Structure-Affinity Binding Relationships by Principal-Component-Regression Analysis of Anthraquinone Dyes

GRID formalism for the comparative molecular surface analysis: application to the CoMFA benchmark steroids, azo dyes, and HEPT derivatives

Shape analysis is a powerful tool in chemistry and drug design, and molecular surface defines shape in the molecular scale. In the current publication we presented a novel formalism for the comparative molecular surface analysis (s-CoMSA). The method enables both quantitative modeling of 3D-QSAR and finding possible pharmacophoric sites. The method provides very predictive models for the CBG activity of the benchmark steroid series, tinctorial properties of the heterocyclic azo dyes and anti-HIV activity of the HEPT series.

Comparative Molecular Surface Analysis (CoMSA) for Modeling Dye−Fiber Affinities of the Azo and Anthraquinone Dyes

Despite recent investigations aimed at modeling 3D QSAR for dye molecules a controversy still exists: can a pharamacophore hypothesis be used for such purposes. In the present publication we reported on the application of the CoMSA method for modeling 3D QSAR of azo and anthraquinone dyes. We obtained very predictive models, which significantly outperform those reported in the previous CoMFA studies, especially for the azo dyes. Our results proved the previous conclusion that steric requirements are far less pronounced for the cellulose cavities than for the classical drug receptor. Moreover, our results indicate that all molecular surface segments are important for dye-fiber interactions, which also makes an important difference in relation to the classical drug pharmacophore. On the other hand, high predictivity of the CoMSA models indicates that a pharmacophore concept is suitable for the description of the dye-fiber interactions. However, this pharmacophore must substantially differ from the drug pharmacophore used for the illustration of the drug-receptor interactions. From a theoretical point of view dye-cellulose interactions can be an interesting case in which shape decides the activity rules not by the steric repulsion but as a cofactor determining the electrostatic potential distribution.

Comparative molecular field analysis (CoMFA) of anionic azo dye-fiber affinities I: gas-phase molecular orbital descriptors

This paper presents quantitative structure-activity relationship (QSAR) models for a series of 30 anionic azo dyes applied to cellulose fiber by comparative molecular field analysis. Two forms of the dye molecules (neutral and anionic) are compared. Neutral structures give better statistical results than the anionic species. The electronic and structural properties of these dyes were calculated by the semiempirical AM1 method. The results indicate the predominance of electrostatic interactions in dye-cellulose binding. The dominant contribution of the HOMO orbital molecular energy, used as descriptor, can be explained by the donor ability of the dye molecules in the dye adsorption on cellulose.

Steric and electrostatic effects in dye-cellulose interactions by the MTD and CoMFA approaches

This paper presents the application of the MTD (minimal steric difference) analysis and CoMFA (comparative molecular field analysis) to series of anthraquinone vat, mono and disazo and disperses dyes with known affinities for cellulose fiber. A comparison of the results demonstrates that these methods usually agree with the prediction of structural features favorable for dyeing. A series of n = 49 anthraquinone vat dyes was studied by MTD with r2 between 0.903 and 0.941 and r2CV values in the range of 0.827-0.878. For CoMFA, r2 = 0.992, r2CV = 0.841 were obtained; the CoMFA field is in rather good agreement with vertex attributions, by MTD for attractive and repulsive vertices. Anionic disazo dyes were studied by the CoMFA method (n = 21, r2 = 0.999, r2CV = 0.703). Monoazo dyes (several series) were studied by CoMFA and MTD. The effect of lipophilicity on dye fiber affinity was, also, studied for these dyes. Disperse dye adsorption was analyzed by MTD and CoMFA (n = 27, r2 = 0.925, r2CV = 0.776). Conclusions refer to the effect of structural features of dye molecules upon adsorption on cellulose fibers.

A chemometric approach to understanding the bioelimination of anionic, water-soluble dyes by a biomass using empirical and semi-empirical molecular descriptors

Single correlation and multiple linear regression analyses have been applied to understand the bioelimination of 103 anionic, water-soluble dyes by a biomass at a wastewater treatment works. The chemometric approach highlighted that anionic, water-soluble dyes with larger molecular size/ionic charge ratios and containing more primary aromatic amines and unsulphonated naphthalene nuclei and fewer aliphatic alcohol groups had superior levels of bioelimination.