title: Effect of glycolic acid on UVB-induced skin damage and inflammation in guinea pigs.
abstract: OBJECTIVE
  Recently the use of glycolic-acid-containing cosmetics has received increased public interest in their supposed ability to reduce wrinkles, roughness, age spots and other skin damage. However, the safety of such products when used excessively or chronically, especially by photosensitive people, is being questioned. The purpose of this study was to examine the effects of glycolic acid alone or in combination with UVB on skin damage and inflammatory response.
  
  
  METHODS
  Guinea pigs were treated with glycolic acid (from 1 to 7 mg/cm(2)) alone or in combination with UVB (0.4 or 3 J/cm(2)) for 14 days. Skin damage was evaluated by scoring the skin irritation value by the method of Draize and by histopathological observations. Cyclooxygenase 2 (COX-2) expression and prostaglandin E(2) (PGE(2)) production were also assessed.
  
  
  RESULTS
  Glycolic acid caused an increase in the level of skin damage in a dose- and time-dependent manner. Lower doses (1 and 3 mg/cm(2)) of glycolic acid mostly caused erythema and eschar, and these consequently formed scales, whereas higher doses (5 and 7 mg/cm(2)) of glycolic acid caused redness, edema and necrotic ulceration. Glycolic acid also increased the thickness of the epidermal layer, reduced the organization of the stratum corneum and eventually destroyed some parts of the epidermal layer at 7 mg/cm(2). UVB (0.4 and 3 J/cm(2)) caused redness and edema as well as reduced the integrity of the stratum corneum. Glycolic acid enhanced the UVB-induced skin damage. The magnitude of the damage caused by combined UVB and glycolic acid treatment was much greater than that caused by glycolic acid or UVB alone. Moreover, partial destruction of the epidermal layer was observed in skin treated with 3 J/cm(2) UVB and 3 mg/cm(2) glycolic acid. However, glycolic acid did not change the basal and UVB-induced PGE(2) production and COX-2 protein expression.
  
  
  CONCLUSIONS
  These results show that glycolic acid causes skin damage in a dose- and time-dependent manner and that it enhances UVB-induced skin damage without accompanying PGE(2) production or COX-2 protein expression. Therefore, caution should be exercised by those using glycolic acid on a chronic basis or excessively. Moreover, those with photosensitive skins and those more exposed to the sun should be particularly careful.
authors.affiliation: Department of General Toxicology, National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea.
authors.forename: K S
authors.initials: KS
authors.lastname: Park
authors.forename: H J
authors.initials: HJ
authors.lastname: Kim
authors.forename: E J
authors.initials: EJ
authors.lastname: Kim
authors.forename: K T
authors.initials: KT
authors.lastname: Nam
authors.forename: J H
authors.initials: JH
authors.lastname: Oh
authors.forename: C W
authors.initials: CW
authors.lastname: Song
authors.forename: H K
authors.initials: HK
authors.lastname: Jung
authors.forename: D J
authors.initials: DJ
authors.lastname: Kim
authors.forename: Y W
authors.initials: YW
authors.lastname: Yun
authors.forename: H S
authors.initials: HS
authors.lastname: Kim
authors.forename: S Y
authors.initials: SY
authors.lastname: Chung
authors.forename: D H
authors.initials: DH
authors.lastname: Cho
authors.forename: B Y
authors.initials: BY
authors.lastname: Kim
authors.forename: J T
authors.initials: JT
authors.lastname: Hong
mesh_terms: D000818:Animals; D051546:Cyclooxygenase 2; D020405:Dermis / Q000473:pathology; D015232:Dinoprostone / Q000096:biosynthesis; D004817:Epidermis / Q000473:pathology; D005260:Female; D006016:Glycolates / Q000009:adverse effects*; D006168:Guinea Pigs; D007249:Inflammation / Q000209:etiology; D007527:Isoenzymes / Q000378:metabolism; D007641:Keratolytic Agents / Q000009:adverse effects*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D012867:Skin / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D006016:Glycolates; D007527:Isoenzymes; D007641:Keratolytic Agents; C031149:glycolic acid; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone