Analysis of metabolic variations throughout growth and development of adventitious roots in Silybum marianum L. (Milk thistle), a medicinal plant

摘要

Silybum marianum L. is a medicinal plant used in the treatment for jaundice and liver diseases. In this study, an adventitious root culture was developed for the production of health promoting phytochemicals. Adventitious roots were induced from nodal explants on solid Murashige and Skoog medium supplemented with 1.0 mg l(-1) of alpha-Naphthalene acetic acid. Growth kinetics of the roots was investigated every week, for 8 weeks of culture period. Highest fresh biomass formation (153 mg l(-1)) was observed in 6-week old cultures. Adventitious roots were harvested from different growth stages as control (CTR), lag phase (LAG), logarithmic phase (LOG) or stationary phase (STN). Metabolite profiling of the samples was investigated using electro spray ionization time of flight mass spectrometry. Significant phenylpropanoids such as cinnamic acid and di-hydro kaempferol were predominantly found in LOG phase, whereas the highest amount of malonic acid was detected in STN as compared to other growth phases. More sucrose content was detected in CTR, while the tryptophan content was higher in LOG phase. Among the vital fatty acids, prostaglandin A1 and phenyl acetic acid were at highest levels in STN phase. However, more brassicasterols were observed in LAG phase than other growth phases. Punicic acid and lignan pinoresinol were detected abundantly in the LOG phase. Biochemical characterization revealed significant correlations between silymarin content and DPPH as well as TPC and TFC in the growth curve. Interestingly, among all growth stages there was no correlation of PAL activity with TFC and silymarin content.