Nanostructured lipid carriers as a strategy for encapsulation of active plant constituents: Formulation and in vitro physicochemical characterizations.

Active plant constituents obtained from edible sources have manifested their pharmacological potential as a therapy against several diseases. But the lack of their desired physicochemical properties such as solubility, permeability ultimately leads to poor bioavailability. Two potent active plant constituents namely, quercetin and piperine having a problem with either solubility or permeability or both, and hence require an advanced lipid-mediated separate formulation system to improve their aforementioned concerns. Concerning advancement in nanoformulations, lipid-based nano-carriers systems have created their mark as a novel drug delivery system. Therefore, an advanced formulation like nanostructured lipid carriers (NLCs) has been formulated individually for both the active plant constituents/drugs through the solvent evaporation technique using high shear homogenization method followed by sonication. Compritol® 888 ATO, a solid lipid, and squalene as liquid lipid was used in their optimized ratios to formulate individual NLCs. Blank and individual drugs loaded NLCs were further characterized for their in vitro physicochemical properties. NLCs showed a negative surface charge with an average particle size below 200 nm. Electron microscopy images showed an anomalous structure of both the formulated NLCs with higher % drug encapsulation efficiency (DEE) with the desired in vitro drug release profile. In the case of quercetin-NLCs, 93.18 ± 5.5 % DEE was observed followed by drug release up to 45.0 ± 1.3 % within 12 h, while piperine-NLCs showed 91.80 ± 2.51 % DEE and drug release up to 38 ± 5.2 % at the same time. XRD and DSC plots showed the conversion of both the drugs into an amorphous structure encapsulated in a lyophilized NLCs matrix. Finally, the safety profile for formulated NLCs was confirmed by haemolysis assay. Hence, the developed active plant constituents enriched NLCs can further be delivered separately and/or in combination, and also may further be evaluated both in vitro and in vivo means.