http://repositorio.ufc.br/handle/riufc/347 2026-06-11T18:19:29Z 2026-06-11T18:19:29Z 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 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

2026-01-01T00:00:00Z Bezerra, Victor Breno Faustino http://repositorio.ufc.br/handle/riufc/85601 2026-03-31T18:34:44Z 2025-01-01T00:00:00Z

Título: Papel funcional da família de enzimas glicolato oxidase (GOX) e catalase (CAT) em feijão-caupi (Vigna unguiculata [L.] Walp.) na resposta ao Cowpea Severe Mosaic Virus Autor(es): Bezerra, Victor Breno Faustino Abstract: With the increase in food shortages and nutritional deficiencies, the choice of alternative crops with relevant characteristics is important. Vigna unguiculata L. is therefore a crop of great interest. However, cowpeas are still susceptible to some pathogens, such as the CowPea Severe Mosaic Virus (CPSMV). Under adverse conditions, such as infection by pathogens, one of the initial mechanisms for the stress response involves the production of reactive oxygen species. One of these molecules is hydrogen peroxide, which has its highest production rate related to Glycolate Oxidase (GOX), an enzyme in the photorespiration process, but like all reactive species, its production and consumption must be finely balanced, so there is the peroxisomal enzyme Catalase (CAT), responsible for this control during a stress phenomenon. The aim of this study was therefore to analyse the expression of GOX and CAT gene copies, at transcript and activity level, in response to CPSMV. To this end, the plant specimens were inoculated with CPSMV at three time points (16 hours, 48 hours and 144 hours). Analyses of catalase enzyme activity showed differences between the cultivars only in the initial hours (16h), in the control conditions of inoculated Pitiúba and Mock, possibly related to the initial response to the pathogen. In addition, analyses using DAB (3,3'-Diaminobenzidine) staining, MDA (Malonaldehyde) and peroxide content were used to determine the degree of oxidative stress, again with differences only between Pitiúba Mock and inoculated at 16 and 48 hours. In addition, the expression data showed differences mainly in the VuGOX1 gene in the Macaíbo cultivar, whose expression was induced during infection compared to the Mock. While VuGOX2 was the gene with the highest abundance at transcript level, showing differences between the cultivars at times of 16 and 144h, with reduced expression in inoculated Pitiúba compared to Mock 144h. Analysis of cis-elements showed regions that corroborate points raised in the discussion, mainly related to the pathogen response route and the synthesis of salicylic acid (SA). Thus, it is hoped that the results found will help breeding programmes and understanding of the resistance phenomenon. Tipo: Dissertação

2025-01-01T00:00:00Z Carvalho, Rayara Joice Paulino http://repositorio.ufc.br/handle/riufc/85389 2026-03-18T14:29:03Z 2023-01-01T00:00:00Z

Título: Atividade antimicrobiana do óleo essencial de Croton pluriglandulosus Carn. (Euphorbiaceae) contra microrganismos de interesse clínico Autor(es): Carvalho, Rayara Joice Paulino Abstract: Fungal and bacterial infections remain significant causes of morbidity and mortality, exacerbated by increasing resistance to conventional antimicrobials. Yeasts of the genus Candida cause infections in both immunocompetent and immunocompromised individuals, while associated pathogenic bacteria are the primary cause of urinary, respiratory, and systemic infections, often resistant to multiple classes of antimicrobials. In this context, plant-derived essential oils stand out as promising therapeutic alternatives due to their antifungal and antibacterial properties. Their antimicrobial activity is mainly related to the destabilization of the plasma membrane and interference in essential metabolic processes, contributing to the fight against microbial resistance. This study aims to evaluate the antimicrobial activity and mechanisms of action of the essential oil (EO) extracted from the leaves of Croton pluriglandulosus Carn.-Torres & Riina (CpEO) on human pathogenic microorganisms in planktonic lifestyles and biofilms. The results demonstrated that the essential oil of Croton pluriglandulosus has 26 different metabolites, with elemicin (25.77%), bicyclogermacrene (9.37%), caryophyllene (8.99%), 1,3,5-trimethoxybenzene (6.86%), and hedicariol (6.21%) being the major compounds. The oil, at a concentration of 50 μg mL−1 , was able to inhibit the planktonic growth of C. krusei (89.3%) and C. parapsilosis (80.70%). Furthermore, biofilm formation was initiated in 85.5% of C. krusei and 77.9% of C. parapsilosis. There was no reduction in the biomass of the pre-formed biofilm. The prevention data were not excessive for the species C. albicans and all tested bacterial species (B. subtilis, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus e Salmonella enterica). Fluorescence microscopy analyses showed that the oil ages, causing cell membrane damage, cell death, and inducing the production of reactive oxygen species (ROS). Electron microscopy images showed high-resolution morphological damage to the cells upon contact with the oil. Furthermore, the oil did not cause hemolysis in human erythrocytes at the concentrated level. The data obtained offer a future alternative for obtaining drugs and active compounds to be used by the clinical sector for microbiological control purposes. Tipo: Dissertação

2023-01-01T00:00:00Z