PMID- 33023030
OWN - NLM
STAT- MEDLINE
DCOM- 20210223
LR  - 20210223
IS  - 1422-0067 (Electronic)
IS  - 1422-0067 (Linking)
VI  - 21
IP  - 19
DP  - 2020 Oct 3
TI  - Nonenzymatic Spontaneous Oxidative Transformation of 5,6-Dihydroxyindole.
LID - 10.3390/ijms21197321 [doi]
LID - 7321
AB  - Melanin is an important phenolic skin pigment found throughout the animal 
      kingdom. Tyrosine and its hydroxylated product dopa provide the starting material 
      for melanin biosynthesis in all animals. Through a set of well-established 
      reactions, they are converted to 5,6-dihydroxyindole (DHI) and DHI-2-carboxylic 
      acid (DHICA). Oxidative polymerization of these two indoles produces the brown to 
      black eumelanin pigment. The steps associated with these transformations are 
      complicated by the extreme instability of the starting materials and the 
      transient and highly reactive nature of the intermediates. We have used mass 
      spectral studies to explore the nonenzymatic mechanism of oxidative 
      transformation of DHI in water. Our results indicate the facile production of not 
      only dimeric and trimeric products but also higher oligomeric forms of DHI upon 
      exposure to air in solution, even under nonenzymatic conditions. Such 
      instantaneous polymerization of DHI avoids toxicity to self-matter and ensures 
      the much-needed deposition of melanin at (a) the wound site and (b) the infection 
      site in arthropods. The rapid deposition of DHI melanin is advantageous for 
      arthropods given their open circulatory system; the process limits blood loss 
      during wounding and prevents the spread of parasites by encapsulating them in 
      melanin, limiting the damage.
FAU - Sugumaran, Manickam
AU  - Sugumaran M
AUID- ORCID: 0000-0003-1508-9020
AD  - Department of Biology, University of Massachusetts, Boston, MA 02125, USA.
FAU - Evans, Jason
AU  - Evans J
AD  - Department of Chemistry, University of Massachusetts, Boston, MA 02125, USA.
FAU - Ito, Shosuke
AU  - Ito S
AUID- ORCID: 0000-0001-9182-5144
AD  - Department of Chemistry, Fujita Health University School of Medical Sciences, 
      Toyoake 470-1192, Japan.
FAU - Wakamatsu, Kazumasa
AU  - Wakamatsu K
AUID- ORCID: 0000-0003-1748-9001
AD  - Department of Chemistry, Fujita Health University School of Medical Sciences, 
      Toyoake 470-1192, Japan.
LA  - eng
PT  - Journal Article
DEP - 20201003
PL  - Switzerland
TA  - Int J Mol Sci
JT  - International journal of molecular sciences
JID - 101092791
RN  - 0 (Carboxylic Acids)
RN  - 0 (Indoles)
RN  - 0 (Melanins)
RN  - 0 (Polymers)
RN  - 12627-86-0 (eumelanin)
RN  - 63-84-3 (Dihydroxyphenylalanine)
RN  - EC 1.14.18.1 (Monophenol Monooxygenase)
RN  - Z3OC8499KG (5,6-dihydroxyindole)
SB  - IM
MH  - Animals
MH  - Carboxylic Acids/immunology/metabolism
MH  - Dihydroxyphenylalanine/immunology/metabolism
MH  - Immunity, Innate/*genetics/immunology
MH  - Indoles/immunology/*metabolism
MH  - Melanins/immunology/*metabolism
MH  - Monophenol Monooxygenase/genetics
MH  - Oxidative Stress/*genetics/immunology
MH  - Polymers/metabolism
PMC - PMC7583787
OTO - NOTNLM
OT  - 5,6-dihydroxyindole
OT  - DHI melanin
OT  - innate immunity
OT  - melanogenesis
OT  - oxidative polymerization
OT  - wound healing in arthropods.
COIS- The authors declare no conflict of interest.
EDAT- 2020/10/08 06:00
MHDA- 2021/02/24 06:00
PMCR- 2020/10/01
CRDT- 2020/10/07 01:01
PHST- 2020/08/27 00:00 [received]
PHST- 2020/09/26 00:00 [revised]
PHST- 2020/10/01 00:00 [accepted]
PHST- 2020/10/07 01:01 [entrez]
PHST- 2020/10/08 06:00 [pubmed]
PHST- 2021/02/24 06:00 [medline]
PHST- 2020/10/01 00:00 [pmc-release]
AID - ijms21197321 [pii]
AID - ijms-21-07321 [pii]
AID - 10.3390/ijms21197321 [doi]
PST - epublish
SO  - Int J Mol Sci. 2020 Oct 3;21(19):7321. doi: 10.3390/ijms21197321.