Ultra-high-performance liquid chromatography supports a new reaction mechanism between free radicals and ferulic acid with antimicrobial and antioxidant activities

[Display omitted] •A new stable product based on the reaction of DPPH radical and ferulic acid.•Elucidation of the reaction mechanism by efficient method (UHPLC-ESI-Q-TOF-MS/MS).•The main reaction path between ferulic acid and DPPH is by hydrogen atom transfer.•The ferulic acid has a similar power antioxidant to Trolox. The chemical reaction involving phenolic antioxidants from plant´ extracts have not been adequately studied. In this study, we investigate a quick, accurate, and innovative strategy to elucidate the ferulic acid reaction employing a conclusive analytical tool (ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry, UHPLC-ESI-Q-TOF-MS/MS) used in pharmaceutical, cosmetic, food, and biomedical applications. The ferulic acid- DPPH(2,2-diphenyl-1-picrylhydrazyl) reaction presented three chromatographic peaks with retention times at 5.95, 8.69, and 9.04 min. The peak at 385.0928 mass/charge (m/z) is assigned to the ferulic acid-ferulic acid dimer, while the m/z 586.1193 signal indicates the adduct presence. This statement is confirmed by the fragmentation step, which supports characteristics peaks ascribed to the original DPPH at m/z 195.9986 and m/z 225.9972. The peak m/z 778.1605 is attributed to the formation of a new compound (called radimerSB) that has never identified before. According to the reaction mechanism, the ferulic acid may provide antioxidant activity mainly by hydrogen-atom transfer reaction. Furthermore, we compare the antimicrobial action of ferulic acid and Trolox. We show that against ferulic acid prevents the crop growth of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The ferulic acid biological activities can be useful to develop new bio-based materials for technological applications (e.g., medical purposes). It is essential to understand the reaction mechanism between DPPH and antioxidants. The DPPH can quantify the concentration of antioxidants in plant extracts. The biological activities (antimicrobial, cytotoxicity, and others) of these extracts depend on the type and concentration of antioxidants and their reaction products.