Potentiating Effects of Lactuca sativa on Pentobarbital-Induced Sleep

Traditionally, Lactuca sativa (lettuce) has been recommended for its hypnotic property.The present study was planned to investigate sleep-prolonging effect of this plant. The hydroalcoholicextract (HAE) of lettuce and its water fraction (WF), ethyl acetate fraction (EAF),and n-butanol fraction (NBF) were administrated (IP) to mice 30 min before the pentobarbitalinjection. Moreover, both in-vivo and in-vitro toxicity of the extracts were determined. Thequality of HAE and NBF was also evaluated using HPLC fingerprint. The HAE prolonged thepentobarbital-induced sleep duration at dose of 400 mg/Kg. The NBF was the only fractionwhich could increase the sleep duration and decrease sleep latency. The effects of NBF werecomparable to those of induced by diazepam. The LD50-value for HAE was found to be 4.8g/Kg. No neurotoxic effect was observed either by HAE or by its fractions in cultured PC12neuron-like cells. The results suggest that lettuce potentiates pentobarbital hypnosis withoutmajor toxic effect. The main component(s) responsible for this effect is most likely to be nonpolaragent(s) which found in NBF of this plant.