Linalool as a novel natural factor enhancing ginsenoside production in hairy root cultures of American ginseng

Ginsenosides are triterpenoid saponins, accumulated in root of Panax qiunquefolius. These secondary metabolites have numerous pharmacological properties such as: antimicrobial, antioxidant, anti-inflammation, anticancer. They have been found to regulate the functioning of the nervous and endocrine systems, thus maintaining homeostasis. Root harvesting for ginsenoside extraction for pharmaceutical industry destroys the entire plant, limiting its natural occurrence and impacts on wild populations of ginseng. The present study showed that hairy root cultures of P. quinquefolius, after using linalool as elicitor, can increase ginsenoside yield without the use of field-grown plants and independently of the vegetative season. The content of seven ginsenosides (Rb1, Rb2, Rb3, Rc, Rd, Rg1, Re) was determined. We found linalool to stimulate most studied saponin accumulation regardless of exposure time (24 and 72 h). Shorter time of elicitation and 0.1 µM linalool in medium proved to be optimum conditions to obtain the highest total saponin content (29% higher level than that of untreated roots) and Rg-group metabolites (2.28 fold higher amount than untreated roots). Ginsenosides, belonging to protopanaxadiol derivatives, were found to have different dynamics of their content changes depending on linalool concentration. The highest increase in untreated roots was noted for compound Rd. Therefore, elicitation with linalool can be an effective method of enhancing ginsenoside production in P. quinquefolium hairy root cultures cultivated in shake flasks.