Phenylpropanoids in Silybum marianum cultures treated with cyclodextrins coated with magnetic nanoparticles

The glucose oligosaccharide-derived cyclodextrins (CDs) are used for improving bioactive compound production in plant cell cultures because, in addition to their elicitation activity, CDs promote product removal from cells. However, despite these advantages, the industrial application of CDs is hampered by their high market price. A strategy to overcome this constraint was recently tested, in which reusable CD polymers coated with magnetic Fe₃O₄ nanoparticles were harnessed in Vitis vinifera cell cultures to produce t-resveratrol (t-R). In this study, we applied hydroxypropyl-β-CDs (HPCD) and HPCDs coated with magnetic nanoparticles (HPCD-EPI-MN) in methyl jasmonate (MJ)-treated transgenic Silybum marianum cultures ectopically expressing either a stilbene synthase gene (STS) or a chalcone synthase gene (CHS), and compared their effects on the yields of t-R and naringenin (Ng), respectively. HPCD-EPI-MN at 15 g/L stimulated the accumulation of metabolites in the culture medium of the corresponding transgenic cell lines, with up to 4 mg/L of t-R and 3 mg/L of Ng released after 3 days. Similar amounts were produced in cultures treated with HPCD. Concentrations higher than 15 g/L of HPCD-EPI-MN and prolonged incubation periods negatively affected cell growth and viability in both transgenic cell lines. Reutilization of HPCD-EPI-MN was possible in three elicitation cycles (72 h each), after which the polymer retained 25-30% of its initial efficiency, indicating good stability and reusability. Due to their capacity to adsorb metabolites and their recyclability, the application of magnetic CD polymers may reduce the costs of establishing efficient secondary metabolite production systems on a commercial scale. KEY POINTS: • Long-term transgenic S. marianum suspensions stably produce transgene products • t-R and Ng accumulated extracellularly in cultures elicited with HPCD and HPCD-EPI-MN • The recyclability of HPCD-EPI-MN for metabolite production was proven.