Production of Biomass and Bioactive Compounds in Adventitious Root Cultures of Eleutherococcus koreanum Nakai

Abstract

Eleutherococcus koreanum Nakai is an endemic medicinal plant grown in Jeju Island, South Korea. Extracts from this plant have traditionally been used in Korea as a tonic and for treating rheumatism, diabetes and hepatitis. These extracts contain many useful bioactive substances, particularly eleutherosides, chlorogenic acid and other phenolic compounds. The quality and quantity of major bioactive compounds from naturally grown plants are greatly affected by harvest time and environmental conditions. Therefore, determination of suitable growing and harvesting conditions is necessary to achieve reliable supply of E. koreanum-based bioactive compounds for commercial use. To establish an efficient method for the year-round production of bioactive compounds, adventitious roots of E. koreanum were tested with various physical and chemical factors (inoculum density, aeration volume, salt strength, nitrogen source, and sucrose concentration) that affect root biomass and production of target bioactive compounds. Root biomass, concentrations of five target bioactive compounds (eleutherosides B and E, chlorogenic acid, total phenolics, and flavonoids), physiological responses of the adventitious roots and other environmental conditions in the culture vessels were determined. In addition, responses of roots subjected to chemical elicitors (methyl jasmonate and salicylic acid) were evaluated to determine a strategy for enhancing the final production of bioactive compounds. Finally, we compared the contents of bioactive compounds and typical DNA histograms for the adventitious roots and naturally grown plants to verify the competitive ability and genetic stability of cultured E. koreanum adventitious roots. The development of in vitro culture protocol, which controls the quality and quantity of elicited bioactive compounds, will be beneficial for the pilot-scale production of E. koreanum-based bioactive compounds for commercial use.