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Uso de abordagens computacionais integradas para obtenção e caracterização de peptídeos antimicrobianos a partir de inibidores de proteases de plantas

Wed, 01 Jan 2025 00:00:00 GMT

Título: Uso de abordagens computacionais integradas para obtenção e caracterização de peptídeos antimicrobianos a partir de inibidores de proteases de plantas Autor(es): Silva, Amanda Olímpia da Abstract: Serious bacterial infections are a global health issue, and plant protease inhibitors have the ability to inhibit or regulate proteases involved in the progression of several diseases. The aim of this work was to use computational methods in an integrated manner to discover antimicrobial peptides with potential for future clinical use, from plant protease inhibitors. For this, two approaches were used: in the first methodology, the peptides were generated from the hydrolysis of the amino acid sequence of the inhibitors and in the second through the prospecting of fragments with antimicrobial potential based on conserved regions. To evaluate the antimicrobial potential, the average scores of the CAMPR4, AI4AMP and HydrAMP platforms were used, and with the promising analyzes, libraries of variants were constructed using the Scramble platform to broadly evaluate the potential of these peptides. In addition, characterizations were performed regarding the physicochemical parameters with the aid of tools such as APD3, Heliquest, Expasy; Biological parameters such as antigenic, hemolytic, toxic potential, biofilm inhibition capacity, antioxidant and enzymatic susceptibility of the peptides were analyzed through platforms such as AnOxPP, HemoPI2.0, ToxinPred3; in the pharmacokinetic parameters, absorption by the human intestine and metabolism by CYP450 enzyme isoforms were evaluated through the ADMETSar platform; structural characteristics were also evaluated through Pepfold3.5. As a result, a total of 17 (7.32%) peptides and 24 (40%) variants with antimicrobial potential were obtained in the first approach; in the second, the results found were 6 (100%) and 17 (85%) analyzed with antimicrobial potential, respective to the peptides and their variants; All of these 64 peptides were characterized according to the parameters already mentioned. It is expected to offer important information for the use of peptides derived from plant protease inhibitors as possible candidates in in vitro and in vivo tests for clinical use. Tipo: Dissertação

Imunogenicidade de proteínas de Bertholletia excelsa H.B.K.

Tue, 01 Jan 1991 00:00:00 GMT

Título: Imunogenicidade de proteínas de Bertholletia excelsa H.B.K. Autor(es): Melo, Vânia Maria Maciel Abstract: The immunogenicity of proteins extracted from the seed meal of Bertholletla excelsa H.B.K. with l M NaCl, 0,035 M sodium phosphate buffer pH 7,5 (crude extract) was evaluated through the levels of IgGi and IgE determined by PCA reaction. [...] Tipo: Dissertação

Purificação e caracterização de uma [alfa]-amilase cotiledonária de feijão-de-corda Pitiuba (Vigna unguiculata (L.) Walp)

Tue, 01 Jan 1991 00:00:00 GMT

Título: Purificação e caracterização de uma [alfa]-amilase cotiledonária de feijão-de-corda Pitiuba (Vigna unguiculata (L.) Walp) Autor(es): Bastos, João Luiz Pinheiro Abstract: Pitiuba cowpea (Vigna. unguiculata (L.) Walp) cotyledons were excised from 5-day-old seedlings grown in water soaked paper towels kept under darkness. [...] Tipo: Dissertação

Investigação sobre o mecanismo da ação antifúngica de uma osmotina de Calotropis procera contra cepas de Candida

Thu, 01 Jan 2026 00:00:00 GMT

Título: Investigação sobre o mecanismo da ação antifúngica de uma osmotina de Calotropis procera contra cepas de Candida Autor(es): Farias, Ádria Helen Pessoa Abstract: Osmotins are defense proteins (PR-5) that exhibit antifungal activity. An osmotin isolated from Calotropis procera (CpOsm) has shown activity against phytopathogenic fungi; however, its effects against Candida, a medically important yeast genus, remain poorly explored. To address this gap, this study aimed to investigate the antifungal activity and mechanism of action of CpOsm against strains of three Candida species (C. albicans, C. tropicalis, and C. auris). For this purpose, the protein was produced in Escherichia coli BL21(DE3) and purified by affinity chromatography. The recombinant osmotin (rCpOsm) exhibited antifungal activity against all strains tested, including fluconazole-resistant isolates. Minimum inhibitory concentration (MIC) values were 1.49 nM for C. albicans, 0.373 nM for C. tropicalis, and 2.99 nM for C. auris, whereas minimum fungicidal concentration (MFC) values were 2.99 nM, 1.49 nM, and 5.97 nM, respectively. rCpOsm demonstrated significant anti-biofilm activity (p < 0.05) against fluconazole-sensible and fluconazole-resistant C. auris strains, with a dual effect: inhibition of biofilm formation and disruption of mature biofilms. At 10×MIC concentration, the protein significantly reduced biomass and metabolic activity by up to 92% and 97% (biofilms in formation) and 57.5% and 86.0% (mature biofilms), as assessed by crystal violet and MTT assays. Investigation of the mechanism of action in vitro suggested that the antifungal effect on C. aurisis mediated by an interaction of rCpOsm with ergosterol in the yeast plasma membrane, as evidenced by an increase in MIC (> 10-fold) in the presence of exogenous ergosterol. Fluorescence microscopy assays revealed that CpOsm compromised membrane integrity and increased the production of reactive oxygen species in both planktonic cells and biofilms of C. auris. These cellular alterations were accompanied by changes in the protein profile of C. auris cells treated with CpOsm. Proteomic analysis revealed significant alterations in 512 proteins of C. auris, of which 505 showed an increase in abundance [Log2(fold change) > 1.5], mainly related to lipid metabolism, oxidative stress response, cell wall remodeling, and ionic homeostasis, while structural and proliferative proteins showed reduced abundance [Log2(fold change) < 0.5] or were no longer detected. Maintenance of fungicidal activity at low concentrations indicates that adaptive mechanisms are insufficient to restore cellular viability. Collectively, these findings highlight rCpOsm as a promising molecule for the development of novel antifungal strategies against clinically relevant drug-resistant pathogens. Tipo: Dissertação