Padimate O
| Padimate O | |
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2-ethylhexyl 4-(dimethylamino)benzoate |
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Other names
2-ethylhexyl dimethyl PABA |
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| Identifiers | |
| CAS number | 21245-02-3  |
| PubChem | 30541 |
| ChemSpider | 28343 |
| UNII | Z11006CMUZ |
| KEGG | D05335 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C17H27NO2 |
| Molar mass | 277.4 g mol−1 |
| Density | 0.99 g/cm³ |
| Melting point |
<25 °C |
| Boiling point |
362 °C, 635 K, 684 °F |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Padimate O is an organic compound related to the water-soluble compound PABA (4-aminobenzoic acid) that is used as an ingredient in some sunscreens. This yellowish water-insoluble oily liquid is an ester formed by the condensation of 2-ethylhexanol with dimethylaminobenzoic acid. Other names for padimate O include 2-ethylhexyl 4-dimethylaminobenzoate, Escalol 507, octyldimethyl PABA, and OD-PABA.
[edit] Photobiology
Padimate O has been implicated in the sunscreen controversy. Padimate O absorbs ultraviolet rays, thereby preventing direct DNA damage by UV-B. However, the thus-excited padimate O molecule may then react with DNA to produce indirect DNA damage, similar to the effects of ionizing radiation. An in vitro yeast study conducted in 1993 demonstrated the sunlight-induced mutagenicity of padimate O.[1] The photobiological properties of padimate O resemble those of Michler's ketone, which is considered photocarcinogenic in rats and mice. These findings suggest that padimate O might also be photocarcinogenic.[2]
However, multiple in vivo studies conducted in hairless mice following topical application of padimate O have demonstrated no carcinogenic effects and that padimate O reduces the number of and delays the appearance of UV-induced skin tumors.[3][4][5][6]
[edit] See also
- Padimate A, a related sunscreen ingredient
[edit] References
- ^ Knowland, John; McKenzie, Edward A.; McHugh, Peter J.; Cridland, Nigel A. (1993). "Sunlight-induced mutagenicity of a common sunscreen ingredient.". FEBS Letters 324 (3): 309–313. doi:10.1016/0014-5793(93)80141-G. PMID 8405372. http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6T36-44G8DXC-HB-1&_cdi=4938&_user=10&_orig=search&_coverDate=06%2F21%2F1993&_sk=996759996&view=c&wchp=dGLbVlz-zSkzk&md5=52a598965b8eebd278f34d304b27e2a0&ie=/sdarticle.pdf.
- ^ Melanie Gulston, John Knowland; S. H. Moss, D. J. Davies (1999). "Illumination of human keratinocytes in the presence of the sunscreen ingredient Padimate-O and through an SPF-15 sunscreen reduces direct photodamage to DNA but increases strand breaks". Mutation Research 444 (1): 49–60. PMID 10477339. http://www.ncbi.nlm.nih.gov/pubmed/10477339.
- ^ Kligman LH, Akin FJ, Kligman AM (1980). "Sunscreens prevent ultraviolet photocarcinogenesis". J Am Acad Dermatol 3 (1): 30–35. doi:10.1016/S0190-9622(80)80221-0. PMID 6967495.
- ^ Bissett DL, McBride JF, Hannon DP, et al. (1991). "Time-dependent decrease in sunscreen protection against chronic photodamage in UVB-irradiated hairless mouse skin". J Photochem Photobiol B 9 (3-4): 323–334. doi:10.1016/1011-1344(91)80169-I. PMID 1919875.
- ^ Bissett DL, McBride JF (1996). "Synergistic topical photoprotection by a combination of the iron chelator 2-furildioxime and sunscreen". J Am Acad Dermatol 35 (4): 546–549. doi:10.1016/S0190-9622(96)90677-5. PMID 8859281.
- ^ Kerr C (1998). "The effects of two UVB radiation-absorbing sunscreens on UV radiation-induced carcinogenesis, suppression of the contact hypersensitivity response and histological changes in the hairless mouse". Mutat Res 422 (1): 161–164. doi:10.1016/S0027-5107(98)00188-2. PMID 9920441.
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