Abstract
Quercetin (QUE) is a widely studied nutraceutical with a number of potential therapeutic properties. Although QUE is abundant in the plant kingdom, its poor solubility (≤20 μg/mL) and poor oral bioavailability have impeded its potential utility and clinical development. In this context, cocrystallization has emerged as a useful method for improving the physicochemical properties of biologically active molecules. We herein report a novel cocrystal of the nutraceutical quercetin (QUE) with the coformer pentoxifylline (PTF) and a solvate of a previously reported structure between QUE and betaine (BET). We also report the outcomes of in vitro and in vivo studies of QUE release and absorption from a panel of QUE cocrystals: betaine (BET), theophylline (THP), l-proline (PRO), and novel QUEPTF. All cocrystals were found to exhibit an improvement in the dissolution rate of QUE. Further, the QUE plasma levels in Sprague-Dawley rats showed a 64-, 27-, 10- and 7-fold increase in oral bioavailability for QUEBET·MeOH, QUEPTF, QUEPRO, and QUETHP, respectively, compared to QUE anhydrate. We rationalize our in vivo and in vitro findings as the result of dissolution-supersaturation-precipitation behavior.