Development and Optimization of Nanoemulsion from Ethanolic Extract of Centella asiatica (NanoSECA) Using D-Optimal Mixture Design to Improve Blood-Brain Barrier Permeability

The evidence on the neuroprotective impact of Centella asiatica (C. asiatica) has been greatly documented in recent years. However, a major obstacle that remains to be overcome is the capacity of the active molecules in C. asiatica to cross the blood-brain barrier (BBB). In this study, we explored the possibilities of using a D-optimal mixture design to fabricate nanoemulsion of C. asiatica (NanoSECA) for better brain bioavailability. The parameters for optimization were the percentage of water (10-80% w/v) and virgin coconut oil (VCO) (10-80% w/v). Nanoemulsions were formulated using a high-pressure homogenization approach and were characterized for their physicochemical properties. The optimal VCO-based nanoemulsion (VBN: F2) conditions were found at 80% (w/v) of water and 10% (w/v) of VCO. Subsequently, viability tests were conducted on neuroblastoma (SH-SY5Y) and macrophage (RAW 264.7) cell lines. NanoSECA was distinguished for its antioxidant, acetylcholinesterase (AChE), anti-inflammatory, and parallel artificial membrane permeability assay (PAMPA) activities in vitro. The NanoSECA has a particle size of 127.833 ± 8.280 nm, zeta potential (ZP) of -24.9 ± 0.011 mV, polydispersity index (PDI) of 0.493 ± 4.681, percentage prediction error (PPE) of -12.02%, and pH of 6.0 ± 0.006 and is also stable under different storage conditions. Cell viability was improved in a dose-dependent manner on SH-SY5Y and RAW 264.7 cell lines. In addition, NanoSECA significantly reduced the AChE activity, suppressing the level of proinflammatory mediators and oxidative stress. Moreover, NanoSECA showed high BBB permeation with a high value of experimental permeability to cross the BBB. Thus, NanoSECA could efficiently potentiate the central nervous system (CNS) therapeutic activities through enhanced penetration of BBB. These nano-delivery systems are crucial to unlock the full potential of C. asiatica for treating numerous CNS disorders.