PlantForm-Grown Shoots of Rhaponticum carthamoides (Willd.) Iljin as a Source of Caffeoylquinic Acid Derivatives and Antioxidant Potential of Shoot Extract.

Rhaponticum carthamoides (Maral root) is an important medicinal plant species in Siberia and Kazakhstan. The aim of this study was to evaluate the effect of cultivation time (three or five weeks) and immersion frequency (i.e., every 1.5 h, 3 h, or 6 h) on the growth of R. carthamoides shoots in a temporary immersion PlantForm bioreactor; it examines the effect of cultivation on the accumulation and productivity of caffeoylquinic acid derivatives, shoot biomass and propagation. Both growth time and frequency of immersion affected the increase in biomass and phenolic compound production. The highest dry weight (9.35 g/L) was observed for shoots grown for five weeks and immersed every 1.5 h; optimal synthesis (4.5 mg/g DW) and productivity of caffeoylquinic acid derivatives (16 mg per bioreactor) was noted following immersion every three hours. The main class of synthesized compounds was mono-caffeoylquinic acid derivatives (3.3 mg/g DW; 11.85 mg/bioreactor) with chlorogenic acid predominating (2.9 mg/g DW; 10.4 mg/bioreactor), as determined by HPLC-PDA. The antioxidant activity of bioreactor-grown shoot extract was assessed in vitro using three cell-free assay systems: hydroxyl radical (OH•) scavenging, hydrogen peroxide (H2O2) reduction, and superoxide anion (O2•-) scavenging. Our findings indicate that the PlantForm bioreactor can be successfully used to grow R. carthamoides shoots and produce valuable caffeoylquinic acid derivatives.