Ginseng drugs - Molecular and chemical characteristics and possibility as antidementia drugs

Ginseng drugs derived from the underground parts of Panax species show high potential to cure various kinds of diseases. In spite of traditional uses for several centuries, clinical evidences and systematical comparison have been rarely reported. One of the reasons is that herbal drugs from natural resources have difficulties of quality control in botanical sources and chemical constituents. Our studies on gene sequences and quantitative determination of 11 main saponins showed that Panax taxa had the species-specific sequences in plastid trnK gene and nuclear 18S rRNA gene, and each taxon possessed the characteristic pattern in chemical composition. Furthermore, we focused on the Ginseng drugs to find out candidates capable of regenerating neuronal network in the dementia brain. The protopanaxadiol (ppd) type saponins were found to have neurite outgrowth activity in SK-N-SH cells. Since ppd-type saponins are known to be completely metabolized into 20 - O - β - D-glucopyranosyl - (20S) - protopanaxadiol (M1) by intestinal bacteria when taken orally, further studies on M1 suggested that M1 had axonal extension activity in degenerated neurons, and ameliorate memory disorder and synaptic loss in Alzheimer's mouse model induced by Aβ(25-35). M1 was shown to be effective in vitro and in vivo, indicating that Ginseng drugs containing ppd-type saponins may reactivate neuronal function in AD by p.o. administration.