Bidirectional role of synthetic musk tonalide as photosensitizer and activator on amino acids: Formation of sensitizer imine at aqueous chemistry interface of skin

Na Luo; Yanpeng Gao; Mei Wang; Xiaolin Niu; Guiying Li; Taicheng An

doi:10.1016/j.eehl.2023.03.002

Bidirectional role of synthetic musk tonalide as photosensitizer and activator on amino acids: Formation of sensitizer imine at aqueous chemistry interface of skin

Eco Environ Health. 2023 Mar 10;2(1):32-39. doi: 10.1016/j.eehl.2023.03.002. eCollection 2023 Mar.

Authors

Na Luo^{1

2}, Yanpeng Gao^{1

2}, Mei Wang^{1

2}, Xiaolin Niu^{1

2}, Guiying Li^{1

2}, Taicheng An^{1

2}

Affiliations

¹ Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.
² Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China.

Abstract

Personal care products (PCPs) inevitably come into contact with the skin in people's daily life, potentially causing adverse effects on human health. The adverse effects can be exacerbated under UV irradiation but are rarely studied. In this study, to clearly understand the damage of representative PCPs to human skin and their photochemical transformation behaviors, fragrance tonalide (AHTN) was measured in the presence of amino acids as a basic building block of human tissue. The results showed that amino acids could decelerate the photochemical transformation rate of AHTN, increasing the likelihood of AHNT persisting on the skin surface and the health risk to the human being. Further, the interaction between amino acids and AHTN was investigated. AHTN could play bidirectional roles in damaging amino acids: the photosensitizer and reactive activator. As a photosensitizer, the ¹O₂ generated from the AHTN photosensitization was partly employed to oxidative damage amino acids. Furthermore, by combining experiments with quantum chemical computation, the carbonyl group of the activator AHTN was found to be the active site to activate the N-containing group of amino acids. The activation mechanism was the electron transfer between AHTN and amino acids. Imines formed during the photochemical transformation of AHTN with histidine/glycine were the molecular initiating event for potential skin sensitization. This study reported for the first time that skin photosensitizer formation threatens human health during the photochemical transformation of AHTN.

Keywords: Amino acids; Electron transfer; Imines; Personal care products; Photosensitive damage.