Lt. Vandenbroeke et Gmj. Vanhenegouwen, UV-RADIATION PROTECTING EFFICACY OF THIOLS, STUDIED WITH UVA-INDUCED BINDING OF 8-MOP AND CPZ TO RAT EPIDERMAL BIOMACROMOLECULES INVIVO, International journal of radiation biology & related studies in physics, chemistry & medicine, 63(4), 1993, pp. 493-500
The following topically-applied thiols were investigated with regard t
o their possible UV-radiation protective properties: captopril, cystea
mine, ergothioneine, mesna, mercaptopropionylglycine, N-acetyl-cystein
e and penicillamine. As a measure for protection the inhibition of in
vivo irreversible photobinding of the labelled phototoxic drugs chlorp
romazine (CPZ) and 8-methoxypsoralen (8-MOP) to rat epidermal biomacro
molecules was used. Ergothioneine, mesna and penicillamine did not sho
w any effect; probably, as a result of their charge they are not able
to enter the stratum corneum. Captopril, cysteamine, mercaptopropionyl
glycine and N-acetylcysteine showed a considerable inhibition of CPZ a
nd 8-MOP photobinding. Captopril and N-acetylcysteine were clearly the
most potent whereas cysteamine was the least effective. Captopril, me
rcaptopropionylglycine and N-acetylcysteine appeared to have a wider a
ction range and to be a more effective protector than dl-alpha-tocophe
rol and di-butyl-hydroxytoluene. Cysteamine and mercaptopropionylglyci
ne were only capable of protecting the stratum corneum. Captopril and
N-acetylcysteine on the other hand showed an additional dose-dependent
inhibition of photobinding to the viable epidermis. Gradually with in
creasing time after application, the protecting efficacy with regard t
o the viable layer of the epidermis decreased; the duration of protect
ion depending on the dose.