Antibacterial Activity of Glutathione-Stabilized Silver Nanoparticles Against Campylobacter Multidrug-Resistant Strains.

Campylobacter is the leading cause of bacterial diarrheal disease worldwide. Although most episodes of campylobacteriosis are self-limiting, antibiotic treatment is usually needed in patients with serious enteritis, and especially in childrens or the elderly. In the last years, antibiotic resistance in Campylobacter has become a major public health concern and a great interest exists in developing new antimicrobial strategies for reducing the impact of this food-borne pathogen on human health. Among them, the use of silver nanoparticles as antibacterial agents has taken on increased importance in the field of medicine. The aim of the present study was to evaluate the antimicrobial effectiveness of glutathione-stabilized silver nanoparticles (GSH-Ag NPs) against multidrug resistant (MDR) Campylobacter strains isolated from the chicken food chain (FC) and clinical patients (C). The results obtained showed that GSH-Ag NPs were highly effective against all MDR Campylobacter strains tested. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were in a range from 4.92 to 39.4 µg/mL and 9.85 to 39.4 µg/mL, respectively. Cytotoxicity assays were also assessed using human intestinal HT-29, Caco-2, and CCD-18 epithelial cells. Exposure of GSH-Ag NPs to intestinal cells showed a dose-dependent cytotoxic effect in all cell lines between 9.85 and 39.4 µg/mL. More than 60% of the tested Campylobacter strains were susceptible to GSH-Ag NPs concentrations ≤ 9.85 µg/mL, suggesting that practical inhibitory levels could be reached at low GSH-Ag NPs concentrations. Further works are needed with the purpose to evaluate the practical implications of the toxicity studies and to know more about other attributes linked to the biological compatibility. This behavior makes GSH-Ag NPs as a promising tool for the design of novel antibacterial agents for controlling Campylobacter.

Control of the Maillard reaction by ferulic acid.

This study investigated how ferulic acid (FA) affects the formation of certain Maillard reaction products (MRPs), i.e., early MRPs, fluorescent and non-fluorescent advanced glycation end products (AGEs), and melanoidins in model systems. Glycation mixtures were prepared containing soy glycinin or bovine serum albumin (final concentration 10mg/ml) and fructose (222mM) in 0.2% KOH in the presence or absence of FA (12.95mM) and incubated at 60°C for 60min. The extent of the MR was estimated by analysis of free amino groups, the incorporation of sugar into the protein backbone as well as the formation of N(ϵ)-(carboxymethyl)lysine (CML), fluorescent AGEs (λexc=337nm, λem=350-550nm) and melanoidins (absorbance at 420nm). Formation of CML and fluorescent AGEs was reduced by nearly 90% by the addition of FA while early MRPs and melanoidins were inhibited to a lesser extent (∼10% and 28%, respectively) compared to AGE formation. A controlled formation of early MRPs was achieved by use of FA, and it is a new finding. To the best of our knowledge, for the first time the use of FA as a reliable means of obtaining novel glycoprotein preparations containing low amounts of AGEs, with the potential to be used as functional food ingredients, is proposed.