Reactivities of quercetin and metallo‐quercetin with superoxide anion radical and molecular oxygen

Abstract

This work describes the differential quenching of molecular oxygen and superoxide anion radical (O2˙–) by (metallo)‐quercetin (QCR) complexes. The in situ complexes were more reactive with molecular oxygen than preformed complexes. By adjusting the potential range, it was determined that Cu2+ complexes exhibited similar superoxide anion radical (O2˙–) quenching ability as free QCR. The Fe3+ complexes were less reactive than free QCR or Cu2+ complexes. The data indicate that metal ions significantly modulated reactivity of QCR with O2˙– or molecular oxygen, and may regulate antioxidant activity and reactive oxygen species levels in a complex biological setting.

Metal–Flavonoid Interactions—From Simple Complexes to Advanced Systems

“…In this case, the electron-rich flavonoid affects the oxidation state of the metal ion, and vice versa. A common outcome of such in situ interaction is the generation of redox-stable forms [ 84 ]. This chapter describes the redox chemistry of Cu II and Fe III/II complexes with FLs.…”

“…One of the most critical pieces of data on the activity of in situ complexes was delivered by Lewis et al [ 84 ]. In this case, the activities of quercetin, Cu II , Fe III , and their pre-formed and in situ complexes were investigated against the O 2 •− /O 2 redox pair.…”

“…The synthesized Fe III –quercetin was found to be less active against both oxygen chemicals. By contrast, the pre-formed Cu II –quercetin exhibited analogical activity as the free ligand only against the O 2 •− radical [ 84 ].…”

Opto Field-Effect Transistors for Detecting Quercetin–Cu2+ Complex

“…As reported in the literature, using UV–Vis spectrophotometry, quercetin showed band I absorption (~300–380 nm) and band II absorption (240–280 nm). An absorption peak at 370 nm observed upon the reaction with copper ion at a ratio of 1:1 shifted to approximately 450 nm upon increasing the copper ion concentration [ 9 , 12 ]. In this study, we propose the use of a silicon nanowire field effect transistor (bio–NWFET) platform to study the shift and to detect various concentrations of copper based on quercetin–metal ion interactions.…”