Combination of oxytetracycline and quinocetone synergistically induces hepatotoxicity via generation of reactive oxygen species and activation of mitochondrial pathway

Abstract

Oxytetracycline (OTC) and Quinocetone (QCT) are antimicrobials, whose residues have been found in food and environment. These two are sometimes used simultaneously in livestock and aquaculture, potentially resulting in the simultaneous consumption of multi-antimicrobials by consumers. However, the combined toxic effects of this phenomenon have yet to be addressed. Since the liver is a major target of both OTC and QCT, we tested their hepatotoxic effect using both cell cultures and animal models. Results showed that the QCT (5–25 μM) or OTC (20–100 μM) treatments alone caused dose-dependent reductions in cell numbers, while their combination strongly further enhanced inhibitory effects. Mechanistically, the combination enhanced the generation of reactive oxygen species (ROS) and activated mitochondrial cell death pathways. It also showed that the combination of OTC (800 mg/kg, i.g., 5d) and QCT (5000 mg/kg, i.g., 5d) resulted in significantly enhanced liver toxicity in C57BL/6N mice, the serum alanine transaminase (ALT) and aspartate transaminase (AST) were significantly increased by the OTC/QCT. These findings indicate the necessity of considering the combined toxicity of these two antimicrobials in safety assessments.

Keywords:

• Oxytetracycline
• quinocetone
• synergistic cytotoxicity
• ROS
• mitochondrial

Acknowledgments

The authors gratefully acknowledge the advice and suggestions of Shangyun Lu and thank Junying Jia for the flow cytometry used in this study and thank Yuhan Fu for the contribution to the revision of this article.

Ethical approval

All experimental procedures were conducted according to the guidelines approved by the ethical committee of experimental animal care in China Agricultural University (RD-20202041-2).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Key Research and Development Program of China [2018YFC1603005].