Fields of Interest
  • Computational Chemistry

  • Oxidative Strees and Antioxidants

  • Atmosferic Chemistry

  • Carbon Naotubes

Currently Working On

  • Multifunctional antioxidants: From Computational Design to Practical Application.

The goal of this project is to find efficient antioxidant compounds with multipurpose behavior. They would include both primary and secondary antioxidant protection as well as other biological activities for targeting different health issues, particularly those involved in neuro-degenerative disorders.

  • Melatonin and related compounds as protectors against oxidative stress

  • Astrochemistry

  • Chemical reactivity of carbon-based nanomaterials

Juan Raul Alvarez-Idaboy
Adriana Pérez-González
Nino Russo
University of Calabria
Romina Castañeda-Arriaga
Russel J. Reiter
University of Texas
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Recent Publications

Melatonin and its metabolites vs oxidative stress: From individual actions to collective protection

Annia Galano, Russel J. Reiter.

Oxidative stress (OS) represents a threat to the chemical integrity of biomolecules including lipids, proteins, and DNA. The associated molecular damage frequently results in serious health issues, which justifies our concern about this phenomenon. In addition to enzymatic defense mechanisms, there are compounds (usually referred
to as antioxidants) that offer chemical protection against oxidative events. Among them, melatonin and its metabolites constitute a particularly efficient chemical family. They offer protection against OS as individual chemical entities through a wide variety of mechanisms including electron transfer, hydrogen transfer, radical adduct formation, and metal chelation, and by repairing biological targets. In fact, many of them including melatonin can be classified as multipurpose antioxidants. However, what seems to be unique to the melatonin’s family is their collective effects. Because the members of this family are metabolically related, most of them are expected to be
present in living organisms wherever melatonin is produced. Therefore, the protection exerted by melatonin against OS may be viewed as a result of the combined antioxidant effects of the parent molecule and its metabolites. Melatonin’s family is rather exceptional in this regard, offering versatile and collective antioxidant protection
against OS. It certainly seems that melatonin is one of the best nature’s defenses against oxidative damage.

Comprehensive Investigation of the Antioxidant and Pro-oxidant Effects of Phenolic Compounds: A Double-Edged Sword in the Context of Oxidative Stress?

Romina Castañeda-Arriaga, Adriana Pérez-González, Miguel Reina, J. Raúl Alvarez-Idaboy, Annia Galano

Oxidative stress (OS) is a health-threatening process that is involved, at least partially, in the development
of several diseases. Although antioxidants can be used as a chemical defense against OS, they might also exhibit prooxidant effects, depending on environmental conditions. In this work, such a dual behavior was investigated for phenolic compounds (PhCs) within the framework of the density functional theory and based on kinetic data. Multiple reaction mechanisms were considered in both cases. The presence of redox metals, the pH, and the possibility that PhCs might be transformed into benzoquinones were identified as key aspects in the antioxidant versus pro-oxidant effects of these compounds. The main virtues of PhCs as antioxidants are their radical trapping activity, their regeneration under physiological conditions, and their behavior as OH-inactivating ligands. The main risks of PhCs as pro-oxidants are predicted to be the role of phenolate ions in the reduction of metal ions, which can promote Fenton-like reactions, and the formation of benzoquinones that might cause protein arylation at cysteine sites. Although the benefits seem to overcome the hazards, to properly design chemical strategies against OS using PhCs, it is highly recommended to carefully explore their duality in this context.

Estimation of empirically fitted parameters for calculating pKa values of thiols in a fast and reliable way

Adriana Pérez‑González, Romina Castañeda‑Arriaga, Brisa Verastegui, Mirzam Carreón‑González, Juan Raúl Alvarez‑Idaboy, Annia Galano

Two empirically fitted parameters (m and C0) for the calculation of pKa values for thiols are provided for the first time, at 74 levels of theory. The coefficients were obtained by least-squares fits of the difference in Gibbs energy between each acid and its conjugated base versus experimental pKa values. The reliability of this fitted parameters approach (FPA) was confirmed using an independent test set of molecules. It was found that deviations from experiments are systematically lower than 0.5 pKa units, in terms of mean unsigned errors. In addition, all the tested levels of theory produced maximum absolute errors lower than 1 pKa unit. The parameters estimated here are expected to facilitate pKa calculations, using electronic structure-based strategies, with uncertainties close to the experimental ones. Albeit the present study deals only with molecules of modest complexity, i.e., the reliability of the FPA for more complex systems remains to be tested, it seems to be a promising approach for obtaining pKa values of thiols in a fast and reliable way.

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