ABSTRACT
Panax ginseng is one of the most investigated medicinal plants and is cultivated in China and Korea. In the Eastern world, ginseng roots have been used for more than 2000 yr as a tonic and a prophylactic to combat psychophysical tiredness and asthenia. The plant contains more than 200 identified chemical compounds, and among them ginsenosides are considered some of the most pharmacologically important constituents and characteristic markers. The United States Pharmacopeia-National Formulary (USP-NF) describes its attributes. Consistent efficacy and safety require constantly uniform composition, a condition which the raw material (roots) can scarcely fulfill. Standardization is the prerequisite for a constant pharmacological answer. High-performance liquid chromatography (HPLC) methods were developed for the quantification of ginsenosides. Numerous pharmacological studies have been performed on P. ginseng roots and extracts. Among other activities, the following are relevant: free radical scavenging effect, immunological effects, action on the central nervous system, and metabolic effects. These studies show not only the activity but also demonstrate that there is a certain relation between dose and response. Moreover, some experiments reveal that by increasing the dose of the extracts or the ginsenosides beyond certain limits, the desired pharmacological effects are reversed. This could explain the sometimes controversial results observed for the P. ginseng activity. The ginsenosides are considered prodrugs, and in the acidic medium of the stomach are immediately hydrolyzed; further metabolism occurs in the intestine. In humans, the hydrolysis products were detected in plasma and urine after oral administration.
