PMID- 27196900
OWN - NLM
STAT- MEDLINE
DCOM- 20170316
LR  - 20181113
IS  - 1422-0067 (Electronic)
IS  - 1422-0067 (Linking)
VI  - 17
IP  - 5
DP  - 2016 May 17
TI  - "Fifty Shades" of Black and Red or How Carboxyl Groups Fine Tune Eumelanin and 
      Pheomelanin Properties.
LID - 10.3390/ijms17050746 [doi]
LID - 746
AB  - Recent advances in the chemistry of melanins have begun to disclose a number of 
      important structure-property-function relationships of crucial relevance to the 
      biological role of human pigments, including skin (photo) protection and 
      UV-susceptibility. Even slight variations in the monomer composition of black 
      eumelanins and red pheomelanins have been shown to determine significant 
      differences in light absorption, antioxidant, paramagnetic and redox behavior, 
      particle morphology, surface properties, metal chelation and resistance to 
      photo-oxidative wear-and-tear. These variations are primarily governed by the 
      extent of decarboxylation at critical branching points of the eumelanin and 
      pheomelanin pathways, namely the rearrangement of dopachrome to 
      5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA), and 
      the rearrangement of 5-S-cysteinyldopa o-quinoneimine to 1,4-benzothiazine (BTZ) 
      and its 3-carboxylic acid (BTZCA). In eumelanins, the DHICA-to-DHI ratio markedly 
      affects the overall antioxidant and paramagnetic properties of the resulting 
      pigments. In particular, a higher content in DHICA decreases visible light 
      absorption and paramagnetic response relative to DHI-based melanins, but markedly 
      enhances antioxidant properties. In pheomelanins, likewise, BTZCA-related units, 
      prevalently formed in the presence of zinc ions, appear to confer pronounced 
      visible and ultraviolet A (UVA) absorption features, accounting for 
      light-dependent reactive oxygen species (ROS) production, whereas 
      non-carboxylated benzothiazine intermediates seem to be more effective in 
      inducing ROS production by redox cycling mechanisms in the dark. The possible 
      biological and functional significance of carboxyl retention in the eumelanin and 
      pheomelanin pathways is discussed.
FAU - Micillo, Raffaella
AU  - Micillo R
AD  - Department of Clinical Medicine and Surgery, University of Naples "Federico II", 
      Naples 80131, Italy. raffaella.micillo@unina.it.
FAU - Panzella, Lucia
AU  - Panzella L
AD  - Department of Chemical Sciences, University of Naples "Federico II", Naples 
      80126, Italy. panzella@unina.it.
FAU - Koike, Kenzo
AU  - Koike K
AD  - Hair Care Products Research Laboratories, Kao Corporation, Tokyo 131-8501, Japan. 
      koike.kenzo@kao.co.jp.
FAU - Monfrecola, Giuseppe
AU  - Monfrecola G
AD  - Department of Clinical Medicine and Surgery, University of Naples "Federico II", 
      Naples 80131, Italy. monfreco@unina.it.
FAU - Napolitano, Alessandra
AU  - Napolitano A
AD  - Department of Chemical Sciences, University of Naples "Federico II", Naples 
      80126, Italy. alesnapo@unina.it.
FAU - d'Ischia, Marco
AU  - d'Ischia M
AD  - Department of Chemical Sciences, University of Naples "Federico II", Naples 
      80126, Italy. dischia@unina.it.
LA  - eng
PT  - Journal Article
PT  - Review
DEP - 20160517
PL  - Switzerland
TA  - Int J Mol Sci
JT  - International journal of molecular sciences
JID - 101092791
RN  - 0 (Antioxidants)
RN  - 0 (Carboxylic Acids)
RN  - 0 (Melanins)
RN  - 0 (pheomelanin)
RN  - 12627-86-0 (eumelanin)
SB  - IM
MH  - Antioxidants/chemistry
MH  - Biosynthetic Pathways
MH  - Carboxylic Acids/*chemistry
MH  - Humans
MH  - Magnetic Phenomena
MH  - Melanins/*chemistry
PMC - PMC4881568
OTO - NOTNLM
OT  - 5,6-dihydroxyindoles
OT  - 5-S-cysteinyldopa
OT  - antioxidant
OT  - benzothiazines
OT  - dopachrome
OT  - eumelanin
OT  - melanins
OT  - melanocortin-1-receptor
OT  - pheomelanin
OT  - pro-oxidant
EDAT- 2016/05/20 06:00
MHDA- 2017/03/17 06:00
PMCR- 2016/05/01
CRDT- 2016/05/20 06:00
PHST- 2016/04/12 00:00 [received]
PHST- 2016/05/02 00:00 [revised]
PHST- 2016/05/05 00:00 [accepted]
PHST- 2016/05/20 06:00 [entrez]
PHST- 2016/05/20 06:00 [pubmed]
PHST- 2017/03/17 06:00 [medline]
PHST- 2016/05/01 00:00 [pmc-release]
AID - ijms17050746 [pii]
AID - ijms-17-00746 [pii]
AID - 10.3390/ijms17050746 [doi]
PST - epublish
SO  - Int J Mol Sci. 2016 May 17;17(5):746. doi: 10.3390/ijms17050746.