Characterization of phenolic compounds in tincture of edible Nepeta nuda: development of antimicrobial mouthwash.

The activity of edible Nepeta nuda L. (Lamiaceae) tincture and Listerine towards a selected group of oral pathogenic microorganisms (4 bacterial and 9 fungal strains) has been explored. Their potentials to inhibit the formation of biofilm and to diminish established biofilm have been compared. The amount of N. nuda tincture and swishing time necessary for reaching better or equivalent antimicrobial effect than that of Listerine have been predicted. Phenolic compounds in N. nuda tincture are determined by LC-DAD/ESI-MSn. Both Listerine and N. nuda tincture possess good antimicrobial potentials (MIC in the range of 0.8-15 µL per well) including inhibition of biofilms. Rosmarinic acid and verminoside are the most dominant phenolic compounds present in the N. nuda tincture. Based on in vitro results, we infer that it is more desirable to swish 20 mL of mouthwashes (Listerine and N. nuda tincture, 100 mg mL-1) for 30 s when dealing with selected microorganisms in general and for 60 s (N. nuda tincture) when dealing with bacterial biofilms.

Chemical composition and bioactive properties of the wild mushroom Polyporus squamosus (Huds.) Fr: a study with samples from Romania.

In Eastern Europe, wild mushrooms are widely collected in mountain areas and used for their medicinal properties or as healthy foods. This study aimed at determining the chemical composition (nutritional value, free sugars, organic acids, phenolic compounds, fatty acids and tocopherols) and bioactive properties (antioxidant, antimicrobial and antiquorum sensing) of wild Polyporus squamosus (Huds.) Fr from Romania. The results indicate that the fruiting bodies of P. squamosus are rich in carbohydrates (74.22 g per 100 g dw) and proteins (18.7 g per 100 g dw). Trehalose was the main free sugar, while malic acid was the organic acid detected in the highest amount (2.21 g per 100 g dw), and p-hydroxybenzoic acid was the main phenolic compound. Among tocopherols, ß-tocopherol was the most abundant form (114.7 µg per 100 g dw). Additionally, regarding the fatty acids' pattern, polyunsaturated acids represent more than 57% of all fatty acids, followed by monounsaturated fatty acids (24.96%). The highest measured antioxidant effect of P. squamosus extract was found using the TBARS inhibition assay (EC50 = 0.22 mg mL-1), followed by the ß-carotene/linoleate assay (EC50 = 1.41 mg mL-1). A minimal inhibitory concentration of the tested extracts was obtained between 0.61-20.4 mg mL-1, while the bactericidal effect was achieved between 1.2-40.8 mg mL-1. Antibiofilm potential was obtained at all tested concentrations, and subinhibitory concentrations of the extract exhibited an antiquorum effect and reduced the formation of P. aeruginosa pili, which all together influenced the virulence of this bacterium. Due to the investigated bioactivities and compounds of P. squamosus and its well-balanced nutritional profile, this mushroom can be further used as a medicinal ingredient based on its antioxidative and antimicrobial potential.

Chemical, nutritive composition and a wide range of bioactive properties of honey mushroom Armillaria mellea (Vahl: Fr.) Kummer.

A. mellea fruiting bodies collected from nature were chemically characterized and shown to be rich in carbohydrates (81.25 g per 100 g dw), ash, fat and proteins (8.84 g per 100 g dw, 1.97 g per 100 g dw and 1.81 g per 100 g dw, respectively). Mannitol was the main free sugar while malic acid was the most abundant organic acid. δ-Tocopherol was the dominant form of tocopherols with 42.41 µg per 100 g dw. Polyunsaturated fatty acids were predominant, followed by saturated and monounsaturated fatty acids. A methanolic extract prepared from these samples was tested for antioxidant, quorum sensing and antimicrobial assays, as well as for its cytotoxicity effects. The extract showed antimicrobial activity against all tested microorganisms, including Candida albicans. Furthermore, when tested at sub-MIC concentration, it showed reduction of virulence factors and biofilm formation against Pseudomonas aeruginosa. The extract also exhibited antioxidant activity and did not show toxicity against tumor and non-tumor cells. Due to the observed bioactive properties and compounds of the honey mushroom and its well-balanced nutrients, this mushroom emerges as an interesting functional food and a source of nutraceuticals with applications in different diseases based on antioxidant and antimicrobial effects.