Review paper on ginseng in neurological disorders, 2015. Full paper. Only 1 to 3% of original compounds absorbed. More are as metabolites.
Rg1 reduces iron in SN by "regulating the expressions of DMT1 and FP1"
Ginseng reduced dopamine cell loss, locomotor loss, and a-syn
red Korean ginseng in PD mice 1 to 100 mg/kg
Nutriose special fiber from wheat and corn increases gut conversion and absorption of CK a ginseng metabolite that is more useful than ginseng Rgb1 itself
Siberian ginseng is not like other ginsengs. American ginseng is panax quinquefolius which is not the same as Panax ginseng, and wiki discusses these last two. Red ginseng is P.G. that been heated and sun dried. White is sun dried (more?) and may break down more constituents. PG is yang, PQ is yin.
Panax ginseng seems to be the one most studied by a factor of 20.
compounds studied for PD
ginseng extract improves calmness and working memory in young adults (and ginkgo) : (all by Scholey and Kennedy)
Chinese herbs potentially useful: polygonum, triptolide from tripterygium wilfordii hook, polysaccharides from the flowers of nerium indicum, oil from ganoderma lucidum spores, huperzine and stepholidine "In addition, accumulating data have suggested that Chinese herbs or herbal extracts may promote neuronal survival and neurite growth, and facilitate functional recovery of brain injures by invoking distinct mechanisms that are related to their neuroprotective roles as the antioxidants, dopamine transporter inhibitor, monoamine oxidase inhibitor, free radical scavengers, chelators of harmful metal ions, modulating cell survival genes and signaling, anti-apoptosis activity, and even improving brain blood circulation. "