Retardation of skeletal muscle fatigue by the two phenylpropanoid glycosides: verbascoside and martynoside from Pedicularis plicata maxim.

The effects of the phenylpropanoid glycosides verbascoside and martynoside from Pedicularis plicata were investigated on muscle contractility in Bufo gastrocnemius muscle electrically stimulated in vitro. The maximum amplitude and maintained time of contraction were mechanically recorded and used as indices of muscle contractility. After 30 min pretreatment of the muscle, verbascoside at 20.0 microM resisted muscle fatigue significantly while martynoside at 80.0 microM improved muscle contractility only slightly. These two glycosides resisted muscle fatigue depending on their antioxidative activities, which is in agreement with the role of reactive oxygen species (ROS) in promoting fatigue in skeletal muscle.