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Secondary metabolites in Silphium integrifolium in the first 2 years of cultivation

Abstract Evaluation of secondary metabolite contents (essential oil, flavonoids, oleanosides, and phenolic acids) was made in leaves, inflorescences, and rhizomes of Silphium integrifolium during ontogenesis. It was found that the plant's rhizomes contained the highest level of essential oil (up to 0.61% v/w) and thus they are the most interesting raw material. Leaves contained the highest level of flavonoids (up to 1.31%). However, oleanosides occurred the most abundantly in inflorescences (4.59%). Inflorescences were characterised with the largest amounts of phenolic acids (up to 48.19 mg × 100 g–1 dry mass (DM) in total). It was found that caffeic and protocatechuic acids were the dominant phenolic acids in S. integrifolium. The optimum date of harvest was the period just before flowering.