The Sirtuin‐1 relied antioxidant and antiaging activity of 5,5′‐diferulic acid glucoside esters derived from corn bran by enzymatic method

Abstract

Maize is the food crop with the highest total output in the world. However, corn bran is only a by-product with low price. The 5,5'-diferulic acid glucoside esters (DFG) were obtained from corn bran using the enzymatic method. DFG showed obvious antioxidant capacity in cell, Caenorhabditis elegans (C. elegans) and in mouse. DFG decreased ROS and MDA content in 500μM H2 O2 stimulated ARPE-19 cells to 48.6% and 32.2%, respectively. DFG decreased ROS content in C. elegans to 49.1% and MDA content in acute ethanol (50%, 12ml/kg) stimulated mouse to 30.4%. DFG also increased SOD protein content significantly in cell, C. elegans and mouse to 175.5%, 120.1%, and 126.2%, respectively. DFG significantly extended the lifespan of C. elegans both under heat stress and natural situation. The median survival time was prolonged to 133.3% and 116.7%, respectively. This capacity relied on the SIR-2.1 activity. SIR-2.1 is an ortholog of human Sirtuin-1 (SIRT-1). DFG also upregulated SIRT-1 and PCG-1α expression level obviously in H2 O2 -stimulated ARPE-19 cells (to 134.4% and 127.1%, respectively) and in acute ethanol stimulated mouse eyes (to 135.1% and 111.5%, respectively) and liver (to 123.3% and 113.6%, respectively). These results indicate that DFG has multiple bioactivities. Our research provides a new application prospect of corn bran. And to our best knowledge, this is the first time, the sirtuins-relied lifespan extension activity of the 5,5'-diferulic acid extracted from corn bran was reported. PRACTICAL APPLICATIONS: The traditional method for extracting diferulic acid from corn bran is to use the strong alkali. Obviously, this is not welcomed by the food industry. We employed the biological enzyme method in a relatively mild pH range during the extraction process. It is more environmentally friendly and more economical. DFG can be added as a raw material for functional foods like yogurt, fruit juice, and cereals. As well, the solid precipitate obtained after extraction can also be used as high-quality dietary fiber to produce functional food. Meanwhile, concerning for the 5,5'-diferulic acid derived from corn bran, the relevant research is still not abundant. And to our best knowledge, we have reported for the first time about the effect of this kinds of diferulic acid on prolonging life span and its SIRT-1-dependent activity. It also provides a new perspective for the study of diferulic acid.