Untargeted metabolomics of human keratinocytes reveals the impact of exposure to 2,6-dichloro-1,4-benzoquinone and 2,6-dichloro-3-hydroxy-1,4-benzoquinone as emerging disinfection by-products

INTRODUCTION

The 2,6-dichloro-1,4-benzoquinone (DCBQ) and its derivative 2,6-dichloro-3-hydroxy-1,4-benzoquinone (DCBQ-OH) are disinfection by-products (DBPs) and emerging pollutants in the environment. They are considered to be of particular importance as they have a high potential of toxicity and they are likely to be carcinogenic.

OBJECTIVES

In this study, human epidermal keratinocyte cells (HaCaT) were exposed to the DCBQ and its derivative DCBQ-OH, at concentrations equivalent to their IC₂₀ and IC₅₀, and a study of the metabolic phenotype of cells was performed.

METHODS

The perturbations induced in cellular metabolites and their relative content were screened and evaluated through a metabolomic study, using 1H-NMR and MS spectroscopy.

RESULTS

Changes in the metabolic pathways of HaCaT at concentrations corresponding to IC₂₀ and IC₅₀ of DCBQ-OH involved the activation of cell membrane α-linolenic acid, biotin, and glutathione and deactivation of glycolysis/gluconeogenesis at IC₅₀. The changes in metabolic pathways at IC₂₀ and IC₅₀ of DCBQ were associated with the activation of inositol phosphate, pertaining to the transfer of messages from the receptors of the membrane to the interior as well as with riboflavin. Deactivation of biotin metabolism was recorded, among others. The cells exposed to DCBQ exhibited a concentration-dependent decrease in saccharide concentrations. The concentration of steroids increased when cells were exposed to IC₂₀ and decreased at IC₅₀. Although both chemical factors stressed the cells, DCBQ led to the activation of transporting messages through phosphorylated derivatives of inositol.

CONCLUSION

Our findings provided insights into the impact of the two DBPs on human keratinocytes. Both chemical factors induced energy production perturbations, oxidative stress, and membrane damage.

Carbonization of Human Fingernails: Toward the Sustainable Production of Multifunctional Nitrogen and Sulfur Codoped Carbon Nanodots with Highly Luminescent Probing and Cell Proliferative/Migration Properties

A simple yet effective method is employed to prepare multifunctional fluorescent carbon nanodots (CNDs) from human fingernails. The results demonstrate that the CNDs have excellent optical properties and a quantum yield of 81%, which is attributed to the intrinsic composition of the precursor material itself. The CNDs are used to develop an ultrasensitive fluorescent probe for the detection of hexavalent chromium (limit of detection: 0.3 nM) via a combined inner-filter and static mechanism. Moreover, the toxicity of the CNDs over four epithelial cell lines is assessed. A negligible toxicity is induced on the three of the cell lines, whereas an increase in HEK-293 cell viability is demonstrated, granting cell proliferation properties to the as-synthesized CNDs. According to cell cycle analysis, cell proliferation is achieved by enhancing the transition of cells from the S phase to the G2/M one. Interestingly, CNDs are found to significantly promote cell migration, maybe because of their free-radical scavenging ability, making the CNDs suitable for wound healing applications. In addition, relevant experiments have revealed the blood compatibility of the CNDs. Finally, the CNDs were found suitable for cell imaging applications, and all of the aforementioned merits make it possible for them to be used for extraordinary, more advanced biological applications.