Platycodon grandiflorum-derived saponin enhances exercise function, skeletal muscle protein synthesis, and mitochondrial function

Abstract

Lower physical performance is an important risk factor in hypokinetic-related chronic disease, metabolic syndrome, and muscle atrophy. Our previous research demonstrated that Platycodon grandiflorum-derived saponin (PS) protects against eccentric exercise-induced muscle damage and mitochondrial function-related peroxisomal acyl-coenzme A oxidase (ACOX-1) and carnitine palmitoyltransferase (CPT-1) in high-fat diet-induced non-alcoholic steatohepatitis, and it inhibits osteoclast differentiation. However, the effects of PS on physical performance remain unknown. Therefore, we investigated whether PS enhances physical activity and skeletal muscle function. Supplementation with PS (2 mg/kg for 4 weeks) increased grip strength, wheel running repetition, and time to exhaustion in treadmill and swimming exercises. Marked increases in the synthesis of skeletal muscle proteins and muscle stem cell-related paired-box 7 (PAX7) were observed, and a decrease in the negative regulator myostatin was associated with enhanced muscle regeneration. Furthermore, PS induced expression of mitochondrial function proteins, including OXPHOS-III and -IV, in vivo and in vitro. These results suggest that PS enhances exercise function by ameliorating skeletal muscle protein synthesis and mitochondrial function.

Keywords: Exercise function; Oxidative phosphorylation; Platycodon grandiflorum; Saponin; Skeletal muscle synthesis and breakdown.