Padimate O

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Padimate O

IUPAC name	4-dimethylaminobenzoic acid 2-ethylhexyl ester
Other names	2-ethylhexl dimethyl PABA Escalol 507 Sundown
Identifiers
CAS number	[21245-02-3]
PubChem	30541
SMILES	CCCCC(CC)COC(=O)C1=CC=C(C=C1)N(C)C
Properties
Molecular formula	C₁₇H₂₇NO₂
Molar mass	277.402
Density	0.99 g/cm³
Melting point	<25 °C
Boiling point	362 °C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Padimate O is an organic compound that is an ingredient in some sunscreens. It is a derivative of PABA, an ester formed by the condensation of 2-ethylhexanol and dimethylaminobenzoic acid. It is a yellowish oily liquid that is insoluble in water. It absorbs ultraviolet rays, thereby preventing direct DNA damage by UV-B. Unfortunately the excited padimate O molecule reacts bimolecularly with DNA and produces indirect DNA damages, that are similar to those done by ionizing radiation. Therefore padimate o is presumably photocarcinogenic.^[1]

Other names for padimate-O are: 2-ethylhexyl 4-dimethylaminobenzoate, Escalol 507, oxtyldimethyl PABA, or OD-PABA.

This compound does not dissipate energy as fast as melanin, and therefore it is unsuitable as a sunscreen ingredient (see photoprotection).

1 Photobiology
2 See also
3 References
4 External links

[edit] Photobiology

The photobiological properties of padimate O resemble that of Michler's ketone. Both these compounds have been shown to increase the lethal effects of UV-radiation.^[2] Michler's ketone is known to be photocarcinogenic in rats and mice, therefore Padimate O is implicated in the sunscreen controversy.

[edit] See also

Padimate A, a related sunscreen ingredient
photoprotection

[edit] References

^ Melanie Gulston, John Knowland; S. H. Moss, D. J. Davies (1999). "Illumination of human keratinocytes in the presence of sunscreen ingredient padimat-O .... increases strand breaks.". Mutation Research 1999 (444): 49–60.
^ 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.