Preliminary Studies on the Mechanism of Antifungal Activity of New Cationic β-Glucan Derivatives Obtained from Oats and Barley

Antifungal Associations with a Polyelectrolyte Promote Significant Reduction of Minimum Inhibitory Concentrations against Opportunistic Candida spp. Strains

The current global scenario presents us with a growing increase in infections caused by fungi, referred to by specialists in the field as a "silent epidemic", aggravated by the limited pharmacological arsenal and increasing resistance to this therapy. For this reason, drug repositioning and therapeutic compound combinations are promising strategies to mitigate this serious problem. In this context, this study investigates the antifungal activity of the non-toxic, low-cost and widely available cationic polyelectrolyte Poly(diallyldimethylammonium chloride) (PDDA), in combination with different antifungal drugs: systemic (amphotericin B, AMB), topical (clioquinol, CLIO) and oral (nitroxoline, NTX). For each combination, different drug:PDDA ratios were tested and, through the broth microdilution technique, the minimum inhibitory concentration (MIC) of these drugs in the different ratios against clinically important Candida species strains was determined. Overall, PDDA combinations with the studied drugs demonstrated a significant increase in drug activity against most strains, reaching MIC reductions of up to 512 fold for the fluconazole resistant Candida krusei (Pichia kudriavzevii). In particular, the AMB-PDDA combination 1:99 was highly effective against AMB-resistant strains, demonstrating the excellent profile of PDDA as an adjuvant/association in novel antifungal formulations with outdated conventional drugs.

Oat Peptides Alleviate Dextran Sulfate Sodium Salt-Induced Colitis by Maintaining the Intestinal Barrier and Modulating the Keap1-Nrf2 Axis

The prevalence of inflammatory bowel disease (IBD) is progressively rising each year, emphasizing the significance of implementing rational dietary interventions for disease prevention. Oats, being a staple agricultural product, are abundant in protein content. This study aimed to investigate the protective effects and underlying mechanisms of oat peptides (OPs) in a mouse model of acute colitis induced by dextran sulfate sodium salt (DSS) and a Caco-2 cell model. The findings demonstrated that intervention with OPs effectively mitigated the symptoms associated with DSS-induced colitis. The physicochemical characterization analysis demonstrated that the molecular weight of the OPs was predominantly below 5 kDa, with a predominant composition of 266 peptides. This study provides further evidence of the regulatory impact of OPs on the Keap1-Nrf2 signaling axis and elucidates the potential role of WGVGVRAERDA as the primary bioactive peptide responsible for the functional effects of OPs. Ultimately, the results of this investigation demonstrate that OPs effectively mitigate DSS-induced colitis by preserving the integrity of the intestinal barrier and modulating the Keap1-Nrf2 axis. Consequently, these findings establish a theoretical foundation for the utilization of OPs as dietary supplements to prevent the onset of IBD.

The Use of a Barley-Based Well to Define Cationic Betaglucan to Study Mammalian Cell Toxicity Associated with Interactions with Biological Structures

Among potential macromolecule-based pharmaceuticals, polycations seem particularly interesting due to their proven antimicrobial properties and use as vectors in gene therapy. This makes an understanding of the mechanisms of these molecules' interaction with living structures important, so the goal of this paper was to propose and carry out experiments that will allow us to characterize these phenomena. Of particular importance is the question of toxicity of such structures to mammalian cells and, in the work presented here, two lines, normal fibroblasts 3T3-L1 and A549 lung cancer, were used to determine this. In this work, three well-defined cationic derivatives of barley-derived betaglucans obtained in a reaction with glycidyltrimethylammonium chloride (BBGGTMAC) with different degrees of cationization (50, 70, and 100% per one glucose unit) and electrostatic charge were studied. The studies address interactions of these polymers with proteins (bovine serum proteins and BSA), nucleic acids (DNA), glycosaminoglycans (heparin), and biological membranes. The results described in this study make it possible to indicate that toxicity is most strongly influenced by interactions with biological membranes and is closely related to the electrostatic charge of the macromolecule. The presentation of this observation was the goal of this publication. This paper also shows, using fluorescently labeled variants of polymers, the penetration and impact on cell structure (only for the polymer with the highest substitution binding to cell membranes is observed) by using confocal and SEM (for the polymer with the highest degree of substitution, and the appearance of additional structures on the surface of the cell membrane is observed). The labeled polymers are also tools used together with dynamic light scattering and calorimetric titration to study their interaction with other biopolymers. As for the interactions with biological membranes, lipid Langmuir monolayers as model membrane systems were used.