Padimate O Explained

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.

Photobiology

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]

See also

Notes and References

  1. 10.1016/0014-5793(93)80141-G . Sunlight-induced mutagenicity of a common sunscreen ingredient . 1993 . Knowland . John . McKenzie . Edward A . McHugh . Peter J . Cridland . Nigel A . FEBS Letters . 324 . 3 . 309–13 . 8405372. 23853321 .
  2. 10.1016/S1383-5718(99)00091-1 . 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 . 1999 . Gulston . Melanie . Knowland . John . Mutation Research/Genetic Toxicology and Environmental Mutagenesis . 444 . 1 . 49–60 . 10477339.
  3. 10.1016/S0190-9622(80)80221-0 . Sunscreens prevent ultraviolet photocarcinogenesis . 1980 . Kligman . Lorraine H. . Akin . Frank J. . Kligman . Albert M. . Journal of the American Academy of Dermatology . 3 . 30–5 . 6967495 . 1.
  4. 10.1016/1011-1344(91)80169-I . Time-dependent decrease in sunscreen protection against chronic photodamage in UVB-irradiated hairless mouse skin . 1991 . Bissett . Donald L. . McBride . James F. . Hannon . Daniel P. . Patrick . Larry F. . Journal of Photochemistry and Photobiology B: Biology . 9 . 3–4 . 323–334. 1919875 .
  5. 10.1016/S0190-9622(96)90677-5 . Synergistic topical photoprotection by a combination of the iron chelator 2-furildioxime and sunscreen . 1996 . Bissett . Donald L . McBride . James F . Journal of the American Academy of Dermatology . 35 . 4 . 546–9 . 8859281.
  6. 10.1016/S0027-5107(98)00188-2 . 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 . 1998 . Kerr . Caroline . Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis . 422 . 161–4 . 9920441 . 1.

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