Japanese <i>Huperzia serrata</i> extract and the constituent, huperzine A, ameliorate the scopolamine-induced cognitive impairment in mice

<i>Huperzia serrata</i> has been used as a Chinese folk medicine for many years. It contains huperzine A, which has a protective effect against memory deficits in animal models; however, it is unclear if <i>H. serrata</i> extract exerts any effects in Alzheimer’s disease (AD) models. We used <i>H. serrata</i> collected in Japan and determined its huperzine A content using HPLC. We determined its inhibitory effects on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activity. <i>H. serrata</i> extract (30 mg/kg/day) and donepezil (10 mg/kg/day) were orally administrated for 7 days. After repeated administration, we performed the Y-maze and passive avoidance tests. <i>H. serrata</i> extract contained 0.5% huperzine A; <i>H. serrata</i> extract inhibited AChE, but not BuChE. <i>H. serrata</i> extract ameliorated cognitive function in mice. These results indicate that Japanese <i>H. serrata</i> extract ameliorates cognitive function deficits by inhibiting AChE. Therefore, <i>H. serrata</i> extract may be valuable for the prevention or treatment of dementia in AD.