HPLC–UV analysis of sample preparation influence on flavonoid yield from Cirsium japonicum var. maackii

This study was conducted to optimize the extraction conditions of flavonoids from Cirsium japonicum var. maackii (ICF-1). The effects of sample material ratio, solvent concentration, extraction time, solid-to-solvent ratio, and number of extractions on flavonoid extraction efficiency were analyzed. Three flavonoids were specifically investigated: cirsimarin (1), hispidulin (2), and cirsimaritin (3). In single-factor experiments, each variable had a significant effect on the determination of content of compounds 1–3. The optimal conditions for extraction were found to be: mass, 15 g; ratio of spring and fall leaves, 4:1; extraction solvent, 70% ethanol; extraction time, 4 h; solid-to-solvent ratio, 1:20; and number of extractions, 1. The results of the study were used to maximize the potential of ICF-1 samples and optimize the efficiency of the extraction process.