Nanopartículas de quitosana-beta-ciclodextrina para a liberação sustentada de carvacrol e linalol visando aplicações na agricultura

Author(s)

Estefânia Vangelie Ramos Campos

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2018-12-15

Examining board members

Leonardo Fernandes Fraceto; Cátia Ornelas; Daiana Silva Avila; Marcelo Bispo de Jesus; Ricardo Antonio Polanczyk

• Advisor: Leonardo Fernandes Fraceto

Abstract

In recent decades, there has been a large increase in the use of agricultural inputs worldwide to maximize food production. However, the indiscriminate use led to the accumulation of toxic residues in food, soil, air and water, and selection of resistant pests. In order to feed the growing world population, it is necessary to produce more food in a sustainable and safe way with less availability of arable land and water resources. In this context, there has been an increase in interest in compounds, which present less risk to the environment and human health and increase food safety. Recently, the use of substances derived from aromatic plants has become prominent in the world scenario, once they have activity to control agricultural pests. Carvacrol (CVC) and linalool (LNL) are phenolic compounds extracted from plants. The first compound presents insecticide activity whereas the second one has repellent activity. Although they have potential to be applied in crop protection, their instability into the field limits their application in agriculture. The instability of botanical insecticides is directly related to their high volatility and photosensitivity. In this context, the encapsulation has emerged in order to reduce the instability problems and improve the efficacy of these compounds. The objective of this study was to prepare and characterize carrier systems based on chitosan and beta cyclodextrin for the botanical pesticides carvacrol and linalol in order to increase the stability of these compounds for future application in the control of agricultural pests. Inclusion complexes were prepared by the kneading method. Both complexes presented 1:1 host:guest stoichiometry and the highest affinity constants were observed at 20 °C for both molecules, with values of 170.1 and 228.2 mol/L for carvacrol and linalool, respectively. Functionalization of chitosan with ß-cyclodextrin was performed using EDC/NHS crosslinking agents and was confirmed using NMR, XRD, DSC, TG, and FTIR analyses. Cyclodextrin functionalized chitosan nanoparticles were produced by the ionic emulsion/gelling method using gum arabic or sodium tripolyphosphate as a crosslinking agent. The nanoparticles containing carvacrol, linalool and the mixture of these two compounds had a mean diameter of 156.5±1.72 nm, 295.8±2.45 nm and 225.9±5.23 nm, respectively. The polydispersity and zeta potential index for all nanoformulations was less than 0.3 and less than 20 mV, respectively. The nanoparticles presented high encapsulation efficiency for the CVC (93.9±0.9 %) and for the LNL of (86.9±0.9 %) and in the mixed system the encapsulation efficiency was higher than 90% for both bioactive. The nanoparticles were able to modulate the release of the actives and both release profiles were better fitted to the Higuchi mathematical model. Decreased cytotoxicity as well as phytotoxicity was observed when the compounds were nanoencapsulated. Biological assays with mites Tetranychus urticae (Acari:Tetraichydae) and "Helicoverpa armigera" (Lepidoptera: Noctuidae) presented insecticidal activity for both species. In addition, repellent activity and reduction in oviposition were also observed for mites. These nanoformulations are promising for the effective use of botanical pesticides in agriculture, contributing to improve the management of these agricultural pests (AU)

• FAPESP's process: 14/20273-4 - Development of chitosan-²-cyclodextrin nanoparticles for sustained release of carvacrol and linalool aiming agricultural applications
• Grantee: Estefânia Vangelie Ramos Campos
• Support Opportunities: Scholarships in Brazil - Doctorate