Spectrophotometric Study of the Stability the Quercetin and Rutin Solutions at Different Acidity of the Medium
Flavonoids are a group of polyphenolic compounds present in many plants, fruits, vegetables, nuts, flowers etc. They exhibit a wide range of bioactivity and have gained much attraction last two decades because of its potential applications in biology, medicine, and chemical analysis due to their antioxidant, medicinal (antiviral, antibacterial, antiallergic effects) and complexion properties. One of the main properties of flavonoids especially quercetin is their oxidation by oxygen dissolved in water or organic solvents mainly in basic media. This is the main reason for non-reproducibility of quercetin acidity constants determined by several authors. Hence, the aim of our paper was to investigate the pH and time effects on the behavior of quercetin and rutin aqua solutions and to find possibility for stabilization of their solutions. It was established that their stability in solution is determined by three factors: the nature of flavonoids, acidity of the medium (created by acetate-ammonium buffers) and presence of oxygen in solution. It was found that quercetin solutions in the pH interval 3–6 are stable during first ten minutes but at the end of thirty minutes the optical density falls down about 15 percent. In basic media, especially at pH 9–11, the optical density of quercetin falls down at first 1–2 minutes and after 10 minutes the quercetin spectra transform their shape and maximum position that belong to oxidized form of the flavonoid. We found that addition of 0.01 M of sodium sulfite prevents oxidation and stabilizes optical density of quercetin at pH 9–10 during 1–2 minutes; therefore, it is possible to investigate the protolytic reactions and interaction with different substances. The rutin spectra are not significantly change in acidic and basic media during first ten minutes and during next twenty minutes the optical density in the basic media decreases by 15 percent.
1. Корулькин Д. Ю., Абилов Ж. А., Музычкина Р. А., Толстиков Г. А. Природные флавоноиды. Новосибирск : Тео, 2007. 232 с.
2. Тараховский Ю. С., Ким Ю. А., Абдрасилов Б. С., Музафаров Е. Н. Флавоноиды : биохимия, биофизика, медицина. Пущино : Sуnchrobook, 2013. 310 c.
3. Зиятдинова Г. К., Будников Г. К. Природные фенольные антиоксиданты в биоаналитической химии : состояние проблемы и перспективы развития // Успехи химии. 2015. Т. 84, № 2. С. 194–224.
4. Марченко З., Бальцержак М. Методы спектрофотометрии в УФ и видимой областях в неорганическом анализе. М. : БИНОМ. Лаборатория знаний, 2007. 711 с.
5. Зенкевич И. Г., Гущина С. В. Определение констант диссоциации соединений, окисляющихся кислородом воздуха в водных растворах (на примере кверцетина) // Журн. аналит. химии. 2010. Т. 65, № 4. С. 382–387.
6. Zenkevich I. G., Eshchenko A. Yu., Makarova S. V., Vitenberg A. G., DobryakovYu. G., Utsal V. A. Identifi cation of the Products of Oxidation of Quercetin by Air Oxygen at Ambient Temperature // Molecules. 2007. Vol. 12. P. 654–672.
7. Mezzetti A., Protti S., Lapougeb Ch., Cornardb J-P. Protic equilibria as the key factor of quercetin emission in solution. Relevance to biochemical and analytical studies // Phys. Chem. Chem. Phys. 2011. Vol. 13. P. 6858–6864.
8. Alvarez-Diduk R., Ramirez-Silva M. T., Galano A., Merkoci A. Deprotonation Mechanism and Acidity Constants in Aqueous Solutionof Flavonols : a Combined Experimental and Theoretical Study // J. Phys. Chem. B. 2013. Vol. 117, № 41. P. 12347–12359.
9. Барвиченко Н. А., Липковская Н. А., Федянина Т. В. Кето-енольная таутомерия кверцетина в растворах катионного ПАВ мирамистина // Коллоид. журн. 2014. Т. 76, № 1. С. 3–7.
10. Kuntic V., Pejic N., Micic S., Malesev D., Vujic Z. Determination of Dissociation Constants of Quercetin // Pharmazie. 2003. Vol. 58. P. 439–440.
11. Herrero-Martinez J. M., Repolles C., Bosch E., Roses M., Rafols C. Potentiometric Determination of Aqueous Dissociation Constants of Flavonols Sparingly Soluble in Water // Talanta. 2008. Vol. 74. P. 1008–1013.
12. Herrero Martinez J. M., Sanmartin M., Roses M., Bosch E., Rafols C. Determination of Dissociation Constants of Flavonoids by Capillary Electrophoresis // Electrophoresis. 2005. Vol. 28. P. 1886–1895.
13. Topolewski P., Zommer-Urbanska S. Spectrophotometric investigation of protolytic equilibria of rutin // Microchim. Acta. 1989. Vol. 97, № 1–2. P. 75–80.
14. Naseem B., Shah S. W. H., Hasan A., Shah S. S. Interaction of fl avonoids, the naturally occurring antioxidants with different media : A UV–visible spectroscopic study // Spectrochim. Acta. Part A. 2010. Vol. 75. P. 1341–1346.