Synthesis and Nano-Sized Characterization of Bioactive Oregano Essential Oil Molecule-Loaded Small Unilamellar Nanoliposomes with Antifungal Potentialities.

Katya M Aguilar-Pérez,Roberto Parra-Saldívar,Hafiz M N Iqbal,Dora I Medina,Jayanthi Narayanan

doi:10.3390/molecules26102880

Abstract

The development of greener nano-constructs with noteworthy biological activity is of supreme interest, as a robust choice to minimize the extensive use of synthetic drugs. Essential oils (EOs) and their constituents offer medicinal potentialities because of their extensive biological activity, including the inhibition of fungi species. However, their application as natural antifungal agents are limited due to their volatility, low stability, and restricted administration routes. Nanotechnology is receiving particular attention to overcome the drawbacks of EOs such as volatility, degradation, and high sensitivity to environmental/external factors. For the aforementioned reasons, nanoencapsulation of bioactive compounds, for instance, EOs, facilitates protection and controlled-release attributes. Nanoliposomes are bilayer vesicles, at nanoscale, composed of phospholipids, and can encapsulate hydrophilic and hydrophobic compounds. Considering the above critiques, herein, we report the in-house fabrication and nano-size characterization of bioactive oregano essential oil (Origanum vulgare L.) (OEO) molecules loaded with small unilamellar vesicles (SUV) nanoliposomes. The study was focused on three main points: (1) multi-compositional fabrication nanoliposomes using a thin film hydration–sonication method; (2) nano-size characterization using various analytical and imaging techniques; and (3) antifungal efficacy of as-developed OEO nanoliposomes against Trichophyton rubrum (T. rubrum) by performing the mycelial growth inhibition test (MGI). The mean size of the nanoliposomes was around 77.46 ± 0.66 nm and 110.4 ± 0.98 nm, polydispersity index (PdI) of 0.413 ± 0.015, zeta potential values up to −36.94 ± 0.36 mV were obtained by dynamic light scattering (DLS). and spherical morphology was confirmed by scanning electron microscopy (SEM). The presence of OEO into nanoliposomes was displayed by attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. Entrapment efficiency values of 79.55 ± 6.9% were achieved for OEO nanoliposomes. In vitro antifungal activity of nanoliposomes tested against T. rubrum strains revealed that OEO nanoliposomes exhibited the highest MGI, 81.66 ± 0.86%, at a concentration of 1.5 µL/mL compared to the rest of the formulations. In summary, this work showed that bioactive OEO molecules with loaded nanoliposomes could be used as natural antifungal agents for therapeutical purposes against T. rubrum.

Highlights

The demand for bioactive molecules or bioactive agent-loaded nano-constructs with desirable properties has increased in the past few years [1], as an alternative and robust choice to minimize the extensive use of synthetic drugs
Size and morphology were analyzed by dynamic light scattering (DLS) and scanning electron microscopy (SEM) imaging to confirm that the diameters of the prepared vesicles were within the nanometric scale (77.46 ± 0.66 nm) after 1 day, 1 week and 1 month of preparation; Oregano essential oil (OEO) nanoliposomes exhibited spherical morphology
Stability of OEO nanoliposomes under storage was evaluated 1 day, 1 week and 1 month following the synthesis, with zeta potential measurements reaching values around −36.94 ± 0.36 mV throughout

Summary

Introduction

The demand for bioactive molecules or bioactive agent-loaded nano-constructs with desirable properties has increased in the past few years [1], as an alternative and robust choice to minimize the extensive use of synthetic drugs. A functional approach to perform efficient delivery with target specificity and controlled release is the use of nanomaterials (e.g., nanofibers, nanogels, micelles, nanoparticles, nanoliposomes, etc.). Among these nanomaterials, nanoliposomes represent the most used phospholipid-based nanocarrier for drug delivery applications [3]. Nanoliposomes are bilayer structures that maintain their nanometric size within the range of 20 to 150 nm, during storage and applications Their lipid and aqueous composition allow the entrapment of hydrophobic and hydrophilic agents, either individually or simultaneously [4]. Several unilamellar vesicles will form on the inside of those with a smaller size, making a multilamellar structure of concentric phospholipid spheres separated by layers of water [7]. They are non-toxic, biodegradable, biocompatible, and can be prepared using natural ingredients (e.g., egg yolk, soybean lecithin, sunflower oil, etc.) [8]

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