Effect of temperature, pH, β- and HP-β-CDs on the solubility and stability of flavanones: naringenin and hesperetin

Abstract

Naringenin and hesperetin are two of the most abundant flavanones found in citrus with beneficial effects on human health. However, their poor water solubility imposes considerable limitations to their use in functional foods or nutraceuticals development. In order to increase their aqueous solubility and find a new stable system, the effect of different factors as temperature, pH or complexation agents as cyclodextrins has been studied. The solubility of both flavanones increased exponentially with temperature (25-90 ºC): 10-fold in the case of naringenin and 20-fold for hesperetin. The solubility of both flavanones also increased with the media pH (3.5-8.5): 314-fold in the case of naringenin and 3.5-fold for hesperetin. Flavanones solubility also increased with β- or HP-β-CDs concentration. By the addition of β-CDs 13 mM naringenin solubility increased 9.3-fold and hesperetin solubility 30-fold. Using HP-β-CDs 100 mM naringenin solubility increased 143-fold and hesperetin 467-fold. In summary, the higher increase in naringenin solubility was reached by increasing pH up 8.5. However, in the case of hesperetin, the higher increase was obtained by complexation with HP-β-CDs 100 mM. Moreover, the presence of CDs, not only increased the aqueous solubility of flavanones, but also improved the stability of hesperetin at pHs 3.5 and 6.5.