Proteins of the fruit pulp of Acca sellowiana have antimicrobial activity directed against the bacterial membranes

Study of the Antimicrobial Activity of the Human Peptide SQQ30 against Pathogenic Bacteria

Given the continuous increase in antibiotic resistance, research has been driven towards the isolation of new antimicrobial molecules. Short, charged, and very hydrophobic antimicrobial peptides have a direct action against biological membranes, which are less prone to developing resistance. Using a bioinformatic tool, we chose the SQQ30 peptide, isolated from the human SOGA1 protein. The antimicrobial activity of this peptide against various Gram-negative and Gram-positive bacterial strains and against a fungal strain was studied. A mechanism of action directed against biological membranes was outlined. When administered in combination with the antibiotic ciprofloxacin and with the TRS21 (buforin II), another antimicrobial peptide, SQQ30 can be used with a lower MIC, showing additivity and synergism, respectively. Particularly interesting is the ability of SQQ30 to bind LPS in Gram-negative strains, preventing the eukaryotic cell from releasing inflammatory mediators. Our study indicates SQQ30 as a novel and promising antimicrobial agent.

Thymus richardii subsp. nitidus (Guss.) Jalas Essential Oil: An Ally against Oral Pathogens and Mouth Health

The genus Thymus L., belonging to the Lamiaceae family, contains about 220 species with a distribution that mainly extends in Europe, northwest Africa, Ethiopia, Asia, and southern Greenland. Due to their excellent biological properties, fresh and/or dried leaves and aerial parts of several Thymus ssp. have been utilized in the traditional medicine of many countries. To evaluate not only the chemical aspects but also the biological properties, the essential oils (EOs), obtained from the pre-flowering and flowering aerial parts of Thymus richardii subsp. nitidus (Guss.) Jalas, endemic to Marettimo Island (Sicily, Italy), were investigated. The chemical composition of the EOs, obtained by classical hydrodistillation and GC-MS and GC-FID analyses, showed the occurrence of similar amounts of monoterpene hydrocarbons, oxygenated monoterpenes, and sesquiterpene hydrocarbons. The main constituents of the pre-flowering oil were β-bisabolene (28.54%), p-cymene (24.45%), and thymol methyl ether (15.90%). The EO obtained from the flowering aerial parts showed as principal metabolites β-bisabolene (17.91%), thymol (16.26%), and limonene (15.59%). The EO of the flowering aerial parts, and its main pure constituents, β-bisabolene, thymol, limonene, p-cymene, and thymol methyl ether were investigated for their antimicrobial activity against oral pathogens and for their antibiofilm and antioxidant properties.

Antimicrobial, Antibiofilm, and Antioxidant Properties of Essential Oil of Foeniculum vulgare Mill. Leaves

Foeniculum vulgare (Apiaceae) is an aromatic fennel with important practices in medicinal and traditional fields, used in the treatment of digestive complications, and gastrointestinal and respiratory disorders. Its leaves and stems, tender and fresh, are used in the production of pasta dressing and main courses, while its seeds, with a strong smell of anise, are excellent flavoring for baked goods, meat dishes, fish, and alcoholic beverages. The aim of this work is concerning the extraction of essential oil (EO) from the leaves of F. vulgare subsp. vulgare var. vulgare, investigating antimicrobial, antibiofilm, and antioxidant efficacy. In particular, GC-MS analysis showed how the chemical composition of EO was influenced by the massive presence of monoterpene hydrocarbons (α-pinene 33.75%) and phenylpropanoids (estragole 25.06%). F. vulgare subsp. vulgare var. vulgare EO shows excellent antimicrobial activity against both Gram-positive and Gram-negative strains. This EO can inhibit biofilm formation at very low concentrations and has a good ability to scavenge oxygen radicals in vitro. F. vulgare subsp. vulgare var. vulgare EO also has an increased activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) enzymes and decreased ROS levels in zymosan opsonized PMNs (OZ).

Selenite Downregulates STAT3 Expression and Provokes Lymphocytosis in the Liver of Chronically Exposed Syrian Golden Hamsters

Arsenic is considered a worldwide pollutant that can be present in drinking water. Arsenic exposure is associated with various diseases, including cancer. Antioxidants as selenite and α-tocopherol-succinate have been shown to modulate arsenic toxic effects. Since changes in STAT3 and PSMD10 gene expression have been associated with carcinogenesis, the aim of this study was to evaluate the effect of arsenic exposure and co-treatments with selenite or α-tocopherol-succinate on the expression of these genes, in the livers of chronically exposed Syrian golden hamsters. Animals were divided into six groups: (i) control, (ii) chronically treated with 100 ppm arsenic, (iii) treated with 6 ppm α-tocopherol-succinate (α-TOS), (iv) treated with 8.5 ppm selenite, (v) treated with arsenic + α-TOS, and (vi) treated with arsenic + selenite. Urine samples and livers were collected after 20 weeks of continuous exposure. The urine samples were analyzed for arsenic species by atomic absorption spectrophotometry, and real-time RT-qPCR analysis was performed for gene expression evaluation. A reduction in STAT3 expression was observed in the selenite-treated group. No differences in PSMD10 expression were found among groups. Histopathological analysis revealed hepatic lymphocytosis in selenite-treated animals. As a conclusion, long-term exposure to arsenic does not significantly alter the expression of STAT3 and PSMD10 oncogenes in the livers of hamsters; however, selenite down-regulates STAT3 expression and provokes lymphocytosis.

Bioinspired antibacterial PVA/Melanin-TiO2 hybrid nanoparticles: the role of poly-vinyl-alcohol on their self-assembly and biocide activity

Hybrid Melanin-TiO₂ nanoparticles are promising bioinspired antibacterial agents for biomedical coatings and food-packaging fields. However, due to a very low colloidal stability, they showed a high tendency to self-aggregate and rapidly precipitate, making not easy their use in aqueous medium to produce homogeneous antimicrobial coatings or nanocomposites. A valid strategy to improve their dispersion is the combination with a hydrophilic water-soluble polymer such as poly-vinyl-alcohol (PVA), which is a good choice to improve the colloidal stability of nanoparticles and to modulate their agglomeration. In this work, we propose an in-situ synthetic approach based on the hydrothermal route, by which the hybrid Melanin-TiO₂ nanoparticles were prepared starting from the inorganic and organic precursors in the presence of PVA. Combined approach of TEM, XRD, TG/DSC, EPR and DLS techniques allows for assessing the PVA role in the formation of hybrids and on their morphological features as well as colloidal stability and aqueous dispersion. Antibacterial tests demonstrated the biocide activity of PVA/Melanin-TiO₂ nanoparticles against Escherichia coli bacterial cultures, which resulted partially influenced by the PVA content. This study provides key information on the mutual influence of organic/inorganic components on the functional properties of the final hybrid nanocomposites, contributing to define a much more far-reaching implementation in the synthesis of bioinspired polymer-based nanocomposites.

Effect of Feijoa Sellowiana Acetonic Extract on Proliferation Inhibition and Apoptosis Induction in Human Gastric Cancer Cells

Gastric cancer (GC) still represents a relevant health problem in the world for both incidence and mortality rates. Many studies underlined that natural products consumption could reduce GC risk, indicating flavonoids as responsible for the beneficial effects through the modulation of several biological processes, such as the inhibition of cancer antioxidant defense and induction of apoptosis. Since Feijoa sellowiana fruit is known to contain high amounts of flavonoids, among which is flavone, we evaluated the antiproliferative and proapoptotic effects of F. sellowiana acetonic extract on GC cell lines through MTS and Annexin-V FITC assays. Among three GC cell lines tested, SNU-1 results being sensitive to both the F. sellowiana acetonic extract and synthetic flavone, which was used as the reference treatment. Moreover, we evaluated their antioxidant effects, assessing the activity of the antioxidant enzymes supeoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in polymorphonuclear cells. We found a significant increase of their activity after exposure to both F. sellowiana acetonic extract and flavone, supporting the idea that a diet that includes flavone-rich fruits could be of benefit for health. In addition to this antioxidant effect on normal cells, this study indicates, for the first time, an anticancer effect of F. sellowiana acetonic extract in GC cells.