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Updated: Jul 11, 2026

Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model
Published on: September 7, 2013
Long-lasting pigmentation more than its intensity is a reliable indicator of skin sun resistance
Enrico M Procaccini1, Alessandra Napolitano, Lucia Panzella
1Azienda Sanitaria Locale, ASL NA1, Università degli Studi di Napoli Federico II, Napoli, Italy.
Background:
The currently adopted method for predicting sun sensitivity is Fitzpatrick's classification which however is based on self-reported burning tendency and tanning ability.
Objective:
Determination of the individual UV susceptibility based on non-subjective parameters.
Method:
Minimal erythema dose (MED), intensity and duration of pigmentation on days 5, 9 and 16 following 1 MED and the levels of the melanin marker pyrrole-2,3,5-tricarboxylic acid (PTCA) were analysed in non-red-haired subjects (50, aged 20-46 years).
Results:
Phenotype groups or phototypes showed a good correlation with PTCA yields and the persistence of pigmentation on day 16, but not with MED values. MED values did not show a significant correlation with PTCA yields. On the other hand, high values on day 16 were exhibited only by subjects having PTCA values higher than 200 ng/mg.
Conclusions:
Measurement persistence of pigmentation on day 16 represents a non-invasive and easy-to-perform method to evaluate photoprotection in those individuals escaping straightforward classification based on phenotype or anamnesis.
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