PMID- 28002950
OWN - NLM
STAT- MEDLINE
DCOM- 20180129
LR  - 20180129
IS  - 1520-5215 (Electronic)
IS  - 1089-5639 (Linking)
VI  - 120
IP  - 50
DP  - 2016 Dec 22
TI  - Energetics of Radical Formation in Eumelanin Building Blocks: Implications for 
      Understanding Photoprotection Mechanisms in Eumelanin.
PG  - 10018-10022
LID - 10.1021/acs.jpca.6b10122 [doi]
AB  - The supramolecular structure of melanin pigments is characterized by a high 
      concentration of radical species. Therefore, the energetics of the radical 
      formation in melanin building blocks is key for understanding the structure and 
      the electronic properties of the pigments at the molecular level. Nevertheless, 
      the radical energetics of even the simplest melanin building blocks are largely 
      unknown. In order to address this fundamental issue, the bond dissociation 
      enthalpies (BDEs) for the melanin monomers 5,6-dihydroxy-1H-indole-2-carboxylic 
      acid (DHICA), 1H-indole-5,6-diol (DHI), and 1H-indole-5,6-dione (IQ) were 
      determined through high-accuracy ab initio quantum chemistry methods. Our results 
      provide strong evidence of the importance on BDEs for explaining the 
      experimentally observed dependence of the antioxidant properties of eumelanin 
      pigments on the DHICA/DHI ratio, and the role that these two species play on the 
      photoprotection mechanism.
FAU - Agapito, Filipe
AU  - Agapito F
AD  - Centro de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa , 
      1749-016 Lisboa, Portugal.
FAU - Cabral, Benedito J Costa
AU  - Cabral BJ
AUID- ORCID: 0000-0003-4824-3530
AD  - Departamento de Quimica e Bioquimica and Grupo de Fisica Matematica, Faculdade de 
      Ciencias, Universidade de Lisboa , 1749-016 Lisboa, Portugal.
LA  - eng
PT  - Journal Article
DEP - 20161208
PL  - United States
TA  - J Phys Chem A
JT  - The journal of physical chemistry. A
JID - 9890903
RN  - 0 (Free Radicals)
RN  - 0 (Melanins)
RN  - 12627-86-0 (eumelanin)
SB  - IM
MH  - Free Radicals/chemical synthesis/chemistry
MH  - Melanins/chemical synthesis/*chemistry
MH  - Molecular Structure
MH  - Photochemical Processes
MH  - *Quantum Theory
EDAT- 2016/12/23 06:00
MHDA- 2018/01/30 06:00
CRDT- 2016/12/23 06:00
PHST- 2016/12/23 06:00 [entrez]
PHST- 2016/12/23 06:00 [pubmed]
PHST- 2018/01/30 06:00 [medline]
AID - 10.1021/acs.jpca.6b10122 [doi]
PST - ppublish
SO  - J Phys Chem A. 2016 Dec 22;120(50):10018-10022. doi: 10.1021/acs.jpca.6b10122. 
      Epub 2016 Dec 8.