Obtenção e caracterização de microcápsulas à base de cardanol para liberação de óleo essencial de Ocimum gratissimum L.

Abstract

Ticks are hematophagous ectoparasites of mammals, reptiles and birds, and are vectors of several diseases that directly impact the health of the host. One of the main hosts of ticks is cattle and its parasitization generates several problems, both for the health of the animal and for agricultural production. The most common measures to control ticks have been through the use of synthetic acaricides, which generate another problem that is environmental contamination and the development of more resistant tick populations. An alternative to solve this problem is the use of essential oils that can have effects on ticks. In this work, cardanol-based microcapsules were produced for the incorporation of essential oil (EO) of Ocimum gratissimum. Cardanol was extracted from Cashew Nutshell Liquid (CNSL) and its isolation was confirmed by High Performance Liquid Cromatography coupled to an Photo Diode Array (HPLC-PDA). The cardanol obtained was characterized by Fourier transform infrared spectroscopy (FTIR). The EO was extracted from basil leaves (Ocimum gratissimum) by hydrodistillation and its composition was determined by Gas Chromatography coupled to Mass Spectrometry (GC-MS). The EO of Ocimum gratissimum presented the compounds Thymol, γ Terpinene and m-Cymene as the majority with a percentage of composition of 36.69%, 29.08% and 21.31%, respectively. Microencapsulation occurred by polymerization of cardanol in emulsion. A mixture of cardanol/m-cresol monomers was also used in the proportions of 3:1, 1:1 and 1:3 in the production of microcapsules. The microcapsules obtained were characterized by FTIR, Differential Scanning Calorimetry (DSC) and Scanning Electronic Microscopy (SEM). The microcapsules presented irregular shapes, isolated particles and average volumetric diameters that ranged from 1.409 to 3.347 µm. The study of EO release was carried out by reading in a UV-vis spectrometer, which showed gradual release curves up to eight hours and after 24 hours the release rate remained constant. Release kinetics revealed that release occurs by Fickian diffusion. The EO of Ocimum gratissimum showed larvicidal activity in Rhipicephalus microplus, with an average inhibitory concentration (IC50) of 2.377 mg/mL. In this work, cardanol-based microcapsules incorporated with a bioactive with acaricidal properties were successfully obtained.