Identification of contact allergens in C.I. Solvent Red 23 (commercial Sudan III) by chemical analysis and animal testing

Sensitive Method for the Identification of Potential Sensitizing Impurities in Reaction Mixtures by Fluorescent Nitrobenzoxadiazole-Labeled Glutathione

Allergic contact dermatitis is a critical issue in the development of new chemicals. Minor impurities with strong skin-sensitizing properties can be generated as byproducts. However, it is very difficult to identify these skin sensitizers in product mixtures. In this study, fluorescent nitrobenzoxadiazole-labeled glutathione (NBD-GSH) was synthesized to identify small amounts of skin sensitizers in reaction mixtures. Twelve known skin sensitizers and three nonsensitizers were reacted with NBD-GSH. Adducts formed only with the skin sensitizers, which allowed for their detection by a fluorescence detector. Liquid chromatography-mass spectrometry (LC-MS) analyses showed that NBD-GSH reacted with the skin sensitizers via its thiol and amino groups. An adduct of NBD-GSH with the strong skin sensitizer 1-chloro-2,4-dinitrobenzene was detected with a limit of detection of 6 × 10^-8 mol/L by high-performance liquid chromatography with fluorescence detection. When a reaction mixture from primary alcohol oxidation was incubated with NBD-GSH, a NBD-GSH adduct formed with skin-sensitizing aldehyde impurities and could be specifically detected by LC-MS with fluorescence detection. This method will be useful for detection and identification of small amounts of skin sensitizers in raw materials, intermediates, reaction mixtures, and end products in the chemical industry.

Cosmetic Analysis Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI-MSI)

A new "omic" platform-Cosmetomics-that proves to be extremely simple and effective in terms of sample preparation and readiness for data acquisition/interpretation is presented. This novel approach employing Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI-MSI) for cosmetic analysis has proven to readily identify and quantify compounds of interest. It also allows full control of all the production phases, as well as of the final product, by integration of both analytical and statistical data. This work has focused on products of daily use, namely nail polish, lipsticks and eyeliners of multiple brands sold in the worldwide market.

“Fast peaks” in chromatograms of Sudan dyes

The analysis of Sudan dyes has gained considerable attention during last years. In several publications multiple peaks in chromatograms of Sudan III and Sudan IV have been detected. It is demonstrated in this work that if the sample is kept in darkness before analysis, only one chromatographic peak appears for Sudan III or Sudan IV. In normal lighting conditions two peaks are observed. This light-induced effect can lead to under- or overestimation of the Sudan III and Sudan IV content by 10% and false-positive detection of Sudan I and Sudan II, if proper care is not taken. Appearance of the second peak in chromatograms of Sudan III and Sudan IV is attributed to photochromic E-Z isomerization of these dyes.

Allergic contact dermatitis elicitation thresholds of potent allergens in humans

Literature scoured for human allergenicity to individual chemicals yields a limited number of potent sensitizers, which can be classified in four categories: metals, botanicals, biocides and miscellany. Potency is defined as strong for substances eliciting eczematous reactions to patch concentrations of 500 ppm (parts per million) or less in sensitized individuals. Most data encountered stem from studies conducted on dermatology patients tested routinely for hypersensitivity; only few data have been generated by systematic serial dilution testing.

Paradoxical effect of Sudan III on the in vivo and in vitro genotoxicity elicited by 7,12-dimethylbenz(a)anthracene

Effect of the induction of drug metabolizing enzymes by Sudan III on the in vivo and in vitro genotoxicity elicited by 7,12-dimethyl-benz(a)anthracene (DMBA) was investigated. A significant suppression of DMBA-induced micronucleated reticulocytes was observed in C57BL/6 mice treated with Sudan III intraperitoneally for 3 or 5 days before injection of the DMBA. However, the preincubation of DMBA with hepatic microsomes from Sudan III-treated rats caused a marked increase in the in vitro mutagenicity in the Ames assay, paradoxically. Sudan III was found to induce CYP 1A1, 7-ethoxycoumarin O-deethylase activity as well as both UDP-glucuronyl transferase and glutathione S-transferase activities. The increase of mutagenicity of DMBA observed in the Ames assay using hepatic microsomes from Sudan III-treated rats was inhibited by the addition of uridine 5'-diphosphoglucuronic acid or reduced glutathione with cytosol. Mutagenic metabolites of DMBA formed by CYP1A1 appeared to be effectively detoxified by these phase II enzymes. The results of this study suggest that Sudan III-induced prevention of in vivo mutagenesis is due to the induction of both CYP 1A1 and detoxifying phase II enzymes. The induced CYP1A1 may accelerate formation of active metabolic intermediates, but phase II enzymes are also induced and detoxify these intermediates to inactive metabolites. This would reduce residence time of the carcinogen in the body and the time of exposure to active metabolites for target organs.