Standardized Siegesbeckia orientalis L. Extract Increases Exercise Endurance Through Stimulation of Mitochondrial Biogenesis

has been reported to exhibit anti-allergic, anti-infertility, anti-inflammatory, anti-rheumatic, and immunosuppressive activities. However, there are very few studies describing its stimulatory effects on exercise capacity. This study elucidated whether extract (SOE) standardized to kirenol content can enhance exercise endurance by increasing mitochondrial biogenesis. SOE significantly improved the running distance and time in mice fed normal diet (ND) and high-fat diet (HFD). SOE also enhanced mitochondrial biogenesis by stimulating the mitochondrial regulatory genes including peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1 ), estrogen-related receptor (ERR ), nuclear respiratory factor 1 (NRF-1), and mitochondrial transcription factor A (TFAM) in the skeletal muscles of ND and HFD mice. Furthermore, SOE upregulated the AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/PGC-1 /peroxisome proliferator-activated receptor delta (PPAR ) signaling pathway in the skeletal muscles of ND and HFD mice. Kirenol markedly increased adenosine triphosphate production and mitochondrial activity by stimulating the expression of markers of mitochondrial biogenesis and upregulating the AMPK/SIRT1/PGC-1 /PPAR signaling pathway in L6 myotubes. These results show that SOE has the potential to be used to develop an exercise supplement capable of stimulating mitochondrial biogenesis through the AMPK/SIRT1/PGC-1 /PPAR signaling pathway.