Formulation, characterization and antimicrobial efficacy of Aegle marmelos essential oil nanogel

Aegle marmelos (L.) Correa has been widely used in Indian traditional medicine and has many reported pharmacological activities. The aim of this research was to formulate solid lipid nanoparticles (SLNs) of Aegle oil (AO) that enhanced the beneficial antimicrobial activity of the oil.

The chemical composition of Aegle leaf essential oil was analysed by GC-MS. Additionally, a phytochemical study of A. marmelos methanolic leaf extract was conducted using Folin-Ciocalteu colorimetric assay for determination of total phenolic content as well as ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-ESI-MS-MS) analyses for identification of individual components. Six formulations of AO-loaded SLNs (AO-SLNs) were prepared by a double emulsification method. The particle size, zeta potential (ZP), polydispersibility index (PDI) and drug encapsulation efficiency (EE) of the SLNs were determined. The morphology of the SLNs was observed by transmission electron microscopy (TEM). The antimicrobial activity of AO and AO-SLNs was assessed using disc diffusion method.

Thirty-two compounds were identified in the Aegle oil, of which A-carene and a-phellandrene were the most abundant (48.14% and 34.14%, respectively). The estimated total phenolic content was 968mg gallic acid equivalents (GAE)/g, while UPLC-ESI-MS-MS led to the tentative characterization of thirteen metabolites. The SLNs showed ZP, PDI and EE 125 ± 0.22nm, -37.85, 0.282, and 92%, respectively. AO and AO-SLNs showed significant antimicrobial activity, and the SLNs could sustain the release of AO from their gel vehicles.

Our results provide evidence for the application of AO-SLNs in topical and transdermal delivery systems.