Cranberry-derived proanthocyanidins induce a differential transcriptomic response within Candida albicans urinary biofilms

Antibiofilm potential of plant extracts: inhibiting oral microorganisms and Streptococcus mutans

Introduction

A range of disinfectant mouthwashes are available for oral hygiene. The gold standard is Chlorhexidine digluconate (CHX), which, like other available products, cannot be used without side effects in the long term. However, in recent years, therapy with herbal products, often considered antiquated, has regained considerable interest. Therefore, the search for plant compounds as an alternative to existing oral disinfectants is meaningful.

Methods

In this study, eleven Mediterranean plant extracts were tested for their antimicrobial effect in vitro. Methanol extracts of the following plants were produced by the pharmaceutical faculty of the University of Athens: Mentha aquatica, Mentha longifolia, Sideritis euboea, Sideritis syriaca, Stachys spinosa, Satureja parnassica, Satureja thymbra, Lavandula stoechas, Achillea taygetea, Phlomis cretica, and Vaccinium myrtillus. The extracts were dissolved for microdilution experiments at concentrations ranging from 10 to 0.019 mg/ml. The oral pathogens tested were Streptococcus mutans, Streptococcus oralis, Streptococcus sobrinus, Prevotella intermedia, Fusobacterium nucleatum, Parvimonas micra, Porphyromonas gingivalis, and Candida albicans. Enterococcus faecalis, Staphylococcus aureus, and Escherichia coli were used as references.

Results

All extracts, except the methanol extract of V. myrtillus, showed an antibacterial effect at concentrations ranging from 10 to 0.15 mg/ml. None of the extracts exhibited a significant antifungal effect. In general, the anaerobic pathogens could be inhibited and killed at lower concentrations compared to the aerobic pathogens. S. oralis also showed good susceptibility to the extracts. Additionally, the extracts' ability to inhibit biofilm formation by S. mutans was tested. L. stoechas at a concentration of 0.3 mg/ml showed a moderate inhibitory effect. The extracts of L. stoechas, S. thymbra, S. parnassica, and the methanol extract of V. myrtillus were effective at concentrations up to 1.25 mg/ml. P. cretica was able to inhibit and kill S. mutans at a concentration of 0.6 mg/ml, but its effectiveness in biofilm inhibition significantly decreased at 2.5 mg/ml.

Discussion

The study's hypothesis that all extracts would exhibit an antimicrobial effect was thus confirmed.

Preparation and analysis of quinoa active protein (QAP) and its mechanism of inhibiting Candida albicans from a transcriptome perspective

The globe cultivation and industrial production of quinoa have been steadily increasing. Nevertheless, the full potential of quinoa's nutritional and economic benefits remains underexploited. This study investigates the isolation and purification of quinoa active protein (QAP) through the precipitation method using ammonium sulfate from a phosphate extraction solution. The purification process involved gel filtration chromatography with Sephadex G-75 and Sephadex G-50 columns to obtain QAP fractions exhibiting inhibitory effects against Candida albicans (C. albicans). A comprehensive series of experiments was undertaken to examine the antifungal properties of these fractions. Proteomic analysis was employed to elucidate the composition of the active proteins. Furthermore, the activities of succinate dehydrogenase, Ca2+-Mg2+-ATPase, and catalase in C. albicans following treatment with QAP were quantified using an enzyme-linked immunosorbent assay. The effects of QAP on the cell morphology of C. albicans cultured on Spider agar medium was further investigated using scanning electron microscopy (SEM). Furthermore, RNA-seq analysis was conducted to investigate the alterations in gene expression in C. albicans cells subjected to QAP treatment. To elucidate the functional significance of these expression changes, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed. Quantitative real-time polymerase chain reaction was subsequently employed to validate the observed changes in gene expression. Our findings demonstrate that QAP exhibits inhibitory effects against C. albicans, with a minimum inhibitory concentration of 182 µg/mL. Through proteomic analysis, a definitive set of 18 active quinoa proteins was identified. At the molecular level, genes associated with hyphal development, cell wall and membrane integrity, cellular respiration, and energy metabolism were found to be enriched. Protein-protein interaction (PPI) analysis revealed that these QAP inhibit the growth of C. albicans hyphae, compromise cell wall and membrane integrity, and suppress oxidative phosphorylation. These disruptions collectively impair normal cellular metabolic activities, thereby exerting an inhibitory effect on C. albicans.

Using Bioluminescence to Image Candida glabrata Urinary Tract Infections in Mice

The human fungal pathogen Candida glabrata is less virulent compared to the most isolated Candida species including Candida albicans. Its reduced metabolic flexibility, haploidy, and auxotrophies contribute to a "stealth and evasion" infection strategy, resulting in minimal tissue damage in the host. C. glabrata seems to be optimally adapted to infection of the urinary tract (UTI), especially in catheterized patients. UTIs are not well studied and often difficult to treat, given that not all antifungals penetrate in the bladder and that treatments through the catheter are not always possible since maintained catheterization increases the infection risk.In the recent effort to reduce the amount of animals used during scientific experiments, bioluminescence imaging is a useful tool. In this protocol, C. glabrata urinary tract infections were imaged in mice, thus facilitating the testing of possible new antifungals and novel treatment strategies.

Candida albicans Biofilm Inhibition by Two Vaccinium macrocarpon (Cranberry) Urinary Metabolites: 5-(3',4'-DihydroxyPhenyl)-γ-Valerolactone and 4-Hydroxybenzoic Acid

Candida spp. are pathobionts, as they can switch from commensals to pathogens, responsible for a variety of pathological processes. Adhesion to surfaces, morphological switch and biofilm-forming ability are the recognized virulence factors promoting yeast virulence. Sessile lifestyle also favors fungal persistence and antifungal tolerance. In this study, we investigated, in vitro, the efficacy of two urinary cranberry metabolites, 5-(3′,4′-dihydroxy phenyl)-γ-valerolactone (VAL) and 4-hydroxybenzoic acid (4-HBA), in inhibiting C. albicans adhesion and biofilm formation. Both the reference strain SC5314 and clinical isolates were used. We evaluated biomass reduction, by confocal microscopy and crystal violet assay, and the possible mechanisms mediating their inhibitory effects. Both VAL and 4-HBA were able to interfere with the yeast adhesion, by modulating the expression of key genes, HWP1 and ALS3. A significant dose-dependent reduction in biofilm biomass and metabolic activity was also recorded. Our data showed that the two cranberry metabolites VAL and 4-HBA could pave the way for drug development, for targeting the very early phases of biofilm formation and for preventing genitourinary Candida infections.

Grape Seeds Proanthocyanidins: An Overview of In Vivo Bioactivity in Animal Models

Over the last decade, proanthocyanidins (PACs) are attracting attention not only from the food industry but also from public health organizations due to their health benefits. It is well-known that grapes are a good source of PACs and for that reason, the industry is also focused on grape by-products identification and bioactivity evaluation. Grape seeds extract (GSPE) is a rich source of PACs, mainly composed of monomeric catechin and epicatechin, gallic acid and polymeric and oligomeric proanthocyanidins. Thus, this review encompasses the state-of-art structure and the most recent evidence about the impact of GSPE on chronic diseases, with a focus on oxidative stress, inflammation and metabolic syndrome (MeS)-related disorders such as obesity, diabetes and cardiovascular risk disease in vivo to offer new perspectives in the field that allow further research. Despite the controversial results, is undeniable that PACs from grape seeds are highly antioxidants, thus, the capacity of GSPE to improve oxidative stress might mediate the inflammation process and the progress of MeS-related pathologies. However, further well-design animal studies with standardized dosages and GSPE composition are necessary to shed light into the cause-effect relationship in a more accurate way to later allow a deeper study of the effect of GSPE in humans.