Researchers have a range of animal models in which to study Nonalcoholic fatty liver disease (NAFLD). Induction of NAFLD by a high-fat diet in the C57BL/6 strain is the most widely used among mice. In this study, we review works that performed NAFLD induction by a high-fat diet using the C57BL/6 strain, focusing on experiments on the effects of lipid ingestion. Studies are initially distinguished into researches in which mice received lipids by oral gavage and studies in which lipid was added to the diet, and each of these designs has peculiarities that must be considered. Oral gavage can be stressful for animals and needs trained handlers but allows accurate control of the dose administered. The addition of oils to the diet can prevent stress caused to mice by gavage, but possible changes in the consistency, taste, and smell of the diet should be considered. Regarding the experimental design, some variables, such as animal sex, treatment time, and diet-related variables, appear to have a definite pattern. However, no pattern was found regarding the number of animals per group, age at the beginning of the experiment, time of adaptation, the substance used as a vehicle, and substance used as a control.

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Metabolic syndrome (MetS) and obesity are growing in many parts of the world, becoming public health problems. It is proposed that foods with functional properties can assist in the treatment of these diseases. Crude buriti pulp oil (BPO) is a food traditionally consumed by residents in the Pantanal, Cerrado and Brazilian Amazon. It is rich in oleic acid, tocopherols and carotenoids, emerging as a potential functional food. Thus, this study aimed to evaluate the effect of the supplementation of BPO on metabolic disorders caused by a high‐fat diet. Four groups of C57BL6 mice were used, a lean group with AIN‐93M diet and control oil supplementation, an obese group with a high‐fat diet and control oil supplementation, and two obese groups with a high‐fat diet and BPO supplementation in the amounts of 50 and 100 mg/kg. BPO worsened the metabolic state caused by the high‐fat diet, worsening risk factors associated with MetS, as the abdominal circumference and retroperitoneal fat, serum levels of total cholesterol, uric acid, alanine transaminase, glucose and triglycerides, and renal fat, in addition to changes in glycaemic control and oxidative stress markers. C57BL/6 mice fed with a high‐fat diet and supplemented with BPO presented a worsening in metabolic risk factors associated with MetS.

Protease inhibitors have a broad biotechnological application ranging from medical drugs to anti-microbial agents. The Inga laurina trypsin inhibitor (ILTI) previously showed a great in vitro inhibitory effect under the adherence of Staphylococcus species, being a strong candidate for use as an anti-biofilm agent. Nevertheless, this is found in small quantities in its sources, which impairs its utilization at an industrial scale. Within this context, heterologous production using recombinant microorganisms is one of the best options to scale up the recombinant protein production. Thus, this work aimed at utilizing Komagataella phaffii to produce recombinant ILTI. For this, the vector pPIC9K+ILTI was constructed and inserted into the genome of the yeast K. phaffii, strain GS115. The protein expression was highest after 48 h using methanol 1%. A matrix-assisted laser desorption ionization–time-of-flight (MALDI–TOF) analysis was performed to confirm the production of the recombinant ILTI and its activity was investigated trough inhibitory assays using the synthetic substrate Nα-Benzoyl-D,L-arginine p-nitroanilide hydrochloride (BAPNA). Finally, recombinant ILTI (rILTI) was used in assays, showing that there was no significant difference between native and recombinant ILTI in its inhibitory activity in biofilm formation. Anti-tumor assay against Ehrlich ascites tumor (EAT) cells showed that rILTI has a potential anti-tumoral effect, showing the same effect as Melittin when incubated for 48 h in concentrations above 25 µg/mL. All together the results suggests broad applications for rILTI.

Protease inhibitors (PIs) are a part of the plant defense system and reduce the proteolytic activity of the digestive enzymes of insect pests. The current study aimed to isolate and characterize an inhibitor of trypsin (AmTI) within the seed of Anadenanthera macrocarpa (Benth) (Leguminosae-Mimosoideae). Moreover, we tried to assess the defense mechanism of the larvae of Anagasta kuehniella against this inhibitor. Protein seed extracts were purified using Sephadex G-50 and trypsin-Sepharose columns. Electrophoresis revealed the molecular weight of the inhibitor to be 25 kDa. The stability evaluation demonstrated that the inhibitor was not denatured at temperatures of up to 60 °C, pH 2-10, and concentrations of up to 100 mM dithiothreitol for one hour. The inhibitor reacted in a 1:1 ratio with bovine trypsin with an inhibition constant [Ki] = 2.517 ´ 10-8. Incorporating the inhibitor in a 1 mg per 100 mg proportion of artificial diet offered to A. kuehniella larvae led to a significant difference in the weight and survival of larvae of the fourth instar compared to the control. AmTI acted on the enzymatic activities of trypsin and chymotrypsin, not allowing until the fourth larval instar, A. kuehniella, to create adaptations against the inhibitor, as it had a simultaneous effect on larval weight and mortality. Therefore, a new trypsin inhibitor showing inhibitory activity against the digestive enzymes trypsin and chymotrypsin from A. kuehniella was isolated, indicating that these activities are correlated with the deleterious effects of this insect.

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