Investigation of Curcumin Water Solubility Through Emulsifying with Biocompatible Polyethylene Glycol–Based Polymers

The low water solubility of curcumin prevents various biological and pharmacological activities, which prevent adequate bioavailability. Herein, two new emulsifier systems have been developed and optimized to increase the water solubility of curcumin. The first emulsion system containing curcumin was prepared using polyethylene glycol monooleate-460 (PEG-oleate) for the oily phase, Tween 20 as the emulsifier, and acetic acid as stabilizing agent. In this emulsion system, Box–Behnken experiment design was applied to find the most favorable conditions and substance ratios. Transmission electron microscopy (TEM) analysis was performed for the emulsion system obtained under optimum conditions. For this emulsion system, the curcumin solubility was found to be 709 times higher than the solubility of raw curcumin. The second emulsion systems developed was carried out using our newly synthesized methoxy polyethylene glycol monooleate-550 (methoxy PEG-oleate). The best curcumin solubility was obtained when the ratio of curcumin-methoxy PEG-oleate was 1:5 (w/w). The solubility of curcumin in this system was 56 times higher than that of raw curcumin. Interactions were characterized by FTIR measurements. Solubility, encapsulation capacity, dissolution, and stability studies were performed. The amount of curcumin in the emulsion systems was carried out by newly developed reversed phase high-performance liquid chromatography.