RESUMO
Quantum chemical methods allow screening and prediction of peptide antioxidant activity on the basis of known experimental data. It can be used to design the selective proteolysis of protein sources in order to obtain products with antioxidant activity. Molecular geometry and electronic descriptors of redox-active amino acids, as well as tyrosine and methionine-containing dipeptides, were studied by Density Functional Theory method. The calculated data was used to reveal several descriptors responsible for the antioxidant capacities of the model compounds based on their experimentally obtained antioxidant capacities against ABTS (2,2'-Azino-bis-(3-ethyl-benzothiazoline-6-sulfonate)) and peroxyl radical. A formula to predict antioxidant activity of peptides was proposed.
Assuntos
Antioxidantes/química , Dipeptídeos/química , Antioxidantes/farmacologia , Dipeptídeos/farmacologia , Metionina/química , Relação Quantitativa Estrutura-Atividade , Tirosina/químicaRESUMO
Antioxidant capacity (AOC) against peroxyl radical and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical cation was measured for a series of p-hydroxybenzoic (HB) and p-hydroxycinnamic (HC) acids at different pH. Quantum-chemical computation was performed using Gaussian 3.0 software package to calculate the geometry and energy parameters of the same compounds. Significant correlations were revealed between AOC and a number of calculated parameters. The most significant AOC descriptors for the studied compounds against peroxyl radical were found to be HOMO energy, rigidity (η) and Mulliken charge on the carbon atom in m-position to the phenolic hydroxyl. The most significant descriptor of the antioxidant properties against the ABTS radical cation at ÑÐ 7.40 is electron transfer enthalpy from the phenolate ion. The mechanism of AOC realization has been proposed for HB and HC acids against both radicals.
Assuntos
Antioxidantes/química , Hidroxibenzoatos/química , Algoritmos , Ácidos Cumáricos/química , Concentração de Íons de Hidrogênio , Cinética , Parabenos/química , Propionatos , Teoria Quântica , SoftwareRESUMO
European seabass (Dicentrarchus labrax, Linnaeus, 1758) (L) and gilthead seabream (Sparus aurata, Linnaeus, 1758) (C) muscles were hydrolysated by Alcalase (Lalc, Calc) and Chymotrypsin (Lch, Cch) then hydrolysates were examined and their peptide profiles obtained. A total of 765, 794, 132 and 232 peptides were identified in Calc, Lalc, Cch and Lch, respectively. Although, Lch and Cch were expected to have more antioxidant capacity because of their peptide profiles, Alcalase hydrolysates observed in vitro, were slightly higher (TEAC assay for Calc: 848.11⯱â¯60.78⯵mol TE/g protein). Maximum inhibition of oxidative stress was determined for Lalc (12.8%⯱â¯4.5%) in MDCK1 cell lines. Highest proliferative capacity observed for Calc (147.0%⯱â¯3.1%) at MTT assay in MDCK1 cell culture. Lch showed the highest chemopreventive effect with a 40-60% decrease for human colon adenocarcinoma cell line HT-29. This research points out the importance of aquatic sources as raw materials for peptide researches.