Banca de DEFESA: MIRIAN LUZINETE DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : MIRIAN LUZINETE DA SILVA
DATE: 30/07/2024
TIME: 19:00
LOCAL: Auditório do Departamento de Química
TITLE:

ACARICIDAL ACTIVITY OF NANOEMULSIONS FORMULATED BASED ON THE ESSENTIAL OIL OF Melaleuca leucadendra AND (E)-NEROLIDOL ON Tetranychus urticae.

KEY WORDS:

Keywords: Essential oil, Melaleuca leucadendra, nanoemulsion, stability, acaricidal activity.

PAGES: 82
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Química dos Produtos Naturais
SUMMARY:

The use of nanoemulsions for incorporating essential oils as active principles has been increasingly evidenced. Controlled release systems targeted for agricultural applications against pests that cause significant economic losses are becoming more commonly applied, considering that essential oils have some characteristics that limit their applications. Oxidative degradation, low solubility, soil residues, and excessive applications are some of the main reasons driving the search for an alternative controlled release system. Nanoemulsions (NE) are defined as dispersions of droplets with diameters below ~500 nm (0.5 μm), giving a clear or translucent appearance, characterized as thermodynamically unstable dispersions of oil and water formed mechanically. This study aims to develop nanoemulsions with essential oil of Melaleuca leucadendra and the compound (E)-nerolidol, evaluating the physicochemical stability of the nanoemulsified essential oil and its acaricidal activity against the pest Tetranychus urticae. In the formulation development, concentrations of 10% and 20% of the essential oil/compound were used, with various combinations of non-ionic surfactants such as Span 80® - Sorbitan Monooleate and Tween 80® - Polysorbate. The best formulation responses for the essential oil and the compound (E)-nerolidol were obtained with a 10% concentration. The nanoemulsions in proportions ML4 and NE4 (oil and compound, respectively) were the most stable as they remained homogeneous during stability tests. The best encapsulation percentages under stress conditions were under UV radiation, where the oil nanoemulsion showed 68.77% and the compound nanoemulsion 93.09%. The nanoemulsions in proportions ML4 and NE4 were toxic against the pest Tetranychus urticae through the residual contact bioassay, in which mites are placed on treated leaves, presenting LC₅₀ = 4.96 μL/mL (ML4) and LC₅₀ = 5.39 μL/mL (NE4). In the repellency bioassay, the essential oil nanoemulsion showed activity at all tested concentrations, with the best result at LC₁₀ = 0.84 μL/mL compared to Azamax®.

COMMITTEE MEMBERS:
Presidente - CLAUDIO AUGUSTO GOMES DA CAMARA
Interno - JOAO RUFINO DE FREITAS FILHO
Interno - MARCILIO MARTINS DE MORAES
Externa à Instituição - VANESKA BARBOSA MONTEIRO