Formulation of nanoemulsions containing whey protein isolate and Echium plantagineum seed oil and their effect on proinflammatory cytokine modulation in THP-1 cell line

Nanoemulsions (NEs) are attractive to be employed in various applications. Preparation of NEs using whey protein isolate (WPI) renders benefits due to avoidance of chemical utilization. In this study, the NEs stabilized by WPI was prepared using ultrasonic emulsification. The plant seed oil from Echium plantagineum which was rich in omega-3 fatty acid was used. The parameters in the ultrasonication were optimized for generating NEs. In addition, they were investigated on cytotoxic test and anti-inflammatory activities on THP-1 cell line. The WPI-stabilized NEs were obtained at the optimum concentration of 5% (wt.) E. plantagineum seed oil and 20% (wt.) WPI using high intensity ultrasonicator. The optimized conditions were 20% amplitude, 1750 Joules of energy and the temperature at 45oC. The average size of the obtained WPI-stabilized NEs (5% oil) was 225.83 ± 1.52 nm, polydispersity index (PdI) was 0.24 ± 0.01 and zeta potentials was -31.50 ± 0.20 mV. According to the results, 5% wt. oil WPI-stabilized NEs were smaller and more stable than 10% wt. oil NEs. The results revealed that 5% NEs at 1 mg/ml WPI demonstrated no toxic effect on THP-1 cell line after incubated for 24, 48 and 72 hours. Furthermore, a significant decrease (p≤0.05) in the pro-inflammatory cytokines IL-1β, IL-4, IL-6, IL-8, GM-CSF and TNF-α were observed on the lipopolysaccharide (LPS)-induced THP-1 cells treated with WPI-stabilized NEs. The pro-inflammatory cytokines of IFN-γ was also reduced but not statistical significant. The findings in this study were possibly due to enhancing effect of WPI and omega-3 oil composed in NEs and the easily uptake of nano-sized droplet into the cell. Conclusively, WPI-stabilized NEs might be promising system for anti-inflammatory treatment. The further investigation would be on anti-inflammatory mechanisms of the WPI-stabilized NEs and in vivo study.