Nanoemulsion preconcentrate of a pentacyclic triterpene for improved oral efficacy: Formulation design and in-vivo antimalarial activity

Abstract In order to develop new lead from plant, natural product drug discovery is one of the popular choices which deal numerous unprecedented challenges. Lupeol, a monohydroxylated pentacyclic triterpenoid is abundantly distributed in the plants across genus in varying amount and posses antimalarial potential. However, the therapeutic potential of pentacyclic triterpenes is still under-exploited due to their low intestinal absorption. In the present study, a nanoemulsion preconcentrate (NPs) of lupeol with oil phase and ion surfactants was prepared and evaluated for antimalarial action. Lupeol was isolated and characterized from aerial parts of Stereospermum suaveolens DC. Oil phase comprising caprylic acid: oleic acid (2:1) and Smix (surfactant and co-surfactant) was used to develop a colloidal drug carrier following low energy nanoemulsion formation method. The Smix was optimized using tween 20 and transcutol HP (Km 2:1). Optimization of nanoemulsion was achieved in terms of thermodynamic stability, phase behaviour, globule size, polydispersity, rate of drug release, and high solubility without variable absorption for stable nanoemulsion. Developed NPs was investigated for in-vivo antimalarial efficacy. Improved efficacy was observed with a half dose of lupeol in nanoemulsion which attributed to a significant increase in blood glucose and haemoglobin level as compared with vehicle-treated infected mice. The present study is demonstrating that optimized nanoemulsion preconcentrate could be applied as a drug carrier for effective pentacyclic triterpene delivery and improved therapeutic action.