Francesca Mensitieri

Bio: Francesca Mensitieri is an academic researcher from University of Salerno. The author has contributed to research in topics: Medicine & Chemistry. The author has an hindex of 4, co-authored 9 publications receiving 45 citations. Previous affiliations of Francesca Mensitieri include University of Naples Federico II.

Interactions with Microbial Proteins Driving the Antibacterial Activity of Flavonoids.

Abstract: Flavonoids are among the most abundant natural bioactive compounds produced by plants. Many different activities have been reported for these secondary metabolites against numerous cells and systems. One of the most interesting is certainly the antimicrobial, which is stimulated through various molecular mechanisms. In fact, flavonoids are effective both in directly damaging the envelope of Gram-negative and Gram-positive bacteria but also by acting toward specific molecular targets essential for the survival of these microorganisms. The purpose of this paper is to present an overview of the most interesting results obtained in the research focused on the study of the interactions between flavonoids and bacterial proteins. Despite the great structural heterogeneity of these plant metabolites, it is interesting to observe that many flavonoids affect the same cellular pathways. Furthermore, it is evident that some of these compounds interact with more than one target, producing multiple effects. Taken together, the reported data demonstrate the great potential of flavonoids in developing innovative systems, which can help address the increasingly serious problem of antibiotic resistance.

Aptamers and Antisense Oligonucleotides for Diagnosis and Treatment of Hematological Diseases.

Abstract: Aptamers or chemical antibodies are single-stranded DNA or RNA oligonucleotides that bind proteins and small molecules with high affinity and specificity by recognizing tertiary or quaternary structures as antibodies. Aptamers can be easily produced in vitro through a process known as systemic evolution of ligands by exponential enrichment (SELEX) or a cell-based SELEX procedure. Aptamers and modified aptamers, such as slow, off-rate, modified aptamers (SOMAmers), can bind to target molecules with less polar and more hydrophobic interactions showing slower dissociation rates, higher stability, and resistance to nuclease degradation. Aptamers and SOMAmers are largely employed for multiplex high-throughput proteomics analysis with high reproducibility and reliability, for tumor cell detection by flow cytometry or microscopy for research and clinical purposes. In addition, aptamers are increasingly used for novel drug delivery systems specifically targeting tumor cells, and as new anticancer molecules. In this review, we summarize current preclinical and clinical applications of aptamers in malignant and non-malignant hematological diseases.

RHA-P: Isolation, expression and characterization of a bacterial α-l-rhamnosidase from Novosphingobium sp. PP1Y

Abstract: α- l -Rhamnosidases (α-RHAs) are a group of glycosyl hydrolases of biotechnological potential in industrial processes, which catalyze the hydrolysis of α- l -rhamnose terminal residues from several natural compounds. A novel α–RHA activity was identified in the crude extract of Novosphingobium sp. PP1Y, a marine bacterium able to grow on a wide range of aromatic polycyclic compounds. In this work, this α-RHA activity was isolated from the native microorganism and the corresponding orf was identified in the completely sequenced and annotated genome of strain PP1Y. The coding gene was expressed in Escherichia coli, strain BL21(DE3), and the recombinant protein, rRHA-P, was purified and characterized as an inverting monomeric glycosidase of ca. 120 kDa belonging to the GH106 family. A biochemical characterization of this enzyme using pNPR as substrate was performed, which showed that rRHA-P had a moderate tolerance to organic solvents, a significant thermal stability up to 45 °C and a catalytic efficiency, at pH 6.9, significantly higher than other bacterial α-RHAs described in literature. Moreover, rRHA-P was able to hydrolyze natural glycosylated flavonoids (naringin, rutin, neohesperidin dihydrochalcone) containing α- l -rhamnose bound to β- d -glucose with either α-1,2 or α-1,6 glycosidic linkages. Data presented in this manuscript strongly support the potential use of RHA-P as a biocatalyst for diverse biotechnological applications.

The marine Gram-negative bacterium Novosphingobium sp. PP1Y as a potential source of novel metabolites with antioxidant activity

Abstract: The antioxidant activity and protective effect of a methanolic extract obtained from the marine Gram-negative bacterium Novosphingobium sp. PP1Y, isolated from the surface water of a polluted area in the harbour of Pozzuoli (Naples, Italy), was evaluated. The extract was tested in vitro on epithelial colorectal adenocarcinoma cells and in vivo on Caenorhabditis elegans. It showed strong protective activity against oxidative stress, in both experimental systems, by preventing ROS accumulation. In the case of the cells, pre-treatment with methanolic extract was also able to maintain unaltered intracellular GSH levels and phosphorylation levels of mitogen-activated protein kinases p38. Instead, in the case of the worms, the extract was able to modulate the expression levels of stress response genes, by activating the transcription factor skn-1. From a biotechnological and economical point of view, antioxidants from microorganisms are convenient as they provide a valid alternative to chemical synthesis and respond to the ever-growing market demand for natural antioxidants.

“Sweet Flavonoids”: Glycosidase-Catalyzed Modifications

Abstract: Natural flavonoids, especially in their glycosylated forms, are the most abundant phenolic compounds found in plants, fruit, and vegetables They exhibit a large variety of beneficial physiological effects, which makes them generally interesting in a broad spectrum of scientific areas In this review, we focus on recent advances in the modifications of the glycosidic parts of various flavonoids employing glycosidases, covering both selective trimming of the sugar moieties and glycosylation of flavonoid aglycones by natural and mutant glycosidases Glycosylation of flavonoids strongly enhances their water solubility and thus increases their bioavailability Antioxidant and most biological activities are usually less pronounced in glycosides, but some specific bioactivities are enhanced The presence of l-rhamnose (6-deoxy-α-l-mannopyranose) in rhamnosides, rutinosides (rutin, hesperidin) and neohesperidosides (naringin) plays an important role in properties of flavonoid glycosides, which can be considered as “pro-drugs” The natural hydrolytic activity of glycosidases is widely employed in biotechnological deglycosylation processes producing respective aglycones or partially deglycosylated flavonoids Moreover, deglycosylation is quite commonly used in the food industry aiming at the improvement of sensoric properties of beverages such as debittering of citrus juices or enhancement of wine aromas Therefore, natural and mutant glycosidases are excellent tools for modifications of flavonoid glycosides

Applications of Marine-Derived Microorganisms and Their Enzymes in Biocatalysis and Biotransformation, the Underexplored Potentials.

Abstract: Biodiversity has been explored in the search for novel enzymes, including forests, savannas, tundras, deserts, and finally the sea. Marine microorganisms and their enzymes are capable of being active in high-salt concentration, large range of temperature, and high incidence of light and pressure, constituting an important source of unique biocatalysts. This review presents studies employing whole-cell processes of marine bacteria and fungi, aiming for new catalysts for different reactions in organic synthesis, such as reduction, oxidation, hydroxylation, hydrolysis, elimination, and conjugation. Genomics and protein engineering studies were also approached, and reactions employing isolated enzymes from different classes (oxidoreductases, hydrolases, lyases, and ligases) were described and summarized. Future biotechnological studies and process development should focus on molecular biology for the obtention of enzymes with interesting, fascinating and enhanced properties, starting from the exploration of microorganisms from the marine environment. This review approaches the literature about the use of marine-derived bacteria, fungi, and their enzymes for biocatalytic reactions of organic compounds, promoting a discussion about the possibilities of these microorganisms in the synthesis of different substances.

Marine Bacteria versus Microalgae: Who Is the Best for Biotechnological Production of Bioactive Compounds with Antioxidant Properties and Other Biological Applications?

Abstract: Natural bioactive compounds with antioxidant activity play remarkable roles in the prevention of reactive oxygen species (ROS) formation. ROS, which are formed by different pathways, have various pathological influences such as DNA damage, carcinogenesis, and cellular degeneration. Incremental demands have prompted the search for newer and alternative resources of natural bioactive compounds with antioxidant properties. The marine environment encompasses almost three-quarters of our planet and is home to many eukaryotic and prokaryotic microorganisms. Because of extreme physical and chemical conditions, the marine environment is a rich source of chemical and biological diversity, and marine microorganisms have high potential as a source of commercially interesting compounds with various pharmaceutical, nutraceutical, and cosmeceutical applications. Bacteria and microalgae are the most important producers of valuable molecules including antioxidant enzymes (such as superoxide dismutase and catalase) and antioxidant substances (such as carotenoids, exopolysaccharides, and bioactive peptides) with various valuable biological properties and applications. Here, we review the current knowledge of these bioactive compounds while highlighting their antioxidant properties, production yield, health-related benefits, and potential applications in various biological and industrial fields.