Characterization and Stability of the Antimony-Quercetin Complex

Abstract

Purpose: Quercetin is a flavonoid known for its therapeutic properties and for forming complexes. Although the antimony-quercetin (SbQ) complex has been produced before, no previous exploration of its characteristics has been published in literature. Thus, this study aimed to characterize this complex, assess its stability and investigate its complexation site through its antibacterial activity. Methods: The SbQ complex was synthetized using Sb(III) potassium tartrate trihydrate and quercetin anhydrous (1:1) (v/v) as a solution and dried using three methods: rotaevaporation, lyophilization and spray drying. The material, in solution, was analyzed by UV-vis and fluorimetry; and, in the powder, by X-ray diffraction (XRD), both scanning electronic and fluorescence microscopy and infrared spectroscopy (FT-IR). Antimicrobial activity was evaluated via broth microdilution. Results: UV-vis exhibited a shoulder peak at 291 nm indicating metal chelation at C-ring of quercetin and confirmed 1:1 stoichiometry. Spectrofluorimetry showed an increase of intensity with the complex formation with an emission band (525 nm). After drying, XRD and SEM indicated loss of crystallinity and a difference in shape and size of the complex compared to its precursors. FT-IR suggested by a shift of frequency of the carbonyl group (1661 cm-1) that the quercetin bond to antimony by the C-3, followed by positions C-5 and C-4 carbonyl, which has been confirmed by MIC through the structure-activity relationship of the antibacterial activity of quercetin. Conclusion: These results provided a characterization of SbQ complex with the confirmation of its binding site, working as a guide for future studies involving this complex.

Dual-sensitive GO-based self-assembly for the delivery of a hydrophobic anti-cancer drug

“…Furthermore, the peaks at 1650 cm −1 and 1560 cm −1 may be due to the CO stretching vibrations of the amide I and II bonds, 36 which proved that PDPA was grafted on the GO surface by the amide bond. Compared with the infrared spectrum of quercetin, 37 GO–PDPA–CHI@QU had same peaks of QU at 1319 cm −1 related to the bending of C–OH phenol and 1610 cm −1 related to the vibration of the benzene ring skeleton.…”

Site‐Selective Coordination Assembly of Dynamic Metal‐Phenolic Networks

“…[14] The presence of the FeÀ O stretching vibration band at 628 cm À 1 indicated the formation of the coordination complex. [15] Furthermore, the bands at 1443 and 1305 cm À 1 , which were attributed to in-plane OÀ H and CÀ H bending vibrations in the maltol group, [16] were observed in Fe II -QUE complexes at pH 4 (Figure S9 and S10a), while the band at 1474 or 1477 cm À 1 (i.e., CÀ O stretching in the catechol group) [17] was observed in Fe II -QUE complexes at pH 7 and pH 9 (Figure S9 and S10b), suggesting that the dominant coordination modes for Fe II -QUE complexes can be readily modulated by altering the pH.…”

Portable Colorimetric Hydrogel Test Kits and On-Mobile Digital Image Colorimetry for On-Site Determination of Nutrients in Water

“…The stretching of Mo–O–Mo bonding from ammonium molybdate [ 21 ] was observed at 881 cm −1 , confirming the presence of ammonium molybdate in the test kit. The bending of Mo–O–Mo bonding from ammonium molybdate, which commonly presents at 990 cm −1 [ 21 ], may have overlapped with the vibration of the C–O bonding from potassium antimony tartrate (1150 to 1085 cm −1 ) [ 22 ] and/or C–O–C stretching vibration from the cross-linking of PVA and EGDE (1089 cm −1 [ 11 ]) and thus appeared at 1037 cm −1 . The peak at 1676 cm −1 was assigned to the C=C stretching from ascorbic acid [ 23 , 24 ], whereas the peak at 1331 cm −1 might be attributed to the vibration of enol hydroxy [ 24 ].…”

“…The peak at 1676 cm −1 was assigned to the C=C stretching from ascorbic acid [ 23 , 24 ], whereas the peak at 1331 cm −1 might be attributed to the vibration of enol hydroxy [ 24 ]. The peaks at 762 to 669 cm −1 might be attributed to the Sb–O from potassium antimony tartrate [ 22 ].…”