Effects of Gastrodia elata and its active constituents on scopolamine-induced amnesia in rats.

The effects of the rhizome of Gastrodia elata Blume (Orchidaceae) (abbreviated as GE) and its active constituents on learning and memory by using the one-trial passive avoidance task were studied in rats. At the 1.0 g/kg dose administered for one week, the methanol extract of GE significantly prolonged the shortened step-through latency induced by scopolamine in the passive avoidance task. Furthermore, at the 50.0 mg/kg dose administered for one week, the ethyl acetate and n-butanol fractions of the methanol extract prolonged the shortened step-through latency induced by scopolamine in rats. Gastrodin, isolated from the n-butanol fraction of the methanol extract, and p-hydroxybenzyl alcohol, isolated from the ethyl acetate fraction of the methanol extract, also significantly prolonged the shortened step-through latency induced by scopolamine on the passive avoidance task. These results suggested that gastrodin and p-hydroxybenzyl alcohol may be the active constituents of GE.