Enhancing biopharmaceutical parameters of bioflavonoid quercetin by cocrystallization

Quercetin, a polyphenolic nutraceutical belonging to the flavonoid category of natural compounds, has been extensively studied as an antioxidant, anti-inflammatory, anticancer, glycoprotein P450 enzyme inhibitor, cardioprotective and antihaemolytic substance. Despite an increased awareness of the efficacy and utility of this flavonoid, its use has been severely held back owing to its poor aqueous solubility and consequently reduced bioavailability. The present study reports two cocrystals of this valuable natural compound with therapeutically active coformers of GRAS status, namely nicotinamide and picolinic acid, in an endeavour to overcome its limitations and exploit its full potential. The characterization of the cocrystalline phases prepared involved thermoanalytical methods (differential scanning calorimetry) and spectroscopic methods (FT-IR and powder X-ray diffractometry). The confirmation was provided by C-13 solid state NMR analysis. The structures of the prepared cocrystalline phases were finally determined by utilizing the PXRD patterns in Materials Studio (R) software. A phenomenal improvement in the biopharmaceutical parameters of the cocrystals vs. quercetin was evaluated by carrying out dissolution, equilibrium solubility, pharmacokinetic, antihaemolytic and antioxidant studies.