The intestinal barrier, consisting of the vascular endothelium, epithelial cell lining, and mucus layer, covers a surface of about 400 m². The integrity of the gut wall is sustained by transcellular proteins forming tight junctions between the epithelial cells. Protected by three layers of mucin, the gut wall forms a non-permeable barrier, keeping digestive enzymes and microorganisms within the luminal space, separate from the blood stream. Microorganisms colonizing the gut may produce bacteriocins in an attempt to outcompete pathogens. Production of bacteriocins in a harsh and complex environment such as the gastro-intestinal tract (GIT) may be below minimal inhibitory concentration (MIC) levels. At such low levels, the stability of bacteriocins may be compromised. Despite this, most bacteria in the gut have the ability to produce bacteriocins, distributed throughout the GIT. With most antimicrobial studies being performed in vitro, we know little about the migration of bacteriocins across epithelial barriers. The behavior of bacteriocins in the GIT is studied ex vivo, using models, flow cells, or membranes resembling the gut wall. Furthermore, little is known about the effect bacteriocins have on the immune system. It is generally believed that the peptides will be destroyed by macrophages once they cross the gut wall. Studies done on the survival of neurotherapeutic peptides and their crossing of the brain–blood barrier, along with other studies on small peptides intravenously injected, may provide some answers. In this review, the stability of bacteriocins in the GIT, their effect on gut epithelial cells, and their ability to cross epithelial cells are discussed. These are important questions to address in the light of recent papers advocating the use of bacteriocins as possible alternatives to, or used in combination with, antibiotics.

Staphylococcus aureusis a virulent pathogen and a major causative agent of superficial and invasive skin and soft tissue infections (SSSTIs). Antibiotic resistance inS. aureus, among other bacterial pathogens, has rapidly increased, and this is placing an enormous burden on the health care sector and has serious implications for infected individuals, especially immunocompromised patients. Alternative treatments thus need to be explored to continue to successfully treat infections caused byS. aureus, including antibiotic-resistant strains ofS. aureus. In this study, an antimicrobial nanofiber wound dressing was generated by electrospinning nisin (Nisaplin) into poly(ethylene oxide) and poly(d,l-lactide) (50:50) blend nanofibers. Active nisin diffused from the nanofiber wound dressings for at least 4 daysin vitro, as shown by consecutive transfers onto plates seeded with strains of methicillin-resistantS. aureus(MRSA). The nisin-containing nanofiber wound dressings significantly reducedS. aureusXen 36 bioluminescencein vivoand viable cell numbers in a murine excisional skin infection model. The bacterial burden of wounds treated with nisin-containing nanofiber wound dressings was 4.3 × 10²CFU/wound, whereas wounds treated with control nanofiber wound dressings had 2.2 × 10⁷CFU/wound on the last day of the trial (day 7). Furthermore, the wound dressings stimulated wound closure of excisional wounds, and no adverse effects were observed by histological analysis. Nisin-containing nanofiber wound dressings have the potential to treatS. aureusskin infections and to potentially accelerate wound healing of excisional wounds.

Cranberry (Vaccinium macrocarpon) and blueberry (Vaccinium myrtillus) juices are commonly consumed as a source of antioxidants. The aim of this study was to compare bioactivities as well as the differences in the polyphenol content and anthocyanin profile of both juices. Polyphenol and anthocyanin contents were quantified using spectrophotometric and chromatographic methods. Bioassays were carried out in terms of antioxidant properties in cell and cell free systems as well as inhibition of physiological enzymes that are targets involved in the prevention of chronic diseases (monoamine oxidase A, tyrosinase, acetylcholinesterase, α-glucosidase and dipeptidyl peptidase-4). Both juices contained a significant amount of anthocyanins (3.909 mg anthocyanins per mg extract for blueberry juice and 0.398 for cranberry juice) and also exhibited antioxidant properties against DPPH, superoxide radicals and hydrogen peroxide. These juices showed inhibitory effects on the enzymes, showing substantial potential as antioxidant, neuroprotective and anti-hyperglycaemic agents. The total anthocyanin and polyphenol content was higher in blueberry juice, which is indicative of a higher antioxidant activity. Both juices were also able to inhibit monoamine oxidase A, tyrosinase, α-glucosidase and dipeptidyl peptidase-4 in a dose-dependent manner. However, cranberry juice had a greater capacity than blueberry juice as an α-glucosidase inhibitor, revealing a similar activity to acarbose.