An integrated FIDI-MS and UPLC-Q-TOF/MS strategy for rapid functional screening and chemical characterization of antioxidants in Polygonum multiflorum.

A novel integrated strategy combining field-induced droplet ionization mass spectrometry (FIDI-MS) with ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was developed for the rapid screening and identification of antioxidant constituents in herbal extracts. This approach enables real-time assessment of antioxidant activity within microdroplets and comprehensive compositional characterization of complex matrices. Applied to Polygonum multiflorum extract (PME), the method successfully identified known antioxidants such as 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside (TSG) and revealed additional bioactive phytochemicals. Quantitative FIDI-MS dose-response profiling determined the antioxidant potency of key compounds, with trans-TSG exhibiting superior activity (IC50 = 13.33 ± 1.06 μM) compared to its cis-isomer and emodin. By integrating functional screening, reliable chemical profiling, and targeted quantification, the strategy enabled comprehensive analysis of bioactive constituents in complex herbal samples. Furthermore, the utility of FIDI-MS, when coupled with chromatographic separation and high-resolution mass detection, is underscored as a complementary approach for functional and chemical interrogation of bioactive compounds in botanical matrices.