Nanostructured lipid carrier loaded with zingiber officinale and Zingiber zerumbet oil for induction of lipolysis in subcutaneous skin layer

Abstract

Body weight loss strategies include combination of nutrition consultation, regular exercise, drug prescription, invasive intervention and/or non-invasive intervention. A non-invasive intervention such as transdermal administration of active ingredients helps in reducing localized subcutaneous adipose tissue through lipolysis. Zingiber officinale (ZO) and Zingiber zerumbet (ZZ) belong to the Zingiberaceae family and both have been discovered to possess lipolysis activity. An efficient drug delivery system is required to encapsulate ZO and ZZ, and deliver these substances up to the subcutaneous skin layer. In this study, ZO and ZZ oil were successfully encapsulated in nanostructured lipid carrier (NLC) using hot homogenization technique followed by ultrasonication. D-optimal mixture design was used to optimize the NLC in which the composition of ZO and ZZ oil, solid lipid, and liquid lipid were the independent variables, while particle size, polydispersity index (PDI), zeta potential, and encapsulation efficiency were the dependent variables. From the study, the optimum formulation for NLC-ZO was 3.6% ZO oil, 1.4% glyceryl monostearate, and 5.0% virgin coconut oil, and the NLC-ZO obtained had the following properties: 90.7 nm particle size, 0.15 PDI, -45.7 mV zeta potential and 88.8% encapsulation efficiency. The optimum NLC-ZZ formulation was 3.7% ZZ oil, 1.3% glyceryl monostearate, and 5.0% virgin coconut oil, and the NLC-ZZ obtained had the following properties: 91.0 nm particle size, 0.17 PDI, -40.9 mV zeta potential and 94.4% encapsulation efficiency. Morphology study revealed the spherical shape of NLC-ZO and NLC-ZZ, and the particle size obtained through transmission electron microscope conformed with the size measured through dynamic light scattering technique. Thermogram profile of NLC showed incorporation of ZO and ZZ into NLC lowered the melting temperature of lipid mixture, thus producing a less ordered crystalline structure of NLC to accommodate the active ingredients. Fourier transform infrared spectroscopy analysis demonstrated an interaction existed between ZO/ZZ and the NLC system. In vitro penetration study using Strat-M® membrane and freshly excised rat skin showed NLC-ZO and NLC-ZZ had higher penetration flux compared to free ZO and ZZ. The release of ZO from NLC-ZO followed Korsmeyer-Peppas model, and the release of ZZ from NLC-ZZ followed zero order kinetic model. 90-day storage stability study showed no significant changes for both NLC-ZO and NLC-ZZ in terms of particle size, PDI and zeta potential. In vitro lipolysis study revealed the potential of NLC-ZO and NLC-ZZ as anti-obesity agents as they stimulated the release of glycerol in 3T3-L1 adipocytes cells. In vivo NLC distribution in female Sprague- Dawley rats showed penetration deep into the dermis layer after 12 h of application. Free fatty acid release was detected when the rats were treated with NLC-ZO and NLC-ZZ for 3 h. This study demonstrated that ZO and ZZ were successfully encapsulated in NLC and the nanoparticles were effectively utilized to enhance dermis penetration and induce lipolysis activity via in vitro and in vivo.