In vitro Inhibition of Dipeptidyl Peptidase-4 (DPP-4) and Arginase by a Dietary Supplement and Its Potential for Improving Quality of Life Factors in Adults

Aim: Somatopause is the progressive and age-related decline of growth hormone (GH) production due to changes in hypothalamic-pituitary axis signaling and results in typical physiological changes associated with the aging process. The purpose of our study was to investigate the anti-aging potential of several botanical ingredients, including noni fruit juice, as well as a dietary supplement formulation. Methodology: Dipeptidyl peptidase-4 (DPP-4) influences hypothalamic-pituitary axis signaling and reduces GH production and secretion. Since DPP-4 concentrations increase with age, we evaluated the ability of several botanical ingredients to inhibit DPP-4 activity in vitro. We subsequently formulated an anti-aging dietary supplement with this blend of botanical ingredients by adding amino acids (L-arginine, L-Lysine, citrulline and beta-alanine), gamma-aminobutyric acid (GABA), flax seed oil and several nutrients. The supplement was evaluated for anti-arginase activity in vitro, as the expression of this enzyme also increases with age. The dietary supplement was also consumed by three men and one woman, ages 56 to 62, with relevant but disparate medical histories. Following short-term ingestion of the supplement, these volunteers were interviewed to ascertain any changes in health status. Results: We discovered that a blend of the botanical ingredients synergistically inhibited DPP-4 in vitro by up to approximately 99%. A concentration-dependent reduction in arginase activity was also observed for the anti-aging dietary supplement. Further, all volunteers reported positive improvements in at least one quality of life factor, which included more restful sleep, reduced musculoskeletal discomfort, increased energy, improved physical stamina and better skin quality. Conclusion: These initial findings suggest that the anti-aging dietary supplement can mitigate declines in quality of life associated with aging by reducing DPP-4 and arginase activities, thereby supporting healthy GH production and endothelial nitric oxide production.