Improvement of sleep disorders through the adenosine A receptor agonist effect of Phlomoides umbrosa Turczaninow root extract in pentobarbital-induced ICR mice

Sleep deprivation is a serious problem that deteriorates the health, quality of life, and social productivity of affected individuals. Research on safe and effective plant-based materials should be performed to help alleviate sleep disorders. Phlomoides umbrosa Turczaninow is a domestic plant in South Korea that has been used traditionally as a medicine to treat sleep disorders. The effects and mechanism of action of a P. umbrosa Turczaninow root extract (PUTRE) prepared using hot water extraction were investigated. ICR mice were injected with pentobarbital to induce sleep. The PUTRE-treated groups had significantly (p < 0.05) decreased sleep latency and increased sleep time compared with the controls. When PUTRE was co-administered with adenosine antagonists (caffeine and 8-cyclopentyl-1,3-dipropylxanthine), it acted specifically on the adenosine A₁ receptor, because its sleep-enhancing effect was counteracted by the adenosine antagonist. This is the first study to demonstrate that PUTRE can induce sleep through adenosine A₁ receptor-specific agonist activity. Therefore, PUTRE is suggested as a valuable sleep-enhancing substance.