Development and optimization of sulforaphane-loaded nanostructured lipid carriers by the Box-Behnken design for improved oral efficacy against cancer: in vitro, ex vivo and in vivo assessments

In the present study, sulforaphane (SFN)-loaded nanostructured lipid carriers (NLC) were developed and optimized for improved oral efficacy against cancer. The SFN-loaded NLC formulation was developed by melt emulsification ultrasonication technique and optimized by Box-Behnken statistical design. The optimized SFN-loaded NLC formulation composed of precirol((R)) ATO 5 (solid lipid) and vitamin E (liquid lipid) as lipid phase (3% w/v), poloxamer 188 (1%) and Tween 80 (1%) as surfactant. The mean particle size, polydispersity index, zeta potential, entrapment efficiency (%) and drug loading (%) of optimized SFN-loaded NLC formulation was observed to be 145.38 +/- 4.46nm, 0.181 +/- 0.023, -25.12 +/- 2.36mV, 84.94 +/- 3.82% and 14.82 +/- 3.46%, respectively. In vitro drug release studies showed that the release of SFN from optimized NLC formulation was significantly higher (86.52 +/- 5.48%) compared to SFN suspension (38.47 +/- 5.52%) up to 24h. Ex vivo gut permeation studies revealed a very good enhancement in permeation of drug present in the NLC compared to plain SFN solution and were further confirmed by CLSM. MTT assay in different cancer cell lines showed that the optimized SFN-loaded NLC formulation exhibited significantly improved (p<.05) cytotoxicity compared to free SFN solution. SFN-loaded NLC formulation showed significantly improved antioxidant activity compared to free SFN solution. Furthermore, pharmacokinetic study on albino Wistar rats showed 5.04-fold increase in relative oral bioavailability with NLC (p<.05) compared to SFN suspension. Therefore, NLC represents a great potential for improved efficacy of SFN after oral administration.