First and Second Derivative Spectrophotometric Determination of Flavonoids Chrysin and Quercetin

Facile green spectrophotometric approaches for the determination of three natural edible antioxidant polyphenols in different matrices

The combination of Curcumin (CRN), resveratrol (RSV), and quercetin (QRN) has significant antioxidant effects and is found to be more effective than a single polyphenol. Spectrophotometric methods are considered one of the most common analytical techniques for the determination of the drugs due to their sensitivity, rapidness, low cost, and reproducibility. Therefore, the presence of new, and simple methods for the determination of such compounds will be highly valuable, specially in the presence of spectral overlap. In this research, five different facile spectrophotometric methods were investigated for the simultaneous determination of that ternary mixture for the first time, including zero order (I), first derivative (II), ratio difference double divisor (III), first derivative ratio spectra (IV), and mean centering (V) methods. The designed approaches were linear over the concentration ranges of (1.0-10.0), (0.5-8.0), and (1.0-14.0) μg/mL, respectively for curcumin, resveratrol, and quercetin. The different methods were then validated as stated by the International Council of Harmonization. The accuracy and precision have been evaluated by statistical analysis including student t-test, variance ratio F-test, and ANOVA. Moreover, the greenness and whiteness of the proposed methods were assessed to ensure the adherence to the greenness characters.

Application of quercetin flavonoid based hybrid nanocomposites: A review

Natural bioflavonoids are an essential component of dietary supplements possessing antimicrobial properties. Many of the bioflavonoids have resulted in positive antitumor, anticancer, antibacterial, antifungal, anti-inflammatory properties, but the efficacy remains low due to toxicity at the molecular level whereas antiviral property limits to negative. The synergistic link between nanoscience and flavonoid chemistry enhances the epidemiological properties of flavonoid and also diminish the antimicrobial resistivity (AMR) by forming their hybrid nanocomposites. Nanochemistry uses various nanocomposite and nanomaterials for biosensing the flavonoids and their delivery as a drug. The quercetin flavonoid and its derivatives such as rutin, and myricetin are used for sensing and drug delivery. Quercetin with 15Carbon-5Hydroxyl chemical scaffold has been explored for a few decades for the development of hybrid nanocomposite and nanomaterial with metallic as well as organic nano co-composites. This quercetin flavonoid based hybrid nanocomposites seemed to show a significant effect on In vitro and some animal model processes along with attenuating lipid peroxidation, platelet aggregation, and capillary permeability actions. This review mainly focused on the hybrid nanoscience of quercetin bioflavonoid and its application in numerous biological, material fields with a future perspective.

Electrochemical Evaluation of the Total Antioxidant Capacity of Yam Food Samples on a Polyglycine-Glassy Carbon Modified Electrode

Background:

The total antioxidant capacity of yam food grown in southern African regions was investigated by a polyglycine-glassy carbon modified electrode. The modified electrode was fabricated using glycine solution on glassy carbon electrode by electrodeposition method. The proposed modified electrode is found to be nearly 3.15-fold more sensitive than the bare electrode. For the measurement of the total antioxidants of yam, differential pulse stripping voltammetry (DPSV) was employed with standard quercetin compound.

Methods:

The total antioxidant capacity of yam was deduced by DPSV and cyclic voltammetry (CV) methods. The basic parameters for the stripping technique such as pH, accumulation time and accumulation potential were optimized as 20 s, 200 mV and a pH of 3 Britton-Robinson (B-R) buffer solutions in 0.5 mg quercetin/L, respectively.

Results:

In the optimization condition, the linear working range was determined between 5.0 μg/L and 80.0 µg/L for the quercetin. The detection (LOD) and quantification (LOQ) limits of quercetin were found to be 0.39 µg/L and 1.39 µg/L on the modified electrode by DPSV, respectively. The procedure was also applied to natural yam samples and total antioxidant capacity of 0.1 kg of yam was determined as 96.15 ± 0.85 µg/L of equivalent quercetin at 95% confidence level with the relative standard deviations of 0.88%.

Conclusion:

Sensitive and selective voltammetric method was developed for the determination of total antioxidant capacity in yam. Moreover, the modified polyglycine-glassy carbon electrode was constructed more selectively for quercetin. As a result, a simple, sensitive and rapid new voltammetric method for the determination of antioxidants has been developed using the modified electrode.

One-pot green and simple synthesis of actinian nickel-doped carbon nanoflowers for ultrasensitive sensing of quercetin

In this contribution, a one-pot method possessing the advantages of easy preparation, rapidness, efficiency and environmental friendliness has been developed for the first time for the facile synthesis of highly fluorescent actinian nickel-doped carbon nanoflowers (Ni-CNFWs) by using nickel(ii)acetylacetonate as a metal-carbon source. Various characterization studies indicate that metal nickel atoms have been successfully doped into carbon nanoflower frameworks with a weight percentage of 1.46 wt%. The Ni-CNFWs showed a "shell-core" actinian structure with ∼400 nm diameter and highly efficient fluorescence quenching ability in the presence of quercetin (Qut) due to the formed Meisenheimer complexes via the conjugation effect of p, π-electrons between Ni-CNFWs and Qut, which allowed the analysis of Qut in a very facile method. Under the optimal conditions, the decreased fluorescence of Ni-CNFWs showed a good linear relationship with the concentration of Qut ranging from 0.5 to 300.0 μM, and the limit of detection was 0.137 μM (3σ/k). Finally, the content of Qut in bovine serum was successfully detected with the novel on-off sensor, and the recoveries were 97.3-101.9%, which indicate that the constructed on-off sensor has a high selectivity and accuracy.

Hexammine cobalt(iii) coordination complex grafted reduced graphene oxide composite for sensitive and selective electrochemical determination of morin in fruit samples

The RGO/[Co(NH₃)₆]³⁺/GCE modified GCE was potentially applied for the electrochemical detection of MR.

Graphene nanosheets as a sensing platform for amplified electrochemical measurement of quercetin and uric acid in biological fluids

A simple and selective electrochemical method was investigated for the simultaneous determination of quercetin (Qu) and uric acid (UA) in aqueous media (citrate buffer solution, pH 4.0) on a glassy carbon electrode modified with graphene nanosheets as a sensing platform (GNSs/GCE). Cyclic voltammetry, transmission electron microscopy, and Fourier transform infrared spectroscopy were employed to characterize the nanostructure of the sensor. Separation of the oxidation peak potentials for Qu and UA was about 160 mV, and the anodic currents for the oxidation of both Qu and UA are greatly increased at GNSs/GCE, which makes it suitable for simultaneous determination of these compounds. The detection limits were 0.0011 and 0.0137 μmol/L for Qu and UA, respectively. The method was applied to the determination of Qu and UA in human blood serum and urine samples.

Recent Developments of Derivative Spectrophotometry and Their Analytical Applications

Articles about the development of derivative spectrophotometric methods and analytical applications of derivative spectrophotometry (DS) published in the last nine years (since 1994) are reviewed.