Marine algae are sources of bioactive components with defensive properties of great value against microbial infections. This study investigated the bioactivity of extracts from brown algae Fucus vesiculosus against rotavirus, the worldwide leading cause of acute gastroenteritis in infants and young children. Moreover, one of the extracts was tested against four foodborne bacteria: Campylobacter jejuni, Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes, and the non-pathogenic: E. coli K12. In vitro tests using MA104 cells revealed that both whole algae extracts and crude fucoidan precipitates neutralized rotavirus in a dose-responsive manner. The maximum neutralization activity was observed when the rotavirus was incubated with 100 μg mL⁻¹ of the hydrochloric acid-obtained crude fucoidan (91.8%), although crude fucoidan extracted using citric acid also demonstrated high values (89.5%) at the same concentration. Furthermore, molecular weight fractionation of extracts decreased their antirotaviral activity and high molecular weight fractions exhibited higher activity compared to those of lower molecular weight. A seaweed extract with high antirotaviral activity was also found to inhibit the growth of C. jejuni, S. Typhimurium, and L. monocytogenes at a concentration of 0.2 mg mL⁻¹. Overall, this study expands the current knowledge regarding the antimicrobial mechanisms of action of extracts from F. vesiculosus.

Milk is a source of proteins with high nutritional value and relevant biological activities. Bioactive milk proteins, like lactoferrin, are important for newborn development and can also be used as ingredients in functional products to improve health. Lactoferrin is essential in infant’s diet, since protects against infections and promotes immune system maturation. Bovine lactoferrin is used to supplement formula milk in order to strengthen baby’s defences against some pathogenic bacteria. Thus, lactoferrin supplemented formula can be a barrier against emergent pathogens, such as Cronobacter sakazakii, which has caused great concern in the last few years. Milk proteins generate bioactive peptides in the digestion process, and it is known that industrial processing can modify their susceptibility to digestion. Treatments such as heating have been shown to denature whey proteins and make them more easily digestible. Therefore, the aim of this study was to analyze the effect of technological treatments and gastrointestinal digestion on the antibacterial activity against C. sakazakii of proteins present in dairy formulas supplemented with lactoferrin. Commercial bovine lactoferrin has been shown to have antibacterial activity against C. sakazakii, both in the native state and after static in vitro gastrointestinal digestion. In addition, the digests obtained from dairy formulas subjected to technological treatments, either homogenization or pasteurization, have higher antibacterial activity than non-treated formulas. The release of low molecular weight peptides during the in vitro gastric digestion is probably the cause that would explain the enhanced antibacterial activity of the digested dairy formulas.

Nowadays, rotaviruses remain a major health burden, especially in developing countries, and strategies complementary to vaccination are needed. In this view, dairy fractions have attracted great scientific interest, due to their high content of bioactive compounds. The objective of this study was to evaluate the antiviral activity of whey and buttermilk enriched in proteins from hyperimmune bovine colostrum (HBC) against rotavirus. The enriched fractions were spray-dried and subsequently tested for their neutralizing activity against the bovine rotavirus WC3 strain in vitro, using differentiated Caco-2/TC7 cells. The highest antirotaviral activity was observed when whey and buttermilk were enriched in purified immunoglobulin G (IgG), showing complete rotavirus neutralization at concentrations of 3 and 6 mg mL⁻¹ for whey and buttermilk, respectively. Additionally, the use of a crude immunoglobulin fraction also gave satisfactory results. The inhibitory activities of all samples significantly decreased after the application of heat, except for the IgG-enriched buttermilk which showed a slight increase of activity following the application of short-time treatments (75 or 85 °C for 20 s). This sample also showed a significant increase of activity (13%) after the application of low-intensity high hydrostatic pressure treatment (400 MPa for 5 min). The maximum loss of bioactivity was observed at 600 MPa for 10 min (31 and 20% for whey- and buttermilk-based formulas, respectively). This study provides relevant information on the potential of whey, buttermilk, and HBC to be part of functional products as complementary strategies to combat rotavirus infections.

Purification of extracts is an essential procedure in order to remove wax and other undesirable ingredients while retaining the polyphenolic fraction which contains most of bioactive components. This study investigates how different purification methods affect the qualitative characteristics of propolis extracts. Five different purification methods were conducted both for ethanolic and methanolic extracts: (a) centrifugation for 30 min at 370 g; (b) centrifugation at −5 °C for 10 min at 1850 g twice with a 15 min interval; (c) centrifugation at 3340 g for 2.5 min twice with a 15 min interval; (d) filtration through a 0.22 μm polyethersulfone membrane; (e) filtration through a 0.45 μm pore size nylon membrane filter using Buchner vacuum system. Methods were evaluated with reference to the post-treatment antioxidant activity (radical scavenging), total phenolic content and total flavonoid content of each extract. Two different methods of centrifugation were found to be the most effective and stable: centrifugation at 3340 g for 2.5 min or for 10 min at 1850 g, at −5 °C.

The dairy industry generates a large volume of by-products containing bioactive compounds that may have added value. The aim of this study was to evaluate the antioxidant and antigenotoxic effects of milk-derived products, such as whey, buttermilk, and lactoferrin, in two human cell lines: Caco-2 as an intestinal barrier model and HepG2 as a hepatic cell line. First, the protective effect of dairy samples against the oxidative stress caused by menadione was analyzed. All these dairy fractions significantly reversed the oxidative stress, with the non-washed buttermilk fraction presenting the greatest antioxidant effect for Caco-2 cells and lactoferrin as the best antioxidant for HepG2 cells. At concentrations that did not impact cell viability, we found that the dairy sample with the highest antigenotoxic power against menadione, in both cell lines, was lactoferrin at the lowest concentration. Additionally, dairy by-products maintained their activity in a coculture of Caco-2 and HepG2, mimicking the intestinal-liver axis. This result suggests that the compounds responsible for the antioxidant activity could cross the Caco-2 barrier and reach HepG2 cells on the basal side, exerting their function on them. In conclusion, our results show that dairy by-products have antioxidant and antigenotoxic activities, which would allow revaluing their use in food specialties.

Antibiotics, specifically clindamycin (Clin), cause intestinal dysbiosis, reducing the microbiota with anti-inflammatory properties. Furthermore, Clin can induce alterations in the immune responses and oxidative stress. Lactoferrin, among other activities, participates in the maintenance of intestinal homeostasis and reduces dysbiosis induced by antibiotic treatment. The aim of this study was to analyze the effect of native and iron-saturated bovine LF in a murine model of dysbiosis induced by Clin. Six groups of male C57BL/6 mice were treated with saline (control), Clin, native lactoferrin (nLF), iron-saturated lactoferrin (sLF), nLF/Clin, or sLF/Clin. Oxidation caused in the intestinal cells of the ileum of animals subjected to different treatments was analyzed, focusing on lipid peroxidation and protein carbonyl content. The expression of inflammatory mediators was determined by qRT-PCR. Treatment with Clin did not modify lipid peroxidation, but significantly increased protein carbonyl levels up to almost 5-fold respect to the control, an effect that was reversed by orally administering sLF to mice. Furthermore, Clin increased the expression of interleukin-6 and TNF-α by 1- and 2-fold change, respectively. This effect was reversed by treatment with nLF and sLF, decreasing the expression to basal levels. In conclusion, this study indicates that lactoferrin can prevent some of the effects of Clin on intestinal cells and their associated immune system.