A proposed biomarker for human citric acid ester (CAE) exposure, and the potential disturbance on human lipid metabolism

Yayun Zhang; Qianyu Chen; Dan Weng; Hong Sun; Feng Zhu; Fei Shen; Yonglin Zhou; Guanyong Su

doi:10.1016/j.envres.2024.120045

A proposed biomarker for human citric acid ester (CAE) exposure, and the potential disturbance on human lipid metabolism

Environ Res. 2024 Sep 21;263(Pt 1):120045. doi: 10.1016/j.envres.2024.120045. Online ahead of print.

Authors

Yayun Zhang¹, Qianyu Chen¹, Dan Weng¹, Hong Sun², Feng Zhu², Fei Shen², Yonglin Zhou³, Guanyong Su⁴

Affiliations

¹ Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Industry and Information Technology, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
² Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, Jiangsum, 210009, China.
³ Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, Jiangsum, 210009, China. Electronic address: zyl@jscdc.cn.
⁴ Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Industry and Information Technology, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China. Electronic address: sugy@njust.edu.cn.

PMID: 39313169
DOI: 10.1016/j.envres.2024.120045

Abstract

Citric acid esters (CAEs), as one class of important alternative plasticizers, have been proven to be ubiquitous in the environments, leading to an increasing concern regarding their potential health risk to humans. However, information regarding the biomarkers for human CAE biomonitoring is currently unknown. In the present study, we investigated the metabolism characteristics of CAEs by use of in vitro rat liver microsomes (RLMs) and in vivo mice. We observed that CAEs would undergo a rapid metabolism in both in vitro and in vivo conditions, implying that parent CAEs could be not suitable for biomonitoring of human CAE exposure. By use of high-resolution Orbitrap mass spectrometry (MS), ten molecules were tentatively identified as CAE potential metabolites on the basis of their MS and MS/MS characteristics, and CAEs could be metabolized via multiple pathways, i.e. hydrolyzation, hydroxylation, O-dealkylation. Further MS screening in human serum samples demonstrated that most of parent CAEs were not detectable, whereas numerous CAE metabolites were detected in the same batch of analyzed samples. Especially, one of metabolites of tributyl citrate (named with TBC-M1), exhibited a high detection frequency of 73.3%. By use of TBC-M1 as the biomarker of human CAE exposure, alteration of lipid metabolism was further examined in human serum. Interestingly, we observed statistically significant correlations between TBC-M1 levels and population characteristics (i.e., age, BMI, and drinking). Beyond that, we also observed statistically significant correlation between levels of TBC-M1 and lipid molecules (phosphatidylinositol (18:0/20:4) and sphingomyelin (d34:1)). Collectively, this study underscored the property of rapid metabolism of CAEs in exposed organism, and proposed a potential biomarker that could be greatly helpful for further investigating the human CAE exposure and understanding their potential health risks.

Keywords: Biomarkers; Biotransformation; Citric acid esters (CAEs); Health risk assessment; Lipids.