PMID- 15009737
OWN - NLM
STAT- MEDLINE
DCOM- 20040402
LR  - 20141120
IS  - 0022-202X (Print)
IS  - 0022-202X (Linking)
VI  - 122
IP  - 2
DP  - 2004 Feb
TI  - Involvement of photooxidation of melanogenic precursors in prolonged pigmentation 
      induced by ultraviolet A.
PG  - 503-9
AB  - Melanin is usually produced in melanocytes; however, our histologic research 
      indicates that brownish black persistent pigmentation occurs at the basal layer 
      and, partially, at the suprabasal layer of the epidermis, outside of melanocytes, 
      in skin exposed to high doses of ultraviolet (UV) A radiation. This pigmentation 
      remains for several weeks. We examined whether colorless melanogenic precursors 
      participate in this UVA-induced persistent pigmentation. Among them, 
      5,6-dihydroxyindole-2-carboxylic acid (DHICA) and its O-methyl metabolite, 
      6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MICA), can change into 
      dark-colored pigment upon exposure to UVA, but not UVB, radiation, producing 
      irreversible brownish black pigmentation. These hydroxyindole derivatives readily 
      changed into dark-colored pigment upon UVA irradiation in the presence of 
      hydrogen peroxide in vitro. Histochemical and biochemical studies demonstrated 
      that 6H5MICA accumulates in excised skin specimens and supernatant of cultured 
      human melanocytes. These results suggest that dark-colored pigment is generated 
      directly, outside of melanocytes, in response to UVA exposure, by photooxidation 
      of O-methyl metabolites of DHICA, such as 6H5MICA, at least. We propose that the 
      pigmentation derived from this compound at the basal and suprabasal layers of the 
      epidermis is involved in the mechanism of skin persistent pigmentation without 
      reddening, observed after exposure to sunlight.
FAU - Maeda, Kazuhisa
AU  - Maeda K
AD  - Life Science Research Center, Basic Research Division, Shiseido Co. Ltd., 
      Tsuzuki, Yokahama, Japan. kazuhisa.maeda@to.shiseido.co.jp
FAU - Hatao, Masato
AU  - Hatao M
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Invest Dermatol
JT  - The Journal of investigative dermatology
JID - 0426720
RN  - 0 (Indoles)
RN  - 0 (Melanins)
RN  - 0 (Oxidants)
RN  - 0 (Protein Precursors)
RN  - 2638-99-5 (6-hydroxy-5-methoxy-2-indolylcarboxylic acid)
RN  - 4790-08-3 (5,6-dihydroxy-2-indolylcarboxylic acid)
RN  - BBX060AN9V (Hydrogen Peroxide)
RN  - Z3OC8499KG (5,6-dihydroxyindole)
SB  - IM
MH  - Adult
MH  - Humans
MH  - Hydrogen Peroxide/pharmacology
MH  - In Vitro Techniques
MH  - Indoles/metabolism
MH  - Male
MH  - Melanins/*metabolism
MH  - Oxidants/pharmacology
MH  - Photochemistry
MH  - Protein Precursors/*metabolism
MH  - Skin/cytology/drug effects/radiation effects
MH  - Skin Pigmentation/drug effects/*physiology/*radiation effects
MH  - Sunlight
MH  - *Ultraviolet Rays
EDAT- 2004/03/11 05:00
MHDA- 2004/04/03 05:00
CRDT- 2004/03/11 05:00
PHST- 2004/03/11 05:00 [pubmed]
PHST- 2004/04/03 05:00 [medline]
PHST- 2004/03/11 05:00 [entrez]
AID - S0022-202X(15)30676-X [pii]
AID - 10.1046/j.0022-202X.2004.22223.x [doi]
PST - ppublish
SO  - J Invest Dermatol. 2004 Feb;122(2):503-9. doi: 10.1046/j.0022-202X.2004.22223.x.