Navegando por Autor "Pontual, Emmanuel Viana"

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Avaliação da toxicidade do extrato de folhas de Annona squamosa para Aedes aegypti, Nasutitermes corniger e Sitophilus zeamais
(2019-12-20) Santos, Lucas Gabriel Pita dos; Pontual, Emmanuel Viana; Almeida, Welton Aaron de; http://lattes.cnpq.br/6880632191779221; http://lattes.cnpq.br/1777060469196142; http://lattes.cnpq.br/5858954656778360
The high environmental toxicity of the compounds currently used for control of insect pests, as well as the emergence of resistant populations have stimulated the search for new agents with insecticidal activity. In this work, an extract of Annona squamosa (Annonaceae) leaves was evaluated for the presence of proteins and secondary metabolites. The effect of the extract on larvae of Aedes aegypti (vector of dengue, yellow fever, zika and chikungunya) and adults of Nasutitermes corniger (urban pest) and Sitophilus zeamais (agricultural pest) was also investigated. The chemical characterization of the extract revealed the presence of proteins, lectin (HAE = 21,3) and trypsin inhibitor (15,6 U/mg) activities, as well as secondary metabolites the classes of flavonoids (rutin), cinnamic derivatives (chlorogenic acid), saponins, anthraquinones, terpenes and steroids. The extract was in toxic to A. aegypti larvae and the concentration required to kill 50% of larvae (CL50) was 1.9% (m/v). On the other hand, the extract did not affect the survival of N. corniger soldiers and workers. S. zeamais adults showed mortality ranging from 51.2 to 63.8% regarding the control when fed with the diet containing the extract (15 to 75 mg/g), but a strong deterrent feeding effect was detected. This data revealed that the insects die from starvation and not from intoxication due to the extract intake. The treatment with the extract resulted in high mortality of Hyalella sp. at the concentration corresponding to the LC50 for A. aegypti. However, the presence of the extract interferes with the pH and the amount of dissolved O2 in the culture solution, suggesting that Hyalella sp mortality cannot be a result of a direct toxicity of the extract. In conclusion, the A. squamosa leaf extract is an interesting candidate for use in the control of A. aegypti populations and as a protection agent for stored grains against the S. zeamais attack. Additionally, the use of the extract in the environment needs caution due to the high mortality detected for Hyalella sp.
Efeito da lectina de folhas de Schinus terebinthifolia sobre a formação de vasos do saco vitelínico e morfologia de embriões de Coturnix japônica
(2019-08-13) França, Rayssa Perla Martins; Pontual, Emmanuel Viana; http://lattes.cnpq.br/1777060469196142; http://lattes.cnpq.br/4999755464041290
Angiogenesis corresponds to the budding of new blood vessels starting from other preexisting ones. This process is of great importance for development of tumor cells. Schinus terebinthifolia (Brazilian Peppertree) leaves express a thermostable and antimicrobial lectin (SteLL). This work reports the effect of SteLL on the angiogenesis process using the in vivo model of yolk sac membrane of Coturnix japonica (Japanese quail) embryos. The fractal analysis by box counting and information dimension indicated that SteLL at 1.35 mg/mL reduced the angiogenesis of C. japonica yolk sac membrane. The inhibition of the vascular network formation in the yolk sac membrane resulted in decreased blood supply to the embryos, and consequently area, perimeter and percentage of cephalic length of embryos were significantly reduced in the group treated with SteLL, corroborating with the antiangiogenic activity. In conclusion, SteLL is an antiangiogenic agent and this result stimulate future investigations about its antitumor activity.
Folhas de Syzygium malaccense Linnaeus (Myrtaceae): caracterização química e efeitos sobre Plutella xylostella Linnaeus (Lepidoptera: Plutellidae)
(2019-06-28) Santos Neto, Erasmo Guilherme dos; Pontual, Emmanuel Viana; Vila Nova, Isabella Coimbra; http://lattes.cnpq.br/8445185379848462; http://lattes.cnpq.br/1777060469196142; http://lattes.cnpq.br/6695192736858780
Plutella xylostella (Plutellidae) is an important pest that attacks Brassicas cultures worldwide. Syzygium malaccense (Myrtaceae), or jambeiro, is used in popular medicine and its fruits are consumed as foodstuff. Lectins (carbohydrate-binding proteins) and trypsin inhibitors can be insecticidal agents. This work characterized the aqueous extract of S. malaccense for the presence of secondary metabolites, lectins and trypsin inhibitors, as well as for insidicidal activity against P. xylostella. Analysis by thin layer chromatography revealed the presence of polyphenols (hydrolyzed tannins), flavonoids, steroids, saponins and reducing sugars in the leaf extract, which also contained lectins (hemagglutinating activity of 64) and trypsin inhibitor. was inhibited by monosaccharides glucose and Nacetylglucosamine and neutralized by the glycoproteins fetuin and ovalbumin. The leaf extract exerted a detergent feed effect and induced mortality of P. xylostella caterpillars. The mortality rate of 80 ± 15% for the 1% leaf extract was recorded. The oviposition detergent effect was also determined for the leaf extract, since the presence of about 37 eggs was detected in the treated discs against 80 eggs recorded in the control. Exhaustive heating of the leaf extract altered the hemagglutinating and detergent food activities in a similar manner, suggesting that these can be attributed to the same protein. Exposure of leaf extract to environmental conditions for 192 h neutralized its food-producing effect. In conclusion, leaf extract of S. malaccense is a source of secondary metabolites, lectin and trypsin inhibitor, and constitutes an insecticidal agent against P. xylostella for causing mortality of caterpillars and altering their feeding and oviposition behaviors.
Investigação do efeito do extrato de flores de Moringa oleifera Lamarck (Moringaceae) na sobrevivência e atividade de enzimas digestivas de larvas de Plutella xylostella Linnaeus (Lepidoptera: Plutellidae)
(2019-02-01) Ferreira, Camila Azevedo; Pontual, Emmanuel Viana; Almeida, Welton Aaron de; http://lattes.cnpq.br/6880632191779221; http://lattes.cnpq.br/1777060469196142; http://lattes.cnpq.br/1108068314774367
Plutella xylostella is a multiresistant agricultural pest that attacks brassica plantations in Brazil and worldwide. The use of natural products with insecticidal properties to control P. xylostella may be advantageous due to the higher degree of degradability and lower persistence of these compounds in the environment when compared with the effects of synthetic insecticides. Moringa oleifera Lam. (Moringaceae) is a pantropical tree that synthesizes proteins (lectins and trypsin inhibitor) whose insecticidal activity has been reported. In the present work, the M. oleifera flower extract containing trypsin inhibitor (MoFTI, M. oleifera flower trypsin inhibitor) was investigated for the presence of peptides resistant to hydrolysis by digestive proteases and effect on survival and protease activity from midgut of P. xylostella third instar larvae (L3). The flower extract showed a high molecular weight polypeptide, which was resistant to hydrolysis by larval gut proteases up to 270 min incubation, revealed by polyacrylamide gel electrophoresis. The larvae were sensitive to the treatment with the extract and the mortality curve revealed a dose dependent response following a polynomial order 2 regression with R2 = 0.99. The maximum mortality rate (60 ± 10%) of larvae was obtained for the extract at 2% (w/v). The adults who emerged from treatment with flower extract showed morphological alterations, including atrophy of the wings and inability to move. In addition, some insects were not able to abandon the cocoon after the end of the pupal phase. The total protease and trypsin-like activities from larval gut were reduced in 67.75 ± 0.64% and 65.83 ± 6.3% by the flower extract at 0.8% and 1%, respectively. Deterrent alimentary effect was not detected when the larvae were reared with cabbage discs treated with the extract at 0.5 and 1%. In conclusion, the M. oleifera flower extract is a larvicidal agent against P. xylostella by cause larval mortality and malformations in adult insects. The larvicidal effect of the flower extract may be linked to the inhibition of enzymes important for the digestive processes of P. xylostella.
Investigação do extrato de cladódios de Cereus jamacaru quanto à composição química, potencial antimicrobiano contra Staphylococcus aureus e efeito larvicida para Aedes aegypti
(2023-09-21) Guimarães, Júlia Maria Rodrigues; Pontual, Emmanuel Viana; Alves, João Victor de Oliveira; http://lattes.cnpq.br/0882174483226946; http://lattes.cnpq.br/1777060469196142; http://lattes.cnpq.br/3701748857935689
Cereus jamacaru (Cactaceae), mandacaru, is a plant from the Brazilian semi-arid region that has economic importance for livestock farming and use in folk medicine. The use of currently commercialized antibiotics leads to many unwanted effects and has led to the emergence of resistant bacteria, while synthetic insecticides generally have high persistence in the environment and strong non-target toxicity. In this sense, the search for new antimicrobial agents and insecticides has grown. The aim of this work was to investigate the cladode extract of C. jamacaru regarding its chemical composition (presence of lectins, protease inhibitors and secondary metabolites), antimicrobial potential against pathogenic bacteria and larvicidal effect against Aedes aegypti. Cladodes of C. jamacaru were collected in Recife, Pernambuco. The spines were removed and the cladodes were cut into slices and air-dried (28°C, 4 days). Then, the cladodes were crushed and the powder (10 g) was homogenized (28°C, 16 h) with 0.15 M NaCl solution (100 mL) in water, using a magnetic stirrer. The mixture was filtered and centrifuged (3,000 g, 15 min) and the clear supernatant corresponded to cladode extract (CjCE) which was investigated for the presence of lectins using rabbit erythrocytes, protease inhibitor using bovine trypsin (0.1 mg/ mL) and the chromogenic and peptidomimetic substrate BApNA (8 mM), and secondary metabolites by thin layer chromatography. The content of phenolic compounds in CjCE was determined using the Folin-Ciocalteu reagent (10%, v/v) and a gallic acid standard curve, while flavonoids were quantified using the aluminum chloride reagent (20%, m/v) and quercetin as standard. Then, the extract was investigated for antioxidant activity using the DPPH, ABTS and Phosphomolybdenum methods. The antibacterial potential of CjCE was determined using bacterial strains sensitive or resistant to antibiotics by the plate microdilution method. The minimum inhibitory concentration (MIC, lowest concentration of CjCE capable of inhibiting bacterial growth by 50%) was determined. Hemolysis assay by S. aureus was performed using human erythrocytes and the effect of CjCE (128, 64 and 32 µg/mL) on hemolysis was investigated. The larvicidal potential of CjCE (0.40 to 3.5%, m/v) was evaluated by treatment (48 h) of A. aegypti larvae in the third instar (L3). CjCE caused agglutination of rabbit erythrocytes (8 UAH), suggesting the presence of lectins. The extract reduced the hydrolysis of the BApNA substrate by trypsin, indicating the presence of a protease inhibitor. CjCE thin layer chromatography revealed the presence of reducing sugars and qualitative-quantitative analysis showed 40.20±0.97 mgEAG/g of total phenols, among which, 3.36±0.07 mgEAG/g (8, 36%) were flavonoids. CjCE showed relevant oxidant activity, with the ability to scavenge ABTS and DPPH radicals (IC50 of 3,735 µg/mL and 2704.50 µg/mL, respectively), but was not able to cause reduction of phosphomolybdenum. CjCE was toxic only to the Staphylococcus aureus strain (UFPEDA 02), revealing a strong bacteriostatic effect (MIC of 199.09±0.85 µg/mL), and reduced erythrocyte lysis caused by the bacteria by more than 90%, compared to to control. The treatment of L3 of Ae. aegypti with CjCE resulted in dose-dependent mortality (LC50 = 0.68%, m/v). On the other hand, when larvae were treated with CjCE at a concentration 10 times higher than the LC50, the intestinal contents covered by the peritrophic membrane were eliminated in an attempt to eliminate the toxic components of the extract. In conclusion, C. jamacaru cladode extract is a novel antimicrobial agent capable of strongly inhibiting the growth of S. aureus and reducing bacterial toxicity to human erythrocytes. Furthermore, the toxicity to A. aegypti larvae shown here points to the C. jamacaru cladode extract as an interesting starting material for obtaining larvicidal formulations. The antibacterial and insecticidal effects of the extract may be linked to the presence of lectins, protease inhibitors and phenolic compounds.
Investigação do potencial antibiofilme da lectina de folhas de Schinus terebinthifolia Raddi contra Staphylococcus aureus
(2019-12-20) Silva, Talyta Naldeska da; Pontual, Emmanuel Viana; Silva, Pollyanna Michelle da; http://lattes.cnpq.br/0563176148137978; http://lattes.cnpq.br/1777060469196142; http://lattes.cnpq.br/8762925956752737
Biofilms are complex microbial communities that have been associated with the incidence of infections, including in the hospital environment. Its formation is considered a determining factor for virulence in microorganisms and strongly contributes with the microbial resistance to conventional antimicrobials. In this sense, the search for natural compounds with antimicrobial activity that are more effective and less toxic to host cells. Plants are important sources of bioactive compounds, including lectins, a class of carbohydrate-binding proteins whose antimicrobial action has been reported. SteLL is a leaf lectin isolated from Schinus terebinthifolia Raddi (Anacardiaceae) with antimicrobial action that was previously reported. In this work, the antibacterial and antibiofilm potential of SteLL against sensitive (UFPEDA 02) and oxacillin resistant (UFPEDA 670) isolates of Staphylococcus aureus was evaluated. SteLL was a bacteriostatic and bactericidal agent against UFPEDA 02 and UFPEDA 670 isolates with MIC50 (Minimum Inhibitory Concentration) of 12.5 and 25.0 μg/mL and CMB (Minimum Bactericidal Concentration) of 50.0 and 100 μg/mL, respectively. The growth kinetics of the cells treated with SteLL revealed a dose-dependent growth inhibition regarding to control. SteLL caused morphometric alterations in S. aureus cells and inhibited biofilm formation of UFPEDA 02 at concentrations between 400 and 25.0 μg/mL and UFPEDA 670 between 400 and 100 μg/mL. In conclusion, SteLL is an antibacterial agent against Staphylococcus aureus by inhibiting the growth, promoting cell death and inhibiting bacterial biofilm formation.
Potencial biotecnológico do inibidor de tripsina de flores de Moringa oleifera: uma revisão
(2021-12-16) Medeiros, Êsdras da Silva; Pontual, Emmanuel Viana; http://lattes.cnpq.br/1777060469196142; http://lattes.cnpq.br/8379001129790219
This work provides a review on the applications of the Moringa oleifera flower trypsin inhibitor (MoFTI) as an insecticidal, antiparasitic, antitumor, immunomodulatory and anti-inflammatory agent. MoFTI is a 18.2-kDa protein (Ki against trypsin of 2.4 μM) that killed (LC50 of 0.3 mg/mL) or delayed the development of newly hatched Aedes aegypti larvae and impaired the growth and viability of the larval gut microbiota (MIC of 0.031 mg/mL; MBC of 1.0 mg/mL). It was also reported that MoFTI caused lysis of Trypanosoma cruzi trypomastigotes (LC50 of 41.2 μg/mL). The inhibitor stimulated the release of the inflammatory cytokines TNF-α and INF-γ, the anti-inflammatory cytokine IL-10, and NO by T. cruzi-infected human peripheral blood mononuclear cells (PBMCs) with the advantage of exerts low toxicity to murine peritoneal macrophages and Vero cells, and no toxicity to human PBMCs. It is known that MoFTI antitumor activity involves the reduction of sarcoma 180 tumor weight in mice and the impairment of the vascularization in tumor microenvironment without exerting toxicity to the animals. Also the inhibitor is an anti-inflammatory and immunomodulatory agent because it reduced paddle edema and leukocyte migration to the peritoneal cavity in mice, and modulated levels of NO, pro-inflammatory (TNF-α, IL-6 and IL-17A) and anti-inflammatory (IL-4 and IL-10) cytokines, respectively. The reviewed data implicate MoFTI as an interesting molecule for biotechnological applications, whether due to its insecticidal potential or pharmacological value.