Characterization and Stability of the Antimony-Quercetin Complex

Area of Science:

• Medicinal Chemistry
• Materials Science
• Biochemistry

Background:

• Quercetin, a known flavonoid, possesses therapeutic properties and can form complexes.
• The antimony-quercetin (SbQ) complex has been synthesized previously, but its characteristics remain unexplored in scientific literature.

Purpose of the Study:

• To characterize the antimony-quercetin (SbQ) complex.
• To assess the stability of the SbQ complex.
• To investigate the complexation site of SbQ through its antibacterial activity.

Main Methods:

• Synthesis of SbQ complex using Sb(III) potassium tartrate trihydrate and quercetin anhydrous.
• Analysis in solution using UV-vis and fluorimetry.
• Powder analysis using X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence microscopy, and FT-IR spectroscopy.
• Evaluation of antimicrobial activity via broth microdilution.

Main Results:

• UV-vis spectroscopy indicated metal chelation at the C-ring of quercetin and confirmed a 1:1 stoichiometry.
• Spectrofluorimetry revealed an increased intensity with complex formation and an emission band at 525 nm.
• XRD and SEM showed a loss of crystallinity and altered morphology post-drying.
• FT-IR analysis suggested antimony binding to quercetin at the C-3, C-5, and C-4 carbonyl positions, corroborated by structure-activity relationship of antibacterial activity.

Conclusions:

• The study successfully characterized the SbQ complex, confirming its binding site.
• The findings provide a basis for future research on the SbQ complex, including its stability and therapeutic potential.
• The antibacterial activity of the SbQ complex was linked to its specific binding interactions with quercetin.