Effect of pH on the chemical modification of quercetin and structurally related flavonoids characterized by optical (UV-visible and Raman) spectroscopy

Jurasekova, Z.; Domingo, Concepción; Garcı́a-Ramos, José Vicente; Sánchez-Cortés, Santiago

doi:10.1039/c4cp00864b

Cited by 133 publications

(78 citation statements)

References 56 publications

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“…On the other hand, quercetin showed a lower analytical response at pH 7.4, despite the acidification carried out during sample preparation; thus, it was necessary to define an independent regression model for this compound in each pH condition. The lower response of quercetin at alkaline pH could be a consequence of the poor stability of the compound as was confirmed experimentally (Figure , Table ) and supported by other authors …”

Section: Discussionsupporting

confidence: 77%

Matrix effects of the hydroethanolic extract and the butanol fraction of calyces from Physalis peruviana L. on the biopharmaceutics classification of rutin

Moré

Feltrin

Brambila

et al. 2020

Journal of Pharmacy and Pharmacology

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Objectives The Biopharmaceutics Classification System (BCS) categorizes active pharmaceutical ingredients according to their solubility and permeability properties, which are susceptible to matrix or formulation effects. The aim of this research was to evaluate the matrix effects of a hydroethanolic extract of calyces from Physalis peruviana L. (HEE) and its butanol fraction (BF), on the biopharmaceutics classification of their major compound, quercetin‐3‐O‐rutinoside (rutin, RU). Methods Rutin was quantified by HPLC‐UV, and Caco‐2 cell monolayer transport studies were performed to obtain the apparent permeability values (Papp). Aqueous solubility was determined at pH 6.8 and 7.4. Key findings The Papp values followed this order: BF > HEE > RU (1.77 ± 0.02 > 1.53 ± 0.07 > 0.90 ± 0.03 × 10−5 cm/s). The lowest solubility values followed this order: HEE > RU > BF (2.988 ± 0.07 > 0.205 ± 0.002 > 0.189 ± 0.005 mg/ml). Conclusions According to these results, rutin could be classified as BCS classes III (high solubility/low permeability) and IV (low solubility/low permeability), depending on the plant matrix. Further work needs to be done in order to establish how apply the BCS for research and development of new botanical drugs or for bioequivalence purposes.

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Section: Discussionsupporting

confidence: 77%

Matrix effects of the hydroethanolic extract and the butanol fraction of calyces from Physalis peruviana L. on the biopharmaceutics classification of rutin

Moré

Feltrin

Brambila

et al. 2020

Journal of Pharmacy and Pharmacology

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“…However, at pH 8.4 in the absence of metal ions absorption maxima of these bands shifted to higher wavelengths (271 and 385 nm) in comparison to rutin in acidic solutions (256 and 356 nm at pH 3). This bathochromic shift of absorption bands was caused by the partial deprotonation of rutin molecule with increasing pH value of solution as in the case of similar flavonoid molecules (20). Complexation of flavonoids with metal ion causes further bathochromic shift of characteristic absorption bands (19), and in the presence of Mg(II) and Ca(II) ions absorption maximum of the cinnamoyl band shifted to 406 nm and 395 nm, respectively, while there was almost no shift of the benzoyl band.…”

Section: Resultsmentioning

confidence: 99%

The Influence of Mg(II) and Ca(II) Ions on Rutin Autoxidation in Weakly Alkaline Aqueous Solutions

Zivanovic¹,

Nikolić²,

Nikolić³

2016

Acta Facultatis Medicae Naissensis

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Rutin (quercetin-3-O-rutinoside) is one of the most abundant bioflavonoids with various biological and pharmacological activities. Considering the ubiquitous presence of Mg(II) and Ca(II)ions in biological systems we decided to investigate their influence on the autoxidation of rutin in weakly alkaline aqueous solutions. Changes in UV-Vis spectra recorded during the rutin autoxidation in aqueous solution at pH 8.4 revealed that this process was very slow in the absence of metal ions. The presence of Mg(II) and, especially Ca(II) ion, increased the transformation rate of rutin. UV-Vis spectra recorded after prolonged autoxidation indicated the formation of humic acidlike products in the presence of Mg(II) and Ca(II) ions. Four new compounds formed during the initial stage of rutin autoxidation in the presence of Mg(II) and Ca(II) ions were detected by HPLC-DAD. Based on the analysis of their DAD UV-Vis spectra and comparison of their retention times with the retention time value for rutin, we concluded that the initial rutin transformation products were formed by the water addition on double bond in ring C and hydroxylation of ring B. A very small decrease of the initial rutin concentration (4%) was observed by HPLC-DAD in the absence of metal ions for the period of 90 minutes. However, rutin concentration decrease was much larger in the presence of Mg(II) and Ca(II) ions (14% and 24%, respectively). The more pronounced effect of Ca(II) ion on the rutin autoxidation may be explained by the stronger binding of Mg(II) ion to rutin and thus greater stabilizing effect on reaction intermediates caused by its higher ionic potential (charge/ionic radius ratio) in comparison to Ca(II) ion. The results of this study may contribute to the better understanding of interactions of Mg(II) and Ca(II) ions with natural phenolic antioxidants which are important for their various biological activities.Key words: rutin, autoxidation, magnesium, calcium O r i g i n a l a r t i c l e I NT ROD U CT I ONPhenolic compounds are ubiquitous in plants and their dietary intake has many beneficial effects on human health (1, 2). Rutin (quercetin-3-O-rutinoside), the glycoside between the flavonol quercetin and disaccharide rutinose (α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranose) (Figure 1) is one of the most abundant bioflavonoids with various biological and pharmacological activities (2, 3). Oxidation or/and autoxidation of natural phenolic compounds may have profound influence on their biological activity and stability of certain types of foods (4). Compounds having two or three vicinal hydroxyl groups on the same benzene ring are especially susceptible to autoxidation, and it was found that this process is mainly influenced by the pH value (4) and the presence of transition metal ions like Mn(II), Fe(II), and Cu(II) (5, 6) which are redox active and strongly enhance the autoxidation process. However, the influence of Mg(II) and Ca(II) ions on the autoxidation of natural phenolic compounds was studied less frequently (5, 7), although these t...

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“…At this point, the effect of pH should also be considered. While up to pH 7.4 the shift observed in Band I absorption is limited to a few nm, at pH 8.6 this shift may reach up to 25-30 nm, owing to the deprotonation of the B-ring OH groups [18]. Indeed, at pH 8.3 quercetin displayed a bathochromic shift for both Bands I and II, having λ max at 390 and 269 nm.…”

Section: Initial Spectrophotometric Examinationmentioning

confidence: 92%

Empirical Kinetic Modelling of the Effect of l-Ascorbic Acid on the Cu(II)-Induced Oxidation of Quercetin

et al. 2018

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This study aimed at investigating the effect of L-ascorbic acid on the Cu 2+ -induced oxidation of quercetin, within a pH range from 6.7 to 8.3 and temperatures varying from 53 to 87 • C. Initial examinations showed that quercetin degradation obeyed apparent first-order kinetics and it was significantly affected by temperature. Modelling of the effect of L-ascorbic acid by implementing response surface methodology suggested that L-ascorbic acid did not impact quercetin oxidation significantly (p < 0.05) and led to an empirical kinetic model based on temperature (T) and pH. Liquid chromatography-diode array-mass spectrometry analyses revealed the presence of typical quercetin degradation and oxidation products, including protocatechuic acid and 2-(hydroxybenzoyl)-2-hydroxybenzofuran-3(2H)-one. It was concluded that the formation of L-ascorbyl or other radicals (superoxide anion) may be involved in quercetin oxidation and this fact merits further attention to illuminate the possible beneficial or adverse nutritional consequences of such reactions in foods.ChemEngineering 2018, 2, 46 2 of 14 was shown to exhibit improved antioxidant characteristics [7]. More recent data on this particular product were in the same line, revealing a 200-fold higher cytoprotective potency [8].L-Ascorbic acid (vitamin C) is a well-known food antioxidant that may eliminate a spectrum of oxidising species, such as superoxide anion radical (O 2 •− ), hydroxyl radical (OH • ) and singlet oxygen, due to its ease of oxidation by either a one-or two-electron transfer [9,10]. Ascorbic acid may also lower the oxidation state of metals, such as iron and copper, and their valence, thus affecting oxidation catalysis. These unique features make L-ascorbic acid a powerful antioxidant, capable to protect a variety of substrates from oxidation. L-Ascorbic acid may be rapidly oxidised in the presence of bivalent copper (Cu 2+ ), but the extent of oxidation may be limited in the presence of metal-chelating flavonoids, such as quercetin [11,12]. However, L-ascorbic acid may also act as an antioxidant in such a system, protecting quercetin from Cu 2+ -induced oxidative degradation [5]. Therefore, depending on the conditions (pH, temperature, the presence of other redox species, relevant amounts of redox species implicated), in a system containing L-ascorbic acid, quercetin and Cu 2+ , one antioxidant may be sacrificed at the expense of the other, yet a prediction regarding the eventual shift of such a cascade of reactions would be rather difficult, due to the high complexity. This being the case, this study aimed at modelling the effect of L-ascorbic acid on quercetin stability in the presence of Cu 2+ , considering the kinetic behaviour of quercetin degradation as a function of pH and temperature. Following a preliminary investigation, the interactions between L-ascorbic acid and quercetin were modelled by deploying response surface methodology. Tentative characterisation of major quercetin oxidation products using liquid chromatography-mass spectrometry ...

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Effect of pH on the chemical modification of quercetin and structurally related flavonoids characterized by optical (UV-visible and Raman) spectroscopy

Abstract: The chemical modifications undergone by flavonoids under alkaline conditions in aqueous solution and on Ag nanoparticles studied by optical spectroscopy are presented and discussed.

Cited by 133 publications

References 56 publications

Matrix effects of the hydroethanolic extract and the butanol fraction of calyces from Physalis peruviana L. on the biopharmaceutics classification of rutin

Matrix effects of the hydroethanolic extract and the butanol fraction of calyces from Physalis peruviana L. on the biopharmaceutics classification of rutin

The Influence of Mg(II) and Ca(II) Ions on Rutin Autoxidation in Weakly Alkaline Aqueous Solutions

Empirical Kinetic Modelling of the Effect of l-Ascorbic Acid on the Cu(II)-Induced Oxidation of Quercetin

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