Protective role of citric acid against oxidative stress induced by heavy metals in Caenorhabditis elegans

  • Shaojuan SongEmail author
  • Yan Han
  • Yun Zhang
  • Honglian Ma
  • Lei Zhang
  • Jing Huo
  • Peisheng Wang
  • Mengrui Liang
  • Ming Gao
Research Article


The adverse effects of heavy metals, such as cadmium, zinc, and copper, occur due to the generation of reactive oxygen species (ROS). The use of Caenorhabditis elegans for the purposes of conservation and biomonitoring is of great interest. In the present study, ROS, malondialdehyde (MDA), and citric acid levels and superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities in a model organism were tested to study toxicity. C. elegans was exposed to three different concentrations of cadmium (CdCl2, 5, 10, 50 μM), zinc (ZnSO4, 10, 100, 500 μM), and copper (CuSO4, 10, 100, 500 μM) for 3 days. ROS levels increased by 1.3- to 2.1-fold with increasing metal concentrations. The MDA content increased by approximately 7-, 5-, 2-fold after exposure to high concentrations of cadmium, zinc, and copper, respectively. Furthermore, the citric acid content increased by approximately 3-fold in the cadmium (Cd, 5 μM), zinc (Zn, 10 μM), and copper (Cu, 100 μM) treatment groups compared to that in untreated C. elegans. Therefore, citric acid may play an important role in heavy metal detoxification. Excess citric acid also slightly increased the LC50 by 1.3- to 2.0-fold, basic movements by 1.0- to 1.5-fold, decreased the ROS content by 2.4- to 2.1-fold, the MDA content by 4- to 2-fold, the SOD activity by 9- to 3-fold, the GPx activity by 4.0- to 3.0-fold, and the mRNA expression levels of GPxs by 3.2- to 1.8-fold after metals treatment. And it is most significantly in the alleviation of citric acid to cadmium. This study not only provides information to further understand the effects of heavy metal exposure on ROS, MDA, GPx, SOD, and citric acid in worms but also indicates that supplemental citric acid can protect animals from heavy metal stress and has broad application prospects in decreasing oxidative damage caused by heavy metals.


Caenorhabditis elegans ROS MDA Citric acid Antioxidative enzymes Heavy metals 



The authors thank WormBase and WormBook.

Funding information

This work was supported by the Outstanding Graduate Science Innovation Foundation of Shanxi Province (Grant no. 021852901008), the Science and Technology Innovation Team Project of Changzhi Medical College (Grant no. CX201510), and an Innovation and Entrepreneurship Training Program for college students in Shanxi (Grant nos. 2016306, 2016309, 2016314).


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Changzhi Medical CollegeChangzhiChina
  2. 2.School of Life ScienceShanxi UniversityTaiyuanChina

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