Psoralen and isopsoralen, two coumarins of Psoraleae Fructus, can alleviate scopolamine-induced amnesia in rats.

In this study we have found that the crude extract of Psoraleae Fructus inhibited acetylcholinesterase activity in vitro and ameliorated impairment of the inhibitory avoidance response and of the water maze spatial performance caused by scopolamine in rats. Among all fractions, the chloroform fraction showed the best inhibitory effect on acetylcholinesterase activity and could reduce the scopolamine-induced inhibitory avoidance response impairment. Psoralen and isopsoralen, two major constituents of the chloroform fraction of Psoraleae Fructus identified by high performance liquid chromatography, also reduced the extent of the inhibitory avoidance response impairment. The results suggest that psoralen and isopsoralen are the major active ingredients of Psoraleae Fructus responsible for the progressive reversal of scopolamine-induced amnesia, whose effects are partially associated with inhibition of AchE activity and hence activation of the central cholinergic neuronal system.