Selection of quantum chemical descriptors by chemometric methods in the study of antioxidant activity of flavonoid compounds

Abstract

ABSTRACT:In the present study, the aim was to select electronic properties responsible for free radical scavenging ability of a set of 25 flavonoid compounds employing chemometric methods. Electronic parameters were calculated using the AM1 semiempirical method, and chemometric methods (principal component analysis, hierarchical cluster analysis, and k-nearest neighbor) were used with the aim to build models able to find relationships between electronic features and the antioxidant activity presented by the compounds studied. According to these models, four electronic variables can be considered important to discriminate more and less antioxidant flavonoid compounds: polarizability (␣), charge at carbon 3 (QC3), total charge at substituent 5 (QS5), and total charge at substituent 3Ј (QS3Ј). The features found as being responsible for the antioxidant activity of the flavonoid compounds studied are consistent with previous results found in the literature. The results obtained can also bring improvements in the search for better antioxidant flavonoid compounds.

Comprehensive evaluation of antioxidant activity: A chemometric approach using principal component analysis

“…In addition, the PCA profiles provide additional insights on the radical scavenging activity characterization by allowing visualization of a complex dataset, related both to the concentration and also the kinetic profiles of reaction with DPPH • , by a simple graphical representation. As we can see from this pattern, the natural occurring catecholamine (compounds 2, 5, 6) and their related drugs (compounds 10,12,13) show the same kinetic reaction profiles as the strong reference antioxidants gallic acid (19) and quercetin (22) while the profiles of synthetic catecholamine isoprenaline (8) is more similar with that of other antioxidants as caffeic acid (20), ascorbic acid (23), trolox (24) or α-tocopherol (25). Moreover the maxPC1 parameters showed an increasing of radical scavenging activity with the increase of compounds concentration, generally for the phenols and some common reference antioxidants (ascorbic acid, caffeic acid, kaempherol, trolox, α-tocopherol) and a different behavior for the investigated amines (with the exception of dopamine) and the most powerful antioxidants (quercetin and gallic acid) (Fig.…”

“…As a consequence, efforts have been made during the last years to standardize analytical methods and provide valid guidelines that should be pursued by future researchers. In this order, new methodologies and parameters were proposed and different regression tools and multivariate mathematical approaches were applied to find insights into the antiradical process and generate a complete antioxidant profile of different classes of compounds [23][24][25][26][27][28][29][30]. Therefore new chemometric derived parameters for expressing results are trying to be used which more or less serve the same purpose.…”

SAR and QSAR of the Antioxidant Activity of Flavonoids

“…Weber et al [135] used chemometric methods (principal component analysis (PCA), hierarchical cluster analysis (HCA), and k-nearest neighbour (KNN)) to build a model able to find a relationship between electronic features of a set of 25 flavonoid compounds and their antioxidant activity (TEAC). Quantum chemical calculations using the AM1 method were employed for the evaluation of molecular descriptors.…”

Propriedades químico-quânticas empregadas em estudos das relações estrutura-atividade

“…Desta forma, os métodos multivariados de análise são ferramentas de muita utilidade em estudos desse tipo, ou seja, análise de [16][17][18][19][20][21][22][23][24][25][26][27][28] Muitos trabalhos empregando descritores químico-quânticos são realizados na área da QSAR, mais do que em QSPR, ou seja, os descritores têm sido correlacionados com atividades biológicas, tais como atividade de inibição enzimática, atividade alucinogênica etc. 29,30 Em parte isto ocorre porque, historicamente, a procura por relações quantitativas com estruturas químicas iniciou-se com o desenvolvimento de métodos teóricos para a descoberta de fármacos. O emprego de descritores químico-quânticos tem grande utilidade para correlacionar a reatividade de compostos orgânicos, coeficientes de partição octanol/água, índices de retenção cromatográfica e várias outras propriedades físicas de moléculas.…”