Lizandra Lima Santos

Mosquito-borne diseases remain a major global public health concern, and the development of safer botanical repellents represents an important complementary strategy to synthetic products. In this study, the essential oil of Pogostemon cablin (PCEO) was chemically characterized and incorporated into a topical cream formulation to evaluate its repellent potential against Aedes aegypti. Phytochemical analysis by GC-MS revealed patchouli alcohol as the major constituent, consistent with the classical patchouli chemotype. The cream formulation was assessed for physicochemical properties and subjected to in vivo repellency testing using an arm-in-cage bioassay, with protection expressed as complete protection time. Molecular docking assays confirmed binding of PCEO constituents to the AaegOBP1 and AgamOBP1 binding sites with α-guaiene and β-elemene showing binding affinities comparable to DEET, supporting their potential contribution to olfactory disruption in mosquitoes. The PCEO cream demonstrated significant repellency, with complete protection time of 180 min. These findings suggest that PCEO-based formulations may represent a promising natural alternative for topical mosquito repellents, integrating phytochemical characterization, formulation design, and mechanistic insights.

O presente estudo tem como objetivo caracterizar os impactos ambientais associados à implantação e operação da rodovia BR-156/210, especificamente no trecho que liga Macapá à localidade de Cupixi, no município de Laranjal do Jari, no Amapá. A caracterização considera os efeitos diretos e indiretos da obra sobre os componentes físicos, bióticos e socioeconômicos da região, propondo medidas mitigadoras e compensatórias para minimizar os danos ambientais gerados. A construção civil, tradicionalmente associada a externalidades negativas, tem buscado evoluir através da adoção de práticas sustentáveis, especialmente em obras de infraestrutura viária como esta, que são fundamentais para o escoamento de produtos e a integração regional. A área de estudo compreende a porção sudeste do estado do Amapá, abrangendo os municípios de Macapá, Santana e Mazagão. Trata-se de uma região ecologicamente rica, marcada por elevados índices pluviométricos, clima tropical úmido (Amw), vegetação diversificada e solos pertencentes ao período Quaternário. A implantação da rodovia atravessa áreas sensíveis que abrigam ecossistemas diversos, como florestas equatoriais, campos cerrados e manguezais, cuja conservação é vital para a manutenção da biodiversidade regional. Durante a fase que antecede a implantação, observou-se que os principais impactos incidem sobre a cobertura vegetal e a fauna silvestre. A supressão da vegetação para abertura da via causa fragmentação de habitats, perda de nichos ecológicos e desequilíbrio nos ecossistemas locais, comprometendo também as cadeias tróficas e as relações ecológicas entre as espécies. Além disso, a presença de canteiros de obras e o uso de áreas de empréstimo contribuem para a degradação ambiental, enquanto as queimadas aumentam a emissão de poluentes e reduzem a resiliência ecológica. Diante desse cenário, foram propostas medidas mitigadoras voltadas ao controle dos impactos sobre solo, ar, água, flora, fauna e ruídos. Entre as ações recomendadas estão a instalação de cercas ecológicas, programas de monitoramento ambiental, supressão vegetal controlada, umectação de vias para controle de poeira, barreiras acústicas e proibição de queimadas. Tais práticas visam garantir o equilíbrio ambiental e reduzir os efeitos negativos da obra, preservando os ecossistemas adjacentes. Por fim, a Tabela 1 resume os impactos identificados, indicando sua relevância e intensidade, reafirmando a necessidade de planejamento ambiental criterioso em empreendimentos viários na Amazônia.

The present study evaluated the antioxidant, cytotoxic, and larvicidal potential of the essential oil of Tridax procumbens leaves, as well as identified the compounds present in the essential oil. The antioxidant activity was evaluated by the sequestration method of 2,2-diphenyl-1-picrylhydrazyl radical, the cytotoxic activity was evaluated using Artemia salina, the larvicidal bioassay was performed with larvae in the third stage of development of the Aedes aegypti mosquito, and the identification of the metabolites was performed by gas chromatography coupled to the mass spectrometer (GC-MS). The phytochemical oil analysis showed the presence of 20 compounds, with thymol and γ-terpinene being the main ones. It presented antioxidant activity with an IC₅₀ of 194.51μg mL⁻¹, demonstrating antioxidant activity in the highest concentrations tested. It presented low cytotoxic activity against A. salina, with an LC₅₀ of 1238.67μg mL⁻¹, demonstrating atoxicity in the concentrations tested. The essential oil presented good larvicidal activity when compared to the literature, with an LC₅₀=79.0μg mL⁻¹ in 24 hours and LC₅₀ of 69.15μg mL⁻¹ in 48 hours. In this way, it was possible to identify that the essential oil of the leaves of T. procumbens presented potential for the development of a natural larvicide, as well as antioxidant activity satisfactory to the radical DPPH and low toxicity to A. salina.

Ayapana triplinervis is a plant species used in traditional medicine and in mystical-religious rituals by traditional communities in the Amazon. The aim of this study is to evaluate the larvicidal activity against A. aegypti of nano-emulsions containing essential oils from A. triplinervis morphotypes, and acute oral toxicity in non-target organism. Essential oils were identified and nano-emulsions were prepared using the low energy method. The mortality test of A. aegypti larvae was performed according to the protocol recommended by the World Health Organization, and toxicity in non-target mammals was performed according to the OECD. Phytochemical analyses indicated the major compounds (E)-Caryophyllene (45.93%) and Thymohydroquinone Dimethyl Ether (32.93%) in morphotype A, and in morphotype B, Thymohydroquinone Dimethyl Ether (84.53%) was found. Morphotype A essential oil nano-emulsion showed a particle size of 101.400 ± 0.971 nm (PdI = 0.124 ± 0.009 and ZP = −19,300 ± 0.787 mV). Morphotype B essential oil nano-emulsion had a particle size of 104.567 ± 0.416 nm (PdI = 0.168 ± 0.016 and ZP = −27,700 ± 1,307 mV). Histomorphological analyses showed the presence of inflammatory cells in the liver of animals treated with morphotype A essential oil nano-emulsion (MAEON) and morphotype B essential oil nano-emulsion (MBEON). Congestion and the presence of transudate with leukocyte infiltration in the lung of animals treated with MAEON were observed. The nano-emulsions containing essential oils of A. triplinervis morphotypes showed an effective nanobiotechnological product in the chemical control of A. aegypti larvae and safe for non-target mammals.

The objective of this work was to collect information on the chemical constituents that demonstrate the larvicidal activity against Aedes aegypti, as well as the antioxidant, microbiological, and cytotoxicity potential of the essential oil of Pogostemon cablin leaves. The chemical characterization was performed by gas chromatography coupled to mass spectrometer (GC-MS). The larvicidal activity was performed according to the protocol of the World Health Organization. The antioxidant activity was evaluated through the sequestering capacity of 2,2-diphenyl-1-picryl-hydrazine (DPPH). As for the microbiological evaluation, the microdilution technique was used, according to the protocol of the Clinical and Laboratory Standards Institute. The cytotoxic activity was evaluated against the larvae of Artemia salina. The species P. cablin presented the following compounds: Patchouli alcohol (33.25%), Seyshellene (6.12%), α-bulnesene (4.11%), Pogostol (6.33%), and Norpatchoulenol (5.72%), which was in synergy with the other substances may significantly potentiate the larvicidal action of the species with the LC₅₀ of 28.43 μg·mL⁻¹. There was no antioxidant activity, however, it presented antimicrobial activity against all bacteria tested with Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of 62.5 μg·mL⁻¹. The species demonstrated significant toxic action with LC₅₀ of 24.25 μg·mL⁻¹. Therefore, the P. cablin species showed significant larvicidal potential, antimicrobial activity, the absence of antioxidant action, and high toxicity.