Enhanced stability of curcumin and polyethylene glycol composites in the presence of flavonoids and whey protein concentrate: synthesis, structural evaluation and thermal analysis

Curcumin (CCM) is a natural polyphenol with promising pharmacological potential. This potential is severely restricted, however, due to its limited bioavailability, poor solubility and stability. To address this, several systems of curcumin and polyethylene glycol, PEG (PEG4000 or PEG6000), were synthetized, with or without whey protein concentrate (WPC), trans-resveratrol (RES) or silymarin (SIL) using solid dispersion technique. Firstly, CCM-PEG composites were synthesized using PEG4000 or PEG6000 for 1:8 mol ratio by polymer melting method. Further, the CCM-WPC-PEG4000 composite for 1:0.4:8 mol ratio and CCM-WPC-PEG6000 composite for 1:0.5:10 mol ratio were synthesized. Furthermore, CCM-RES-WPC-PEG and CCM-SIL-WPC-PEG composites were prepared for 1:2.5:0.4:10 mol ratio for PEG4000 or PEG6000. The composite formation was investigated by Fourier transform infrared spectroscopy (FTIR). The thermal stability of synthesized composites was analyzed through thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealing a high stability up to 200 degrees C. Thus, each composite formulation was optimized to carry CCM, RES and WPC or CCM, SIL and WPC within PEG matrix primarily by hydrogen bonds and van der Waals interactions. This study demonstrated that all synthesized composites may have potential advantages for applications such as nutraceuticals, functional foods, supplements and pharmaceuticals.