Ginsenoside Re: Its chemistry, metabolism and pharmacokinetics

Ginseng is a key herb in Chinese medicine, and has a wide range of therapeutic and pharmacological uses [1-3]. Panax ginseng is a slow growing perennial herb of the Araliaceae family usually cultivated in China, Japan, Korea and Russia, as well as in the United States and Canada. Ginseng root has been used as an oriental folk medicine for several thousand years [2,4]. It is a highly valued medicinal plant in the Far East that and also popular in the West in the past 20 years [2,4-7].A number of studies suggest that both Panax ginseng C.A. Meyer (also known as Asian ginseng, Chinese ginseng or Korea ginseng) and Panax quinquefolius (also known as American ginseng) have multiple components and pharmacological functions [7-14]. Among the complex constituents of ginseng, ginsenosides (also known as ginseng saponins or triterpene saponins) are the major components responsible for biochemical and pharmacological actions of ginseng [9,15-17]. With the development of modern technology, more than 150 naturally occurring ginsenosides have been isolated from Panax species [18]. About 40 ginsenosides have been identified from the root of Panax ginseng [1,19-22].In order to explore the pharmacological actions, mechanisms and clinical applications of ginseng, some researchers focused on purified individual ginsenosides rather than whole ginseng extracts [1,23]. Individual ginsenosides may have different characteristics in chemistry, metabolism, and pharmacokinetics. Ginsenoside Re (Re) belongs to 20(S)-protopanaxatriol group (Figure 1), and is a major ginsenoside in ginseng [7,10,16,22,24-27]. Literature shows that Re exhibits multiple pharmacological activities via different mechanisms [12,16,28]. For example, in cardiovascular system, Re possesses negative effects on cardiac contractility and autorhythmicity, anti-arrhythmic and anti-ischemic effects, angiogenic regeneration activities and cardiac electrophysiological functions [28]. Xie et al. and Li et al. [13,29-32] found th