Synthesis of quercetin-iron (Fe) complex and its in silico and in vitro confirmation towards antibacterial activity

Aim: In this study quercetin-iron complex (QFC) was synthesized, and the structural characterizations such as x-ray diffraction, field emission-scanning electron microscopy, energy-dispersive x-ray and Brunner-Emmitt-Teller adsorption-desorption isotherm analysis revealed the crystallinity state, surface morphology and nature of the adsorbing surface with surface area value. Methodology: Functional characterizations such as UV-visible spectrometric and Fourier transform infrared analysis collectively indicated the chemical changes that appeared after complex formation in terms of characteristic change in the spectrum and band position, respectively. Results: The in vitro antibacterial activity against Escherichia coli and Staphylococcus aureus has shown a dose-dependent decrease in colony count and achieved significant removal at 15 mg/ml concentration of QFC. Conclusion: The molecular docking study supports the therapeutic application of QFC.

Spectrophotometric determination of gold(III) in forensic and pharmaceutical samples and results complemented with ICP AES and EDXRF analysis

Spectrophotometric method with three systems were developed here for the determination of gold(III) using o-dianisidine, aniline sulphate and catechol. Gold(III),in the system 1 it oxidizes o-dianisidine, in the system 2 it oxidizes catechol followed by its coupling with o-dianisidine, in the system 3 it oxidizes catechol followed by its coupling with aniline sulphate forming dye products with respective λ_max 446nm, 540nm, and 505nm. All the three systems were optimized and analytical parameters were calculated. The molar absorptivity values were 9.27×10⁴, 1.97×10⁴ and 1.62×10⁴ respectively for the systems 1, 2 and 3 with the corresponding Sandell sensitivity values (μgcm^-2), 0.0021, 0.0096 and 0.011. The optimized systems were used for the determination of gold present in some forensic jewellery and pharmaceutical samples and the results obtained were compared with the results of all samples determined by Inductively Coupled Plasma - Atomic Emission Spectrometric method and a few of them were also complemented by Energy Dispersive X-Ray Fluorescent spectral analysis.

Properties and applications of flavonoid metal complexes

Flavonoid metal complexes have a wide spectrum of activities as well as potential and actual applications.

Osmium assay in fixatives and stained rat tissues by means of acid and o,o′-dihydroxo substituted monoazo dyes and some flavonoids

New simple, rapid and accurate spectrophotometric techniques for osmium assays in fixatives and stained tissues have been elaborated using acid (Tropaeolin O, Tropaeolin OOO-I, Tropaeolin OOO-II, Orange G), o,o′-dihydroxo substituted azo dyes (Eriochrome Blue Black R, Acid Chrome Dark-Blue, Eriochrome Black T) and flavonoids (morin, quercetin, luteolin). Methods are based on sensitive osmium(IV) reactions with reagents and the formation of stable coloured compounds. Tolerance ratios of main matrix components of histological specimens during Os(IV) spectrophotometric determination with reagents has been established. Results of osmium determination in fixatives and fixed tissues, obtained by means of different reagents, appeared to be sufficiently similar, although effects of matrix components differ. The accuracy of spectrophotometric osmium assay in fixatives with azo dyes has been confirmed with voltammetric investigations. Results obtained from osmium uptake by rat gum tissues are valuable for clinical testing of dental drugs, indicating the influence of drug treatment on the gums.

Selective determination of Fe(III) in Fe(II) samples by UV-spectrophotometry with the aid of quercetin and morin

Selective UV-spectrophotometric methods for determination of iron(III) in iron(II) samples have been developed. The methods are based on the interaction of Fe(III) with quercetin and morin, compounds of the flavonoid group. Redox reactions occurring between Fe(III) ions and the reagents used make the basis for the detection. Iron(II) does not react with quercetin and morin under the conditions applied [aqueous-methanolic (3:2) soluions, 0.3 mol L(-1) HCl, 1.2 x 10(-4) mol L(-1) quercetin (morin)] and does not interfere with the determination of Fe(III). Iron(III) can be determined up to 15 microg mL(-1) using both the examined systems. The detection limits are 0.06 and 0.38 microg mL(-1) when using quercetin or morin, respectively. The method with quercetin was applied to the determination of Fe(III) (ca. 0.2%) in a Fe(II) pharmaceutical product.

A Simple and Selective Spectrophotometric Method for the Determination of Trace Gold in Real, Environmental, Biological, Geological and Soil Samples Using Bis (Salicylaldehyde) Orthophenylenediamine

A simple high sensitive, selective, and rapid spectrophotometric method for the determination of trace gold based on the rapid reaction of gold(III) with bis(salicylaldehyde)orthophenylenediamine (BSOPD) in aqueous and micellar media has been developed. BSOPD reacts with gold(III) in slightly acidic solution to form a 1:1 brownish-yellow complex, which has an maximum absorption peak at 490 nm in both aqueous and micellar media. The most remarkable point of this method is that the molar absorptivities of the gold-BSOPD complex form in the presence of the nonionic TritonX-100 surfactant are almost a 10 times higher than the value observed in the aqueous solution, resulting in an increase in the sensitivity and selectivity of the method. The apparent molar absorptivities were found to be 2.3 × 10⁴ L mol⁻¹ cm⁻¹ and 2.5 × 10⁵ L mol⁻¹ cm⁻¹ in aqueous and micellar media, respectively. The reaction is instantaneous and the maximum absorbance was obtained after 10 min at 490 nm and remains constant for over 24 h at room temperature. The linear calibration graphs were obtained for 0.1–30 mg L⁻¹ and 0.01–30 mg L⁻¹ of gold(III) in aqueous and surfactant media, respectively. The interference from over 50 cations, anions and complexing agents has been studied at 1 mg L⁻¹ of Au(III); most metal ions can be tolerated in considerable amounts in aqueous micellar solutions. The Sandell’s sensitivity, the limit of detection and relative standard deviation (n = 9) were found to be 5 ng cm⁻², 1 ng mL⁻¹ and 2%, respectively in aqueous micellar solutions. Its sensitivity and selectivity are remarkably higher than that of other reagents in the literature. The proposed method was successfully used in the determination of gold in several standard reference materials (alloys and steels), environmental water samples (potable and polluted), and biological samples (blood and urine), geological, soil and complex synthetic mixtures. The results obtained agree well with those samples analyzed by atomic absorption spectrophotometry (AAS).