Review on experimental research of herbal medicines with anti-amnesic activity.

Amnesia is characterized by the inability to form memories or total or partial loss of memory secondary to cerebral malfunction following degenerative diseases, cerebral infections, traumatic injuries and emotional events which could be differentiated from dementia. However, no effective treatment for amnesia is currently available. Much research effort has been focused on developing new drugs from herbal medicines which have multifunctional properties. Novel plant extracts and their major or bioactive components including alkaloids, flavonoids, glycosides and saponins with promising antioxidant effects, various effects on cholinergic, GABAergic, glutaminergic, serotonergic, catecholaminergic and histaminergic systems, enhancement of cerebral blood flow and elevation of ribonucleic acid (RNA) as well as protein levels have been studied. In this review, we discuss the research findings on novel plant extracts and their bioactives with anti-amnesic effects on different neurotransmitter systems. Developing new drugs from herbal medicines for the treatment of amnesia is a hopeful attempt to meet the unmet medical needs. Georg Thieme Verlag KG Stuttgart-New York.