Programa de Pós-Graduação em Bioquímica e Biologia Molecular
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Doctoral Thesis Caracterização clínica, molecular e epidemiológica da síndrome de alport em famílias consanguíneas do Rio Grande do Norte(Universidade Federal do Rio Grande do Norte, 2025-08-29) Araújo, Washington Candeia de; Jerônimo, Selma Maria Bezerra; http://lattes.cnpq.br/7120263570947836; http://lattes.cnpq.br/3939811669371707; Scortecci, Katia Castanho; https://orcid.org/0000-0002-4690-2785; http://lattes.cnpq.br/4808910380593455; Bezerra, Francisco Silvestre Brilhante; https://orcid.org/0000-0001-6484-143X; http://lattes.cnpq.br/0699685084143652; Almeida, José Bruno de; http://lattes.cnpq.br/1398736458693233; Fernandes, Thales Allyrio Araújo de Medeiros; https://orcid.org/0000-0003-4559-8918; http://lattes.cnpq.br/5229478510326510Alport Syndrome is a progressive hereditary kidney disease characterized by hematuria and proteinuria, in addition to extra-renal manifestations (hearing loss and ophthalmological abnormalities). Its inheritance profile is classified into three types: autosomal dominant or recessive (variants in COL4A3 and COL4A4, chromosome 2) and X-linked (COL4A5). These genes encode the alpha chains of type IV collagen, a key component of the basement membrane. Furthermore, a phenotypic spectrum of chronic kidney disease manifests in individuals affected by this syndrome. In this context, secondary data obtained via DataSUS on mortality (SIM) and hospitalizations (SIH) were used for an epidemiological assessment of chronic kidney disease (CKD) in the state of Rio Grande do Norte, Brazil. Additionally, clinical data from two families in the state were used to evaluate the spectrum of chronic kidney disease and to identify the genetic causal factor. DNA isolated from peripheral blood of cases and family members was used for whole exome sequencing (WES). After alignment of each exome to the human genome (GRCh38/hg38 build), mutations associated with Alport syndrome were identified. Variant calling revealed a deleterious variant not previously reported in the COL4A3 locus (family 1). Another mutation, previously reported as non-pathogenic, was detected in COL4A4 in family 2. Both variants were found in homozygosity in the probands and in heterozygosity in the other family members (father, mother, and sibling). The main mutation detected in family 1 is a nonsense mutation at position 481 of the COL4A3 gene (stop codon, premature termination codon). This case presents several variants located within a broad region encompassing the type IV collagen chain loci on chromosome 2, characterized by Runs of Homozygosity (ROH). These regions are marked by low heterozygosity of single nucleotide polymorphisms (SNPs). This newly reported variant indicates a case of recessively inherited Alport syndrome, directly influenced by consanguinity in this family from the interior of Rio Grande do Norte. Clinical data showed severe phenotypic characteristics in family 2, with end-stage kidney disease in a heterozygous individual. Epidemiological data from the state of Rio Grande do Norte show an increase in deaths due to renal failure and nephritic syndrome from 2004 to the end of 2023, as well as a rise in hospitalizations for chronic kidney disease from 2008 to the end of 2023. Furthermore, geoprocessing analyses identified the Seridó region of Rio Grande do Norte as a highincidence cluster for chronic kidney disease. Therefore, these results contribute to the study of Alport syndrome and CKD in the state of Rio Grande do Norte and may serve as a guide for interventions related to environmental modifications aimed at minimizing the risk of chronic kidney disease.Master Thesis Estudo fitoquímico do extrato aquoso de sementes de angico (Anadenanthera colubrina (Vell.) Brenan) com atividade aedicida(Universidade Federal do Rio Grande do Norte, 2025-07-22) Santos, Naara Ferraz dos; Uchôa, Adriana Ferreira; Araújo, Renata Mendonça; https://orcid.org/0000-0001-5514-5192; http://lattes.cnpq.br/4163879756935913; https://orcid.org/0000-0002-3822-6502; http://lattes.cnpq.br/6644671747055211; https://orcid.org/0000-0001-5616-5400; http://lattes.cnpq.br/9382655388766099; Migliolo, Ludovico; Paiva, Patrícia Maria Guedes; https://orcid.org/0000-0003-3467-708X; http://lattes.cnpq.br/2885145995086459The Aedes aegypti mosquito is the principal vector for arboviruses such as dengue, zika, chikungunya, and yellow fever, representing a serious threat to global public health. The increasing resistance to synthetic insecticides and the environmental impacts associated with their use have led to an urgent search for more sustainable and effective control alternatives. This work investigated the chemical components of the aqueous extract from Anadenanthera colubrina (Angico) seeds, seeking to identify those responsible for the aedicidal activity. Phytochemical analysis of the extract was conducted using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS). Structural fragmentation of the mass spectra, processed with the ChemDrawn software, allowed for the identification of six biomolecules: pachymic acid, β-sitosterol, sitostanol, bufotenin, anadanthoside, and anadanthoflavone. The results indicate that the identified biomolecules may act synergistically, affecting multiple physiological mechanisms of the mosquito, which contributes to its aedicidal activity. In silico results suggest that the pachymic acid present in the extract may contribute to the larvicidal activity by interfering with the activity of enzymes such as kinases and topoisomerases. This interference can lead to cell cycle arrest, compromising larval development. β-sitosterol and sitostanol may be interfering with the activity of the acetylcholinesterase (AChE) enzyme, suggesting a neurotoxic mechanism against the mosquito. Bufotenin interacts with serotonin receptors, triggering morphological and motor abnormalities that impair larval development. Finally, the identified anadanthoside is indicated as an inhibitor of chorion peroxidase, which is essential for egg viability, while anadanthoflavone may act as a lipoxygenase inhibitor, which could affect the mosquito's immune response, development, and reproduction. The identification and elucidation of these multicompound mechanisms of action endorse the A. colubrina extract as a promising solution. This work contributes significantly to the development of safer and more sustainable natural aedicides and highlights the importance of prospecting for new bioactive compounds in the Caatinga biodiversity for combating arboviruses.Master Thesis Avaliação in vitro do peptídeo sintético Ts-MAP2 bioinspirado na toxina de Tityus serrulatus frente a bactérias formadoras de biofilme(Universidade Federal do Rio Grande do Norte, 2025-06-11) Nunes, Ellydberto Amancio Correia; Migliolo, Ludovico; Fulco, Umberto Laino; Frihling, Breno Emanuel FariasBacteria are prokaryotic microorganisms that colonize a wide variety of ecosystems, performing both beneficial roles, such as in the human microbiota, and harmful ones, acting as pathogenic agents responsible for various infections and diseases. The increasing bacterial resistance, especially in Acinetobacter baumannii, which exhibits multiple virulence factors, has become a critical public health issue, particularly in hospital settings. This problem is exacerbated by the inappropriate use of antibiotics, which facilitates resistance development and limits therapeutic options. Although tests involving tumor cells and bacteria are conducted separately, there is an important biological relationship between these two contexts. Bacterial infections and chronic inflammatory processes can create a microenvironment that promotes the development and progression of tumor cells, thereby influencing cancer progression. Therefore, investigating peptides such as Ts-MAP2, with activity against both bacteria and tumor cells, is relevant to expanding therapeutic possibilities across different health domains. The optimization of Ts-MAP2 focuses on its activity against bacterial cells, tumor cells, and the inhibition of biofilm formation. The research centers on the amphipathic and physicochemical properties of antimicrobial peptides, seeking effective alternatives for infection treatment. Structural modifications altering charge and hydrophobicity are strategies to enhance efficacy. This research line is essential since bacterial resistance, biofilms, and the tumor microenvironment may influence peptide action, impacting therapeutic effectiveness. In addition to direct antimicrobial activity, Ts-MAP2 also demonstrates immune system modulation capabilities, contributing to host defense against infections. Results indicate that Ts-MAP2, at a concentration of 74 µM, significantly reduces the growth of A. baumannii, with low hemolysis and high antibacterial specificity, highlighting its potential as a therapeutic alternative. However, the complexity of interactions between synthetic peptides and bacteria suggests that Ts-MAP2 efficacy may vary according to the strain, warranting further studies for better understanding and clinical application.Master Thesis Interações entre vetor e hospedeiros na dinâmica de transmissão da Leishmania infantum em áreas endêmicas(Universidade Federal do Rio Grande do Norte, 2025-03-10) Falcão, Angelis Maria Alves; Jerônimo, Selma Maria Bezerra; Galvão, Joanna Gardel Valverde; Oliveira, Fabiano; Carvalho, Lucas Pedreira deRio Grande do Norte state (RN) is an endemic area for human and canine visceral leishmaniasis (VL) in Brazil. Leishmania infantum is the major etiologic agent for VL in Latin America. The transmission cycle of this pathogen is anthropozoonotic, and Lutzomyia longipalpis is the most important vector in the Americas. During a blood meal, the vector releases chemical factors contained in its saliva, which have anti-hemostatic activity, facilitating blood suction, but also facilitates the chemotaxis of macrophages and neutrophils. Studies have shown that re-exposure to the vector can increase parasitemia of infected mammalian host. This study aimed to determine the main blood sources, the vector infection rate by L. infantum in sandflies from an endemic VL area, and the role of Lu. longipalpis saliva in parasitemia and plasmatic proteins of dogs infected with L. infantum. A total of 248 female sandflies were collected using light traps in the peridomestic area of residences with the following characteristics: (1) households with a recent history of human VL, (2) neighboring households of a home with human VL, and (3) households without a recent history of human VL. DNA was extracted individually from the sandflies' intestines, and infection with L. infantum and blood sources were identified by qPCR. Additionally, dogs with VL, were studied. Peripheral blood from the dogs was collected before intradermal inoculation of a Lu. longipalpis salivary glands homogenate or saline into the dog's ear. After 24 hours, the blood was collected again to evaluate parasitemia and protein profile in canine plasma. Molecular analysis detected L. infantum DNA in 56% of the sandflies captured. Households with a history of human VL were 3.73 (95% CI = 1.64 to 8.48; p = 4.92e-04) times more likely to have L. infantum DNA in the intestines of sandflies compared to those captured in households without a recent history of VL. Multiple blood sources were detected, with dogs being the primary blood source in all three studied areas. A significant increase in L. infantum was observed in peripheral blood after inoculation with Lu. longipalpis saliva (p=0.0034), unlike dogs inoculated with saline. The concentration of Leishmania in the DNA of skin tissue, including ear and contralateral axillary regions, was higher in both groups compared to the amount of Leishmania present in the left ear, which was used for inoculation. Proliferation of Leishmania in the amastigote form occurred with the presence of Lu. longipalpis saliva. The analysis of differential expression of plasma proteins revealed overexpression of proteins such as coagulation factor V and ApoE, 24 hours after exposure to the vector's saliva. Based on these findings, we conclude that there is an important reservoir of L. infantum near the residences of human VL cases and that dogs are the primary blood source for sandflies in the studied areas. Additionally, we conclude that the intradermal administration of Lu. longipalpis saliva increases parasitemia in dogs naturally infected with L. infantum. Therefore, daily re-exposure to the vector in endemic areas may increase the infectivity of the hosts. These findings corroborate a better understanding of the transmission of L. infantum in endemic areas and indicate a discussion about the role of saliva in infectivity.Doctoral Thesis Conexões entre efeitos biológicos e composição fitoquímica explorando o potencial antioxidante e anti-inflamatório de extratos dos frutos de Myrciaria tenella (DC.) O. Berg (Myrtaceae) e Coccoloba alnifolia Casar (Polygonaceae)(Universidade Federal do Rio Grande do Norte, 2025-07-09) Martins, Verônica Giuliani de Queiroz Aquino; Scortecci, Katia Castanho; Rocha, Hugo Alexandre de Oliveira; https://orcid.org/0000-0003-2252-1221; http://lattes.cnpq.br/4651814546820796; https://orcid.org/0000-0002-4690-2785; http://lattes.cnpq.br/4808910380593455; https://orcid.org/0000-0001-5266-9038; http://lattes.cnpq.br/5236863679801471; Câmara, Rafael Barros Gomes da; https://orcid.org/0000-0001-5109-1991; http://lattes.cnpq.br/9200036511632745; Hoskin, Roberta Targino; https://orcid.org/0000-0003-0900-4983; http://lattes.cnpq.br/7098666299806958; Santos, Deborah Yara Alves Cursino dos; https://orcid.org/0000-0003-0226-1231; http://lattes.cnpq.br/3084343775765440; Maciel, Maria Aparecida Medeiros; http://lattes.cnpq.br/5360188002708095Plants have significant therapeutic potential due to the presence of compounds with antioxidant and anti-inflammatory properties with health-relevant properties. In this study, Myrciaria tenella (Cambuí) and Coccoloba alnifolia (Cauaçu) fruits were evaluated, since they are species commonly used in food and traditional medicine, particularly as herbal teas. The Myrciaria genus is rich in phenolic compounds and terpenoids with antioxidant, anti-inflammatory, antihypertensive, antimicrobial, and gastroprotective activities. Extracts from the Coccoloba genus have shown larvicidal activity against Aedes aegypti, as well as antioxidant, antifungal, and antidiabetic effects. The goal of this study was to produce and characterize extracts from unripe and ripe M. tenella and C. alnifolia fruits regarding their toxicity, antioxidant, and antiinflammatory activities using in vitro and in vivo analyses. Aqueous and hydroethanolic extracts (70% v/v) were prepared, resulting in four different extracts: unripe aqueous (VA), unripe hydroethanolic (VE), ripe aqueous (MA), and ripe hydroethanolic (ME). The phytochemical characterization included quantification of total phenolics, as well as high-performance liquid chromatography with diode-array detection (HPLC-DAD). Antioxidant activity was done using biochemical assays as total antioxidant capacity (TAC), DPPH radical scavenging, reducing power, and copper and iron chelation. Cytotoxicity was evaluated using the MTT assay in both cell models, NIH/3T3 fibroblast cells and RAW 264.7 macrophages. Further assays with NIH/3T3 examined cell migration and protection against oxidative stress. In RAW 264.7, nitric oxide production and protection against oxidative agents were assessed. In vivo assays using Tenebrio molitor larvae evaluated both toxicity and protection against CuSO₄-induced stress, as well as effects on melanization. Zebrafish larvae were used as a second in vivo model to assess toxicity and antioxidant protection in the presence of H₂O₂, with reactive oxygen species (ROS) levels measured via fluorescence. Extracts from both species exhibited strong free radical scavenging and metal-chelating activities. They were noncytotoxic to NIH/3T3 cells and protected them from CuSO₄/ascorbate-induced oxidative damage by reducing intracellular ROS levels. In RAW 264.7 macrophages, all extracts mitigated H₂O₂-induced oxidative stress, with C. alnifolia MA extract significantly reducing nitric oxide production following LPS stimulation. In T. molitor larvae, M. tenella extracts, especially VE and MA, showed low toxicity and protective effects against CuSO₄, and high activity reducing melanization. Among C. alnifolia extracts, MA and VA exhibited the strongest protective effects and melanization reduction. HPLC-DAD analysis identified gallic acid, catechin, and kaempferol in both species; C. alnifolia additionally contained epicatechin, p-coumaric acid, rutin, quercitrin, myricetin, and neohesperidin. All C. alnifolia fruit extracts, in special for VE and MA, which significantly reduced ROS levels in H₂O₂-exposed zebrafish larvae. In conclusion, Myrciaria tenella and Coccoloba alnifolia are rich in phytoconstituents with potent antioxidant and antiinflammatory activities, demonstrating promising potential for therapeutic applications and warranting further investigation for safe and effective use.Doctoral Thesis Conjugação do fucoidan B da alga marrom Spatoglossum schröederi com ácido gálico e avaliação de sua atividade antioxidante in vitro, em células (fibroblasto murino L929) e in vivo (Danio rerio)(Universidade Federal do Rio Grande do Norte, 2025-09-18) Santos, Joicy Ribeiro dos; Rocha, Hugo Alexandre de Oliveira; Campos, Julliane Tamara Araújo de Melo; https://orcid.org/0000-0002-8501-5521; http://lattes.cnpq.br/3504274193684794; https://orcid.org/0000-0003-2252-1221; http://lattes.cnpq.br/4651814546820796; http://lattes.cnpq.br/9608275964810999; Nobre, Leonardo Thiago Duarte Barreto; http://lattes.cnpq.br/2904787727374331; Sabry, Diego de Araújo; https://orcid.org/0000-0001-7939-8135; http://lattes.cnpq.br/3279791999280557; Melo, Karoline Rachel Teodosio de; http://lattes.cnpq.br/0895722042592717; Medeiros, Valquiria Pereira de; http://lattes.cnpq.br/8687225336984575Oxidative stress is associated with a wide range of health problems. In recent years, the scientific community has been continuously searching for molecules that prevent the formation of reactive oxygen species (ROS), their accumulation in the body, and/or mitigate the damage they cause. Fucoidans are sulfated polysaccharides (SPs) found exclusively in brown algae, which display several pharmacological activities, such as anticoagulant, anti-inflammatory, and antioxidant effects. Moreover, chemical modifications of these SPs may enhance such activities. In this work, fucoidan B was obtained from the brown seaweed Spatoglossum schröederi, chemically conjugated with gallic acid (GA), and its antioxidant activity was tested both in vitro and in vivo. The resulting compound, named FucB-GA, was physicochemically characterized. The results indicated that FucB-GA has a molecular weight of 22.6 kDa, contains approximately 3% phenolic compounds, and shows no protein contamination. FT-IR and ¹H NMR analyses confirmed the insertion of GA into the polymeric chain. Changes in the amorphous nature of FucB-GA, as well as in its thermal stability, were observed when compared with FucB. In in vitro antioxidant assays, FucB, FucB-GA, and GA alone were not able to chelate ferrous ions (Fe²⁺); however, FucB-GA showed higher Cu²⁺ chelation capacity compared to FucB. Regarding radical scavenging, no statistically significant differences were observed for H₂O₂ scavenging. On the other hand, FucB-GA reached a superoxide radical scavenging capacity of 91.96%, compared with 80.51% for FucB. Concerning electrondonating capacity, FucB-GA exhibited an activity approximately three times higher than FucB in the total antioxidant capacity (TAC) assay. In the reducing power assay, this difference was about fourfold. Under the conditions tested, except for H₂O₂ scavenging, GA alone did not display antioxidant activity. Cell-based assays demonstrated that FucB-GA was able to reverse oxidative stress-induced damage, showing both reparative and concomitant protective effects against H₂O₂-induced stress. In the zebrafish (Danio rerio) animal model, FucB-GA increased embryo survival rates after stress and reduced ROS production. Taken together, the results demonstrated that the chemical modification enhanced the antioxidant capacity of FucB-GA, suggesting that it may become a promising molecule with potential antioxidant activity for future applications.Master Thesis Carcinoma NUT: relato de саsо e análise do microambiente tumoral através dos marcadores VEGFA, STAT3 E CD163(Universidade Federal do Rio Grande do Norte, 2025-04-10) Lopes, Rayssa Thainná Silva; Campos, Julliane Tamara Araújo de Melo; Araújo Júnior, Raimundo Fernandes de; https://orcid.org/0000-0003-2349-2354; http://lattes.cnpq.br/1903940945895093; https://orcid.org/0000-0002-8501-5521; http://lattes.cnpq.br/3504274193684794; http://lattes.cnpq.br/5622318246677544; Farias, Naisandra Bezerra da Silva; http://lattes.cnpq.br/6590909272236189; Pereira, Karuza Maria Alves; https://orcid.org/0000-0002-2880-6466; http://lattes.cnpq.br/3193698890688967NUT Carcinoma (NC) is a rare, rapidly progressing epithelial malignant neoplasm that affects both sexes at any age and is genetically characterized by a translocation involving the NUTM1 gene. The main challenge of the disease is its resistance to conventional therapies, highlighting the importance of analyzing past clinical cases to investigate tumor biology mechanisms and, consequently, improve clinical management of current cases. In this context, the aim of this study was to characterize a new case of NC occurred in the city of Natal, Rio Grande do Norte, Brazil, and to analyze the tumor microenvironment using three new markers (VEGFA, STAT3, and CD163) through immunohistochemistry (IHC). For this purpose, the patient's medical records and imaging exams were used for clinical characterization; histopathological slides were obtained for histopathological image capture, and paraffinembedded tumor tissue samples were acquired for IHC testing. The clinical case presented involved a 28-year-old man with a primary tumor located in the nasal cavity and metastasis to the T11 thoracic vertebra. He underwent conventional therapies, including surgical resection, chemotherapy, and radiotherapy; however, the tumor exhibited resistance to treatments, progressed rapidly, and the patient died 21 months after diagnosis. Histopathological analyses revealed a population of monomorphic round tumor cells, predominantly mononuclear inflammatory infiltrate, hemorrhagic foci, and the presence of macrophages. These findings guided the selection of three new IHC markers, which showed immunoreactivity in the tumor sample. Therefore, VEGFA overexpression suggests intense angiogenic activity, the presence of STAT3 indicates a signaling context that promotes immunosuppression and resistance to apoptosis, and CD163+ indicates the presence of tumor-associated M2 phenotype macrophages. Thus, the implementation of these markers in IHC panels may assist in NC monitoring by providing information on metastatic potential, inflammatory activity, and tumor resistance, as well as foment the development of immunotherapeutic approaches.Master Thesis Extratos termorresistentes de sementes da caatinga: atividade larvicida e efeitos morfofisiológicos em Aedes aegypti e Aedes albopictus(Universidade Federal do Rio Grande do Norte, 2025-02-17) Bezerra, Pedro Vitor Vale; Uchôa, Adriana Ferreira; Silva, Giulian César da; https://orcid.org/0000-0002-4734-4228; http://lattes.cnpq.br/2134578884742038; https://orcid.org/0000-0002-3822-6502; http://lattes.cnpq.br/6644671747055211; https://orcid.org/0000-0002-8674-6959; http://lattes.cnpq.br/0567529774568955; Pessoa, Felipe Arley Costa; http://lattes.cnpq.br/0065844952697911; Barbosa, Patricia Batista Barra Medeiros; Andrade Neto, Valter Ferreira de; http://lattes.cnpq.br/4863082845974813Arboviruses constitute a significant group of viral diseases primarily transmitted by hematophagous mosquitoes, notably Aedes aegypti (Linnaeus, 1762) and A. albopictus (Skuse, 1894). Conventional management strategies for these diseases predominantly rely on synthetic chemical insecticides as the primary control measure. However, this approach raises concerns regarding environmental toxicity and the potential development of resistance among mosquito populations. In light of these challenges, botanical insecticides, including plant extracts, represent a compelling alternative due to their biocompatibility and diverse modes of action, minimizing environmental impacts and insect resistance. This study investigates the insecticidal properties of extracts from the seeds of two legumes indigenous to the Caatinga biome, specifically Amburana cearensis ((Allem.) A. C. Smith) and Erythrina velutina (Willd.), against A. aegypti and A. albopictus larvae (L4). The extraction process involved solubilizing the seed powder in distilled water (1:10, w/v) at a temperature of 80 °C. The lethal concentrations for 50% (LC50) and 90% (LC90) of the larvae were assessed over 24 and 48 hours. Morphological alterations were examined using a stereomicroscope equipped with a camera, and larval development was monitored for 15 days. Furthermore, zymographic analyses were conducted to assess the inhibition of digestive proteases in the treated larvae. The results indicated that both extracts exhibited larvicidal activity, with A. cearensis extract demonstrating particularly notable efficacy. Specifically, the extract recorded LC50 values of 0,45 mg/mL and 0,23 mg/mL for 24 and 48 hours in A. aegypti, respectively, and LC50 values of 0,34 mg/mL and 0,11 mg/mL in A. albopictus. Additionally, A. cearensis extract reduced the enzymatic activity of intestinal proteases of both species by more than 70%, while E. velutina extract had no significant effect. Delays in larval development in A. albopictus suggest a pronounced influence of protease inhibition resulting from A. cearensis extract. Morphological changes suggest the presence of other deleterious effects of the extracts: acetylcholinesterase inhibition (A. cearensis and E. velutina), disruption of chitin synthesis, and internal tissue damage or infection leading to melanization (E. velutina). This study highlights the promising potential of A. cearensis and E. velutina extracts for larval control of A. aegypti and A. albopictus, with A. cearensis extract emerging as a particularly viable candidate for the development of botanical larvicides. The findings underscore the importance of plant biodiversity within the Caatinga biome in the creation of bioproducts, thereby enhancing its cultural, biotechnological, and economic significance while contributing to integrated management strategy for arboviral diseases.Master Thesis Previsão do efeito terapêutico e avaliação de riscos de carotenóides e retinóides em um modelo de urolitíase por meio de análise in silico e ensaios in vitro(Universidade Federal do Rio Grande do Norte, 2025-05-26) Aquino, Leonardo de Medeiros; Rocha, Hugo Alexandre de Oliveira; https://orcid.org/0000-0003-2252-1221; http://lattes.cnpq.br/4651814546820796; http://lattes.cnpq.br/5030249371462635; Santos, Pablo de Castro; https://orcid.org/0000-0003-0081-9609; http://lattes.cnpq.br/6456286305129050; Medeiros, Valquiria Pereira de; https://orcid.org/0000-0002-9378-6481; http://lattes.cnpq.br/8687225336984575Oxidative stress can cause several damages to the organism and its molecules. An example of the consequences of this stress is urolithiasis, the formation of renal calculi, contributing to the formation of crystals, mainly calcium oxalate crystals, monohydrate (COM) and dihydrate (COD). Beta-carotene (BCAR), astaxanthin (AST) and retinol (RET) are described as antioxidant molecules that can be used to combat the damage caused by oxidative stress. However, there is no data regarding how these three molecules are used to prevent or specifically combat urolithiasis. In this context, this study initially evaluated in vitro the potential of BCAR, AST and RET, known antioxidants, as inhibitors of renal calculi formation. BCAR, AST or RET (10 and 15 µg/mL) were not toxic to canine renal cell line (MDCK) cells, but they were also unable to protect these cells from damage caused by the presence of H2O2. Regarding the direct formation of calcium oxalate crystals, it was found that the compounds evaluated here equally affected the balance between the quantity of the types of calcium oxalate crystals formed, inducing the formation of a greater quantity of COD crystals, which are more harmful. These data, although initial, demonstrate an undesirable effect not yet described for this class of molecules. Given this new context, in-silico techniques were used to evaluate carotenes (BCAR and lycopene), retinoids (RET and isotretinoin) and xanthophylls (AST, fucoxanthin, zeaxanthin, betacryptoxanthin, canthaxanthin and lutein) and identify other possible adverse effects. Within their relevant groups, similarities can be seen in the ADMET (Absorption, Distribution, Metabolism, Excretion and Toxicity) profile of the compounds evaluated. Using the PredHerg platform, we found weak cardiotoxic potential for lycopene, beta-cryptoxanthin, and fucoxanthin, and moderate cardiotoxic potential for lutein. Using the PredSkin platform, we found that lycopene and the tested xanthophylls, except canthaxanthin, have the potential to cause allergic skin reactions. The results of this study suggest that although BCAR, AST, and RET are known antioxidants, they may have undesirable negative effects on kidney stone formation by promoting the formation of more harmful calcium oxalate crystals. Furthermore, a symbiotic analysis revealed potential risks of cardiotoxicity and allergic skin reactions for some of the compounds evaluated. These initial results highlight the need for further investigation into the safety and efficacy of these antioxidant molecules, especially in the context of kidney health and oxidative stress.Doctoral Thesis Bioprospecção de compostos do fungo Langermannia bicolor: potencial modulador de antibióticos, atividade antioxidante e avaliação de toxicidade(Universidade Federal do Rio Grande do Norte, 2024-12-04) Moura, Geovanna Maria de Medeiros; Santos, Elizeu Antunes dos; Rocha, Hugo Alexandre de Oliveira; https://orcid.org/0000-0003-4372-2161; http://lattes.cnpq.br/6762251930590306; https://orcid.org/0000-0002-3480-2218; http://lattes.cnpq.br/0915146393491834; Veras, Bruno Oliveira de; Oliveira, Maria Tatiana Alves; Santos, Paula Ivani Medeiros dos; Paiva, Weslley de SouzaThe emergence of multidrug-resistant bacteria has driven the search for new therapeutic agents and adjuvants. In this study, we investigated the properties of an extract from the mushroom Langermannia bicolor as a modulator of antibiotics (gentamicin, norfloxacin, and ampicillin) against multidrug-resistant strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, as well as its antioxidant activity and toxicity. The crude aqueous extract of L. bicolor was fractionated using increasing volumes of acetone, resulting in three fractions (F0.5, F1, and F2), which exhibited different biochemical profiles. Tests with human erythrocytes revealed that the extract and its fractions did not exhibit hemolytic activity, while MTT reduction assays in fibroblast cells (NHI/3T3) showed that the crude extract reduced viability by 50%. In vivo tests with zebrafish embryos, up to young larvae (Danio rerio), confirmed the absence of toxicity of the fractions through embryotoxic analyses, heart rate measurements, and behavioral tests. Although none of the fractions demonstrated direct antibacterial activity, all exhibited significant modulatory effects when combined with conventional antibiotics against the tested multidrug-resistant bacteria. Notably, fraction F2, rich in proteins with higher proteolytic and hemagglutinating activities, reduced the Minimum Inhibitory Concentration (MIC) of gentamicin across all tested strains. The fractions also displayed potent antioxidant properties both in vitro and in vivo. Fraction F0.5, enriched with phenolic compounds and flavonoids, exhibited the broadest spectrum of antioxidant activities, including metal chelation (Fe²⁺ and Cu²⁺), free radical scavenging (•OH and O₂⁻•), and both concurrent and preventive cellular protection against hydrogen peroxide (H₂O₂) induced oxidative stress in 3T3 cells. Meanwhile, fraction F1, which was carbohydrate-rich, was able to repair oxidative damage following H₂O₂ stress. In vivo, all fractions protected zebrafish embryos exposed to H₂O₂. When quantifying reactive oxygen species (ROS) using a fluorescent probe (DCFH), zebrafish larvae treated with F0.5 followed by H₂O₂ significantly reduced ROS production in their cells, yielding values even lower than those of larvae not exposed to the oxidizing agent. To a lesser extent, F1 and F2 also protected zebrafish cells by reducing ROS production. By pioneering the therapeutic potential of L. bicolor, our study paves the way for future investigations into the bioactive composition of this mushroom and its respective molecular mechanisms involved in the observed properties: antibiotic potentiation and protection against oxidative stress.