Synthesis and Optimisation of Glyceryl Monosterate Coated Solid Lipid Nanoparticle of Asparagus racemosus Petroleum Ether Extract: Characterisation and in vitro Therapeutic Potential

Abstract

The therapeutic potential of Asparagus racemosus arises from its diverse phytoconstituents; however, the petroleum ether extract contains comparatively fewer phytochemicals since it primarily extracts non-polar constituents. To improve the bioavailability and therapeutic efficacy of this extract, glyceryl monostearate-coated solid lipid nanoparticles (SLNs) were synthesised using the non-ionic surfactant Tween 80. Plant extraction was carried out using a Soxhlet apparatus with petroleum ether as the extraction solvent and the potential bioactive compounds were identified by GC-MS analysis. Glyceryl monostearate-coated solid lipid nanoparticles (SLNs) were prepared by the reverse-phase solvent evaporation method, followed by spectral, morphological, thermal characterisation and subsequently evaluated for in vitro drug release, antioxidant, anti-inflammatory and diuretic activities in comparison with the crude extract. The compound pregnane-3,20β-diol,14α,18α-[4-methyl-3-oxo-(1-oxa-4-azabutane-1,4-diyl)]-diacetate exhibited the highest relative abundance, accounting for 37.33% of the total peak area in the GC-MS chromatogram. The optimised SLNs has mean particle size of 104.0 ± 8.01 nm, zeta potential -40.09 ± 7.5 mV and a polydispersity index (PDI) value of 0.33. The particle size revealed non-uniform, spherical particles with nanoscale formulation and structural integrity was confirmed by microscopic study. FTIR and thermal analyses confirmed the chemical compatibility of the formulation components and its good thermal stability. The optimised SLN formulation (1:1:1) exhibited sustained drug release and superior therapeutic efficacy compared with the crude extract, which may be attributed to improved permeability of the major steroidal alkaloid.