Pomegranate extract-loaded solid lipid nanoparticles: design, optimization, and in vitro cytotoxicity study

Abstract

Background: Pomegranate extract (PE) is a natural product with potent antioxidant and anticancer activity because of its polyphenols content. The main purpose of this study was to maximize the PE chemotherapeutic efficacy by loading it in an optimized solid lipid nanoparticles (SLNs) formula.

Materials and methods: The influence of independent variables, which were lipid concentration (X₁), surfactant concentration (X₂) and cosurfactant concentration (X₃), on dependent ones, which were particle size (Y₁), polydispersity index (Y₂), zeta potential (Y₃), entrapment efficiency (Y₄) and cumulative % drug release (Y₅), were studied and optimized using the Box-Behnken design. Fifteen formulations of PE-SLNs were prepared using hot homogenization followed by ultra-sonication technique. Response surface plots, Pareto charts and mathematical equations were produced to study the impact of independent variables on the dependent quality parameters. The anti-proliferative activity of the optimized formula was then evaluated in three different cancer cell lines, namely, MCF-7, PC-3 and HepG-2, in addition to one normal cell line, HFB-4.

Results: The results demonstrated that the particle sizes ranged from 407.5 to 651.9 nm and the entrapment efficiencies ranged from 56.02 to 65.23%. Interestingly, the 50% inhibitory concentration of the optimized formula had more than a 40-fold improved effect on the cell growth inhibition in comparison with its free counterpart. Furthermore, it was more selective against cancer cells than normal cells particularly in MCF-7 breast cancer cells.

Conclusion: These data proved that nanoencapsulation of PE enhanced its anticancer efficacy. Therefore, our results suggested that a PE-loaded SLNs optimized-formula could be a promising chemo therapeutic agent.

Keywords: Box-Behnken design; cancer cell lines; optimization; pomegranate extract; solid lipid nanoparticles.

Figure 1

Particle size distribution for batch F1.

Figure 2

Transmission electron microscopy image for pomegranate extract solid lipid nanoparticles obtained from batch F5.

Figure 3

In vitro release of stearic acid SLNs-loaded PE through cellulose membrane after 48 h. Abbreviations: PE, pomegranate extract; SLNs, solid lipid nanoparticles.

Figure 4

Pareto charts of all independent variables on Y₁, Y₂, Y₃, Y₄, and Y₅. Abbreviations: X₁, lipid concentration; X₂, surfactant concentration; X₃, cosurfactant concentration; Y₁, particle size; Y₂, polydispersity index; Y₃, zeta potential; Y₄, entrapment efficiency; Y₅, cumulative % drug release.

Figure 5

Estimated three-dimensional response surfaces plot for the effect of the studied variables on (A) particle size, (B) polydispersity index, (C) zeta potential, (D) entrapment efficiency % and (E) cumulative % drug release.

Figure 6

Cytotoxicity profile of the free PE, PE-SLNs-optimized formula and the void optimized formula against HepG-2, PC-3, MCF-7 and HFB-4 cell lines. Abbreviations: PE, pomegranate extract; PE-SLNs, pomegranate extract-solid lipid nanoparticles; void, PE-free.