The effects of topically applied glycolic acid and salicylic acid on ultraviolet radiation-induced erythema, DNA damage and sunburn cell formation in human skin.
BACKGROUND
alpha-Hydroxy acids (alphaHAs) are reported to reduce signs of aging in the skin and are widely used cosmetic ingredients. Several studies suggest that alphaHA can increase the sensitivity of skin to ultraviolet radiation. More recently, beta-hydroxy acids (betaHAs), or combinations of alphaHA and betaHA have also been incorporated into antiaging skin care products. Concerns have also arisen about increased sensitivity to ultraviolet radiation following use of skin care products containing beta-HA.


OBJECTIVE
To determine whether topical treatment with glycolic acid, a representative alphaHA, or with salicylic acid, a betaHA, modifies the short-term effects of solar simulated radiation (SSR) in human skin.


METHODS
Fourteen subjects participated in this study. Three of the four test sites on the mid-back of each subject were treated daily Monday-Friday, for a total of 3.5 weeks, with glycolic acid (10%), salicylic acid (2%), or vehicle (control). The fourth site received no treatment. After the last treatment, each site was exposed to SSR, and shave biopsies from all four sites were obtained. The endpoints evaluated in this study were erythema (assessed visually and instrumentally), DNA damage and sunburn cell formation.


RESULTS
Treatment with glycolic acid resulted in increased sensitivity of human skin to SSR, measured as an increase in erythema, DNA damage and sunburn cell formation. Salicylic acid did not produce significant changes in any of these biomarkers.


CONCLUSIONS
Short-term topical application of glycolic acid in a cosmetic formulation increased the sensitivity of human skin to SSR, while a comparable treatment with salicylic acid did not.
Kornhauser
Andrija
A
Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD 20740, USA. akornhause@aol.com
Wei
Rong-Rong
RR
Yamaguchi
Yuji
Y
Coelho
Sergio G
SG
Kaidbey
Kays
K
Barton
Curtis
C
Takahashi
Kaoruko
K
Beer
Janusz Z
JZ
Miller
Sharon A
SA
Hearing
Vincent J
VJ
D000287:Administration, Topical; D000328:Adult; D004249:DNA Damage; D004890:Erythema / Q000209:etiology* / Q000473:pathology; D005260:Female; D006016:Glycolates / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D007641:Keratolytic Agents / Q000008:administration & dosage / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011740:Pyrimidine Dimers / Q000378:metabolism; D011832:Radiation Injuries / Q000139:chemically induced* / Q000473:pathology; D020156:Salicylic Acid / Q000008:administration & dosage / Q000009:adverse effects*; D012867:Skin / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects; D013471:Sunburn / Q000209:etiology* / Q000473:pathology; D014466:Ultraviolet Rays / Q000009:adverse effects*
D006016:Glycolates; D007641:Keratolytic Agents; D011740:Pyrimidine Dimers; C031149:glycolic acid; D020156:Salicylic Acid