 3.0 cm). A Mexameter(®) MX 18 was used to evaluate the extent of coloration in the moulted snake skin at T(0) (before the application) and after 24, 48, 72, 168, 192 and 216 h. The moulted snake skins can be used as an alternative membrane model for in vitro sunless tanning efficacy tests due to their similarity to the human stratum corneum. The DHA concentration was found to influence the initiation of the pigmentation in both sunless tanning systems (emulsion and gel) as well as the time required to increases by a given amount on the tanning index. In the emulsion system, the DHA concentration also influenced the final value on the tanning index. The type of system (emulsion or gel) has no influence on the final value in the tanning index after 216 h for samples with the same DHA concentration.

Formulation of rhamnolipid‐containing cosmetics without sulfate surfactants: A rheology and stability study

“…This article also explored the applicability of rhamnolipids in formulation of the moisturizing creams which is usually composed of solid (SA)/liquid (SL) oils. With the further use of the Carbopol thickener CBM940 for gel (Balogh et al, 2011; Ganesan et al, 2023), the rhamnolipid‐containing creams were created as Table 3. As shown in Figure 6a, with the decrease of SA/SL ratios in creams of F1‐F3 from 10:0, 8:2, to 5:5, the viscosity of the cream decreased with the increase of shear rate, presenting a typical shear‐thinning behavior of cream (Xiao et al, 2021), while the decrease of the zero‐shear viscosity was due to the reduction of solid fats.…”

Effect of Simultaneous Administration of Dihydroxyacetone on the Diffusion of Lawsone Through Various In Vitro Skin Models

“…This was accomplished using a system consisting only of the active ingredients, lawsone and DHA, applied as a mixture created at the time of application in vitro through the use of the porcine and shed snake skin models. These models have been well documented for their correlation to human systems (6,(26)(27)(28)(29)(30)(31)(32)(33)(34) and are abundantly available. The shed snake skin model was chosen for these studies in our lab to examine the specific interactions of lawsone in the presence of DHA with the stratum corneum.…”