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Fri Jun 15, 2007 2:13 pm  |
| ginnielizz wrote: |
methoxycinnamate and avobenzone work. I'd love to know if there's any "catch" or negative trick to these chemicals - in my opinion they're too new on the market to tell, but then again, they've been in Europe and elsewhere for ages.
Sadly, I don't have access to the medical journals I did in college, so it's harder to find real studies about these ingredients. Anyone who's savvy, I'd love a reply! |
I've been trying to do this sort of research on tinosorb for a while. I'm neither a chemist nor a medical professional, so I'm not the ideal researcher on this topic, but I have found a few interesting articles on photostability and on safety. Worth noting: a couple are by CIBA scientists, and since they’re the creators of Tinosorb, they have an obvious interest…
Maybe I’m being overcautious, but I'll just post abstracts so as not to bring the wrath of the copyright lawyers on me. I hope the abstracts aren’t uselessly scanty. Obviously, the few articles here don’t cover every potential area of concern, so for all I know there could be all sorts of “negative catches” hiding in the background. I haven’t been researching mexoryl, so I can’t contribute anything there for the time being.
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CHIMIA 2004, 58, No. 7/8
Chimia 58 (2004) 554–559
New UV Absorbers for Cosmetic
Sunscreens – A Breakthrough for thePhotoprotection of Human Skin
Bernd Herzog*, Dietmar Hüglin, Elek Borsos, Albert Stehlin, and Helmut Luther
Abstract: Two new UV filters for use in cosmetic sunscreens have been developed. Bis-ethylhexyloxyphenolmethoxyphenyl triazine (BEMT) is a hydroxy-phenyl-triazine derivative, which has been designed for optimal spectral performance, excellent photostability, and solubility in cosmetic oils. Methylene bis-benzotriazolyl tetramethylbutylphenolMBBT) is the active ingredient of a particulate UV-filter system, which is available as a50% dispersion of MBBT. Since the UV-attenuating efficacy depends strongly on particle size, the material is micronised to particle sizes below 200 nm. The mode of action of this photostable filter system is governed to about 90% by
absorption and 10% by scattering of UV light. Both filters show broad-spectrum characteristics with significant protection in the UVA range
[The abstract isn’t that informative, so I’ll just note that I believe this is by the creators of Tinosorb at CIBA. It has an interesting but very technical explanation on tinosorb’s photostability, how it dissipates absorbed energy and avoids breaking down. It also has comparisons to avobenzone and to zinc oxide.]
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Regulatory Toxicology and Pharmacology 34, 287–291 (2001)
Lack of Binding to Isolated Estrogen or Androgen Receptors, and
Inactivity in the Immature Rat Uterotrophic Assay, of the Ultraviolet
Sunscreen Filters Tinosorb M-Active and Tinosorb S
J. Ashby,¤,1 H. Tinwell,¤ J. Plautz,y K. Twomey,¤ and P. A. Lefevre¤
¤Syngenta Central Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire SK10 4TJ, United Kingdom;and yCiba Speciality Chemicals, 4002 Basel, Switzerland
The presence of structurally diverse chemicals as contaminants in the environment has led to concerns regarding their possible endocrine disturbing effects. Recently, some ultraviolet absorbing components of sunscreen preparations have given positive responses in assays monitoring estrogen-like activity both in vitro and in vivo. Consequently, two recently developed sunscreen components, Tinosorb M-active and
Tinosorb S, were evaluated using the in vitro estrogen and androgen receptor competitive binding assays. Neither compound gave a positive response in either of the assays, consistent with the large molecular dimensions of each chemical disfavoring binding to
the hormone receptors. Both of the chemicals were inactive in immature rat uterotrophic assays conducted using the subcutaneous route of administration. It is concluded that neither of these agents possess intrinsic estrogenic/antiestrogenic or androgenic/antiandrogenic activity. The several positive control chemicals
evaluated gave the expected positive responses in the assays used.
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In vitro percutaneous absorption and in vivo stratum corneum distribution of an organic and a mineral sunscreen
Author Mavon, A; Miquel, C; Lejeune, O; Payre, B; Moretto, P
Source SKIN PHARMACOLOGY AND PHYSIOLOGY,vol.20,no.1,pp.10-20,2007
Abstract Sunscreens, whose main function is to protect the skin against the harmful effects of solar irradiation, should remain at the skin surface or impregnate the first layers of the stratum corneum only and not penetrate into the underlying living tissue. The goal of this work was to assess the penetration of titanium dioxide (TiO2) and methylene bis-benzotriazoyl tetramethylbutylphenol (MBBT), included in a broad-spectrum sunscreen formulation, into human skin in vivo, using the tape stripping method, and in vitro, using a compartmental approach. An additional objective was to propose an easy and minimally invasive approach to determining the percutaneous uptake of sunscreens following topical application. TiO2 and MBBT were quantified using colorimetric assay and HPLC analysis, respectively. The transmission electron microscopy and particle-induced Xray emission techniques were used to localize the TiO2 in skin sections. More than 90% of both sunscreens was recovered in the first 15 tape strippings. In addition we have shown that the remaining 10% did not penetrate the viable tissue, but was localized in the furrows and in the opened infundibulum. Less than 0.1% of MBBT was detected in the receptor medium, and no TiO2 was detected in the follicle, viable epidermis or dermis. Thus, this in vivo and in vitro penetration study showed an absence of TiO2 penetration into the viable skin layers through either transcorneal or transfollicular pathways and negligible transcutaneous absorption of MBBT. However, differences in distribution within the stratum corneum reinforced the need for a complementary approach, using minimally invasive in vivo methodology and in vitro compartmental analysis. This combination represents a well-adapted method for testing the safety of topically applied sunscreen formulations in real-life conditions. Copyright (c) 2007 S. Karger AG, Basel.
Volume 74, Issue 3 (September 2001)
Photochemistry and Photobiology
Article: pp. 401–406 | Abstract | PDF (188K)
Photostabilization of Butyl methoxydibenzoylmethane (Avobenzone) and Ethylhexyl methoxycinnamate by Bis-ethylhexyloxyphenol methoxyphenyl triazine (Tinosorb S), a New UV Broadband Filter¶
Eric Chatelain*, Bernard Gabard
Department of Biopharmacy, Spirig Pharma Ltd, Egerkingen, Switzerland
It is now well documented that chronic UVA exposure induces damage to human skin. Therefore, modern sunscreens should not only provide protection from both UVB and UVA radiation but also maintain this protection during the entire period of exposure to the sun. UVA filters, however, are rare and not sufficiently photostable. We investigated the effect of the introduction of a new UV filter, bis-ethylhexyloxyphenol methoxyphenyl triazine (Tinosorb S), in oil in water sunscreen formulations on the photostability of butyl methoxydibenzoylmethane (Avobenzone [AVB]) after irradiation with an optically filtered Xenon arc source (UV irradiance adjusted at 1 mean effective dose [MED]/min). With spectrophotometrical methods to assess the sun protection factor (SPF) and UVA ratio and chromatographical methods to determine the amount of UV filters recovered after irradiation we showed that Tinosorb S prevented the photodegradation of AVB in a concentration-dependent way, leading to a sustained SPF and UVA ratio even after irradiation with doses of up to 30 MED. Since AVB was shown to destabilize ethylhexyl methoxycinnamate (EHM) we tested the effect of Tinosorb S in sunscreens containing this UV filter combination. Here too Tinosorb S showed photoprotective properties toward both UV filters. Thus, Tinosorb S can be used successfully to improve the photostability and efficiency of sunscreens containing AVB and EHM.
Christelle Gélis, Stéphanie Girard, Alain Mavon, Maxence Delverdier, Nicole Paillous, Patricia Vicendo (2003)
Assessment of the skin photoprotective capacities of an organo-mineral broad-spectrum sunblock on two ex vivo skin models
Photodermatology, Photoimmunology & Photomedicine 19 (5), 242–253.
UV irradiation can cause cutaneous damage that may be specific according to the wavelength of UV rays. For example, damage from UVB irradiation manifests itself in the form of sunburn cells and enhancement of the expression of p53, while damage from UVA exposure results in an increase in the expression of vimentin. These reactions to UV irradiation were used in this work to evaluate the photoprotective capacities of two sunblock preparations that were applied to the surface of the skin. One sunblock preparation is a UVB absorber containing zinc oxide (ZnO) and titanium oxide (TiO2) exclusively. The other sunblock preparation is a new organo-mineral sunblock containing Tinosorb™ M, OCM, ZnO and TiO2. Evaluation of the photoprotective capacities of both preparations on hairless rat skin and on in vitro reconstructed human epidermis revealed that they were effective in preventing UVB-induced damage. In contrast, only the organo-mineral sunblock was effective in the prevention of UVA-specific damage such as dermal alterations characterized by the expression of vimentin. Furthermore, our data support the fact that hairless rat skin and in vitro reconstructed human epidermis are a reliable basis for the evaluation of the photoprotective capacities of various sunscreens against UVB and UVA damage. |
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