http://repositorio.ufc.br/handle/riufc/336 2026-06-15T22:42:26Z 2026-06-15T22:42:26Z Tivane, Orpa Miguel http://repositorio.ufc.br/handle/riufc/86747 2026-06-12T22:36:39Z 2026-01-01T00:00:00Z

Título: Interação entre fungos endofíticos melanizados septados da caatinga e genótipos contrastantes de Vigna unguiculata [L.] Walp. sob déficit hídrico Autor(es): Tivane, Orpa Miguel Abstract: Drough is one of the main environmental stresses that limit agricultural productivity, especially in the semi-arid region of the northeast, where crops such as cowpea (Vigna unguiculata) have great socioeconomic importance. Melanized and septate endophytic fungi (DSEs) have been associated with plant growth promotion and the mitigation of water deficit effects, bult their functionality in agricultural crops is still poorly understood. This study avaluated the potential of DSE isolates native to the Caatinga to promove growth and contribute to water stress tolerance in contrasting genotypes of V. unguiculata, Pingo-de-Ouro ,2 (PO) and Santo Inácio (SI). Of the 14 isolated species, 14 colonized cowpea and 11 colonized corn. Among them, the DSE2 strain was selected for showing the best effects of water stress and maintaining plant growth. Inoculation with DSE2 resulted in a higher colonization rate under water stress, especially in the susceptible cultivar (SI). Additionally, it promoted an increase in intrinsic water use efficiency, with a more pronounced effect in the tolerant cultivar (PO). The water regime was the main determining fator for changes in the leaf and root metabolome, while inoculation with DSE2 exerted a secundary modulatory effect. However, in the root system of the SI cultivar, the presence of DSE2 promoted more expressive metabolic reprogramming associated with the response to water stress. The results show that native DSEs from the Caatinga have the potential to modulate physiological and metabolic responses of V.unguiculata under water deficit, with effects depending on the water regime, genotype, and organ analyzed. Tipo: Dissertação

2026-01-01T00:00:00Z Santos, Arthur Vieira http://repositorio.ufc.br/handle/riufc/86538 2026-06-02T17:27:50Z 2025-01-01T00:00:00Z

Título: Investigação da atividade de nuclease da albumina-2s (Mo-CBP3) de sementes de Moringa oleifera Autor(es): Santos, Arthur Vieira Abstract: The plant Moringa oleifera (Moringaceae) is present in the semi-arid region. Its seeds have a high lipid content, and the flour obtained from its seeds is used to induce the flocculation of solid particles in turbid waters, allowing for removal and improving water quality for human consumption. At least three chitin-binding proteins, without chitinase activity, have been detected and studied from moringa seeds. However, a nuclease activity seems to coexist in one of the purified fractions of the chitin-binding proteins. This was the problem that motivated this research. Through chitin affinity chromatography, a protein fraction with affinity (PAC) is obtained, and this chromatographic peak was subjected to ion exchange, giving rise to 3 characteristic peaks, with peak 3 (CM-PIII) designated as Mo-CBP3. Preliminary studies with this sample demonstrated nucleolytic activities against plasmidial DNA in the amount of 1,25 ug of protein and 1 ug of nucleic acid. 15% polyacrylamide gel electrophoresis revealed 3 previously undescribed bands. Different purification approaches were used to separate Mo-CBP3 from its contaminants: reverse phase chromatography, ultra centrifugation filtration, and size exclusion chromatography (SEC). Size exclusion chromatography using PAC showed the best protein recovery and presented 4 peaks, which were subjected to electrophoresis analysis. Electrophoresis revealed the separation of the unknown proteins from the known proteins as Mo-CBPs (Moringa oleifera chitin-binding proteins). The SEC peaks were subjected to plasmidial DNA and RNA cleavage assays obtained from Klebsiella pneumoniae ATCC 10031, showing activity comparable to commercial nucleases in peak 3 (P3-SE). In summary, the refined purification by size exclusion chromatography (SEC) was crucial to isolate the biological activity. The results demonstrated that the P3-SE of the SEC, corresponding to the Mo-CBP3 protein, possesses remarkable nucleolytic activity against plasmidial DNA and RNA from Klebsiella pneumoniae. This discovery of a new activity for Mo-CBP3 expands the vast potential of Moringa oleifera seeds as a promising source for nuclease bioprospection. Tipo: Dissertação

2025-01-01T00:00:00Z Castro, George Meredite Cunha de http://repositorio.ufc.br/handle/riufc/86536 2026-05-29T20:11:42Z 2021-01-01T00:00:00Z

Título: Atividades de Iota-Carragenana hidrolisada: influência da massa molecular Autor(es): Castro, George Meredite Cunha de Abstract: Carbohydrates have many applications in several areas, such as food and medical. Sulfated polysaccharides, due to their chemical structure, can be recognized by enzymes or receptors of animal and plant cells to trigger responses such as anticoagulant activity or plant growth and defense. The objective of this work was to demonstrate that the activity of the sulfated polysaccharide ι-carrageenan in animal or vegetable models is directly related to its molecular mass. For this, the acid hydrolysis of this polysaccharide was carried out at a concentration of 3% (m / v) in a reaction cell under shaking and with controlled temperature. A design was elaborated using the Software Statistica with 11 independent hydrolysis experiments for the study of two factors (HCl concentration - 40 to 90 ° C - and reaction temperature - 1 to 100 mM); two response (molecular mass and viscosity) were analyzed. The 11 hydrolysates and the intact polysaccharide were analyzed by Gel Permeation Chromatography and Rheometer. Tables with result ANOVA tables, mathematical models, response surfaces and contour curves for responses were generated. After analysis, two hydrolysates and the intact polysaccharide were selected for further assays. The selected samples were subjected to characterization tests: Fourier Transform Infrared Spectroscopy and Determination of soluble proteins. They were also analyzed for their activities: Cell cytotoxicity, Antioxidant activity in vitro, Anticoagulant activity in vitro (by the methods of activated partial thromboplastin time - APTT - and prothrombin time - PT), Tail bleeding time, Plant growth and defense. After analyzing the molecular masses and viscosity, samples with 123 and 14.1 KDa and the intact ι- carrageenan (1,700 KDa) were selected for subsequent assays. This selection was made due to test ι- carrageenan activities in different order of molecule sizes. The hydrolysis process did not generate changes in the products. The samples had good purity and were considered non-toxic. The hydrolysis of ι- carrageenan promoted a reduction in the antioxidant capacity of the hydrolyzate (64.05 ± 6.11%) in comparison with a whole ι- carrageenan (78.44 ± 8.95%). For the anticoagulant activity ATPP, the longest time of activity of the hydrolysates was 257.5 ± 8.1 s for the sample with 123 KDa at the concentration of 4.0 mg / mL while the intact ι- carrageenan presenting a time of 126,6 ± 19.6 s. An increase of 7.5 times in the normal clotting time was promoted in relation to intact ι- carrageenan, which promoted an increase of 3.7 s. All sources had no PT anticoagulant activity. The sample with 123 KDa was tested at the time of tail bleeding and showed bleeding tendency at 1.0 and 2.0 mg / kg. In the experiments with Vigna unguiculata plants, the sample with 123 KDa promoted an increase in leaf area (71.12 ± 9.31 cm2) compared to the control (57.22 ± 9.62 cm2). It was observed an increase in the height of plants treated with a sample with 14.1 KDa. The sample with 123 KDa promoted an increase in the fresh weight and moisture of the the plants (22.9 ± 3.73 and 20.7 ± 3.37 g, respectively) and did not change the dry mass in relation to the control. None of the samples was able to activate the defense system of V. unguiculata against the Cowpea severe mosaic virus. Tipo: Tese

2021-01-01T00:00:00Z Mourão, Dário Ryan Arruda Lopes Mourão, Dário Ryan Arruda Lopes http://repositorio.ufc.br/handle/riufc/86216 2026-05-11T22:41:28Z 2026-01-01T00:00:00Z

Título: Prospecção e otimização de peptídeos antimicrobianos de Nicotiana sp como alternativa aos antibióticos convencionais Autor(es): Mourão, Dário Ryan Arruda Lopes; Mourão, Dário Ryan Arruda Lopes Abstract: Bacterial resistance to conventional antibiotics is one of the main challenges facing public health, driving the search for new therapeutic strategies. In this context, antimicrobial peptides (AMPs) stand out as promising candidates due to their structural diversity and distinct mechanisms of action. Six natural peptides (Pep 1-6) previously identified in the floral nectar of a species of Nicotiana, extracted, purified by chromatographic techniques, and characterized by mass spectrometry, were evaluated for antibacterial activity against Staphylococcus aureus, S. epidermidis, Klebsiella pneumoniae, and Pseudomonas aeruginosa through inhibitory concentration assays. epidermidis, Klebsiella pneumoniae, and Pseudomonas aeruginosa using minimum inhibitory concentration (MIC) assays. Among them, only Pep6 (later named Nicotianin-I, NI) showed inhibitory activity and, although moderate, was selected as a model molecule for structural modifications by rational design. The modifications resulted in two bioinspired analogues, NI-A and NI-B, with significantly higher antibacterial activity than the precursor peptide. Mechanistically, NI-A showed greater membrane permeabilization, especially against S. epidermidis, while NI-B induced high production of reactive oxygen species in K. pneumoniae, associated with morphological damage. Both showed greater affinity for the bacterial membrane, attributed to the strengthening of electrostatic interactions. Structurally, NI-A and NI-B adopted an α-helix conformation in membrane-mimetic environments and remained disordered in aqueous media. In hemolysis assays, NI-A showed a concentration-dependent effect, while NI-B did not show significant hemolysis, indicating greater selectivity. Together, the results show that the rational modification of peptides derived from Nicotiana nectar made it possible to obtain analogues with greater antibacterial efficacy and differentiated toxicity profiles, reinforcing their potential as prototypes for the development of new therapies against resistant bacterial infections. Tipo: Dissertação

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