E. Paparis

Quercetin and Rutin as Potential Sunscreen Agents: Determination of Efficacy by an in Vitro Method

Given that flavonoids are known for their ultraviolet (UV)B photoprotective properties in plants that contain them, we chose to study quercetin (1) and rutin (2) as agents that could potentially be used in sunscreen products. These two substances proved to behave in similar ways. When incorporated in oil-in-water emulsions, at a concentration of 10% (w/w), 1 and 2 give sun protection factor (SPF) values similar to that of homosalate, a standard substance. These two flavonoids also provided a non-negligible level of photoprotection in the UVA range. When used in association with titanium dioxide, the SPF obtained was around 30.

UV filters, ingredients with a recognized anti-inflammatory effect.

Background To explain observed differences during SPF determination using either an in vivo or in vitro method, we hypothesized on the presence of ingredients having anti-inflammatory properties. Methodology/Principal Findings To research our hypothesis, we studied the 21 UV filters both available on the market and authorized by European regulations and subjected these filters to the phorbol-myristate-acetate test using mice. We then catalogued the 13 filters demonstrating a significant anti-inflammatory effect with edema inhibition percentages of more than 70%. The filters are: diethylhexyl butamido triazone (92%), benzophenone-5 and titanium dioxide (90%), benzophenone-3 (83%), octocrylène and isoamyl p-methoxycinnamate (82%), PEG-25 PABA and homosalate (80%), octyl triazone and phenylbenzimidazole sulfonic acid (78%), octyl dimethyl PABA (75%), bis-ethylhexyloxyphenol methoxyphenyl triazine and diethylamino hydroxybenzoyl hexylbenzoate (70%). These filters were tested at various concentrations, including their maximum authorized dose. We detected a dose-response relationship. Conclusions/Significance The anti-inflammatory effect of a sunscreen ingredient may affect the in vivo SPF value.

Interest of external photoprotection by means of clothing and sunscreen products in young children.

Background  Protecting young children is a major public health issue.

Influence of certain ingredients on the SPF determined in vivo

When determined in vitro, the SPF of certain commercial sunscreen products can be lower than the SPF indicated on the label. The study of the composition of this type of product enabled us to note that the majority contained substances reputed to have anti-inflammatory properties. This effect is shown by inhibiting the erythema, without protecting the skin, which constitutes a serious public health problem. The anti-inflammatory effects of αbisabolol-, allantoin- and 18-β-glycyrrhetinic acid-based emulsions, as well as commercial sun products containing any one of these molecules, have been tested with phorbol myristate acetate on mice. The effectiveness of these sunscreens products is quantified using two indicators: SPF (sun protection factor) and PF-UVA (protection factor-UVA) by in vitro method. We were thus able to show that certain sun products have an anti-inflammatory effect, which in turn causes the SPF value shown on the product to be overestimated, indeed sometimes by considerably large margins.

Silymarin, a molecule of interest for topical photoprotection

Some UV-filters have side effects. For example, oestrogenic effect was demonstrated for 4-methylbenzylidene camphor. Given that secondary metabolites are known for their UVB photoprotective properties in plants that contain them, we chose to study silymarin as an agent which could potentially be used in sun products. This determination is based on the physical determination of the reduction of the energy in the UV range, through a film of product which has previously been spread on an adequate substrate. About 15 mg of O/W emulsion containing silymarin at various concentrations was applied on roughened PMMA plates and the transmission measurements were carried out using a spectrophotometer equipped with integrating sphere. Incorporated in O/W creams, at a concentration of 10% (w/w), silymarin gives a Sun Protection Factor similar to that of octylmethoxicinnamate, which is why it is predominantly used in Europe. Overall, these results demonstrate that silymarin is a promising new sunscreen agent.

In vitro UV-A protection factor (PF-UVA) of organic and inorganic sunscreens

The objective of this research was to evaluate the efficacy of various sunscreen agents incorporated into an O/W emulsion. Within the scope of this study only an in vitro method was used. According to selected filter UVA, we can obtain more or less effective creams. With the seven available filters, we can cover a range of values between 2 and 12. In addition to these seven filters absorbing in UVA range, variously coated titanium dioxide and zinc oxide were tested as well. So it appears that the best organic UVA filter is anisotriazine at 10% (PF-UVA = 11.82). Its effectiveness is comparable with that of the titanium dioxide forms used at 25%. Photostability in Suntest® showed that the more photostable UVA-filters are the benzophenones.

Foundations and self‐tanning products: Do they provide any protection from the sun?

As soon as the weather turns sunny, everyone wants a tan. People with skin phototypes III and IV, called melanocompetent, have no problem meeting this fashion requirement. But things are quite different for people with phototypes I and II and so these individuals look for alternative solutions. In essence, light skin burns easily when exposed to the sun. Therefore, light‐skinned people are offered a cosmetic solution through self‐tanning products or foundations. It seemed interesting to us to evaluate the sun protection power of this type of product. To do this, we used an in vitro method to determine the typical indicators related to sunscreen products, such as sun protection factor (SPF), ultraviolet (UV)‐A protection factor (PF‐UVA), UV‐B/UV‐A ratio as well as the critical wavelength because these artificial tanning products could be considered sunscreen products by users. It is important to know whether a self‐tanning product and/or a foundation provide sun protection and whether they meet the standards set for other sunscreen products. Protection which is imbalanced for either UV‐B or UV‐A radiation is potentially harmful for users believing themselves adequately protected. To do this, we assembled the requisite conditions for forming melanoidins in the cosmetic itself. We tested seven amino acids found in the corneal cells of the epidermis. Regardless of the amino acid used, the corresponding SPF was essentially zero (approximately SPF 2). Foundations, on the other hand, proved to be much more interesting because they possess a non‐negligible SPF as well as good photostability making these products safe in terms of their mode of application (applied once daily).

Interest of ferulic acid ethyl ester in photoprotective creams: Measure of efficacy by in vitro method

Topical sunscreens have been used for many years on exposed areas to protect the skin from the damaging effects of ultraviolets. If the sunscreens were essential, it is suggested that they have adverse effects. We chose to study ferulic acid ethyl ester (FAEE) as agent which could potentially be used in sunscreen products. FAEE was incorporated at various concentrations into O/W emulsions. Total of 30 mg of product exactly weighed were spread on poly(methylmethacrylate) plates over the whole surface (25 cm2). So, sun protection factor (SPF) and PF-UVA of the creams were measured in vitro. Transmission measurements between 290 and 400 nm were carried out using a spectrophotometer equipped with an integrating sphere. Incorporated in O/W creams, at a concentration of 10%, FAEE give a SPF similar to that of benzymidazilate, a filter permitted in EU.

Photoprotective activity of propolis

The purpose of this study was to determine the photoprotective properties of propolis. The sun protection factor (SPF) of ethanol extract of propolis was evaluated by an in vitro method, using homosalate as control. This determination is based on the physical determination of the reduction of the energy in the UV range, through a film of product which has previously been spread on an adequate substrate. About 15 mg of O/W emulsion containing propolis at various concentrations were applied on roughened Polymethylmethacrylate (PMMA) plates and the transmission measurements were carried out using a spectrophotometer equipped with integrating sphere. The results may justify their use as a natural sunscreen agent.

The effect of ultraviolet radiation on the anti-inflammatory effect of filters

A certain number of filters have notable anti-inflammatory properties with percentage inhibition of PMA-induced edema in mice at over 70%. The question arose as to whether this effect was likely to continue after UV irradiation. It can be noted that 7 filters retain an equivalent anti-inflammatory effect before and after 2h of irradiation in a Suntest device (650 W/m(2)). For 9 filters, the anti-inflammatory effect decreases and for 5 filters, the anti-inflammatory effect increases. Various behaviors should be noted. 3 groups of substances can be distinguished: such as phenylbenzimidazole sulfonic acid which loses its anti-inflammatory character after irradiation (the percentage inhibition falls from 80 to 44%), oxybenzone which retains a constant anti-inflammatory character (89% inhibition before and after irradiation and also octyl methoxycinnamate which becomes very anti-inflammatory (with a percentage inhibition of 93%). The same phenomenon is observed in the case of commercial products. This should be made known as it can have a considerable impact on the results which are displayed on the packaging of sun products.