Cutting-edge analytical technologies for the comprehensive metabolic profiling of Alkanna tinctoria roots cultured in greenhouse conditions

The use of plants containing naphthoquinone derivatives Alkannins & Shikonins (A/S) by humans dates back to ancient times. In recent decades, the use of A/S has seen a resurgence and A/S have risen to a pivotal role as pharmaceutical and cosmeceutical agents, since they possess strong wound healing, antimicrobial, anti-inflammatory, tissue regenerative and antitumor properties. It is thus crucial to enhance the biosynthesis of bioactive A/S in Alkanna tinctoria plants, that naturally produce high amounts of these metabolites [1]. In the frame of “MICROMETABOLITE” EU H2020 project, we have optimized a workflow for the metabolic profiling of A. tinctoria roots, cultured in the greenhouse from plants obtained by in vivo shoot cuttings. A fast and reliable extraction procedure was achieved for comprehensive profiling and identification of A/S and other metabolites biosynthesized in the roots. The aim of this work was to determine the growth stage with peak A/S production, while simultaneously obtaining additional information on the root metabolome. A combination of UHPLC-HRMS and NMR was used for metabolite identification, HPLC was utilized for reliable quantitation of A/S and the extracts were subjected to chiral HPLC analysis [2] for determination of the enantiomeric A/S ratio. Different A/S derivatives and other metabolites were identified in plant roots using UHPLC-HRMS and NMR. Six A/S derivatives and total A/S were quantified using HPLC-DAD. From six vegetation stages of A. tinctoria grown under greenhouse conditions, fruiting period was found to peak A/S production (1% wt/wt of root), while the enantiomeric alkannin/shikonin ratio remained constant (93.7%)