Endogenous production of specific flavonoids and verbascoside in agar and agitated microshoot cultures of Scutellaria lateriflora L. and biotransformation potential

Key message After testing of 10 media variants in two types of in vitro cultures high amounts of flavonoids (app. 3 g%) and verbascoside (0.54 g%) were obtained. Additionally, 5.6 g% of arbutin as hydroquinone beta-d-glucosylation product was confirmed. Methanolic extracts of microshoots from agar cultures and of microshoots and media from agitated cultures ofScutellaria laterifloragrown on identical five variants of the Murashige-Skoog (MS) and Linsmaier-Skoog (LS) media with different 6-benzyladenine (BA) and 1-naphthaleneacetic acid (NAA) concentrations (0.5-3.0 mg/l) were analyzed for flavonoids (27 compounds), phenylpropanoid glycosides (2 compounds) and phenolic acids (19 compounds) using the DAD-HPLC method. The amounts of individual compounds and total amounts of the above mentioned metabolite groups in the biomass from both types of the tested cultures were dependent on the composition of basal media and concentrations of BA and NAA in the media variants. In media extracts, no metabolites were confirmed. Higher total amounts of flavonoids were obtained in agar cultures (max. 722.04 and 2989.55 mg/100 g DW on MS and LS media variants, respectively), which were 1.1 and 1.7 times higher, respectively, than in agitated cultures. In both types of cultures, glycosidic conjugates: baicalin and wogonoside were the main flavonoids (max. amounts: 513.93 and 1838.18 mg/100 g DW, and 305.92 and 700.85 mg/100 g DW in agar cultures on MS and LS variants, respectively). High amounts of verbascoside in agar cultures were also confirmed (max. 384.99 and 543.17 mg/100 g DW on MS and LS media variants, respectively). The cells grown in agitated cultures converted exogenous precursors, i.e. hydroquinone (HQ) and 4-hydroxybenzoic acid (4-HBAc) into arbutin (beta-d-glucoside of HQ). The highest amount of this product reached 5.63 and 1.45 g/100 g DW after the addition of these two precursors, respectively. This is the first large-scale report documenting in vitro biosynthetic potential ofScutellaria laterifloramicroshoots cultivated in two tested culture.