Kaempferol as a phytochemical increases ATP content in C2C12 myotubes under hypoxic conditions

Abstract

• ATP increasing effect of 65 phytochemicals was evaluated under hypoxic conditions. • Kaempferol increased intracellular ATP content under hypoxic conditions. • Required structure in flavonoids to increase intracellular ATP content was clarified. • Hypoxic environment increased biosynthesis of kaempferol in crops. Hypoxic conditions in the body have been reported to occur in aging and exercising muscles. It has been suggested that a reduction in ATP, due to hypoxia, may contribute to related declines in muscle performance. In this study, we established hypoxic assay systems and evaluated the effects of 65 phytochemicals on intracellular ATP content in C 2 C 12 myotubes, to more accurately determine their physiological activities. We found intracellular ATP content in C 2 C 12 myotubes to be reduced, under hypoxic conditions. However, kaempferol markedly increased it in this assay systems, by activating oxidative metabolism. The level of kaempferol in crops cultivated in highland areas or an artificial hypoxic environment, was significantly increased, while that of quercetin was either unchanged or significantly decreased. These results suggest crops may biosynthesize kaempferol to adapt to hypoxic environments, and that highland residents may benefit from eating such crops, with adaptive consequences.