Marise Maleck

Khellin: A furanochromone with toxicity against Oncopeltus fasciatus (Hemiptera) and Aedes aegypti (Diptera)

Natural products isolated from plants may be an alternative source of larvicidal and insecticide activity. Khellin is a natural furanochromone isolated from fruits of Ammi visnaga (L.) Lam. (Umbelliferae family), which grows extensively in the Mediterranean region. This substance shows several types of biological activity, such as in vitro cytotoxicity, antispasmodic action, and phototherapeutic potential. Dengue is a tropical disease caused by an arbovirus transmitted by Aedes aegypti; the milkweed bug, Oncopeltus fasciatus, is a phytophagous Hemiptera and a Phytomonas vector. Our main goal was to evaluate the toxicity of khellin in relation to the nymphs of O. fasciatus (Hemiptera) and larvae of A. aegypti (Diptera). To the best of our knowledge, this is the fi rst report concerning furanochromone bioactivity against insect vectors for human disease.

Cytotoxicity of Piperamides Towards Aedes aegypti (Diptera: Culicidae)

ABSTRACT The effectiveness of the amides piplartine and piperlonguminine isolated from Piper species for controlling L3 and L4 of Aedes aegypti (L.) was assessed through bioassays at concentrations ranging from 1 to 300 µg/ml. Piplartine reduced the mosquito development period and caused larval mortality only at concentrations >100 µg/ml, whereas piperlonguminine resulted in an extended period of mosquito development (10 µg/ml) and caused 100% larval mortality (30 µg/ml) within 24 h. The toxicity and cytotoxic effects of piperlonguminine on epithelial cells of the digestive system of Ae. aegypti were viewed using transmission electron microscopy, which indicated vacuolization of cytoplasm, mitochondrial swelling and leaking of nuclear material. Piperlonguminine was the more effective amide, showing toxic activity with LD50 of ≈12 µg/ml against the larvae of Ae. aegypti.

Burchellin: study of bioactivity against Aedes aegypti

BackgroundThe dengue mosquito Aedes aegypti Linnaeus, 1762 is a widespread insect pest of serious medical importance. Since no effective vaccine is available for treating dengue, the eradication or control of the main mosquito vector is regarded as essential. Since conventional insecticides have limited success, plants may be an alternative source of larvicidal agents, since they contain a rich source of bioactive chemicals. The aim of this study was to evaluate the larvicidal activity of the neolignan burchellin isolated from Ocotea cymbarum (Lauraceae), a plant from the Amazon region, against third instar larvae of A. aegypti.MethodsBurchellin obtained from O. cymbarum was analyzed. The inhibitory activity against A. aegypti eggs and larvae and histological changes in the digestive system of treated L3 larvae were evaluated. In addition, nitric oxide synthase activity and nitric oxide levels were determined, and cytotoxicity bioassays performed.ResultsThe data showed that burchellin interfered with the development cycle of the mosquito, where its strongest toxic effect was 100% mortality in larvae (L3) at concentrations ≥ 30 ppm. This compound did not show target cell toxicity in peritoneal macrophages from BALB/c mice, and proved to have molecular stability when dissolved in water. The L3 and L4 larvae treated with the compound showed cellular destruction and disorganization, cell spacing, and vacuolization of epithelial cells in small regions of the midgut.ConclusionThe neolignan burchellin proved to be a strong candidate for a natural, safe and stable phytolarvicidal to be used in population control of A. aegypti.

Aedes aegypti: modelo experimental de atividade biológica de fitoprodutos

Aedes aegypti (Linnaeus, 1762) e reconhecido como transmissor de varias arboviroses de importância na saude publica, como a dengue, zika, chikungunya e febre amarela urbana. O principal metodo de prevenir a transmissao desses virus ainda e o controle do mosquito vetor. Produtos naturais de origem vegetal vem sendo investigados, como mais uma ferramenta no controle de vetores, e compostos menos impactantes ao meio ambiente e a saude humana. Devido a importância deste culicideo, buscou-se extrato e fracoes de C. catharinensis com atividade larvicida sobre Ae. aegypti . O extrato bruto metanolico (EBM) e sua fracao (EBM 1) obtidos da embauba foram aplicados no meio de criacao das larvas (L3) nas concentracoes de 10, 30 e 50 μg/mL. O tratamento com C. cahtarinensis resultou na alteracao do periodo de desenvolvimento larval, pupal e de L3-adulto do mosquito. A mortalidade pupal (25%) foi obtida pela fracao EBM1. Este estudo demonstrou a eficacia de C. catharinensis sobre o periodo de desenvolvimento de Ae. aegypti .

Toxicity and Larvicidal Activity of Podophyllum-Based Lignans Against Aedes aegypti (Diptera: Culicidae)

Abstract Aedes aegypti L. (Diptera: Culicidae) is a mosquito species that has adapted to urban environments and is the main vector of dengue viruses. Because of the increasing incidence of dengue, a more environmentally acceptable insecticide needs to be found. Natural products have been and continue to be an important source of leading compounds that can be modified in order to develop new drugs. The lignan family of natural products includes compounds with a diverse spectrum of biological activity. Podophyllotoxin and its related lignans represent an exciting class of natural products that can be targeted at different types of biological activity and are therefore worth exploring further. This study had the aim of evaluating the larvicidal activity of an ethanolic extract from the rhizomes and roots of Podophyllum hexandrum (PM-3) and its isolated lignans, podophyllotoxone (1) and desoxypodophyllotoxin (2), on the larvae of the mosquito vector Ae. aegypti. The PM-3 extract and the compounds (1) and (2) were dissolved in a mixture of acetone and dimethylsulfoxide at final concentrations of 1, 10, 30, 50, 100, and 200 μg/ml. After dilution, the solutions were applied (μg/ml) to the larvae-rearing medium. Overall, the ethanolic extract from the rhizomes and roots of P. hexandrum and the compounds (1) and (2) showed larvicidal activity against the larvae of Ae. aegypti. According to the results from this study, it can be concluded that podophyllotoxone (1) and desoxypodophyllotoxin (2) exhibited significant toxicity toward Ae. aegypti larvae.