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Fungal infections are a growing public health concern worldwide and the emergence of antifungal resistance has limited the number of therapeutic options. Therefore, developing novel strategies for identifying and developing new antifungal compounds is an active area of research in the pharmaceutical industry. In this study, we purified and characterized a trypsin protease inhibitor obtained from Yellow Bell Pepper (Capsicum annuum L.) seeds. The inhibitor not only showed potent and specific activity against the pathogenic fungus Candida albicans, but was also found to be non-toxic against human cells. Furthermore, this inhibitor is unique in that it also inhibits α-1,4-glucosidase, positioning it as one of the first plant-derived protease inhibitors with dual biological activity. This exciting discovery opens new avenues for the development of this inhibitor as a promising antifungal agent and highlights the potential of plant-derived protease inhibitors as a rich source for the discovery of novel multifunctional bioactive molecules.

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The Leucaena leucocephala trypsin inhibitor (LTI) + Bacillus thuringiensis (Bt) protoxins mix has been proposed as a novel larvicide agent in order to control the vector mosquito of dengue virus, Aedes aegypti, in their aquatic breeding sites. However, use of this insecticide formulation has raised concerns about its impacts on aquatic biota. In this context, this work aimed to assess the effects of LTI and Bt protoxins, separately or in combination, in zebrafish, in regard to the evaluation of toxicity at early life stages and to the presence of LTI inhibitory effects on intestinal proteases of this fish. Results showed that LTI and Bt concentrations (250 mg/L, and 0.13 mg/L, respectively), and LTI + Bt mix (250 mg/L + 0.13 mg/L) - 10 times superior to those with insecticidal action - did not cause death nor did it induce morphological changes during embryonic and larval development (3 to 144 h post-fertilization) of zebrafish. Molecular docking analyses highlighted a possible interaction between LTI and zebrafish trypsin, especially through hydrophobic interactions. In concentrations near to those with larvicidal action, LTI (0.1 mg/mL) was able to inhibit in vitro intestinal extracts of trypsin in female and male fish by 83 % and 85 %, respectively, while LTI + Bt mix promoted trypsin inhibition of 69 % in female and 65 % in male ones. These data show that the larvicidal mix can potentially promote deleterious effects to nutrition and survival in non-target aquatic organisms, especially those with trypsin-like dependent protein digestion.

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The study aimed to evaluate the nanoparticles (ECW) containing tamarind trypsin inhibitor (TTI) concerning the storage effect under different conditions on antitrypsin activity and the bioactive potential in a preclinical model. ECW was exposed to different pH and temperatures to evaluate the interaction between TTI and its encapsulating agents, monitored by antitrypsin activity. Wistar rats (n = 25) with obesity induced by diet were divided into groups: untreated; treatment with nutritionally adequate diet; treatment with nutritionally adequate diet and ECW/12.5 mg/kg; treatment with ECW/12.5 mg/kg; and treatment with TTI/25 mg/kg. The groups were evaluated over ten days with regards to satiety, zoometric, biochemical, and inflammatory parameters, using ten times less TTI (2.5 mg/kg) contained in ECW. TTI was protected and encapsulated in ECW without showing residual inhibitory activity. Only at gastric pH did ECW show antitrypsin activity. At different temperatures, it showed high antitrypsin activity, similar to TTI. The animals treated with ECW had significantly reduced body weight variation (p < 0.05), and only TTI treatment reduced the inflammatory parameters significantly (p < 0.05). The study showed that by using lower concentrations of TTI in ECW it was possible to perceive promising effects with perspectives of use in functional products for managing obesity and its complications.

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The objectives of this study were to evaluate the hypoglycemic effect of the trypsin inhibitor isolated from tamarind seeds (TTI) in an experimental model of T2DM and the in silico interaction between the conformational models of TTI 56/287 and the insulin receptor (IR). After inducing T2DM, 15 male Wistar rats were randomly allocated in three groups (n = 5): 1-T2DM group without treatment; 2-T2DM group treated with adequate diet; and 3-T2DM treated with TTI (25 mg/kg), for 10 days. Insulinemia and fasting glucose were analyzed, and the HOMA-IR and HOMA-ß were calculated. The group of animals treated with TTI presented both lower fasting glucose concentrations (p = 0.0031) and lower HOMA-IR indexes (p = 0.0432), along with higher HOMA-ß indexes (p = 0.0052), than the animals in the other groups. The in silico analyses showed that there was an interaction between TTIp 56/287 and IR with interaction potential energy (IPE) of -1591.54 kJ mol-1 (±234.90), being lower than that presented by insulin and IR: -894.98 kJ mol-1 (±32.16). In addition, the presence of amino acids, type of binding and place of interaction other than insulin were identified. This study revealed the hypoglycemic effect of a bioactive molecule of protein origin from Tamarind seeds in a preclinical model of T2DM. Furthermore, the in silico analysis allowed the prediction of its binding in the IR, raising a new perspective for explaining TTI's action on the glycemic response.

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INTRODUCTION: Obesity has emerged as one of the main public health problems. This condition triggers a series of hormonal and metabolic changes related to a low-grade chronic inflammatory condition. The trypsin inhibitor purified from tamarind (TTIp) seeds is a promising anti-inflammatory molecule, but its safety needs to be evaluated. This study aimed to evaluate TTIp bioactive dose effects on organs involved in its metabolism (liver and pancreas) and affected tissues (small intestine and perirenal adipose tissue) in an obesity model. METHODS: Three groups of adult male Wistar rats were used (n = 5). Two of these groups had diet-induced obesity, and a third group was eutrophic. TTIp was administered by gavage in one of the obese groups for 10 days, while the remaining groups received a vehicle. The chromatographic profile and the inhibition assay corroded the purification of the inhibitor. Physical and behavioral changes, liver enzymes, and stereological and histopathological analyses of tissues were evaluated. RESULTS: TTIp did not cause visible signs of toxicity, nor caused changes in liver enzymes, the liver, and pancreatic tissues. TTIp did not cause changes in the intestinal mucosa, showing improvement in the villi's histopathological characteristics compared to the group of animals with obesity without treatment with TTIp (p = 0.004). The analysis of perirenal adipose tissue showed that the average sectional area of animals with obesity that received TTIp did not differ from the control. There was a difference between the high glycemic load diet group and the group treated with the inhibitor (351.8 ± 55.5) (p = 0.016). In addition, the group that received TTIp had no inflammatory infiltrates. CONCLUSION: Based on histological and stereological analysis, the use of TTIp is potentially safe and anti-inflammatory in the evaluated obesity model and can be investigated as a possible adjuvant in obesity therapy.

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Abstract Background: Soybean milk by-product (SMBP) is a potential alternative feed ingredient in swine diets due to its high protein content. However, information on energy and nutritional values of SMBP used as swine feed ingredient is limited. Objective: To estimate energy values and protein digestibility of SMBP in pigs based on in vitro assays. Methods: Four SMBP samples were obtained from 3 soybean milk-producing facilities. In vitro total tract disappearance (IVTTD) and in vitro ileal disappearance (IVID) of dry matter (DM) in the SMBP samples were determined. In vitro ileal disappearance of crude protein was determined by analyzing crude protein content in undigested residues after determining IVID of DM. Digestible and metabolizable energy of SMBP were estimated using gross energy, IVTTD of DM, and prediction equations. Results: Sample 4 had greater IVTTD of DM than that of sample 3 (97.7 vs. 94.4%, p<0.05), whereas IVID of DM in sample 4 was lower compared with sample 1 (53.5 vs. 65.0%, p<0.05). In vitro ileal disappearance of crude protein in sample 2 was greater than that in sample 1 and 3 (92.6 vs. 90.6 and 90.1%; p<0.05). The estimated metabolizable energy of SMBP ranged from 4,311 to 4,619 kcal/kg as-is basis and the value of sample 3 was the least (p<0.05) among SMBP samples. Conclusion: Energy values and protein digestibility should be determined before using SMBP in swine diets.

Resumen Antecedentes: El subproducto de la leche de soja (SMBP) es un ingrediente alimenticio alternativo con uso potencial en dietas porcinas dado su alto contenido de proteína. Sin embargo, la información sobre sus valores energéticos y nutricionales para alimentación de cerdos es muy limitada. Objetivo: Estimar los valores de energía y la digestibilidad de la proteína del SMBP en cerdos con base en ensayos in vitro. Métodos: Se obtuvieron cuatro muestras de SMBP de tres empresas productoras de leche de soja. Se determinaron la desaparición de tracto total in vitro (IVTTD) y la desaparición ileal in vitro (IVID) de la materia seca (DM) en las muestras de SMBP. La desaparición ileal in vitro de proteína cruda se determinó analizando el contenido de proteína cruda en residuos no digeridos después de determinar la IVID de la DM. La energía digestible y metabolizable de SMBP se estimó utilizando la energía bruta, IVTTD de la DM y ecuaciones de predicción. Resultados: La muestra 4 tuvo una mayor IVTTD de la DM que la muestra 3 (97,7 vs. 94,4%, p<0,05), mientras que la IVID de la DM en la muestra 4 fue menor en comparación con la muestra 1 (53,5 vs. 65,0%, p<0,05). La desaparición ileal in vitro de la proteína cruda en la muestra 2 fue mayor que la de las muestras 1 y 3 (92,6 vs. 90,6 y 90,1%; p<0,05). La energía metabolizable estimada de SMBP varió de 4.311 a 4.619 kcal/kg (en base húmeda) y el valor de la muestra 3 fue el menor (p<0.05) entre las muestras de SMBP. Conclusión: Los valores de energía y la digestibilidad de la proteína deben determinarse antes de usar el SMBP en dietas porcinas.

Resumo Antecedentes: O subproduto do leite de soja (SMBP) é um potencial ingrediente alternativo na dieta de suínos, considerando seu alto teor de proteínas. No entanto, as informações sobre os valores energéticos e nutricionais do SMBP usado como ingrediente alimentar para suínos são limitadas. Objetivo: Estimar valores energéticos e digestibilidade protéica do SMBP em suínos com base em ensaios in vitro. Métodos: Foram obtidas quatro amostras de SMBP de três instalações produtores de leite de soja. Foram determinados o desaparecimento total do trato in vitro (IVTTD) e o desaparecimento ileal in vitro (IVID) da matéria seca (DM) nas amostras de SMBP. O desaparecimento ileal in vitro da proteína bruta foi determinado pela análise do conteúdo de proteína bruta em resíduos não digeridos após a determinação da IVID do DM. A energia digerível e metabolizável do SMBP foi estimada usando energia bruta, IVTTD do DM e equações de predição. Resultados: a amostra 4 apresentou maior IVTTD de DM do que a amostra 3 (97,7 vs. 94,4%, p<0,05) enquanto a IVID do DM na amostra 4 foi menor em comparação com a amostra 1 (53,5 vs. 65,0%, p<0,05). O desaparecimento ileal in vitro da proteína bruta na amostra 2 foi superior ao da amostra 1 e 3 (92,6 vs. 90,6 e 90,1%; p<0,05). A energia metabolizável estimada do SMBP variou de 4.311 a 4.619 kcal/kg no estado em que se encontra e o valor da amostra 3 foi o menor (p<0,05) entre as amostras do SMBP. Conclusão: os valores energéticos e a digestibilidade das proteínas devem ser determinados antes do uso do SMBP nas dietas suínas.

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rBmTI-A is a recombinant serine protease inhibitor that belongs to the Kunitz-BPTI family and that was cloned from Rhipicephalus microplus tick. rBmTI-A has inhibitory activities on bovine trypsin, human plasma kallikrein, human neutrophil elastase and plasmin with dissociation constants in nM range. It is characterized by two inhibitory domains and each domain presents six cysteines that form three disulfide bonds, which contribute to the high stability of its structure. Previous studies suggest that serine protease inhibitor rBmTI-A has a protective potential against pulmonary emphysema in mice and anti-inflammatory potential. Besides that, rBmTI-A presented a potent inhibitory activity against in vitro vessel formation. In this study, the tertiary structure of rBmTI-A was modeled. The structure stabilization was evaluated by molecular dynamics analysis. Circular dichroism spectroscopy data corroborated the secondary structure found by the homology modelling. Also, in circular dichroism data it was shown a thermostability of rBmTI-A until approximately 70 °C, corroborated by inhibitory assays toward trypsin.

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Protease inhibitors (PIs) have been traditionally recognized by their potential biomedical application in events with exacerbation of endogenous proteases activity. Plant PIs have gained interest as naturally occurring molecules, which usually show lower environmental impact residual toxicity than synthetic compounds. In this work, we isolated, cloned, expressed and purified a novel trypsin inhibitor from S. tuberosum subsp. andigenum var. overa, named oPTI. A significant over-expression of the oPTI coding gene after 48 h exposure of methyl jasmonate compared to the gene of reference. This inhibitor showed a molecular mass of 12 kDa and a Ki of 7.3 × 10-7 M. Finally, we evaluated the antimicrobial activity of oPTI against different pathogenic microorganisms. The oPTI demonstrated inhibitory effect on the growth of Acinetobacter baumannii S-1, Acinetobacter baumannii R, Acinetobacter calcoaceticus R, Acinetobacter calcoaceticus S, Bacillus stearothermophilus, Escherichia coli, Pseudomonas aeruginosa, Salmonella braenderup, Salmonella enteritidis, Salmonella typhimurium and Yersinia enterocolitica strains. This study represents the first report for the antimicrobial activity of a plant PI over a wide range of microorganisms. Our studies reinforce the importance of natural PIs as promising molecules for their potential application in the biomedical field and/or in the food industry as natural food preservatives.

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BACKGROUND: Disease vector insects are barriers for human development. The use of synthetic chemicals to control these vectors has caused damage to the environment and contributed to the arising of resistant insect populations. This has led to an increased search for plant-derived molecules with insecticidal activity or that show synergistic effects with known insecticidal substances, such as protease inhibitors. Thus, we aimed to evaluate the effect of Enterolobium contortisiliquum trypsin inhibitor (EcTI) on Aedes aegypti development as well as its effect on insecticidal activity of Bacillus thuringiensis toxins. RESULTS: EcTI showed an apparent molecular mass about of 20 kDa in SDS-PAGE and was able to inhibit in vitro the activity of trypsin and proteases from midgut of Ae. aegypti larvae. EcTI was not able to cause acute toxicity on mosquito larvae even at 1000 µg mL-1 , however it promoted a delay in larval development after prolonged exposure. The zymogram results for EcTI-treated larvae (from 50 to 200 µg mL-1 ) showed an increase of midgut proteases activity as a larvae defense mechanism, however no changes in the enzyme profile was observed. These same concentrations were able to enhance up to three fold the insecticidal activity of B. thuringiensis toxins without causing toxicity to Artemia sp. nauplii, a non-target organism. CONCLUSIONS: The results offer a novel approach by combining EcTI and B. thuringiensis toxins for combating Ae. aegypti larvae. © 2020 Society of Chemical Industry.

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This study investigated the inhibitory activity of serine protease, as well as antibacterial and antibiotic modifying activities of the crude extract and fractions of A. cearensis seeds. Microdilution assay was used to evaluate the antibacterial activity and the antibiotic resistance-modulating effects of samples against multiresistant bacteria Staphylococcus aureus (SA10) and Escherichia coli (EC06). In the inhibition test for serine protease, all the samples showed inhibition of enzymatic activity. Crude extract and fractions of A. cearensis seeds showed a Minimum Inhibitory Concentration ≥1024 µg/mL for all microorganisms tested. However, the samples acted as resistance modifying agent, presenting synergism when associated with gentamicin, norfloxacin and penicillin. The present study provides data indicating a possible use of the seeds extract of A. cearensis in association with antibiotics in the fight against bacterial infections.

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