Distribution and quantitative analysis of homoanserine and its 2-oxo derivative in mouse tissues

Abstract

Imidazole-containing dipeptides (IDPs), such as carnosine and anserine, are endogenously produced and have been shown to function as antioxidants. Recently, we have characterized the endogenous production of 2-oxo-imidazole-containing dipeptides (2-oxo-IDPs), such as 2-oxo-carnosine, 2-oxo-anserine, and 2-oxo-homocarnosine in mouse tissues, including brain, and demonstrated that 2-oxo-IDPs exhibit higher antioxidant activities than the corresponding IDPs. In this study, we established a highly sensitive, specific, and quantitative method for the detection of the IDP homoanserine and its oxidized derivative 2-oxo-homoanserine via high-performance liquid chromatography tandem mass spectrometry coupled with a stable-isotope dilution method, and quantitatively analyzed its tissue distribution and age-related intra-brain distribution in C57BL/6J mice. The quantitative analysis revealed that homoanserine exists abundantly not only in the mouse brain but also in other tissues, such as the muscle and lungs. Further, we successfully detected the endogenous production of 2-oxo-homoanserine in the mouse brain. The mass spectrometric analysis revealed that homoanserine predominantly exists in the cerebrum and cerebellum and the concentrations in 10-week-old mice were approximately 50-fold higher than those in 1-week-old mice. Accordingly, this is the first study that reports the spatial and temporal expression patterns of homoanserine and its 2-oxo derivative in C57BL/6J mice.

Keywords:

• 2-Oxo-homoanserine
• brain
• homoanserine
• imidazole-containing dipeptides
• LC-MS/MS

Acknowledgement

We would like to thank Editage (www.editage.com) for English language editing.

Disclosure statement

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

Additional information

Funding

This work was supported in part by Grant-in-Aid for JSPS Fellows 19J12416 (to Y. K.), Grant-in-Aid for Scientific Research (S) 17H06170 (to K. U.), Grant-in-Aid for Scientific Research (B) 16H04674 (to H. I.), Grant-in-Aid for Challenging Exploratory Research 16K13089 and 20K21256 (to H. I.), and Grant-in-Aid for Scientific Research on Innovative Areas “Oxygen Biology: a new criterion for integrated understanding of life” 26111011 (to K. U., and H. I) from the Japanese Ministry of Education, Sciences, Sports, Technology. This work was also supported by the Smoking Research Foundation 2017G036 (to H. I.).