Quercetin belongs to the chemical class of flavonoid and is widely distributed in vegetables and plants. It has been demonstrated to possess a wide array of biological effects that are considered beneficial to health, including antioxidative, free radical scavenging and anticancer. However, quercetin is sparingly soluble in water, which has limited its absorption upon oral administration.
The effects of various process parameters including the co-solvent, temperature, pressure, and flow rates on the particle size and morphology of pure quercetin was studied. In most cases long needles of quercetin were formed, ranging from 1 to several microns long. With very low concentrations of quercetin rod like particles in the 500 nm range were formed. The anti-oxidative activity of quercetin is maintained following processing with the SAS system as shown using 2,2-diphenyl-1-picrylhydrazyl (DPPH) as a radical scavenger.
The particles were also encapsulated with a biodegradable polymer, poly(lactic acid), for controlled-release of drug and to maintain antioxidative activity during storage and delivery. The effect on encapsulation yield and release of quercetin was shown to vary with polymer concentration, choice of co-solvents, and flow rates. The SAS method proved to be a suitable process for encapsulating quercetin and these particles are now further studied in animal models to follow their fate in vivo.