The simultaneous separation and determination of six flavonoids and troxerutin in rat urine and chicken plasma by reversed-phase high-performance liquid chromatography with ultraviolet–visible detection

Unique Host Matrix to Disperse Pd Nanoparticles for Electrochemical Sensing of Morin: Sustainable Engineering Approach

Biomass-based carbon nanospheres derived from Mimosa pudica (commonly called "Touch-me-not") smeared on carbon fiber paper have been used as a host matrix for electrochemical deposition of palladium nanoparticles. The physicochemical characterization of modified electrodes was performed by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy techniques. Cyclic voltammetry and electrochemical impedance spectroscopy were used to study the electroanalytical properties of the electrodes. The modified electrode demostrated an excellent electrocatalytic activity for the oxidation of a flavonoid, morin, which gave a sensitive anodic peak at -0.30 V (vs SCE). An ultralow-level detection limit of 572 fM with a linear dynamic range of 37.50-130 pM was achieved. The proposed electrochemical sensor was successfully employed for the analysis of morin in mulberry and guava leaves. This is a sustainable engineering approach where a perfect unique host matrix is created using carbon nanospheres from biomass.

UHPLC-UV Analysis of Morin and Structurally Related Flavonoids with Potential Anticancer Activity

Background:

Flavonoids as secondary metabolites of plants fulfill various functions in cell protection. They are of a considerable scientific interest because of their potentially medical use due to their anticancer, chemoprotective, antimicrobial, antiallergic, anti-inflammatory and antiviral activities. </P><P> Objective: The study aimed to develop a new UHPLC-UV method for morin and 2 other structurally related flavonoids - naringenin and kaempferol as the structural similarity of huge numbers of flavonoids does not limit their various biological functions and activities.

Methods:

Separation of morin and 2 other structurally related flavonoids - naringenin and kaempferol - was achieved by using BEH C18 (1.7 µm, 2.1 x 50 mm) analytical column (Waters® Acquity UPLC) and a mobile phase composed of 0.05%v/v Formic acid in water and acetonitrile in proportion of 77:23 v/v and pumped at a flow rate of 0.4 ml/min. Column temperature was set at 25 ºC and samples were analyzed (3 µl injection volume) at a wavelength of 340 nm. Waters® Xevo G2-S QToF coupled with Waters® Acquity UPLC system with binary Solvent Manager (I-Class) via electrospray ionization (ESI) interface was used to confirm the identity of the peaks in biological samples.

Results:

A rapid and simple UHPLC-UV separation of morin, kaempferol and naringenin is documented including methods validation. The developed method was applied to measuring morin, kaempferol and naringenin in human plasma after a solid phase extraction. Additionally, stability of morin in tissue culture medium was verified. The extraction method and UHPLC-UV elution conditions described provide a practical means to analyze morin, kaempferol and naringenin in biological matrices.

Conclusion:

The developed method is fast and highly sensitive. Moreover, the flavonoids used were stable in human plasma for more than 10 days.

Quantitative separation of hesperidin, chrysin, epicatechin, epigallocatechin gallate, and morin using ionic liquid as a buffer additive in capillary electrophoresis

Recently, an increasing interest has been observed in ionic liquids (ILs) due to their potentialities in various chemical processes. ILs have some unique properties making them excellent additives in CE. In this work a simple, rapid, and reliable CZE method has been developed and validated using 1-butyl-3-methyl imidazolium hexafluorophosphate (BMIM-PF₆ ) ionic liquid as a buffer additive for the determination/separation of five flavonoids including hesperedin, epicatechin (EC), epigallocatechin gallate (EGCG), and morin using photodiode array (PDA) detector. The effect of several parameters such as concentration and pH of the running buffer, applied voltage, and concentration of ionic liquid were optimized. CZE at 25°C with 25 mM borate buffer of pH 9.0 at an applied voltage of 17 kV by adding 17.5 mM of IL was found to be suitable for the separation/determination of all five analytes within 08 min. Validation of the method was performed in terms of linearity, accuracy, precision, and limit of detection and quantification. The calibration curves were plotted in the concentration range of 1-200 μg/mL for all five analytes. The response was linear with R²  = 0.990 for EC, chrysin, and hesperidin, 0.992 for morin, and 0.988 for EGCG. LOD and LOQ were obtained within the range of 0.4-0.5 and 1.4-1.7 μg/mL, respectively. The proposed method showed good reproducibility with RSD of less than 3% for both migration time and peak height. The method was successfully applied for the determination of flavonoids from citrus fruits and tea samples.

Troxerutin, a mixture of O-hydroxyethyl derivatives of the natural flavonoid rutin: Chemical stability and analytical aspects

Troxerutin (TRX) is a mixture of semisynthetic hydroxyethylrutosides (Hers) arising from hydroxyethylation of rutin, a natural occurring flavonoid. TRX is commonly used for its anti-oxidant and anti-inflammatory properties in chronic venous insufficiency and other vascular disorders. In recent studies, the protective effects of TRX in Alzheimer's disease, colon carcinogenesis and hepatocellular carcinoma are emerged. However, the chemical stability of TRX has never been studied. Hence, the aims of the work were to study the TRX chemical stability through a forced degradation study and to develop and validate a new stability indicating LC-UV method for determination of TRX. In order to perform the study, TRX stability was tested in various stress conditions analysing the degradation samples by LC-MS. Three degradation products (DPs; D1, D2 and D3, 3',4',7-Tri-O-(β-hydroxyethyl)quercetin, 3',4',5,7-Tetra-O-(β-hydroxyethyl)quercetin and 3',4'-Di-O-(β-hydroxyethyl)quercetin respectively) arising from degradation in acidic conditions were identified and synthesized: among them, D1 resulted the stability indicator for hydrolytic degradation. Furthermore, a stability-indicating LC-UV method for simultaneous determination of triHer (3',4',7-Tri-O-(β-hydroxyethyl)rutin, the principal component of the mixture) and D1 was developed and validated. The LC-UV method consisted in a gradient elution on a Phenomenex Kinetex EVO C18 (150 × 3 mm, 5 μm) with acetonitrile and ammonium bicarbonate buffer (10 mM, pH 9.2). The method was linear for triHer (20-60 μg mL^-1) and D1 (5.1-35 μg mL^-1). The intraday and interday precision were determined and expressed as RSDs: all the values were ≤ 2% for both triHer and D1. The method demonstrated also to be accurate and robust and the average recoveries were 98.8 and 97.9% for triHer and D1, respectively. Moreover, the method resulted selective and specific for all of the components present in the degradation pattern of TRX (diHer (3',4'-Di-O-(β-hydroxyethyl)rutin), triHer, tetraHer (3',4',5,7-Tetra-O-(β-hydroxyethyl)rutin), D3, D1 and D2) and it was successfully applied for the stability studies of both drug substances and drug products.

Analysis of isoflavones and flavonoids in human urine by UHPLC

A rapid, ultra high-performance liquid chromatographic (UHPLC) method has been developed and validated for simultaneous identification and analysis of the isoflavones genistein, daidzein, glycitin, puerarin, and biochanin A, and the flavonoids (±)-catechin, (−)-epicatechin, rutin, hesperidin, neohesperidin, quercitrin, and hesperetin in human urine. Urine samples were incubated with β-glucuronidase/sulfatase. UHPLC was performed with a Hypersil Gold (50 × 2.1 mm, 1.9 μm) analytical column. Elution was with a gradient prepared from aqueous trifluoroacetic acid (0.05%) and acetonitrile. UV detection was performed at 254 and 280 nm. The calibration curves were indicative of good linearity (r² ≥ 0.9992) in the range of interest for each analyte. LODs ranged between 15.4 and 107.0 ng mL⁻¹ and 3.9 and 20.4 ng mL⁻¹ for flavonoids and isoflavones, respectively. Intra-day and inter-day precision (C.V., %) was less than 3.9% and 3.8%, respectively, and accuracy was between 0.03% and 5.0%. Recovery was 70.35–96.58%. The method is very rapid, simple, and reliable, and suitable for pharmacokinetic analysis. It can be routinely used for simultaneous determination of these five isoflavones and seven flavonoids in human urine. The method can also be applied to studies after administration of pharmaceutical preparations containing isoflavones and flavonoids to humans.