The natural anthraquinone dye emodin: Eco/genotoxicological characterization for aquatic organisms.

Emodin is an anthraquinone secondary metabolite produced by several species of plants and fungi. Emodin is known for its pharmacological versatility, and, in the textile industry, for its good dyeing properties. However, its use in the textile industry can result in the formation and disposal of large volumes of wastewater. Emodin mutagenicity has been shown in bacteria and in human cells, but little is known about its possible toxic, genotoxic, or mutagenic effects in aquatic organisms. We have evaluated the eco/genotoxicity of emodin to aquatic organisms. Emodin was toxic to Daphnia similis (EC50 = 130 µg L-1) and zebrafish embryos (LC50 = 25 µg L-1). No toxicity was observed for Raphidocelis subcapitata, Ceriodaphnia dubia, or Parhyale hawaiensis. Additional biochemistry/molecular studies are needed to elucidate the toxic/mutagenic pathways of emodin in aquatic organisms. The PNEC value for emodin was 0.025 µg L-1. In addition to mutagenicity in the Salmonella/microsome assay, emodin was mutagenic in the micronucleus assay in the amphipod P. hawaiensis. Among the anthraquinone dyes tested to date, natural or synthetic, emodin was the most toxic to aquatic species.

Waterless Dyeing and In Vitro Toxicological Properties of Biocolorants from Cortinarius sanguineus.

As a part of an ongoing interest in identifying environmentally friendly alternatives to synthetic dyes and in using liquid CO2 as a waterless medium for applying the resulting colorants to textiles, our attention turned to yellow-to-red biocolorants produced by Cortinarius sanguineus fungus. The three principal target anthraquinone colorants (emodin, dermocybin, and dermorubin) were isolated from the fungal bodies using a liquid-liquid separation method and characterized using 700 MHz NMR and high-resolution mass spectral analyses. Following structure confirmations, the three colorants were examined for dyeing synthetic polyester (PET) textile fibers in supercritical CO2. We found that all three biocolorants were suitable for dyeing PET fibers using this technology, and our attention then turned to determining their toxicological properties. As emodin has shown mutagenic potential in previous studies, we concentrated our present toxicity studies on dermocybin and dermorubin. Both colorants were non-mutagenic, presented low cellular toxicity, and did not induce skin sensitization. Taken together, our results indicate that dermocybin and dermorubin possess the technical and toxicological properties needed for consideration as synthetic dye alternatives under conditions that are free of wastewater production.

Copaifera langsdorffii Desf. bark extract: optimisation of dyeing conditions to wool and colour fastness properties.

The ability to add value to waste materials from industrial operations has come to the attention of the wood processing industry, with reports, for example, of extracts from the bark tree conveying colour and UV protection to textile fibres. The objective of the present work was to expand our developments in this arena by using Copaifera langsdorffii Desf. bark extract as a natural dye for textile dyeing. A complete 2³-statistical experimental design and the central point was elaborated. The results showed that the optimal dyeing conditions were 98 °C, for 60 min, using undiluted bark extract. The dyed fabric was analysed by a spectrophotometer using the CIELAB system for evaluation of the colour strength. The results showed a K/S value of 5.78, and the dyed fabric had good colour fastness to rubbing and washing.

Molecular characterization and ecotoxicological evaluation of the natural dye madder and its chlorinated products.

There has been increased interest in the use of natural dyes for textile coloration as alternatives to synthetic dyes, due to the general belief that natural dyes are more environmentally friendly. However, natural dyes have poor affinity for textiles, which can lead to high dye levels in the resultant wastewater. While chlorine treatment has proven to be effective for dye wastewater disinfection and decolorization, this process can also lead to the formation of more toxic degradation products for certain synthetic dyes. On the other hand, little information is available regarding the ecotoxicity of natural dyes and their chlorination products. To advance knowledge in this area, madder was selected due to its historical importance and wide application in the textile industry. Specifically, we sought to characterize the chlorine-induced degradation products of an aqueous madder solution and to assess their ecotoxicity. The main component of the present madder sample was Alizarin (89.8%). Chlorination led to complete decolorization, and 2-hydroxynaphthalene-1,4-dione and phthalic anhydride were identified as key degradation products. Chlorination of madder decreased toxicity to Daphnia similis (microcrustacean) 10-fold and removed the toxicity to Raphidocellis subcapitata (algae), when compared to the parent dye.

In situ Chelation of Monoazo Dyes in Human Hair Keratin Fibers Using Environmentally Benign Metal Ions.

The coloration of human hair keratin fibers has long involved the oxidative coupling of primarily aromatic amines and phenols inside the fibers with the aid of harsh agents such as H2O2 and NH4OH. Further, the traditional process has exposed millions of consumers and their hairstylists to toxic substances such as skin sensitizers. While alternative hair dyeing processes have been explored, they fail to be competitive with the traditional method, for reasons including impracticality and limited colors achievable. In the present study, we developed an approach to imparting color to human hair fibers that involves entrapping colorants inside hair fibers by forming chelated monoazo dyes in situ. Dyes employed were based on monoarylide, arylazopyrazolone, and arylazonaphthol families, which display yellow, orange, and magenta colors on dyed hair. The dyes were applied at 40 °C without the use of oxidants and alkali associated with current commercial hair dyes, with the best dye uptake observed when the arylazonaphthol dye was employed. The dyed hair fibers showed good durability to washing, and treatment of these fibers with Al3+ or Fe3+ ions at 40 °C led to the rapid in situ formation of 1:2 metal/dye structures. In addition, the dyed hair was soft, indicating that chelated dye occupies the interior of the fibers rather than the surface. Such an approach can be applied to the coloration of other materials, including textiles.

A promising Ames battery for mutagenicity characterization of new dyes.

When testing new products, potential new products, or their impurities for genotoxicity in the Ames test, the quantity available for testing can be a limiting factor. This is the case for a dye repository of around 98,000 substances the Max Weaver Dye Library (MWDL). Mutagenicity data on dyes in the literature, although vast, in several cases is not reliable, compromising the performance of the in silico models. In this report, we propose a strategy for the generation of high-quality mutagenicity data for dyes using a minimum amount of sample. We evaluated 15 dyes from different chemical classes selected from 150 representative dyes of the MWDL. The purity and molecular confirmation of each dye were determined, and the microplate agar protocol (MPA) was used. Dyes were tested at the limit of solubility in single and concentration-response experiments using seven strains without and with metabolic activation except for anthraquinone dyes which were tested with eight strains. Six dyes were mutagenic. The most sensitive was YG1041, followed by TA97a > TA98 > TA100 = TA1538 > TA102. YG7108 as well as TA1537 did not detect any mutagenic response. We concluded that the MPA was successful in identifying the mutagenicity of dyes using less than 12.5 mg of sample. We propose that dyes should be tested in a tiered approach using YG1041 followed by TA97a, TA98, and TA100 in concentration-response experiments. This work provides additional information on the dye mutagenicity database available in the literature.

Data from X-ray crystallographic analysis and DFT calculations on isomeric azo disperse dyes.

X-ray crystallography and DFT calculations were used to characterize the molecular nature and excited state properties of isomeric photostable azo dyes for textile fibers undergoing extensive sunlight exposure. Structural data in CIF files arising from X-ray analysis are reported and the complete files are deposited with the Cambridge Crystallographic Data Centre as CCDC 1548989 (https://www.ccdc.cam.ac.uk/structures/Search?Ccdcid=1548989) and CCDC 1548990 (https://www.ccdc.cam.ac.uk/structures/Search?Ccdcid=1548990). Data from calculating the vertical electronic excitation of 20 excited states for each dye and from calculating excited state oxidation potential (ESOP) and Frontier HOMO/LUMO isosurfaces are also presented. This data is related to the article "Molecular and excited state properties of isomeric scarlet disperse dyes" (Lim et al., 2018) [1].

Weaver's historic accessible collection of synthetic dyes: a cheminformatics analysis.

We present the Max Weaver Dye Library, a collection of ∼98 000 vials of custom-made and largely sparingly water-soluble dyes. Two years ago, the Eastman Chemical Company donated the library to North Carolina State University. This unique collection of chemicals, housed in the College of Textiles, also includes tens of thousands of fabric samples dyed using some of the library's compounds. Although the collection lies at the core of hundreds of patented inventions, the overwhelming majority of this chemical treasure trove has never been published or shared outside of a small group of scientists. Thus, the goal of this donation was to make this chemical collection, and associated data, available to interested parties in the research community. To date, we have digitized a subset of 2700 dyes which allowed us to start the constitutional and structural analysis of the collection using cheminformatics approaches. Herein, we open the discussion regarding the research opportunities offered by this unique library.

Developments in PDT Sensitizers for Increased Selectivity and Singlet Oxygen Production.

Photodynamic therapy (PDT) is a minimally-invasive procedure that has been clinically approved for treating certain types of cancers. This procedure takes advantage of the cytotoxic activity of singlet oxygen (¹O2) and other reactive oxygen species (ROS) produced by visible and NIR light irradiation of dye sensitizers following their accumulation in malignant cells. The main two concerns associated with certain clinically-used PDT sensitizers that have been influencing research in this arena are low selectivity toward malignant cells and low levels of ¹O2 production in aqueous media. Solving the selectivity issue would compensate for photosensitizer concerns such as dark toxicity and aggregation in aqueous media. One main approach to enhancing dye selectivity involves taking advantage of key methods used in pharmaceutical drug delivery. This approach lies at the heart of the recent developments in PDT research and is a point of emphasis in the present review. Of particular interest has been the development of polymeric micelles as nanoparticles for delivering hydrophobic (lipophilic) and amphiphilic photosensitizers to the target cells. This review also covers methods employed to increase ¹O2 production efficiency, including the design of two-photon absorbing sensitizers and triplet forming cyclometalated Ir(III) complexes.

Aromatic amines: use in azo dye chemistry.

This chapter provides an overview of the chemical structures and properties of aromatic amines and their role in the development and utility of azo dyes. Approaches to the design of environmentally benign alternatives to genotoxic primary aromatic amines, as azo dye precursors, are included.

Chlorine disinfection of dye wastewater: implications for a commercial azo dye mixture.

Azo dyes, the most widely used family of synthetic dyes, are often employed as colorants in areas such as textiles, plastics, foods/drugs/cosmetics, and electronics. Following their use in industrial applications, azo dyes have been found in effluents and various receiving waters. Chemical treatment of effluents containing azo dyes includes disinfection using chlorine, which can generate compounds of varying eco/genotoxicity. Among the widely known commercial azo dyes for synthetic fibers is C.I. Disperse Red 1. While this dye is known to exist as a complex mixture, reports of eco/genotoxicity involve the purified form. Bearing in mind the potential for adverse synergistic effects arising from exposures to chemical mixtures, the aim of the present study was to characterize the components of commercial Disperse Red 1 and its chlorine-mediated decoloration products and to evaluate their ecotoxicity and mutagenicity. In conducting the present study, Disperse Red 1 was treated with chlorine gas, and the solution obtained was analyzed with the aid of LC-ESI-MS/MS to identify the components present, and then evaluated for ecotoxicity and mutagenicity, using Daphnia similis and Salmonella/microsome assays, respectively. The results of this study indicated that chlorination of Disperse Red 1 produced four chlorinated aromatic compounds as the main products and that the degradation products were more ecotoxic than the parent dye. These results suggest that a disinfection process using chlorine should be avoided for effluents containing hydrophobic azo dyes such commercial Disperse Red 1.

Effects of bis-carbazole based D-π-A sensitizers on solar energy capture in DSSCs.

A new series of molecular engineered dyes having a carbazole (CA) based bulky donor was synthesized and compared to a previously studied set of dyes having a diphenyl amine (DP) donor for their use in dye sensitized solar cells. In this work, their photophysical, electrochemical, and kinetic properties were measured and molecular modeling methods were used to predict their electronic and physical properties. Regarding the latter, TDDFT studies adopting different exchange correlation functionals were performed to predict solar capture behavior of these sensitizers. The calculated electronic energies showed that the introduction of the bulky CA donor gave a greater negative shift on E(HOMO) rather than E(LUMO), imparting the CA series of dyes a red shifted absorption. On the other hand, tuning of the spacer unit by using different heterocylic rings was sensitive to the shift of E(LUMO) shift. Better light absorption and driving force of devices based on the CA series were counteracted with negative effects related to the electron injection yield and electron recombination lifetime. The origin of the lower efficiency of the CA dye based devices was investigated in terms of dye load, charge recombination lifetime, in tandem with modeling studies. Results from assessing the effects of different heterocyclic rings, as a π conjugation unit on photovoltaic performance showed that the thiophene unit gave the highest current. On the other hand, CA- and DP-based dyes having an N-methyl pyrrole unit afforded the highest V(oc). The best DSSC performance in the CA series was achieved by the thiophene derivative, where η = 3.05% with J(sc) = 6.29 mA cm(-2), V(oc) = 673 mV and FF = 0.72 under 100 mW m(-2) irradiation.

Dye Sensitizers for Photodynamic Therapy.

Photofrin® was first approved in the 1990s as a sensitizer for use in treating cancer via photodynamic therapy (PDT). Since then a wide variety of dye sensitizers have been developed and a few have been approved for PDT treatment of skin and organ cancers and skin diseases such as acne vulgaris. Porphyrinoid derivatives and precursors have been the most successful in producing requisite singlet oxygen, with Photofrin® still remaining the most efficient sensitizer (quantum yield = 0.89) and having broad food and drug administration (FDA) approval for treatment of multiple cancer types. Other porphyrinoid compounds that have received approval from US FDA and regulatory authorities in other countries include benzoporphyrin derivative monoacid ring A (BPD-MA), meta-tetra(hydroxyphenyl)chlorin (m-THPC), N-aspartyl chlorin e6 (NPe6), and precursors to endogenous protoporphyrin IX (PpIX): 1,5-aminolevulinic acid (ALA), methyl aminolevulinate (MAL), hexaminolevulinate (HAL). Although no non-porphyrin sensitizer has been approved for PDT applications, a small number of anthraquinone, phenothiazine, xanthene, cyanine, and curcuminoid sensitizers are under consideration and some are being evaluated in clinical trials. This review focuses on the nature of PDT, dye sensitizers that have been approved for use in PDT, and compounds that have entered or completed clinical trials as PDT sensitizers.

Evaluation of new 2,2'-dimethyl-5,5'-dipropoxybenzidine- and 3,3'-dipropoxybenzidine-based direct dye analogs for mutagenic activity by use of the Salmonella/mammalian mutagenicity assay.

As part of a continuing study aimed at establishing structure-activity relationships and heuristic principles useful for the design of non-genotoxic azo dyes, a series of new direct dyes based on two non-mutagenic benzidine analogs, 2,2'-dimethyl-5,5'-dipropoxybenzidine and 3,3'-dipropoxybenzidine, were evaluated for mutagenic activity in Salmonella typhimurium strains TA98 and TA100. These strains are widely used for mutagenicity screening and have been shown to detect the mutagenic activity of benzidine analogs. While some toxicity was seen with some dyes at high doses, all of the dyes examined were judged non-mutagenic with and without metabolic activation in the standard Salmonella plate-incorporation assay. The results in the standard test are consistent with the properties of the diamines themselves. However, only one of the dyes was non-mutagenic when a reductive-metabolism pre-incubation assay was used. The results of this study suggest that although benzidine analogs are potential replacements for benzidine, there is a need to understand which mutagenic products are produced when reductive metabolism is present. There is also a need to know whether or not metal complexes of these dyes are mutagenic. Such information will allow the development of new non-mutagenic azo dyes.

The contribution of azo dyes to the mutagenic activity of the Cristais River.

To verify whether dyes emitted within the discharge of a dye processing plant were contributing to the mutagenicity repeatedly found in the Cristais River, Sao Paulo, Brazil, we chemically characterized the following mutagenic samples: the treated industrial effluent, raw and treated water, and the sludge produced by a Drinking Water Treatment Plant (DWTP) located approximately 6 km from the industrial discharge. Considering that 20% of the dyes used for coloring activities might be lost to wastewaters and knowing that several dyes have mutagenic activity, we decided to analyze the samples for the presence of dyes. Thin layer chromatographic analysis indicated the presence of three prevalent dyes in all samples, except for the drinking water. This combination of dyes corresponded to a commercial product used by the industry, and it tested positive in the Salmonella assay. The structures of the dye components were determined using proton magnetic resonance and mass spectrometric (MS) methods, and the dyes were tested for mutagenicity. The blue component was identified as the C.I. Disperse Blue 373, the violet as C.I. Disperse Violet 93, and the orange as C.I. Disperse Orange 37. The dyes showed mutagenic responses of 6300, 4600, and 280 revertants/microg for YG1041 with S9 respectively. A bioassay-directed fractionation/chemical analysis showed that the C.I. Disperse Blue 373 contributed 55% of the mutagenic activity of the DWTP sludge. We showed that these dyes contributed to the mutagenic activity found in the Cristais River environmental samples analyzed and are indirectly affecting the quality of the related drinking water. Therefore, we believe that this type of discharge should be more thoroughly characterized chemically and toxicologically. Additionally, human and ecological risks associated with the release of dye processing plant effluents should be more fully investigated, especially where the resultant water is taken for human consumption.

Developing azo and formazan dyes based on environmental considerations: Salmonella mutagenicity.

In previous papers, the synthesis and chemical properties of iron-complexed azo and formazan dyes were reported. It was shown that in certain cases iron could be substituted for the traditionally used metals such as chromium and cobalt, without having an adverse effect on dye stability. While these results suggested that the iron analogs were potential replacements for the commercially used chromium and cobalt prototypes, characterization of potentially adverse environmental effects of the new dyes was deemed an essential step in their further development. The present paper provides results from using the Salmonella/mammalian microsome assay to determine the mutagenicity of some important commercial metal complexed dyes, their unmetallized forms, and the corresponding iron-complexed analogs. The study compared the mutagenic properties of six unmetallized azo dyes, six commercial cobalt- or chromium-complexed azo dyes, six iron-complexed azo dyes, six unmetallized formazan dyes, and six iron-complexed formazan dyes. The results of this study suggest that the mutagenicity of the unmetallized dye precursors plays a role in determining the mutagenicity of the iron-complexes. For the monoazo dye containing a nitro group, metal complex formation using iron or chromium decreased or removed mutagenicity in TA100; however, little reduction in mutagenicity was noted in TA98. For the formazan dye containing a nitro group, metal-complex formation using iron increased mutagenicity. Results varied for metal-complexes of azo and formazan dyes without nitro groups, but in general, the metal-complexed dyes based on mutagenic ligands were also mutagenic, while those dyes based on nonmutagenic ligands were nonmutagenic.

Non-mutagenic organic pigment intermediates. I. 3,3'-dipropoxybenzidine.

Crystals of the title compound, C(18)H(24)N(2)O(2), were grown from ethanol by slow evaporation and the structure has been determined. The molecule resides on a crystallographic inversion center and the biphenyl moiety is essentially planar. The structure forms an infinite two-dimensional array of N-H.pi(arene) interactions parallel to the (101) direction.