Effects of Digestive Enzyme Tuna Hydrolysate on Expression of Longevity Gene-Related Nad-Dependent Sirtuin Protein, Mitochondrial Activity, and Antioxidant Capacity in Peripheral Blood Mononuclear Cells In Vitro

The longevity gene-associated protein sirtuin, which has NAD-dependent deacetylation enzyme activity, plays an important role in genomic stability, antioxidant potential, DNA repair, mitochondrial and energy metabolism all of which are associated with a healthy state. NAD+ and sirtuin levels can be increased by supplementing with NAD precursors including nicotinamide mononucleotide (NMN) and some polyphenols. If meals contain NAD precursors and NAD synthesis activators, a daily diet, as well as NMN supplements, may support NAD+ augmentation and the resultant sirtuin activation. This can then lead to a resulting improvement in mitochondrial metabolism and health. Because tuna meat contains NAD precursors, we postulate that a daily diet of fish has the potential to increase the levels of sirtuins which are NAD-dependent regulators of mitochondria in human cells. In the present study, we investigated whether tuna meat regulates mitochondrial function and energy metabolism in human peripheral blood mononuclear cells (PBMCs). A digestive enzyme tuna meat hydrolysate was prepared from tuna dark red meat. Mitochondrial activity (NAD+/NADH level), sirtuin expression, energy production (ATP level) and antioxidant activity in PBMCs were analyzed after the treatment of cells with the digestive enzyme tuna hydrolysate or controls in vitro. Our results demonstrate that the digestive enzyme tuna hydrolysate has the potential to increase the expression of longevity gene-related proteins sirtuin 1 and 2, NAD+/NADH levels, and ATP production by mitochondria in PBMCs. Furthermore, tuna meat showed high antioxidant capacity in vitro. These findings indicate the favorable effect of tuna meat on mitochondrial function and homeostasis. Our study underscores the benefits of tuna meat as a dietary choice and provides scientific support for promotion of healthy aging.