Synthesis, Characterization, and Biomedical Applications of an Alkylated Quercetin–Gadolinium Complex

Abstract

Flavonoids and their derivatives have been extensively studied for their pharmaceutical applications due to their antioxidant and anti-inflammatory properties. The coordination complexes of several flavonoids have demonstrated DNA binding ability that can confer anticancer properties. The structure of the flavonoid has a pronounced influence on its pharmacological properties. Herein we report the synthesis and characterization of alkylated quercetin and its complex with gadolinium. The structure of the complex was confirmed using spectroscopic techniques. The ability of the gadolinium–alkylated quercetin complex to serve as a magnetic contrast agent was compared with gadolinium–quercetin complex. The quercetin–gadolinium complex was found to exhibit better contrast property with a relaxivity of 0.2952 μg mL–1 s–1 when compared to the gadolinium complex of alkylated quercetin. This difference primarily arises due to the greater hydrophobicity of the alkylated quercetin complex that restricts access of water. However, the alkylated quercetin was found to exhibit better enzyme mimic activity as the metal ion served as a redox center that enabled quantification of hydrogen peroxide in the concentration range 50–450 μM within 5 s with a sensitivity of 64 nA/μM and limit of detection of 7.3 μM. The better sensing performance of the alkylated quercetin–gadolinium complex, reported here for the first time, when compared to quercetin–gadolinium complex can be attributed to the enhanced electroactive area on the working electrode.

Quercetin@Gd3+ doped Prussian blue nanocubes induce the pyroptotic death of MDA-MB-231 cells: combinational targeted multimodal therapy, dual modal MRI, intuitive modelling of r1–r2 relaxivities

“…Herein, a red shift (∼12 cm −1 ) of the characteristic peak of GPB 0.5 and improved intensity of the peak at 1612 cm −1 due to overlap of δ (N–H) and ν (CO) confirms the successful loading of Qu onto the surface of GPB 0.50 @PDA@PEG@HA. 57 Besides this, the optical absorption spectra of bare Qu exhibits an absorption band, centered at 382 nm (Fig. 5(d)), while the peak gets shifted to 338 nm for GPB 0.50 @PDA@PEG@HA@Qu, corroborating successful loading.…”

Iron (III)-Quercetin Complex: Synthesis, Physicochemical Characterization, and MRI Cell Tracking toward Potential Applications in Regenerative Medicine

“…It was reported that the chemical reaction of iron (III) at the catechol site of gallic acid, gallic acid methyl ester, and catechin resulted in characteristic absorption peaks of 415 nm and 690–695 nm [ 57 ], while the chemical reaction of iron (III) at the hydroxychromone site of quercetin revealed an absorption peak of 420 nm [ 22 ]. On the other hand, the complex of Gd (III)-quercetin, whose complex site is located at C 4 on ring C and C 5 on ring A of quercetin, did not reveal an absorption peak at a wavelength higher than 450 nm [ 46 ]. The complex between iron (III) and 3, 5, 7-tri-O-methyl-quercetin (free -OH at the catechol site) revealed a characteristic absorption peak of 600 nm [ 58 ].…”

Efficacy of 3D printed anatomically equivalent thermoplastic polyurethane guide conduits in promoting the regeneration of critical-sized peripheral nerve defects

“…1 H-NMR spectra for pristine TPU filament were recorded using the JEOL NMR 600 MHz instrument with tetramethyl silane (TMS) as the reference (δ = 0 ppm). Approximately 50 mg of TPU filament was dissolved in 1 ml of deuterated DMSO (DMSOd 6 ) solvent, and the spectra were analyzed by Delta 5.3.1 software to predict the chemical structure of the TPU filament [17].…”