Maria Taciana Holanda Cavalcanti

Kinetic and Thermodynamic Investigation on Ascorbate Oxidase Activity and Stability of a Cucurbita maxima Extract

The kinetic and thermodynamic properties of ascorbate oxidase (AO) activity and stability of a Cucurbita maxima extract were investigated. Activity tests performed at 25 °C using initial ascorbic acid concentration in the range 50–750 μM allowed estimating the Michaelis constant for this substrate (Km = 126 μM) and the maximum initial rate of ascorbic acid oxidation (A0,max = 1.57 mM min−1). The main thermodynamic parameters of the enzyme reaction (ΔH* = 10.3 kJ mol−1; ΔG* = 87.2 kJ mol−1; ΔS* = –258 J mol−1 K−1) were estimated through activity tests performed at 25–48 °C. Within such a temperature range, no decrease in the initial reaction rate was detected. The long‐term thermostability of the raw extract was then investigated by means of residual activity tests carried out at 10–70 °C, which allowed estimating the thermodynamic parameters of the irreversible enzyme inactivation as well (ΔH*D = 51.7 kJ mol−1; ΔG*D = 103 kJ mol−1; ΔS*D = –160 J mol−1 K−1). Taking into account the specific rate of AO inactivation determined at different temperatures, we also estimated the enzyme half‐life (1047 min at 10 °C and 21.2 min at 70 °C) and predicted the integral activity of a continuous system using this enzyme preparation. This work should be considered as a preliminary attempt to characterize the AO activity of a C. maxima extract before its concentration by liquid‐liquid extraction techniques.

Analysis of Plasma Citrulline and Intestinal Morphometry in Mice with Hepatosplenic Schistosomiasis

BACKGROUND Portal hypertension in the mucosa of the intestine and the presence of granulomas in the wall of this organ can alter digestive function in patients with schistosomiasis. Citrulline is a potential marker of intestinal function in some diseases that affect the morphometry of the mucosa because of its close association with enterocytes. The aims of the present study were to determine serum citrulline concentrations in mice with hepatosplenic schistosomiasis, analyze the morphologic repercussions for the mucosa of the small intestine, correlate citrulline concentrations with morphometric changes in the intestinal mucosa, and evaluate the effect of splenectomy on citrulline concentration. METHODS After approval from the local ethics committee, 46 adult female albino Swiss mice were divided into two groups: Control (23 healthy mice) and experimental (23 mice with hepatosplenic schistosomiasis). Blood samples were collected for the analysis of plasma citrulline before and after splenectomy. A segment of the jejunum was resected for morphometric analysis. RESULTS The average body mass in the control group was greater than that in the experimental group (p = 0.00062). The average citrulline concentration in the control group was greater than that in the experimental group both before and after splenectomy (p < 0.001). In the experimental group, the villi had less height and area, and there was a smaller perimeter of the mucosal surface (p = 0.003, <0.001, and p = 0.001, respectively). There was a direct correlation between citrulline concentration and the height and area of the villi (p = 0.003 and 0.04, respectively). There was no correlation between citrulline concentration and the perimeter of the surface of the jejunal mucosa. After splenectomy, there was a reduction in the mean citrulline concentration in the experimental group (p = 0.009). CONCLUSIONS Serum citrulline concentrations were reduced in mice with schistosomiasis, and a direct correlation was found between the citrulline concentration and the morphometry of the jejunal villi. Moreover, there was a reduction in the plasma concentration of citrulline after splenectomy.

Probiotics as a preventive strategy for surgical infection in colorectal cancer patients: a systematic review and meta-analysis of randomized trials

BACKGROUND Infection following abdominal surgery remains a major factor in morbidity among colorectal cancer (CRC) patients. Probiotic therapy has been suggested to improve the clinical and laboratory outcome of patients undergoing gastrointestinal surgery. The aim of this study was to investigate the efficacy of probiotic lactic acid bacteria in patients with CRC in the pre- and postoperative phases. METHODS Systematic database searches identified 1,080 related articles. However, only seven articles were selected according to the eligibility criteria for qualitative and quantitative evaluation. RESULTS Most of the reviewed articles presented satisfactory results related to the prevention of surgical inflammation in patients undergoing resection of CRC when using strains of Lactobacillus genus, predominantly. CONCLUSIONS Probiotics are suggested to prevent surgical inflammation of CRC, at the same time that the combination of particular microorganisms administered is beneficial to the treatment and surgical recovery.

Brazilian Kefir-Fermented Sheep’s Milk, a Source of Antimicrobial and Antioxidant Peptides

Fermented milks are a source of bioactive peptides and may be considered as functional foods. Among these, sheep’s milk fermented with kefir has not been widely studied and its most relevant properties need to be more thoroughly characterized. This research study is set out to investigate and evaluate the antioxidant and antimicrobial properties of peptides from fermented sheep’s milk in Brazil when produced by using kefir. For this, the chemical and microbiological composition of the sheep’s milk before and after the fermentation was evaluated. The changes in the fermented milk and the peptides extracted before the fermentation and in the fermented milk during its shelf life were verified. The antimicrobial and antioxidant activities of the peptides from the fermented milk were evaluated and identified according to the literature. The physicochemical properties and mineral profile of the fermented milk were like those of fresh milk. The peptide extract presented antimicrobial activity and it was detected that 13 of the 46 peptides were able to inhibit the growth of pathogenic microorganisms. A high antioxidant activity was observed in the peptides extracted from fermented milk (3.125 mg/mL) on the 28th day of storage. Two fractions displayed efficient radical scavenging properties by DPPH and ABTS methods. At least 11 peptides distributed in the different fractions were identified by tandem mass spectrometry. This sheep’s milk fermented by Brazilian kefir grains, which has antioxidant and antimicrobial activities and probiotic microorganisms, is a good candidate for further investigation as a source for bioactive peptides. The fermentation process was thus a means by which to produce potential bioactive peptides.

Colagenase de pescada branca: extração, purificação parcial, caracterização e teste de especificidade ao colágeno para aplicação industrial

1Laboratory of Technology of Bioactive Product (LABTECBIO). Department of Morphology and Animal Physiology, DMFA, Federal Rural University of Pernambuco UFRPE, Av. Dom Manoel de Medeiros, s/n, 52171-900, Recife, PE; vagne_melo@hotmail.com (corresponding author) 2Laboratory of Enzymology (LABENZ). Department of Biochemistry, Federal University of Pernambuco-UFPE, Campus Universitário, s / n, 50670-901, Recife, PE ABSTRACT