Potential oxidative pathways of brain catecholamines

Abstract

The possibility that catecholamines can be oxidized via aberrant pathways in vivo is open to question, but in vitro oxidation via aerobic manipulations is established. Assuming oxidation does occur, we have examined quantitatively the fast chemical reactions of the initial oxidation products, the o-quinones. The nature and rates of these reactions were studies under the conditions simulating closely those which presumably exist in mammalian brain. The results are in close accord with existing literature and especially support oxidation pathways recently reported in [3H]-norepinephrine binding to particulate cell fractions.

Electrochemical reactions of catechol, methylcatechol and dopamine at tetrahedral amorphous carbon (ta-C) thin film electrodes

“…In neutral PBS at a scan rate of 50 mV/s, the oxidation peak appears at +0.39 V and the reduction peak at 0.00 V. The magnitude of the reduction peak is very small and the I red / I ox value is only 0.11 (Table 5). This behavior is explained by a coupled chemical reaction in which the dopamine o-quinone undergoes an intramolecular cyclization via 1,4-Michael addition with its amine side chain to form leucodopaminechrome (LDAC) [49][50][51]. At very slow scan rates, the o-quinone is completely consumed in the chemical reaction before it is reduced back to dopamine and therefore reduction does not occur at all.…”

Melanin as a virulence factor of Paracoccidioides brasiliensis and other dimorphic pathogenic fungi: a minireview

“…In C. neoformans, laccase appears to localize predominantly to the outer region of the cell wall where it can interact more directly with extracellullar substances and host immune products without the need for ancillary membrane or cytosolic transporters [54]. For example, oxidation of catecholamines on the outermost region of the cell wall lessens the exposure to oxidized dopamine products, which are cytotoxic in other systems [55]. Besides the oxidative effects on catecholamine, recombinant cryptococcal laccase exhibits iron oxidation activity converting Fe 2+ to Fe 3+ .…”

Molecularly imprinted silica films prepared by electroassisted deposition for the selective detection of dopamine

“…not complicated by the formation of leucodopaminechrome or polydopamine since the chemical step is much slower in acidic pH than in neutral medium. [16,23,46] As observed, the scan towards positive potentials shows an oxidation peak at +0.63 V corresponding to the irreversible oxidation of AA, and the oxidation peak of DA M a n u s c r i p t 11 appears at +0.81 V, overlapped to the diffusion tail of the AA oxidation. In the reverse scan dopaminechrome is reduced in a single peak at +0.79 V. …”

“…[22][23][24][25][26][27][28]. However, there are a number of problems associated to the electrochemical detection of DA due to the oxidative reaction of this compound.…”