Effect of purines on the oxidation of ascorbic acid induced by copper

Smith, Robert C.; Gore, J.

doi:10.1007/bf01129207

Cited by 7 publications

(3 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Accordingly, UAC and MUA are expected to be the most efficient purines for protecting ascorbate from copper‐catalyzed oxidation. They both have unsubstituted N atoms at positions 3 and 9 (Scheme ), which confirms earlier predictions . However, substitution on the N atoms in the purine skeleton is not the only important factor for this effect to take place.…”

Section: Resultssupporting

confidence: 88%

“…Albeit there seems to be no doubt that purines are excellent metal chelators, this feature alone may not be enough for them to act as protectors against metal‐induced OD. One of the earliest studies on the subject showed that purines are capable of protecting ascorbate from copper‐catalyzed oxidation, provided that the N atoms at positions 3 and 9 (Scheme ) are unsubstituted . Caffeine, theobromine, and xanthine have been reported to exhibit both antioxidant and pro‐oxidant effects .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Role of purines on the copper‐catalyzed oxidative damage in biological systems: Protection versus promotion

Castañeda‐Arriaga

Pérez-González

Álvarez-Idaboy

et al. 2017

Int J of Quantum Chemistry

View full text Add to dashboard Cite

Oxidative damage to biomolecules is a serious health-threatening issue, which leads to the development of several diseases. Oxidative conditions are frequently catalyzed by metal ions. In this study, the role of purines in the copper-catalyzed oxidative stress was investigated using the density functional theory. The obtained results indicate that purines can have a dual behavior, acting as both protectors and promoters of oxidative stress. Their protection role arises from their known radical scavenging activity, as well as their ability to chelate Cu(II) leading to complexes that areto some extent-harder to reduce than free Cu(II). Conversely, their pro-oxidant role is a consequence of their reductant behavior, when deprotonated. Thus, the purines' anions can reduce Cu (II) to Cu(I), making the latter available to be involved in Fenton-like reactions. Consequently, mixtures of purines and Cu(II), at pHs where the fraction of deprotonated purines is rather significant, would yield • OH radicals. In turn, these very reactive radicals would damage biological targets such as lipids, proteins, and DNA.antioxidants, kinetics, pro-oxidants, rate constants, reaction mechanism 1 | I N TR ODU C TI ON Oxidative damage (OD) to biological targets such as lipids, proteins, and DNA is a serious health-threatening phenomenon. It has been held responsible, at least in part, for the onset and development of several diseases including cancer [1][2][3] ; rheumatoid arthritis [4][5][6] ; neurodegenerative disorders such as Parkinson's and Alzheimer's diseases, depression, multiple sclerosis, and memory loss [7][8][9][10][11][12][13] ; cardiovascular diseases such as atherosclerosis, ischemia, hypertension, cardiac hypertrophy, heart failure, and cardiomyopathy [14][15][16][17] ; as well as renal [18][19][20] and pulmonary failure. [21][22][23] OD arises as a consequence of a chemical imbalance between the production and consumption of oxidants, known as oxidative stress (OS). [24] One of the most damaging oxidants in biological systems is the hydroxyl radical ( • OH). It can be produced, in the presence of metal ions such as Fe(II) or Cu(I), by Fenton or Fenton-like reactions (M q 1 H 2 O 2 ! M q11 1OH -1 • OH). However, the most stable and abundant forms of these two metals, under physiological conditions, are Fe(III) and Cu(II). Thus, • OH production would actually involve the metal-catalyzed Haber-Weiss recombination (HWR). It comprises two chemical steps. The first one is the reduction of the metal ions (M q11 1 O •2 2 ! M q 1 3 O 2 ) and the second one is the Fenton reaction. Consequently, redox active metal ions are of particular interest for the chemistry of living systems. These ions cannot only bind to DNA, but they can also promote OD to DNA by mediating the production of oxygen reactive species (ROS). [25] In fact metal-mediated OD to DNA has become an important topic in metal toxicity and carcinogenesis. [26][27][28][29]

show abstract