Nanosystems for encapsulation and release of plant extracts with insecticidal activity

Besides the pharmaceutical potential of several plant extracts, their use as repellents and green insecticides has been recently described, but this application can be hampered by the volatility and easy degradation of the active compounds.

The encapsulation in suitable nanostructures is a relevant strategy for preservation and controlled release of bioactive compounds, allowing a safe application. In this work and following previous studies, the extracts of Mentha suaveolens Ehrh. and Phytolacca americana L. in dichloromethane, after removal of chlorophylls, demonstrated potential as biopesticides in assays using the Sf9 (Spodoptera frugiperda) insect cell line.

Encapsulation in chitosan nanostructures and liposomes of soybean lecithin were carried out, the latter prepared either by thin film hydration or ethanolic injection methods. For chitosan, the ionic gelation technique was used. The nanosystems were characterized regarding their size and polydispersity. Encapsulation efficiencies of the extracts were determined (being higher than 60%) and the release profiles were fitted with suitable models. Liposomes generally allowed a delayed release of the extracts, while chitosan nanosystems are suitable for a faster and complete release of the potential bioinsecticides.