The effect of cytokinins on growth, phenolics, antioxidant and antimicrobial potential in liquid agitated shoot cultures of Knautia sarajevensis

Endemic plants are under constant threat of extinction and micropropagation protocols that can provide not only mechanisms for their revitalisation, but also a possibility for potential sources of new biologically active substances. This study describes the very first use of the liquid culture system for in vitro Knautia sarajevensis shoot multiplication, production of biomass, and an increase in biological activities of the extracts. Murashige and Skoog media containing various concentrations of cytokinins (6-benzyladenine, zeatin, and kinetin) were used to establish agitated shoot cultures of this endemic plant species and to evaluate their effect on shoot morphology. HPLC analysis of phenolic compounds show that the main metabolite in all extracts was salicylic acid with accumulation of rosmarinic and 4-hydroxybenzoic acid for some treatments. The richest sources of phenolics were shoots cultivated in media containing zeatin, which also had high influence on biomass production. Analysis of antioxidant and antimicrobial potential suggests that this plant could have beneficial biological activities. Methanol extracts of shoots cultivated in media containing 2.0 mg/L 6-benzyladenine were moderately active against Staphylococcus aureus and Bacillus spizizeni. DPPH assay showed radical scavenging activity of shoot cultures with IC50 10–90 µg/mL.