Cinnamaldehyde Alleviates the Oxidative Stress of Caenorhabditis elegans in the Presence of Lactic Acid.

Cinnamaldehyde is an excellent natural antioxidant with high antioxidant activity, but its function in food or human digestive tract under acidic conditions remains to be studied. The effects of cinnamaldehyde in the presence of lactic acid on oxidative stress of Caenorhabditis elegans and the underlying molecular mechanisms were investigated in the present study. Results showed that cinnamaldehyde with or without lactic acid exhibited good antioxidant ability, represented by high SOD and CAT activities in C. elegans, while lactic acid exerted no effect on the antioxidant enzymes. Trace elements, like Cu, Fe, or Se, are important for the activities of antioxidant enzymes. Data of metal elements analysis revealed that cinnamaldehyde made big differences on the levels of Mn, Cu, Se of worms compared with single lactic acid treatment. Moreover, mechanistic study suggested that in the presence of lactic acid, cinnamaldehyde could enhance the expressions of akt-2, age-1 to increase the antioxidant activities. In addition, we found that lactic acid was able to change the metabolic profile of cinnamaldehyde in C. elegans, characterized by nucleosides and amino acids, which were involved in the purine metabolism, the biosynthesis, and metabolism of some amino acids, etc. This study provides a theoretical basis for further revealing the functional activity and mechanism of cinnamaldehyde under acidic conditions.