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22 result(s) for "Valletta, Alessio"
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Remediation of hexavalent chromium contaminated water through zero-valent iron nanoparticles and effects on tomato plant growth performance
Contaminated water with hexavalent chromium Cr(VI) is a serious environmental problem. This study aimed to evaluate the Cr(VI) removal by zero valent iron nanoparticles (nZVI) reduction process and the impact of Cr(VI), nZVI and combined treatment with nZVI and Cr(VI) on tomato growth performance. To evaluate the Cr(VI) toxic effect on germination capability, seeds were exposed to increasing Cr(VI) concentrations up to 1000 mg L −1 . The inhibition of seed germination and the decrease of hypocotyl and root length started from Cr(VI) 5 mg L −1 . Under treatment with Cr(VI) + nZVI 5 mg L −1 , seed germination, hypocotyl and root length resulted significantly higher compared to Cr(VI) 5 mg L −1 treatment. The impact of only nZVI was investigated on chlorophyll and carotenoid in leaves; iron levels in leaves, roots, fruits and soil; carotenoid, fat-soluble vitamin and nicotianamine in mature fruits. A significant increase of leaf chlorophyll and carotenoids was observed after nZVI 5 mg L −1 treatment compared to controls. No significant variations were observed in carotenoids, fat-soluble vitamins and nicotianamine levels after treatment with nZVI 5 mg L −1 in mature fruits. For their ability to reduce Cr(VI) and to stimulate tomato growth, nZVI might to be considered as alternative for remediation purposes.
Impact of Environmental Factors on Stilbene Biosynthesis
Stilbenes are a small family of polyphenolic secondary metabolites that can be found in several distantly related plant species. These compounds act as phytoalexins, playing a crucial role in plant defense against phytopathogens, as well as being involved in the adaptation of plants to abiotic environmental factors. Among stilbenes, trans-resveratrol is certainly the most popular and extensively studied for its health properties. In recent years, an increasing number of stilbene compounds were subjected to investigations concerning their bioactivity. This review presents the most updated knowledge of the stilbene biosynthetic pathway, also focusing on the role of several environmental factors in eliciting stilbenes biosynthesis. The effects of ultraviolet radiation, visible light, ultrasonication, mechanical stress, salt stress, drought, temperature, ozone, and biotic stress are reviewed in the context of enhancing stilbene biosynthesis, both in planta and in plant cell and organ cultures. This knowledge may shed some light on stilbene biological roles and represents a useful tool to increase the accumulation of these valuable compounds.
Rice Phytoalexins: Half a Century of Amazing Discoveries; Part I: Distribution, Biosynthesis, Chemical Synthesis, and Biological Activities
Cultivated rice is a staple food for more than half of the world’s population, providing approximately 20% of the world’s food energy needs. A broad spectrum of pathogenic microorganisms causes rice diseases leading to huge yield losses worldwide. Wild and cultivated rice species are known to possess a wide variety of antimicrobial secondary metabolites, known as phytoalexins, which are part of their active defense mechanisms. These compounds are biosynthesized transiently by rice in response to pathogens and certain abiotic stresses. Rice phytoalexins have been intensively studied for over half a century, both for their biological role and their potential application in agronomic and pharmaceutical fields. In recent decades, the growing interest of the research community, combined with advances in chemical, biological, and biomolecular investigation methods, has led to a notable acceleration in the growth of knowledge on rice phytoalexins. This review provides an overview of the knowledge gained in recent decades on the diversity, distribution, biosynthesis, chemical synthesis, and bioactivity of rice phytoalexins, with particular attention to the most recent advances in this research field.
Anti-Candida Biofilm Activity of Pterostilbene or Crude Extract from Non-Fermented Grape Pomace Entrapped in Biopolymeric Nanoparticles
Polymeric nanoparticle-based carriers are promising agents to deliver drugs to cells. Vitis vinifera phenolic compounds are known for their antifungal activity against Candida albicans. The aim of the present study was to investigate the antifungal activity of pterostilbene or crude extracts from non-fermented grape pomace, entrapped in poly(lactic-co-glycolic) acid nanoparticles (NPs), with diameters of 50 and 150 nm, on Candida biofilm. The fluorescent probe coumarin 6 was used to study the uptake of poly(lactic-co-glycolic)acid (PLGA) NPs in planktonic cells and biofilm. The green fluorescent signal of coumarin 6 was observed in Candida biofilm after 24 and 48 hours. Both pterostilbene and crude pomace extract entrapped in NPs exerted a significantly higher anti-biofilm activity compared to their free forms. The entrapment efficiency of both pterostilbene and crude pomace extract in PLGA NPs was ~90%. At 16 µg/mL, pterostilbene loaded in PLGA NPs reduced biofilm formation of 63% and reduced mature biofilm of 50%. Moreover, at 50 µg/mL, the pomace extract loaded in NPs reduced mature biofilm of 37%. These results strongly suggest that PLGA NPs are promising nanodevices for the delivery of antifungal drugs as the crude grape pomace extract, a by-product of white wine making.
Histology of Pompia Peel and Bioactivity of Its Essential Oil: A New Citrus-Based Approach to Skin Regeneration
Background/Objectives: Pompia is an ancient, endemic citrus ecotype native to Sardinia (Italy), characterized by distinctive morphology and high content of bioactive compounds. Despite increasing interest, several aspects of this fruit, including its histological characteristics, remain poorly understood. This study aims to address this gap by investigating the anatomical features and spatial distribution of secretory cavities involved in essential oil (EO) production and accumulation, while also evaluating the EO’s chemical profile and associated biological activity. Methods: Pompia peel (flavedo and albedo) was subjected to histological analysis through fixation, dehydration, resin inclusion and sectioning. Sections were stained with 0.05% toluidine blue and observed under a light microscope to measure different parameters of secretory cavities. Essential oil (EO) was obtained from Pompia peel by hydrodistillation and characterized by gas chromatography–mass spectrometry (GC–MS) analysis. The biological activity of Pompia EO was assessed in vitro using NIH/3T3 fibroblasts, where wound-healing was evaluated by scratch assay and anti-senescence effects by β-galactosidase and γH2AX activity. Results: Microscopic analysis of the peel revealed pronounced variability in depth and size of the secretory cavities, along with the presence of lenticel-like structures in the epidermis. GC–MS analysis showed that Pompia EO is dominated by limonene (89%), with minor compounds including myrcene, geranial and neral. In vitro biological assays demonstrated that the EO promotes cell migration in a wound-healing model at concentrations ≥ 12.5 µg/mL and reduces markers of cellular senescence, including β-galactosidase activity and γH2AX foci, in etoposide-induced senescent fibroblasts. Conclusions: Overall, this study provides the first histological characterization of Pompia peel and confirms the bioactive potential of its EO. These findings support future applications in skin regeneration and anti-aging strategies and contribute to the valorization of this underexplored Citrus ecotype.
Amino‐Functionalized Carbon Nanodots Inhibit Biofilms and Infections in a Burn Wound Model, Both Caused by Staphylococcus aureus , Escherichia coli , Candida albicans , and Aspergillus brasiliensis
Burn wounds are debilitating injuries that contribute significantly to global morbidity and mortality. The disruption of skin integrity elevates the risk of infection, which can impede healing and potentially lead to sepsis. Furthermore, antibiotic resistance, primarily driven by biofilm formation, poses a major challenge to effective treatment. This study is aimed at evaluating the potential of positively charged carbon dots (CDs) in inhibiting biofilm formation, with possible applications in wound care. Specifically, carbon nanodots (CDs‐NH 2 ) were tested in vitro against both planktonic cells and biofilms formed by a range of pathogens, including the Gram‐positive bacterium Staphylococcus aureus , the Gram‐negative bacterium Escherichia coli , the yeast Candida albicans , and the mold Aspergillus brasiliensis . Additionally, the activity of CDs‐NH 2 was assessed against polymicrobial biofilms composed of S. aureus and C. albicans . The in vivo efficacy of CDs‐NH 2 was evaluated using the Galleria mellonella burn wound infection model for both monomicrobial and polymicrobial infections. The ability of CDs‐NH 2 to penetrate fungal cells was demonstrated by fluorescence microscopy analysis. Biomass quantification showed that CDs‐NH 2 reduced biofilm formation by over 50% for C. albicans , E. coli , and A. brasiliensis , as well as for C. albicans – S. aureus cocultures, at concentrations below 62.5 μ g/mL. The in vivo studies further confirmed the antimicrobial activity of CDs‐NH 2 against all tested strains in burn wound infections. Strategies that target biofilm‐forming microorganisms at wound sites may enhance infection control and promote wound healing.
Enzyme-Based Biostimulants Influence Physiological and Biochemical Responses of Lactuca sativa L
Biostimulants (BSs) are natural materials (i.e., organic or inorganic compounds, and/or microorganisms) having beneficial effects on plant growth and productivity, and able to improve resilience/tolerance to biotic and abiotic stresses. Therefore, they represent an innovative alternative to the phyto- and agrochemicals, being environmentally friendly and a valuable tool to cope with extreme climate conditions. The objective of this study was to investigate the effects of several biomolecules (i.e., Xylanase, β-Glucosidase, Chitinase, and Tramesan), alone or in combinations, on lettuce plant growth and quality. With this aim, the influence of these biomolecules on biomass, pigment content, and antioxidant properties in treated plants were investigated. Our results showed that Xylanase and, to a lesser extent, β-Glucosidase, have potentially biostimulant activity for lettuce cultivation, positively influencing carotenoids, total polyphenols, and ascorbic acid contents; similar effects were found with respect to antioxidative properties. Furthermore, the effect of the more promising molecules (Xylanase and β-Glucosidase) was also evaluated in kiwifruit cultured cells to test their putative role as sustainable input for plant cell biofactories. The absence of phytotoxic effects of both molecules at low doses (0.1 and 0.01 µM), and the significantly enhanced cell biomass growth, indicates a positive impact on kiwifruit cells.
Cell-specific expression of tryptophan decarboxylase and 10-hydroxygeraniol oxidoreductase, key genes involved in camptothecin biosynthesis in Camptotheca acuminata Decne (Nyssaceae)
Background Camptotheca acuminata is a major natural source of the terpenoid indole alkaloid camptothecin (CPT). At present, little is known about the cellular distribution of the biosynthesis of CPT, which would be useful knowledge for developing new strategies and technologies for improving alkaloid production. Results The pattern of CPT accumulation was compared with the expression pattern of some genes involved in CPT biosynthesis in C. acuminata [i.e., Ca-TDC1 and Ca-TDC2 (encoding for tryptophan decarboxylase) and Ca-HGO (encoding for 10-hydroxygeraniol oxidoreductase)]. Both CPT accumulation and gene expression were investigated in plants at different degrees of development and in plantlets subjected to drought-stress. In all organs, CPT accumulation was detected in epidermal idioblasts, in some glandular trichomes, and in groups of idioblast cells localized in parenchyma tissues. Drought-stress caused an increase in CPT accumulation and in the number of glandular trichomes containing CPT, whereas no increase in epidermal or parenchymatous idioblasts was observed. In the leaf, Ca-TDC1 expression was detected in some epidermal cells and in groups of mesophyll cells but not in glandular trichomes; in the stem, it was observed in parenchyma cells of the vascular tissue; in the root, no expression was detected. Ca-TDC2 expression was observed exclusively in leaves of plantlets subjected to drought-stress, in the same sites described for Ca-TDC1 . In the leaf, Ca-HGO was detected in all chlorenchyma cells; in the stem, it was observed in the same sites described for Ca-TDC1 ; in the root, no expression was detected. Conclusions The finding that the sites of CPT accumulation are not consistently the same as those in which the studied genes are expressed demonstrates an organ-to-organ and cell-to-cell translocation of CPT or its precursors.
Endocytic pathways involved in PLGA nanoparticle uptake by grapevine cells and role of cell wall and membrane in size selection
Key message PLGA NPs’ cell uptake involves different endocytic pathways. Clathrin-independent endocytosis is the main internalization route. The cell wall plays a more prominent role than the plasma membrane in NPs’ size selection. In the last years, many studies on absorption and cell uptake of nanoparticles by plants have been conducted, but the understanding of the internalization mechanisms is still largely unknown. In this study, polydispersed and monodispersed poly(lactic-co-glycolic) acid nanoparticles (PLGA NPs) were synthesized, and a strategy combining the use of transmission electron microscopy (TEM), confocal analysis, fluorescently labeled PLGA NPs, a probe for endocytic vesicles (FM4-64), and endocytosis inhibitors (i.e., wortmannin, ikarugamycin, and salicylic acid) was employed to shed light on PLGA NP cell uptake in grapevine cultured cells and to assess the role of the cell wall and plasma membrane in size selection of PLGA NPs. The ability of PLGA NPs to cross the cell wall and membrane was confirmed by TEM and fluorescence microscopy. A strong adhesion of PLGA NPs to the outer side of the cell wall was observed, presumably due to electrostatic interactions. Confocal microscopy and treatment with endocytosis inhibitors suggested the involvement of both clathrin-dependent and clathrin-independent endocytosis in cell uptake of PLGA NPs and the latter appeared to be the main internalization pathway. Experiments on grapevine protoplasts revealed that the cell wall plays a more prominent role than the plasma membrane in size selection of PLGA NPs. While the cell wall prevents the uptake of PLGA NPs with diameters over 50 nm, the plasma membrane can be crossed by PLGA NPs with a diameter of 500–600 nm.