In the field of nutrion, serine is widely considered as a nonessential amino acid, which means that de novo serine synthesis could meet the demands of whole body serine homeostasis in healthy conditions. In addition, it is not necessary to add additional serine in diet.

However, recent studies found that a significant decrease of plasma serine concentration is observed under oxidative stress, which play a key role in the pathogenesis of diabetes, obesity, insulin resistance, hypertension and cardiovascular disease. Moreover, serine deficiency would exacerbate cellular damage of oxidative stress. Thus, dietary serine might be required when the body is under oxidative stress.

A team of researchers from the Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA) studied the effects of supplementation with serine in water on oxidative damage and its relative mechanisms in a mouse model of diquat-induced oxidative stress.

The researchers found that hepatic glutathione anti-oxidant systems were impaired and reactive oxygen species were increased in diquat--induced mice and hepatocytes, while such disadvantageous changes were diminished by serine supplementation. However, when expression of cystathionine β-synthase (a key enzyme involved in glutathione synthesis) was inhibited by interference RNA in hepatocytes, the effects of serine supplementation on the improvement of glutathione synthesis and the alleviation of oxidative stress were diminished.

Moreover, when hepatocytes were treated with cycloleucine, an inhibitor of methionine adenosyltransferase, the effects of serine supplementation on the improvement of methionine cycle and the alleviation of DNA hypomethylation and oxidative stress were also diminished. “Our findings not only indicated that serine supplementation could alleviate oxidative damage but also elucidated the underlying mechanisms.” said ZHOU Xihong, an assistant researcher in ISA.

This work was supported by National Key Research and Development Program of China (2016YFD0500504；2016YFD0501201) and Natural Science Foundation of Hunan Province (2017JJ3373).

The study entitled “Serine alleviates oxidative stress via supporting glutathione synthesis and methionine cycle in mice” has been published in Molecular Nutrition & Food Research on September 1, details could be found at http://onlinelibrary.wiley.com/doi/10.1002/mnfr.201700262/full.