Hydrolysis-Driven Compositional Modification of Flavonoids in the Aerial Parts of Lespedeza cyrtobotrya Miq. and Its Impact on Monoamine Oxidase A Inhibitory Activity.

This study was conducted to investigate processing-induced compositional modification of flavonoids in Lespedeza cyrtobotrya and its impact on food-relevant bioactivity using a quantitative and validated analytical approach. Extracts, fractions, and isolated compounds from the aerial parts were systematically evaluated for monoamine oxidase inhibitory activity as a functional indicator. Nine flavonoid glycosides were isolated and structurally characterized, including two newly identified acetylated derivatives that exhibited moderate inhibitory effects. To assess the influence of processing, acid hydrolysis was applied to convert flavonoid glycosides to aglycone forms. Quantitative analysis revealed a pronounced shift in flavonoid composition after hydrolysis, with kaempferol increasing from undetectable levels to 907.1 mg/g of the extract. This compositional transformation was accompanied by a significant enhancement of MAO-A inhibitory activity, which showed a strong correlation to kaempferol enrichment. Overall, the results demonstrate that controlled hydrolysis effectively modulates flavonoid composition and functionality, highlighting L. cyrtobotrya as a promising raw material for food chemistry and functional ingredient applications.