Antioxidant, Antimicrobial, and Other Biological Properties of Pompia Juice.

Pompia is a Citrus species belonging to Sardinian endemic biodiversity. Health benefits were attributed to its flavedo rind extracts and essential oils while the juice qualities have never been investigated. In this paper, the antioxidant, antimicrobial, and other biological properties of Pompia juice were studied. A combined LCMS/electrochemical/biological approach was used to clarify a still debated phylogeny of this species and to explain the role of its juice phenolic compounds. A closer phylogenetic relationship with lemon and citron, rather than oranges was suggested. Sensors-based electrochemical measures, together with LCMS qualitative and quantitative analyses, revealed a high contribution of ascorbic acid and phenolics with low redox potential, isorhamnetin 3-O-rutinoside, diosmin, and diosmetin 6,8-diglucoside, to antioxidant capacity. The biological assays demonstrated a marked effect of low concentration of Pompia juice against reactive oxygen species (ROS) starting from 50 µg mL-1, and a moderate capacity to reduce ROS damages on cell membrane. Treatments with Pompia juice also resulted in a significant reduction (20%) of the metabolic activity of SW48 colon cancer cells. Lastly, MIC, MBC, and MBIC antimicrobial assays demonstrated that Pompia and lemon juices have inhibitory and antibiofilm effects against the pathogenic bacteria Pseudomonas aeruginosa, Streptococcus aureus, and Enterococcus faecalis.

Bioinspired versus Enzymatic Oxidation of Some Homologous Thionine Dyes in the Presence of Immobilized Metalloporphyrin Catalysts and Ligninolytic Enzymes.

Thionines are recalcitrant and polluting textile dyes presenting various degrees of N-methylation. In this paper, a complete series of homologous thionines was used as the substrates for oxidation in the presence of a bioinspired commercial iron-porphyrin immobilized on to imidazole- and pyridine-functionalized fumed silica, to emulate the active site of ligninolytic peroxidases. The obtained catalytic adducts showed a remarkable ability to catalyze thionine dye oxidation in the presence of different oxidants such as potassium monopersulfate and hydrogen peroxide. Different oxidation patterns were obtained and mechanistically discussed, in comparison with those observed in the presence of some ligninolytic oxidizing enzymes.

Agarose and Its Derivatives as Supports for Enzyme Immobilization.

Agarose is a polysaccharide obtained from some seaweeds, with a quite particular structure that allows spontaneous gelation. Agarose-based beads are highly porous, mechanically resistant, chemically and physically inert, and sharply hydrophilic. These features-that could be further improved by means of covalent cross-linking-render them particularly suitable for enzyme immobilization with a wide range of derivatization methods taking advantage of chemical modification of a fraction of the polymer hydroxyls. The main properties of the polymer are described here, followed by a review of cross-linking and derivatization methods. Some recent, innovative procedures to optimize the catalytic activity and operational stability of the obtained preparations are also described, together with multi-enzyme immobilized systems and the main guidelines to exploit their performances.

Immobilized Lignin Peroxidase-Like Metalloporphyrins as Reusable Catalysts in Oxidative Bleaching of Industrial Dyes.

Synthetic and bioinspired metalloporphyrins are a class of redox-active catalysts able to emulate several enzymes such as cytochromes P450, ligninolytic peroxidases, and peroxygenases. Their ability to perform oxidation and degradation of recalcitrant compounds, including aliphatic hydrocarbons, phenolic and non-phenolic aromatic compounds, sulfides, and nitroso-compounds, has been deeply investigated. Such a broad substrate specificity has suggested their use also in the bleaching of textile plant wastewaters. In fact, industrial dyes belong to very different chemical classes, being their effective and inexpensive oxidation an important challenge from both economic and environmental perspective. Accordingly, we review here the most widespread synthetic metalloporphyrins, and the most promising formulations for large-scale applications. In particular, we focus on the most convenient approaches for immobilization to conceive economical affordable processes. Then, the molecular routes of catalysis and the reported substrate specificity on the treatment of the most diffused textile dyes are encompassed, including the use of redox mediators and the comparison with the most common biological and enzymatic alternative, in order to depict an updated picture of a very promising field for large-scale applications.

Inorganic materials as supports for covalent enzyme immobilization: methods and mechanisms.

Several inorganic materials are potentially suitable for enzymatic covalent immobilization, by means of several different techniques. Such materials must meet stringent criteria to be suitable as solid matrices: complete insolubility in water, reasonable mechanical strength and chemical resistance under the operational conditions, the capability to form manageable particles with high surface area, reactivity towards derivatizing/functionalizing agents. Non-specific protein adsorption should be always considered when planning covalent immobilization on inorganic solids. A huge mass of experimental work has shown that silica, silicates, borosilicates and aluminosilicates, alumina, titania, and other oxides, are the materials of choice when attempting enzyme immobilizations on inorganic supports. More recently, some forms of elemental carbon, silicon, and certain metals have been also proposed for certain applications. With regard to the derivatization/functionalization techniques, the use of organosilanes through silanization is undoubtedly the most studied and the most applied, although inorganic bridge formation and acylation with selected acyl halides have been deeply studied. In the present article, the most common inorganic supports for covalent immobilization of the enzymes are reviewed, with particular focus on their advantages and disadvantages in terms of enzyme loadings, operational stability, undesired adsorption, and costs. Mechanisms and methods for covalent immobilization are also discussed, focusing on the most widespread activating approaches (such as glutaraldehyde, cyanogen bromide, divinylsulfone, carbodiimides, carbonyldiimidazole, sulfonyl chlorides, chlorocarbonates, N-hydroxysuccinimides).

Structure-activity relationships of various amino-hydroxy-benzenesulfonic acids and sulfonamides as tyrosinase substrates.

BACKGROUND: o-Aminophenols have been long recognised as tyrosinase substrates. However their exact mode of interaction with the enzyme's active site is unclear. Properly vic-substituted o-aminophenols could help gain some insight into tyrosinase catalytic mechanism. METHODS: Eight vic-substituted o-aminophenols belonging to two isomeric series were systematically evaluated as tyrosinase substrates and/or activators and/or inhibitors, by means of spectrophotometric techniques and HPLC-MS analysis. Some relevant kinetic parameters have also been obtained. RESULTS: Four o-aminophenolic compounds derived from 3-hydroxyorthanilic acid (2-amino-3-hydroxybenzenesulfonic acid) and their four counterparts derived from the isomeric 2-hydroxymetanilic acid (3-amino-2-hydroxybenzenesulfonic acid) were synthesised and tested as putative substrates for mushroom tyrosinase. While the hydroxyorthanilic derivatives were quite inactive as both substrates and inhibitors, the hydroxymetanilic compounds on the contrary all acted as substrates for the enzyme, which oxidised them to the corresponding phenoxazinone derivatives. GENERAL SIGNIFICANCE: Based on the available structures of the active sites of tyrosinases, the different affinities of the four metanilic derivatives for the enzyme, and their oxidation rates, we propose a new hypothesis regarding the interaction between o-aminophenols and the active site of tyrosinase that is in agreement with the obtained experimental results.

Ethnopharmacobotany and Diversity of Mediterranean Endemic Plants in Marmilla Subregion, Sardinia, Italy.

Human populations in various regions across the world exploit the medicinal properties of plants to treat a wide variety of diseases. Areas with both high rates of endemic taxa and persisting traditional uses of the local botanical resources are key sites for the investigation of Traditional Botanical Knowledge (TBK). Commonly, in these areas, information regarding the medicinal properties of native plants has been transmitted orally from generation to generation, however, a rapid decline in this knowledge has been observed, which can be attributed to socio-economic changes in recent years. The Mediterranean basin is one such site, where human history is intimately entwined with nature. The unique geographical situation and unrivaled environmental heterogeneity of the area, have allowed both the development of diverse civilizations as well as providing the basis for the evolution of extraordinary biodiversity. The Mediterranean basin can therefore be considered a global hotspot of endemic vascular plants, and of traditional knowledge of medicinal and aromatic species. This study researches the historical subregion of Marmilla (central-southern Sardinia, Italy), which was chosen because of its specific cultural and demographic characteristics: i.e., prolonged isolation and extreme longevity of the inhabitants of the area. Semi-structured interviews were conducted with 145 people from the region, and 137 medicinal plants belonging to 62 families were identified, of which around 57,3% were taxa exclusive to the Mediterranean Basin. Findings showed that the most used parts of the plant were the leaves (49%), while as far as preparations are concerned, decoction (50%) was the most used to prepare medicinal formulations, making this the highest number of medico-botanical taxa reported in a study carried out in Sardinia using a similar methodology. In addition, this study contributes towards preventing the loss of TBK by documenting the medicinal traditions, passed down orally for centuries, in the words of the participants, shedding new light on the traditional knowledge of the inhabitants of the island. The findings lay the foundations for future applied studies in the fields of phytotherapy and phytochemical investigation.

Cytinus under the Microscope: Disclosing the Secrets of a Parasitic Plant.

Well over 1% of all flowering plants are parasites, obtaining all or part of the nutrients they need from other plants. Among this extremely heterogeneous assemblage, the Cytinaceae form a small group of holoparasites, with Cytinus as the main representative genus. Despite the small number of known species and the fact that it doesn't attack crops or plants of economic importance, Cytinus is paradigmatic among parasitic plants. Recent research has indeed disclosed many aspects of host-parasite interactions and reproductive biology, the latter displaying a vast array of adaptive traits to lure a range of animal pollinators. Furthermore, analysis of biological activities of extracts of the most common species of Cytinus has provided evidence that this plant could be a valuable source of compounds with high potential in key applicative areas, namely food production (nutraceuticals) and the development of antimicrobial therapeutics. This article offers a complete overview of our current knowledge of Cytinus.

Enzyme immobilization on metal organic frameworks: Laccase from Aspergillus sp. is better adapted to ZIF-zni rather than Fe-BTC.

Laccase from Aspergillus sp. (LC) was immobilized within Fe-BTC and ZIF-zni metal organic frameworks through a one-pot synthesis carried out under mild conditions (room temperature and aqueous solution). The Fe-BTC, ZIF-zni MOFs, and the LC@Fe-BTC, LC@ZIF-zni immobilized LC samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The kinetic parameters (KM and Vmax) and the specific activity of the free and immobilized laccase were determined. Immobilized LCs resulted in a lower specific activity compared with that of the free LC (7.7 µmol min-1 mg-1). However, LC@ZIF-zni was almost 10 times more active than LC@Fe-BTC (1.32 µmol min-1 mg-1 vs 0.17 µmol min-1 mg-1) and only 5.8 times less active than free LC. The effect of enzyme loading showed that LC@Fe-BTC had an optimal loading of 45.2 mg g-1, at higher enzyme loadings the specific activity decreased. In contrast, the specific activity of LC@ZIF-zni increased linearly over the loading range investigated. The storage stability of LC@Fe-BTC was low with a significant decrease in activity after 5 days, while LC@ZIF retained up to 50% of its original activity after 30 days storage. The difference in activity and stability between LC@Fe-BTC and LC@ZIF-zni is likely due to release of Fe3+ and the low stability of Fe-BTC MOF. Together, these results indicate that ZIF-zni is a superior support for the immobilization of laccase.

Nucleotide recognition and phosphate linkage hydrolysis at a lipid cubic interface.

Mononucleotides, when entrapped within a mono-olein-based cubic Ia3d liquid crystalline phase, have been found to undergo hydrolysis at the sugar-phosphate ester bond in spite of their natural inertness toward hydrolysis. Here, kinetics of the hydrolysis reaction and interactions between the lipid matrix and the mononucleotide adenosine 5'-monophosphate disodium salt (AMP) and its 2'-deoxy derivative (dAMP) are thoroughly investigated in order to shed some light on the mechanism of the nucleotide recognition and phosphate ester hydrolysis. Experiments evidenced that molecular recognition occurs essentially through the sn-2 and the sn-3 alcoholic OH groups of mono-olein. As deduced from the apparent activation energies, the mechanism underlying the hydrolysis reaction is the same for AMP and dAMP. Nevertheless, the reaction proceeds slower for the latter, highlighting a substantial difference in the chemical behavior of the two nucleotides. A model that explains the hydrolysis reaction is presented. Remarkably, the hydrolysis mechanism appears to be highly specific for the Ia3d phase.

The Anti-Microbial Peptide (Lin-SB056-1)2-K Reduces Pro-Inflammatory Cytokine Release through Interaction with Pseudomonas aeruginosa Lipopolysaccharide.

The ability of many anti-microbial peptides (AMPs) to modulate the host immune response has highlighted their possible therapeutic use to reduce uncontrolled inflammation during chronic infections. In the present study, we examined the anti-inflammatory potential of the semi-synthetic peptide lin-SB056-1 and its dendrimeric derivative (lin-SB056-1)2-K, which were previously found to have anti-microbial activity against Pseudomonas aeruginosa in in vivo-like models mimicking the challenging environment of chronically infected lungs (i.e., artificial sputum medium and 3-D lung mucosa model). The dendrimeric derivative exerted a stronger anti-inflammatory activity than its monomeric counterpart towards lung epithelial- and macrophage-cell lines stimulated with P. aeruginosa lipopolysaccharide (LPS), based on a marked decrease (up to 80%) in the LPS-induced production of different pro-inflammatory cytokines (i.e., IL-1ß, IL-6 and IL-8). Accordingly, (lin-SB056-1)2-K exhibited a stronger LPS-binding affinity than its monomeric counterpart, thereby suggesting a role of peptide/LPS neutralizing interactions in the observed anti-inflammatory effect. Along with the anti-bacterial and anti-biofilm properties, the anti-inflammatory activity of (lin-SB056-1)2-K broadens its therapeutic potential in the context of chronic (biofilm-associated) infections.

Cofactor recycling for selective enzymatic biotransformation of cinnamaldehyde to cinnamyl alcohol.

The enzymatic, selective hydrogenation of cinnamaldehyde to cinnamyl alcohol is reported here. Yeast alcohol dehydrogenase was used in a substrate-coupled process with cofactor recycling. Both 100% selectivity and aldehyde conversion were achieved within 3 h. The reaction took place under very mild conditions, in the absence of toxic organic solvent. The overall process proved inexpensive and deserves further optimization studies in order to evaluate industrial applications.

Assembly of Multicomponent Nano-Bioconjugates Composed of Mesoporous Silica Nanoparticles, Proteins, and Gold Nanoparticles.

The purpose of this work was the assembly of multicomponent nano-bioconjugates based on mesoporous silica nanoparticles (MSNs), proteins (bovine serum albumin, BSA, or lysozyme, LYZ), and gold nanoparticles (GNPs). These nano-bioconjugates may find applications in nanomedicine as theranostic devices. Indeed, MSNs can act as drug carriers, proteins stabilize MSNs within the bloodstream, or may have therapeutic or targeting functions. Finally, GNPs can either be used as contrast agents for imaging or for photothermal therapy. Here, amino-functionalized MSNs (MSN-NH2) were synthesized and characterized through various techniques (small angle X-rays scattering TEM, N2 adsorption/desorption isotherms, and thermogravimetric analysis (TGA)). BSA or lysozyme were then grafted on the external surface of MSN-NH2 to obtain MSN-BSA and MSN-LYZ bioconjugates, respectively. Protein immobilization on MSNs surface was confirmed by Fourier transform infrared spectroscopy, ζ-potential measurements, and TGA, which also allowed the estimation of protein loading. The MSN-protein samples were then dispersed in a GNP solution to obtain MSN-protein-GNPs nano-bioconjugates. Transmission electron microscopy (TEM) analysis showed the occurrence of GNPs on the MSN-protein surface, whereas almost no GNPs occurred in the protein-free control samples. Fluorescence and Raman spectroscopies suggested that proteins-GNP interactions involve tryptophan residues.

Mediterranean shrubs as potential antioxidant sources.

Several Mediterranean shrubs, both autochthonous and naturalized, have been traditionally used as food, flavouring and/or spicing agents, and as phytopharmaceuticals. The interest around 'natural' and 'biological' products is steadily increasing in developed countries. Therefore, it seems reasonable to screen some shrubs with regard to the actual information about their content of phytochemicals, in relation to both real and putative beneficial properties, and with particular concern to their 'antioxidant' power. Moreover, striking molecules from the examined shrubs are compared according to their occurrence in the various genera. Also, their structures and structure/activity relationship are discussed in the light of possible practical application.

Physiological and Phylogenetic Characterization of Rhodotorula diobovata DSBCA06, a Nitrophilous Yeast.

Agriculture and intensive farming methods are the greatest cause of nitrogen pollution. In particular, nitrification (the conversion of ammonia to nitrate) plays a role in global climate changes, affecting the bio-availability of nitrogen in soil and contributing to eutrophication. In this paper, the Rhodotorula diobovata DSBCA06 was investigated for growth kinetics on nitrite, nitrate, or ammonia as the sole nitrogen sources (10 mM). Complete nitrite removal was observed in 48 h up to 10 mM initial nitrite. Nitrogen was almost completely assimilated as organic matter (up to 90% using higher nitrite concentrations). The strain tolerates and efficiently assimilates nitrite at concentrations (up to 20 mM) higher than those previously reported in literature for other yeasts. The best growth conditions (50 mM buffer potassium phosphate pH 7, 20 g/L glucose as the sole carbon source, and 10 mM nitrite) were determined. In the perspective of applications in inorganic nitrogen removal, other metabolic features relevant for process optimization were also evaluated, including renewable sources and heavy metal tolerance. Molasses, corn, and soybean oils were good substrates, and cadmium and lead were well tolerated. Scale-up tests also revealed promising features for large-scale applications. Overall, presented results suggest applicability of nitrogen assimilation by Rhodotorula diobovata DSBCA06 as an innovative tool for bioremediation and treatment of wastewater effluents.

Supercritical CO2 extract of Cinnamomum zeylanicum: chemical characterization and antityrosinase activity.

The volatile oil of the bark of Cinnamomum zeylanicum was extracted by means of supercritical CO2 fluid extraction in different conditions of pressure and temperature. Its chemical composition was characterized by GC-MS analysis. Nineteen compounds, which in the supercritical extract represented >95% of the oil, were identified. (E)-Cinnamaldehyde (77.1%), (E)-beta-caryophyllene (6.0%), alpha-terpineol (4.4%), and eugenol (3.0%) were found to be the major constituents. The SFE oil of cinnamon was screened for its biological activity about the formation of melanin in vitro. The extract showed antityrosinase activity and was able to reduce the formation of insoluble flakes of melanin from tyrosine. The oil also delayed the browning effect in apple homogenate. (E)-Cinnamaldehyde and eugenol were found to be mainly responsible of this inhibition effect.

Aflatoxin B1 and M1 Degradation by Lac2 from Pleurotus pulmonarius and Redox Mediators.

Laccases (LCs) are multicopper oxidases that find application as versatile biocatalysts for the green bioremediation of environmental pollutants and xenobiotics. In this study we elucidate the degrading activity of Lac2 pure enzyme form Pleurotus pulmonarius towards aflatoxin B1 (AFB1) and M1 (AFM1). LC enzyme was purified using three chromatographic steps and identified as Lac2 through zymogram and LC-MS/MS. The degradation assays were performed in vitro at 25 °C for 72 h in buffer solution. AFB1 degradation by Lac2 direct oxidation was 23%. Toxin degradation was also investigated in the presence of three redox mediators, (2,2'-azino-bis-[3-ethylbenzothiazoline-6-sulfonic acid]) (ABTS) and two naturally-occurring phenols, acetosyringone (AS) and syringaldehyde (SA). The direct effect of the enzyme and the mediated action of Lac2 with redox mediators univocally proved the correlation between Lac2 activity and aflatoxins degradation. The degradation of AFB1 was enhanced by the addition of all mediators at 10 mM, with AS being the most effective (90% of degradation). AFM1 was completely degraded by Lac2 with all mediators at 10 mM. The novelty of this study relies on the identification of a pure enzyme as capable of degrading AFB1 and, for the first time, AFM1, and on the evidence that the mechanism of an effective degradation occurs via the mediation of natural phenolic compounds. These results opened new perspective for Lac2 application in the food and feed supply chains as a biotransforming agent of AFB1 and AFM1.

Structure-Activity Relationship Study of Hydroxycoumarins and Mushroom Tyrosinase.

The structure-activity relationships of four hydroxycoumarins, two with the hydroxyl group on the aromatic ring of the molecule and two with the hydroxyl group replacing hydrogen of the pyrone ring, and their interactions with mushroom tyrosinase were studied. These compounds displayed different behaviors upon action of the enzyme. The two compounds, ar-hydroxylated 6-hydroxycoumarin and 7-hydroxycoumarin, were both weak substrates of the enzyme. Interestingly, in both cases, the product of the catalysis was the 6,7-hydroxycoumarin, although 5,6- and 7,8-isomers could also theoretically be formed. Additionally, both were able to reduce the formation of dopachrome when tyrosinase acted on its typical substrate, L-tyrosine. Although none of the compounds that contained a hydroxyl group on the pyrone ring were substrates of tyrosinase, the 3-hydroxycoumarin was a potent inhibitor of the enzyme, and the 4-hydroxycoumarin was not an inhibitor. These results were compared with those obtained by in silico molecular docking predictions to obtain potentially useful information for the synthesis of new coumarin-based inhibitors that resemble the structure of the 3-hydroxycoumarin.

Isolation and characterization of polyphenol oxidase from Sardinian poisonous and non-poisonous chemotypes of Ferula communis (L.).

Ferula communis (L.), a plant belonging to Apiaceae, is widely present in Sardinia, Italy. Currently, interest in F. communis focuses on the presence of two chemotypes in the wild. One chemotype is poisonous to animals, whereas the other chemotype is non-poisonous. Polyphenol oxidase (PPO) has been extracted and partially purified from the two chemotypes of F. communis. The biochemical characterization of the enzymes showed significant differences. In particular, while the two PPOs were not able to use 6- and 7-hydroxycoumarin as substrates, they showed distinct specificity for 6,7- and 7,8-dihydroxycoumarin. Significant differences in the enzyme behavior towards common PPO inhibitors were also observed. In addition, activation energy and activation energy for denaturation were determined, showing significant differences between FP-PPO and FNP-PPO, particularly for denaturation kinetics. The possible roles of the two PPOs in determining differences in composition and toxicity of the two F. communis chemotypes are also discussed.

Evaluation of antioxidant potential of "maltese mushroom" (Cynomorium coccineum) by means of multiple chemical and biological assays.

Cynomorium coccineum is an edible, non-photosynthetic plant widespread along the coasts of the Mediterranean Sea. The medicinal properties of Maltese mushroom - one of the oldest vernacular names used to identify this species - have been kept in high regard since ancient times to the present day. We evaluated the antioxidant potential of fresh specimens of C. coccineum picked in Sardinia, Italy. Both aqueous and methanolic extracts were tested by using multiple assay systems (DPPH, FRAP, TEAC, ORAC-PYR). Total phenolics and flavonoids were also determined. Gallic acid and cyanidin 3-O-glucoside were identified as the main constituents and measured. Both extracts showed antioxidant capacities; ORAC-PYR assay gave the highest antioxidant value in both cases. The methanolic extract was further investigated with in vitro biological models of lipid oxidation; it showed a significant activity in preventing cholesterol degradation and exerted protection against Cu2+-mediated degradation of the liposomal unsaturated fatty acids. Results of the present study demonstrate that the extracts of C. coccineum show a significant total antioxidant power and also exert an in vitro protective effect in different bio-assays of oxidative stress. Therefore, Maltese mushroom can be considered a valuable source of antioxidants and phytochemicals useful in the preparation of nutraceuticals and functional foods.