Toward the Rational Design of Sustainable Hair Dyes Using Cheminformatics Approaches: Step 2. Identification of Hair Dye Substance Database Analogs in the Max Weaver Dye Library
Tova N. Williams, George A. Van Den Driessche, Alain R. B. Valery, Denis Fourches, and Harold S. Freeman
ACS Sustainable Chemistry & Engineering
We report on part 2 of the cheminformatics-assisted development of sustainable hair dyes with enhanced technical and toxicological properties. In this study, an initial similarity search analysis was performed using two reference probes (C.I. Basic Orange 1 and Orange 2) as structural templates for the identification of potential analogs among the Max Weaver Dye Library (MWDL). The analysis revealed an interesting subset of 158 MWDL compounds that were close analogs of the classical aminoazobenzene dyes. A more detailed similarity search analysis of this subset ultimately led to the selection of four dyes for further in silico quantum calculations and experimental dye uptake (color depth on hair) studies. Results from quantum calculations indicated that the ESP surface properties of these dyes were consistent with nonionic interactions between dye and keratin. Among the four dye analogs, 2-amino-6-methyl-5-(phenyldiazenyl)pyrimidin-4-ol and 2-amino-4-chloro-1,6-dimethyl-5-(phenyldiazenyl)-pyrimidin-1-ium methyl sulfate achieved the best dye uptake on hair (∑K/S 227.31 and 149.26). The results of this study show that cheminformatics-based tools can be used to both build and screen dye databases containing potential alternatives to colorants believed to pose environmental concerns, providing a more sustainable (green) approach to hair dye design, by reducing the number of compounds requiring synthesis and analysis before suitable replacements are identified.
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