Biomaterial Database

Fe(III)-coordination properties of neuromelanin components: 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid. 2006

Louise K Charkoudian, and Katherine J Franz

Department of Chemistry, Duke University, P.O. Box 90346, Durham, North Carolina 27708, USA.

The Fe(III)-coordination chemistry of neuromelanin building-block compounds, 5,6-dihydroxyindole (DHI), 5,6-dihydroxyindole-2-carboxylic acid (DHICA), and 5,6-dihydroxy-N-methyl-indole (Me-DHI), and the neurotransmitter dopamine were explored in aqueous solution by anaerobic pH-dependent spectrophotometric titrations. The Fe(III)-binding constants and pH-dependent speciation parallel those of catechol in that mono, bis, and tris FeLx species are present at concentrations dependent on the pH. The bis FeL2 dihydroxyindole species are favorable for L = DHI and DHICA under neutral to mildly acidic conditions. DHI and DHICA are stronger Fe(III) chelates than catechol, dopamine, and Me-DHI at pH values from 3 to 10. Oxidation studies reveal that iron accelerates the air oxidation of DHI and DHICA.

UI	MeSH Term	Description	Entries
D007211	Indoles	Benzopyrroles with the nitrogen at the number one carbon adjacent to the benzyl portion, in contrast to ISOINDOLES which have the nitrogen away from the six-membered ring.
D007501	Iron	A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN.	Iron-56,Iron 56
D008543	Melanins	Insoluble polymers of TYROSINE derivatives found in and causing darkness in skin (SKIN PIGMENTATION), hair, and feathers providing protection against SUNBURN induced by SUNLIGHT. CAROTENES contribute yellow and red coloration.	Allomelanins,Melanin,Phaeomelanins
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D010300	Parkinson Disease	A progressive, degenerative neurologic disease characterized by a TREMOR that is maximal at rest, retropulsion (i.e. a tendency to fall backwards), rigidity, stooped posture, slowness of voluntary movements, and a masklike facial expression. Pathologic features include loss of melanin containing neurons in the substantia nigra and other pigmented nuclei of the brainstem. LEWY BODIES are present in the substantia nigra and locus coeruleus but may also be found in a related condition (LEWY BODY DISEASE, DIFFUSE) characterized by dementia in combination with varying degrees of parkinsonism. (Adams et al., Principles of Neurology, 6th ed, p1059, pp1067-75)	Idiopathic Parkinson Disease,Lewy Body Parkinson Disease,Paralysis Agitans,Primary Parkinsonism,Idiopathic Parkinson's Disease,Lewy Body Parkinson's Disease,Parkinson Disease, Idiopathic,Parkinson's Disease,Parkinson's Disease, Idiopathic,Parkinson's Disease, Lewy Body,Parkinsonism, Primary
D004298	Dopamine	One of the catecholamine NEUROTRANSMITTERS in the brain. It is derived from TYROSINE and is the precursor to NOREPINEPHRINE and EPINEPHRINE. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. A family of receptors (RECEPTORS, DOPAMINE) mediate its action.	Hydroxytyramine,3,4-Dihydroxyphenethylamine,4-(2-Aminoethyl)-1,2-benzenediol,Dopamine Hydrochloride,Intropin,3,4 Dihydroxyphenethylamine,Hydrochloride, Dopamine
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D013057	Spectrum Analysis	The measurement of the amplitude of the components of a complex waveform throughout the frequency range of the waveform. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Spectroscopy,Analysis, Spectrum,Spectrometry
D017186	Titrimetry	The determination of the concentration of a given component in solution (the analyte) by addition of a liquid reagent of known strength (the titrant) until an equivalence point is reached (when the reactants are present in stoichiometric proportions). Often an indicator is added to make the equivalence point visible (e.g., a change in color).