Solubilisation of quercetin: Comparison of hyperbranched polymer and hydrogel

Most of the new chemical entities discovered today are highly lipophilic in nature and show poor solubility and membrane permeability resulting in poor oral bioavailability. Quercetin is a bioactive flavonoid widely used as a health supplement. Being sparingly soluble and chemically unstable in aqueous intestinal fluids, quercetin is poorly absorbed orally. Drug delivery systems, like hydrogels or hyperbranched polymers are able to increase the solubility of drugs, because they carry different functional groups which allow strong interactions with the functional groups of the drug. The solubility of quercetin, as a flavonoid with disease prevention character, in water or in ethanol and the solubilisation of quercetin in water or ethanol using hyperbranched polymer Boltorn H20 or Poly-(nisopropylacrylamide) hydrogels are investigated experimentally. Additionally, the chemical stability of quercetin at room temperature over a long time period is studied. The most important findings are a) the solubility of quercetin in water is extremely low; b) linear or cross-linked Poly-(n-isopropylacrylamide) can be used to avoid the decomposition of quercetin; c) the swelling properties of Poly-(n-isopropylacrylamide) hydrogels are not influenced by the presence of quercetin; and d) hyperbranched polymers can be used to improve the quercetin solubility. (C) 2014 Elsevier B.V. All rights reserved.