7 research outputs found
Silicon-Doped Carbon Nanotubes: Promising CO<sub>2</sub>/N<sub>2</sub> Selective Agents for Sequestering Carbon Dioxide
The
potential ability of single-walled silicon–carbon nanotubes
(SWSiCNTs) as CO<sub>2</sub> scavengers was investigated using density
functional theory calculations and (5,5) SWSiCNT models with 2%, 33%,
and 50% Si. It was found that while the reactions between CO<sub>2</sub> and pristine C tubes are endergonic, Si-doped materials have exergonic
adsorption routes. It was also found that 50–50 Si–C
composition is not required for the SWSiCNTs to be able to sequester
CO<sub>2</sub>, which seems to be relevant because this is the maximum
Si–C proportion allowed to maintain the SWSiCNT stability.
The modeled SWSiCNTs are predicted to be selective to CO<sub>2</sub> over N<sub>2</sub>, which is a critical feature for materials with
potential applications for CO<sub>2</sub> capture. The rate constants
for the SWSiCNT reactions with CO<sub>2</sub> were found to be around
10<sup>5</sup> M<sup>–1</sup> s<sup>–1</sup>,
which suggests that they are fast enough to ensure efficient CO<sub>2</sub> capture at room temperature. In addition, for the SWSiCNT
with 33% Si, the possibility of multiple CO<sub>2</sub> adsorption
was also investigated (up to seven CO<sub>2</sub> molecules). It was
found that all the consecutive reactions are significantly exergonic,
which indicates that one SWSiCNT is able to sequester several CO<sub>2</sub> equivalents. These findings suggest that SWSiCNT-based materials
are promising candidates for selectively, and efficiently, sequestering
CO<sub>2</sub> molecules, in particular, SWSiCNTs with intermediate
(2–33%) Si amounts
Ellagic Acid: An Unusually Versatile Protector against Oxidative Stress
Several
aspects related to the antioxidant activity of ellagic
acid were investigated using the density functional theory. It was
found that this compound is unusually versatile for protecting against
the toxic effects caused by oxidative stress. Ellagic acid, in aqueous
solution at physiological pH, is able of deactivating a wide variety
of free radicals, which is a desirable capability since in biological
systems, these species are diverse. Under such conditions, the ellagic
acid anion is proposed as the key species for its protective effects.
It is predicted to be efficiently and continuously regenerated after
scavenging two free radicals per cycle. This is an advantageous and
unusual behavior that contributes to increase its antioxidant activity
at low concentrations. In addition, the ellagic acid metabolites are
also capable of efficiently scavenging a wide variety of free radicals.
Accordingly, it is proposed that the ellagic acid efficiency for that
purpose is not reduced after being metabolized. On the contrary, it
provides continuous protection against oxidative stress through a
free radical scavenging cascade. This is an uncommon and beneficial
behavior, which makes ellagic acid particularly valuable to that purpose.
After deprotonation, ellagic acid is also capable of chelating copper,
in a concentration dependent way, decreasing the free radical production.
In summary, ellagic acid is proposed to be an efficient multiple-function
protector against oxidative stress
CADMA-Chem: A Computational Protocol Based on Chemical Properties Aimed to Design Multifunctional Antioxidants
A computational protocol aimed to design new antioxidants with versatile behavior is presented. It is called Computer-Assisted Design of Multifunctional Antioxidants and is based on chemical properties (CADMA-Chem). The desired multi-functionality consists of in different methods of antioxidant protection combined with neuroprotection, although the protocol can also be used to pursue other health benefits. The dM38 melatonin derivative is used as a study case to illustrate the protocol in detail. This was found to be a highly promising candidate for the treatment of neurodegeneration, in particular Parkinson’s and Alzheimer’s diseases. This also has the desired properties of an oral-drug, which is significantly better than Trolox for scavenging free radicals, and has chelates redox metals, prevents the ●OH production, via Fenton-like reactions, repairs oxidative damage in biomolecules (lipids, proteins, and DNA), and acts as a polygenic neuroprotector by inhibiting catechol-O-methyl transferase (COMT), acetylcholinesterase (AChE) and monoamine oxidase B (MAOB). To the best of our best knowledge, CADMA-Chem is currently the only protocol that simultaneously involves the analyses of drug-like behavior, toxicity, manufacturability, versatile antioxidant protection, and receptor–ligand binding affinities. It is expected to provide a starting point that helps to accelerate the discovery of oral drugs with the potential to prevent, or slow down, multifactorial human health disorders