**7.4** *Panax quinquefolium* **Linn**

*Panax quinquefolium* is a native plant of North America, but is now cultivated widely and used in many countries. The plant contains dammarane type ginsenosides as the major biologically active constituents particularly Rb1, Rd. and Re ginsenoside saponins [91] which are responsible for most of its bioactive properties. A graded dose study with *P. quinquefolium* revealed differential effects against the ketamine induced hyperactivity in the Digiscan animal activity monitor, and blocked ketamine induced memory impairment in the passive avoidance paradigm. In the chronic studies, *P. quinquefolium* attenuated the ketamine-enhanced immobility in the forced swim test and did not produce extra-pyramidal side effects in bar test and wood block test of catalepsy. These behavioral effects were compared with standard drugs haloperidol and clozapine. *P. quinquefolium* was also found to reduced DA and 5-HT content after prolonged treatment. Furthermore, *P. quinquefolium* extract reduced acetylcholinesterase activity and nitrate levels, conversely it increased glutamate levels in hippocampus. Ultimately, the study revealed that *P. quinquefolium* possess antipsychotic like properties, which may be beneficial in predominant negative and cognitive symptoms of schizophrenia [9].
