On the solubility of quercetin

Abstract

There is considerable disagreement over the solubility of quercetin in water. Experimental values of log Cw with Cw in mol/L range from -2.52 to -5.89, a difference of over three log units. We have applied a methodology based on linear free energy equations for water-solvent and gassolvent partitions to study solubilities. These are related to partition coefficients through Ps = Cs/Cw where Cs and Cw are solubilities of a given solute in a solvent and in water. We find that known solubilities of quercetin in methanol and ethanol at 298 K and a known water-solvent partition coefficient can be accommodated in the same model if the water solubility at 298 K, as log Cw, is taken as -3.90, that is near to the middle of the range of experimental values. Our model successfully predicts solubilities of quercetin in water-ethanol mixtures near to the ethanol rich mixtures.

Solubility of Nutraceutical Compounds in Generally Recognized as Safe Solvents at 298 K

“…Ethanol is a GRAS solvent used in supercritical fluid extraction studies for quercetin from grape seeds [7]. The solubility of quercetin in mixtures of water, methanol and ethanol has also been quantified and correlated [8]- [10]. It is particularly striking that there is a considerable disagreement over the solubility of quercetin in water [8].…”

“…The solubility of quercetin in mixtures of water, methanol and ethanol has also been quantified and correlated [8]- [10]. It is particularly striking that there is a considerable disagreement over the solubility of quercetin in water [8]. In addition to anhydrous quercetin, quercetin dihydrate is also present as a solid form in water [10].…”

Fluorescence Lifetime and UV‐Vis Spectroscopy to Evaluate the Interactions Between Quercetin and Its Yeast Microcapsule

“…In the initial one, the cellular suspension (OD 600 = 10) was mixed with the quercetin solution (4 mg mL −1 in absolute ethanol) in the ratio 5:1 v/v. After several tries modifying the ethanol, quercetin and cell concentrations as well as pH conditions (not shown) in a goal of improving quercetin solubilization, a second procedure was validated in which 1 g (wet weight) of the slurry was mixed with 500 μL of citrate buffer (0.1 M, pH 2) and 500 μL of quercetin solution (5 mg mL −1 in absolute ethanol) . The resulting quercetin/cell ratios was of 0.04 mg quercetin/g of wet cells with 13.5% (m m −1 ) of ethanol for the initial procedure and of 0.0025 mg g −1 and 20.6% (m m −1 ) ethanol for the second one.…”

Studies on the hydrogen bond acidity, and other descriptors and properties for hydroxyflavones and hydroxyisoflavones

“…[32] for log P(oct) for morin (2′,3,4′,5,7-pentahydroxyflavone) and with a calculated value of 2.13 for A, from Table 3, we obtained the descriptors given in Table 8. We have previously obtained descriptors for quercetin (3,3′,4′,5,7-pentahydroxyflavone) from solubility data [37] and the descriptors are also in Table 8. Fisetin (3,3′,4′,7-tetrahydroxyflavone) is well-known.…”