Formulation, Characterization and Biological Assessment of Quercetin Loaded Nanoemulsions: In-Vitro Assay

Quercetin (QT, 3,3ʹ,4ʹ,5,7-pentahydroxyl-flavone), is one of the most distinguished flavonoid, and has been widely explored for its various therapeutic activities, yet it has major issues like low oral bioavailability, poor aqueous solubility and rapid degradation in gastrointestinal environment. The present study was targeted to evaluate the effects of oils, surfactant and co-surfactants for the fabrication of QT-loaded nanoemulsion (QTNE). Based on the results of solubility, compatibility and morphological studies, capmul MCM NF (oil) and cremophor RH 40 (surfactant) were selected for the fabrication of QTNE. The optimized QTNE (QTNE1) was found to be compatible and exhibited average particle size, zeta potential and PDI in the acceptable nanorange. In-vitro drug release studies showed that QTNE1 showed initial burst release followed by sustained release. QT release from QTNE was comparatively more than QT suspension. The in-vitro antioxidant assay (DPPH, standard ABTS and modified ABTS) showed that the antioxidant activity of QTNE1 was comparatively more than QT. Interestingly, the stability of ABTS•+ was more at lower pH and similar activity was reported with QTNE1 and QT also. QTNE1 exhibited significant antibacterial activity against Gram-negative and Gram-positive bacterial strains, although was more sensitive towards Gram-positive bacterial strains. Both antioxidant and antibacterial assay showed time and concentration dependent activity. Conclusively, quercetin-loaded nanoemulsion exhibited enhanced solubility, sustain release property with improved antioxidant and antibacterial activities.