PMID- 3036240
OWN - NLM
STAT- MEDLINE
DCOM- 19870805
LR  - 20190609
IS  - 0006-3002 (Print)
IS  - 0006-3002 (Linking)
VI  - 924
IP  - 3
DP  - 1987 Jun 22
TI  - Photogeneration of free radicals from eumelanogenic intermediates and 
      metabolites.
PG  - 458-66
AB  - We have recently demonstrated that cysteinyldopas, pheomelanogenic precursors and 
      excreted eumelanogenic metabolites, are photolabile and initiate DNA damage in 
      vitro. In this study we have extended our photochemical investigations to 
      eumelanogenic indole intermediates and metabolites. Continuous-wave photolysis of 
      5,6-dihydroxyindole (DHI), 5,6-dihydroxyindole-2-carboxylic acid (DHICA), or its 
      5-methoxylated metabolite (HMICA) with biologically relevant ultraviolet 
      radiation (i.e., wavelengths greater than 300 nm) resulted in rapid destruction 
      of starting material. Using ESR spin-trapping techniques we observed the initial 
      production of free radical species; prolonged photolysis resulted in the 
      formation of polymeric photoproducts. Radicals were trapped by the nitrone spin 
      trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and characterized by their ESR 
      spectra as hydrated electrons and hydrogen atoms. Experiments further 
      demonstrated that while DHI photoionizes, the two indole-2-carboxylic acid 
      derivatives do not ionize appreciably upon irradiation, rather homolysis of X-H 
      bonds appears to be a significant photochemical pathway. The potential 
      photobiological significance of melanogenic indole intermediates is discussed.
FAU - Koch, W H
AU  - Koch WH
FAU - Chedekel, M R
AU  - Chedekel MR
LA  - eng
GR  - AG02380/AG/NIA NIH HHS/United States
GR  - ES02300/ES/NIEHS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - Netherlands
TA  - Biochim Biophys Acta
JT  - Biochimica et biophysica acta
JID - 0217513
RN  - 0 (Free Radicals)
RN  - 0 (Indoles)
RN  - 2638-99-5 (6-hydroxy-5-methoxy-2-indolylcarboxylic acid)
RN  - 4790-08-3 (5,6-dihydroxy-2-indolylcarboxylic acid)
RN  - Z3OC8499KG (5,6-dihydroxyindole)
SB  - IM
MH  - Chromatography, High Pressure Liquid
MH  - Electron Spin Resonance Spectroscopy
MH  - Free Radicals
MH  - Indoles/*radiation effects
MH  - Photolysis
MH  - Spectrophotometry
MH  - Ultraviolet Rays
EDAT- 1987/06/22 00:00
MHDA- 1987/06/22 00:01
CRDT- 1987/06/22 00:00
PHST- 1987/06/22 00:00 [pubmed]
PHST- 1987/06/22 00:01 [medline]
PHST- 1987/06/22 00:00 [entrez]
AID - 0304-4165(87)90161-9 [pii]
AID - 10.1016/0304-4165(87)90161-9 [doi]
PST - ppublish
SO  - Biochim Biophys Acta. 1987 Jun 22;924(3):458-66. doi: 
      10.1016/0304-4165(87)90161-9.