Preparation of non-toxic nano-emulsions based on a classical and promising Brazilian plant species through a low-energy concept

Abstract

A true sustainable and ecofriendly concept of utilization of natural products must involve not only the obtainment of plant material in consonance with biodiversity preservation, but also the potential lower risk to the environment and lower consume of energy in the transformation of the plant into novel products. We therefore describe an elegant study in which the fruits of Pterodon emarginatus, a high promising Brazilian species that can be obtained through a sustainable use of biodiversity, are the natural raw material for the preparation of nano-emulsions. The essential oil was prepared by hydrodistillation, using a classical extraction with a non-toxic solvent instead of organic solvents. Moreover, the utilization of low energy emulsification method at room temperature and rational design with blends of non-ionic surfactants allowed the preparation of nano-emulsions with desirable properties. An optimal nano-emulsion with droplet size around 110−130 nm, low polydispersity index (around 0.14 – 0.20) and high kinetic stability was obtained. The process of preparation of this nano-emulsion was reproducible and it presented stability towards temperature (from 25 Cº to 80 Cº) and also long-term physical stability for 540 days in storage. Moreover, toxicity in vitro assays were also performed in order to evaluate the potential risks of the optimal nano-emulsion. The results showed that it could be considered non-irritant. Therefore, the present study shows the feasibility of classical concepts of nano-emulsion stabilization to generate a novel nano-emulsion with desirable properties.