Oxidation of adenine

A-Chlorosuccinimide 1 N NaOH." With this method, the sulfide is oxidized completely to the sulfone, which is cleaved with hydroxide more readily than the sulfoxide formed by periodate oxidation. It has been reported that oxidation of the sulfide leads to oxidation of adenine and gua-nine." However, see the discussion of the TPTE group below. 

Fig. 16. Mechanism for the electrochemical oxidation of adenine at the PGE. Molar amounts of products are those formed in 1 M HOAc...

Correlations between Electrochemical and Biological Oxidation of Adenine... 

Electrochemical oxidation of natural and synthetic DNA performed at pyrolytic graphite [16] and glassy carbon [3-6,17,18] electrodes showed that at pH 4.5 only the oxidation of the purine residues in polynucleotide chains is observed. Using differential pulse voltammetry, the less positive peak corresponds to the oxidation of guanine residues and the peak at more positive potentials is due to the oxidation of adenine residues. 

G. Dryhurst and P.J. Elving, Electrochemical oxidation of adenine reaction products and mechanisms, J. Electrochem. Soc., 5 (1968) 1014-1022. 

Electrochemical oxidation of adenine and hydroxyadenines in aqueous solution at pH 3-11.2 using a pyrolytic graphite electrode gave after extended oxidation, a diimine species which undergoes a series of reactions to give various ring-opened products <9UCS(P2)1369> (see Section 7.11.5.2.4). 

Peracid iV-oxidation of purines gives 1- and/or 3-oxides, depending on exact conditions. Adenine and adenosine give 1-oxides, whereas guanine affords the 3-oxide. The 3-oxide of purine itself has been obtained via oxidation of 6-cyanopurine (at N-3), then hydrolysis and decarboxylation, the relatively easy loss of carbon dioxide echoing the analogous process discussed for pyridine a-acids (8.11). The A/-7-oxide of adenine can be prepared by oxidation of 3-benzyl-3//-adenine, followed by deprotection. ... 

The structures of the dialdehydes obtained by periodate oxidation of adenine nucleosides have been investigated no free aldehyde was detected, and the major form present in crystalline products was thought to be the di-hemi-acetal hydrate... 

BENDICH A., BROWN G.B., PHILIPS F.S., THIERSCH J.B. Direct oxidation of adenine... 

A mechanism was proposed [143] for electrooxidation of adenine at the graphite electrode that involves two sequential 2e — 2H oxidations to give first 2-oxy- and 2,8-dioxyadenine (Fig. 11 A). Then, a further two electron oxidation at the C(4)=C(5) double bond occurs to give a dicarbonium ion. Thus the mechanism for oxidation of adenine involves three primary 2e"-2H oxidations. The final product (the diimine) may undergo hydrolysis and fragmentation which results in further products. 

In general, it may be said that all of the converraons shown in Fig. 13 occur in various oi nisms, but the quantitative significance of each pathway is not known. In this connection the oxidation of adenine in mammalian tissues was attributed originally to the enzyme adenase 244)- However, adenase was found to be virtually absent from aninud tissues, or present in such extremely low concentrations 244-248) that adenosine breakdown via the free base adenine was unlikely. 

It is now known that small amounts of adenine may be oxidized by xanthine oxidase 201, 247, 248) and that 2,8-dihydroxyadenine is the product 201, 214). In fact, 2,8-dihydroxyadenine crsnstallized in the renal parenchyma after intraperitoneal administration of lai doses of adenine 201,249). 8-Hydroxyadenine is the major intermediate in the oxidation of adenine to 2,8-dihydroxyadenine by xanthine oxidase 250). Of great in-... 

The oxidation of L-tyrosine by hexachloroiridate(lV) exhibits first-order dependence on both Ir(IV) and L-tyrosine. The reaction rate increases with increase in ionic strength and decreases with increase in acidity. Dityrosine has been identified as the main product, activation parameters have been evaluated, and a mechanism has been suggested. DFT study of the oxidation of a guanine nucleotide by platinum(lV) indicated that a key step in the mechanism is electron transfer from guanine to platinum(lV). It has been shown that out of several different Pt(lV)-guanine adducts, one which is formed from replacement of an axial chlorine ligand in the platinum(lV) complex undergoes oxidation more easily. The oxidation of adenine is found to be more difficult as it involves disruption of an aromatic jt system. ... 

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