Padimate O

Chembox new
ImageFile=Padimate O.pngImageSize=
IUPACName=4-dimethylaminobenzoic acid 2-ethylhexyl ester
OtherNames=2-ethylhexl dimethyl PABA
Escalol 507
Sundown
Section1= Chembox Identifiers
CASNo=21245-02-3
PubChem=30541
SMILES=CCCCC(CC)COC(=O)C1=CC=C(C=C1)N(C)C
Section2= Chembox Properties
Formula=C₁₇H₂₇NO₂
MolarMass=277.402
Appearance=
Density=0.99 g/cm³
MeltingPt=<25 °C
BoilingPt=362 °C
Solubility=
Section3= Chembox Hazards
MainHazards=
FlashPt=
Autoignition=

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.cite journal| author=Melanie Gulston, John Knowland| coauthors=S. H. Moss, D. J. Davies| title=Illumination of human keratinocytes in the presence of sunscreen ingredient padimat-O .... increases strand breaks.| journal=Mutation Research| volume=1999| issue=444| pages=49–60| year=1999]

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).

Photobiology

The photobiological properties of padimate O resemble that of Michler's ketone. The compound has been shown to increase the lethal effects of UV-radiation.cite journal |author=Knowland, John; McKenzie, Edward A.; McHugh, Peter J.; Cridland, Nigel A. |title= Sunlight-induced mutagenicity of a common sunscreen ingredient. | journal= FEBS Letters |volume= 324(3) |pages=309–313 |year=1993 |doi= 10.1016/0014-5793(93)80141-G ] Michler's ketone is known to be photocarcinogenic in rats and mice, therefore padimate O is implicated in the sunscreen controversy.

See also

*Padimate A, a related sunscreen ingredient
*photoprotection

References

External links