Quercetin and alendronate multi-functionalized materials as tools to hinder oxidative stress damage

In spite of its remarkable anti-oxidant, anti-inflammatory, anti-cancer properties and its possible inhibition activity towards bone resorption, quercetin therapeutic use is limited by its poor bioavailability. Herein we developed a new multifunctionalized system for the local administration of quercetin and alendronate, one of the most potent anti-osteoporotic drugs, with the aim to get a material with enhanced properties. To this purpose we loaded quercetin on hydroxyapatite functionalized with alendronate, as well as on hydroxyapatite. Characterization was performed by means of X-ray diffraction, FT-IR and Raman spectroscopies, thermogravimetric and spectrophotometric analyses. Loading of quercetin from hydro-alcoholic solution increased with time and reached a constant value of about 5 weight% on both substrates, without causing significant structural and morphological modifications. Quercetin functionalized materials exhibit relevant anti-oxidant properties, in agreement with their high radical scavenging activity, and a quercetin sustained release in phosphate buffer. In vitro osteoblast and osteoclast co-culture in a microenvironment altered by oxidative stress shows that both alendronate and quercetin significantly reduce osteoclast viability, whereas they are able to counteract the negative effect of oxidative stress on osteoblast viability and differentiation, suggesting that their relative amount in the functionalized materials can be utilized to tailor bone cells response. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3293-3303, 2017.