Phenolic acid and flavonoid production in agar, agitated and bioreactor-grown microshoot cultures of Schisandra chinensis cv. Sadova No. 1-a valuable medicinal plant

In vitro cultures and raw materials (fruits and leaves) of the valuable medicinal plant species - Schisandra chinensis cultivar Sadova No. 1 (SchS) - were evaluated for the production of two groups of phenolic compounds, phenolic acids and flavonoids, and their antioxidant potential. A series of experiments was conducted, aimed at optimizing culture conditions for maximum growth and phenolic production in SchS microshoots. Different concentrations of plant growth regulators (6-benzyladenine -BA and 1-naphthaleneacetic acid - NAA, from 0 to 3 mg/l) in Murashige-Skoog (MS) medium were tested in several cultivation systems (agar, agitated, bioreactor) over various growth periods (10, 20, 30, 40, 50 and 60 days). Furthermore, an elicitation experiment was conducted in which the bioreactor-grown microshoots were exposed to yeast extract. HPLC-DAD analyses confirmed the presence of eight phenolic acids - chlorogenic, cryptochlorogenic, gallic, neochlorogenic, protocatechuic, salicylic, syringic and vanillic, and two flavonoids: kaempferol and quercitrin, in the in vitro bio-masses. The highest total phenolic acid (357.93 mg/100 g DW) and flavonoid (105.07 mg/100 g DW) contents were obtained in agar culture extracts cultivated for 30 days on MS medium containing 2 mg/l BA and 0.5 mg/l NAA and for 50 days on MS medium containing 0.1 mg/l BA and 2 mg/l NAA, respectively. These amounts were 1.59- and 5.95-fold lower than in parent plant leaf extracts (569.66 mg/100 g DW), and 4.30- and 1.25-fold higher than in fruit extracts (83.17 mg/100 g DW), respectively. Microshoots grown in a Plantform bioreactor also proved to be a good source of phenolic compounds, however, the elicitor treatment had no noticeable effect on their accumulation. Antioxidant capacity assessed by the Folin-Ciocalteu, FRAP, DPPH and CUPRAC assays revealed significantly higher potential in extracts from in vitro biomass and leaves of the parent plant, as compared to the parent plant fruit extracts.