Multifunctional Ag2O/chitosan nanocomposites synthesized via sol-gel with enhanced antimicrobial, and antioxidant properties: A novel food packaging material.

In this study, a single step in situ sol-gel method was used to syntheses nanocomposite films using chitosan (CS) as the basis material, with the addition of silver oxide nanoparticles (Ag2O) at several weight percentages (5 %, 10 %, and 15 % Ag2O/CS). The structural characteristics of Ag2O/CS films were investigated using a range of analytical techniques. The presence of the primary distinctive peaks of chitosan was verified using FTIR spectra analysis. However, a minor displacement was observed in these peaks due to the chemical interaction occurring with silver oxide molecules. XRD analysis demonstrated a significant increase in the crystallinity of chitosan when it interacted with metal oxide nanoparticles. Furthermore, it is believed that the interaction between silver oxide and the active binding sites of chitosan is responsible for the evenly dispersed clusters shown in the micrographs of the chitosan surface, as well as the random aggregations within the pores. EDS technique successfully identified the presence of distinctive silver signals within the nanocomposite material, indicating the successful absorption of silver into the surface of the polymer. The developed Ag2O/CS nanocomposite showed promising antibacterial activity against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Bacillus subtilis, Enterococcus faecalis and Staphylococcus aureus). Also, Ag2O/CS nanocomposite exhibited marked antifungal activity against Candida albicans, Aspergillus flavus, A. fumigatus, A. niger, and Penicillium chrysogenum. The antioxidant activity of the developed nanocomposite films was studied by ABTS radical scavenging. The highest antioxidant and antibacterial properties were achieved by including 15 % silver oxide into the chitosan. Therefore, our finding indicate that chitosan­silver oxide nanocomposites exhibits significant potential as a viable material for application in several sectors of the food packaging industry.

Preparation, Characterization, Dielectric Properties, and AC Conductivity of Chitosan Stabilized Metallic Oxides CoO and SrO: Experiments and Tight Binding Calculations.

Polymeric films made from chitosan (CS) doped with metal oxide (MO = cobalt (II) oxide and strontium oxide) nanoparticles at different concentrations (5, 10, 15, and 20% wt. MO/CS) were fabricated with the solution cast method. FTIR, SEM, and XRD spectra were used to study the structural features of those nanocomposite films. The FTIR spectra of chitosan showed the main characteristic peaks that are usually present, but they were shifted considerably by the chemical interaction with metal oxides. FTIR analysis of the hybrid chitosan-CoO nanocomposite exhibited notable peaks at 558 and 681 cm-1. Conversely, the FTIR analysis of the chitosan-SrO composite displayed peaks at 733.23 cm-1, 810.10 cm-1, and 856.39 cm-1, which can be attributed to the bending vibrations of Co-O and Sr-O bonds, respectively. In addition, the SEM graphs showed a noticeable morphological change on the surface of chitosan, which may be due to surface adsorption with metal oxide nanoparticles. The XRD pattern also revealed a clear change in the crystallinity of chitosan when it is in contact with metal oxide nanoparticles. The presence of characteristic signals for cobalt (Co) and strontium (Sr) are clearly shown in the EDX examinations, providing convincing evidence for their incorporation into the chitosan matrix. Moreover, the stability of the nanoparticle-chitosan coordinated bonding was verified from the accurate and broadly parametrized semi-empirical tight-binding quantum chemistry calculation. This leads to the determination of the structures' chemical hardness as estimated from the frontier's orbital calculations. We characterized the dielectric properties in terms of the real and imaginary dielectric permittivity as a function of frequency. Dielectric findings reveal the existence of extensive interactions of CoO and SrO, more pronounced for SrO, with the functional groups of CS through coordination bonding. This induces the charge transfer of the complexes between CoO and SrO and the CS chains and a decrease in the amount of the crystalline phase, as verified from the XRD patterns.

Inhibitory Action of Date Palm (Phoenix dactylifera L.) Leaf Extract on Pancreatic Lipase and α-Amylase Activities.

<b>Background and Objective:</b> Cardiovascular Diseases (CVDs) remain the main cause of mortality globally. High cholesterol levels (hypercholesterolemia) and high blood glucose (diabetes) are among the factors that increase the risk for CVDs. Application of inhibitors for the digestive enzymes accountable for the macronutrient hydrolysis, such as carbohydrates and fats, is one of the prevalent approaches in the development of medications against CVDs. The present study was performed to examine, <i>in vitro</i>, the lipase and amylase inhibitory potential of phenolic rich extract of leaves of four date palm cultivars. <b>Materials and Methods:</b> In the current study, the research investigated the potentiality of phytochemicals extracted from leaves of four date palm cultivars (Rawthan, Rabeaa, Barny and Ajwa), collected from Al-Madinah Governorate as lipase and amylase inhibitors and as antioxidants. Moreover, the total contents of flavonoids and phenolics were assessed. <b>Results:</b> The results revealed that all the tested cultivars showed promising lipase and amylase inhibition and antioxidants capacities. However, Rawthan and Ajwa were the most powerful cultivars. <b>Conclusion:</b> Therefore, the results presented herein suggest as the earliest report, the potential use of date palm leaves as a potential source for lipase and amylase inhibitors as an approach to decrease the risk for CVDs.

Interactive effects of mercuric oxide nanoparticles and future climate CO2 on maize plant.

So far, the phytotoxic hazards of nano-sized mercuric oxide (HgO-NPs) are not investigated. Herein, the phytotoxicity of fully characterized HgO-NPs (100 mg/kg soil), prepared by coprecipitation method, on maize grown under ambient (aCO2, 410 ppm) and elevated CO2 (eCO2, 620 ppm) was investigated. Regardless of CO2 concentration, HgO-NPs treatment increased Hg levels in maize organs. HgO-NPs induced severe oxidative stress in aCO2 grown plants as indicated by reduced growth and photosynthesis and accumulation of reactive oxygen species (ROS), through photorespiration and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activities, and lipid and protein oxidation products. Although HgO-NPs increased molecular (polyphenols, flavonoids, tocopherols) and enzymatic (superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, glutathione peroxidase) antioxidants in shoots of aCO2 plants, but this failed to fight the eruption of increased ROS. On contrary, eCO2 treatment mitigated the HgO-NPs impact by promoting photosynthesis and reducing the Hg-induced ROS production. Moreover, eCO2 promoted ROS detoxification via molecular antioxidants overproduction, enhanced superoxide dismutase, catalase and peroxidases activities, and modulation of reduced ascorbate/oxidized ascorbate and reduced glutathione/oxidized glutathione homeostasis. The combined HgO-NPs + eCO2 treatment also enhanced the glutathione-S-transferase activity. This study suggests that HgO-NPs cause severe phytotoxic hazards and this effect will be less detrimental under future CO2 climate.

Interactive Impact of Arbuscular Mycorrhizal Fungi and Elevated CO2 on Growth and Functional Food Value of Thymus vulgare.

Arbuscular mycorrhizal fungi (AMF) and elevated CO2 (eCO2) have been effectively integrated to the agricultural procedures as an ecofriendly approach to support the production and quality of plants. However, less attention has been given to the synchronous application of AMF and eCO2 and how that could affect the global plant metabolism. This study was conducted to investigate the effects of AMF and eCO2, individually or in combination, on growth, photosynthesis, metabolism and the functional food value of Thymus vulgare. Results revealed that both AMF and eCO2 treatments improved the photosynthesis and biomass production, however much more positive impact was obtained by their synchronous application. Moreover, the levels of the majority of the detected sugars, organic acids, amino acids, unsaturated fatty acids, volatile compounds, phenolic acids and flavonoids were further improved as a result of the synergistic action of AMF and eCO2, as compared to the individual treatments. Overall, this study clearly shows that co-application of AMF and eCO2 induces a synergistic biofertilization impact and enhances the functional food value of T. vulgare by affecting its global metabolism.

Global metabolic changes induced by arbuscular mycorrhizal fungi in oregano plants grown under ambient and elevated levels of atmospheric CO2.

Symbiotic plant-microorganisms interaction is a promising approach to avoid the environmental hazards of synthetic fertilizers and pesticides. Among these, arbuscular mycorrhizal fungi (AMF) are known to improve the growth and quality of many plant species; however the detailed metabolic mechanisms behind such beneficial effects are far from complete. Further, elevated levels of atmospheric CO2 (eCO2) could affect such AMF-plant association. Herein, we have investigated the individual and synchronous impact of AMF and eCO2 (620 ppm) on nutrient uptake, growth, photosynthesis, respiration, and levels of primary and secondary metabolites in oregano (Oreganum vulgare), an economically important herbal plant. Enhanced AMF colonization rate and a better mycelial growth were observed in roots of oregano grown under eCO2. Both AMF and eCO2 treatments significantly enhanced the growth and photosynthesis of oregano plants, however much improvements were observed by their synchronous application. eCO2 further increased the AMF-induced dark respiration and accumulation of macro and microelements. Hierarchical clustering analysis of individual primary and secondary metabolites revealed a metabolite-dependent response toward AMF and eCO2. The synchronous application of AMF and eCO2 resulted in promoted accumulation of the majority of the detected sugars, organic acids, amino acids, unsaturated fatty acids, phenolic acids and flavonoids, as compared with the sole treatments. Moreover, AMF and eCO2 acted synergistically in improving the antioxidant capacity and anti-lipid peroxidation activity of oregano. Therefore, this study suggests that AMF treatment induces a global metabolic change in oregano, the effect that is strengthened under eCO2.

Provenance effect on bioactive phytochemicals and nutritional and health benefits of the desert date Balanites aegyptiaca.

Balanites aegyptiaca L. is a multipurpose tree distributed in Africa and Middle East. Several parts of B. aegyptiaca have been suggested to have medicinal uses. So far the effect of ecological origin on the nutritional values and biological activities of B. aegyptiaca genotypes is rarely investigated. Further, metabolic profiling and assessment of the functional food value of B. aegyptiaca leaves are far from complete. In this study, biological activities and profiling of primary and secondary metabolites were investigated in the leaves of five B. aegyptiaca provenances collected from Egypt, Sudan, Saudi Arabia, and Yemen. Interestingly, all provenances showed notable antidiabetic, antioxidant, antiprotozoal, antibacterial, antifungal, and anticancer activities. Hierarchical clustering analysis revealed significant variability in the concentrations of individual sugars, organic acids, amino acids, fatty acids, vitamins, phenolics, and minerals among the provenances and these variations were provenance dependent. Medina provenance showed the heights diphenylpicrylhydrazyl (DPPH) scavenging and antifungal activities and was the most powerful against embryonic kidney adenocarcinoma and urinary bladder carcinoma cells. The highest inhibition against Escherichia coli and colon carcinoma cells was observed by Sudan and Cairo provenances. El-Kharga and Yemen provenances showed the greatest activity against Trypanosoma cruzi and hepatocellular and urinary bladder carcinoma. Therefore, leaves of B. aegyptiaca possess good nutritive and biological capacities and might have potential applications in the food and medical industries. However, the strength of such activities is significantly affected by the provenance. PRACTICAL APPLICATIONS: According to the national Research Council (NRC) of United States, Balanites aegyptiaca L. is recognized among the 24 priority lost crops of Africa. B. aegyptiaca leaves contain considerable amounts of primary metabolites (e.g., sugars, EAAs, USFAs) and secondary (e.g., phenolic acids and flavonoids) metabolites, vitamins, and macro and microelements. The obvious existence of these nutritionally and medicinally related compounds supports the functional food value of B. aegyptiaca leaves. Moreover, the present results revealed that B. aegyptiaca is not only a foliage dietary plant, but also could be considered as a valuable source for neutraceuticals, which support its pharmacological value. So far, this is the first report to explore, in detail, the functional food value of B. aegyptiaca leaves by presenting a clear image about its metabolic profiling and biological activities, and how the provenance factor could affect these values.

CO2 treatment improves the hypocholesterolemic and antioxidant properties of fenugreek seeds.

A high level of serum cholesterol is a major cause of atherosclerosis. Fenugreek is a well-known hypocholesterolaemic agent with amazing phytochemical composition. Due to its impact on plant metabolism, CO2 enrichment was tested as a strategy to support functional values in fenugreek seeds. Phytochemical composition and biological activities of three fenugreek cultivars (G2, G6 and G30) grown under ambient (aCO2, 400 µmol mol-1) and elevated CO2 (eCO2, 620 µmol mol-1) were assessed. Applying eCO2 improved physical parameters of fenugreek seeds, and enhanced their biological activities. A significant increase in hypocholesterolaemic potential, as indicated by inhibition of cholesterol micellar solubility and pancreatic lipase activity, was recorded. In addition, antioxidant, anti-lipid peroxidation and antibacterial activities were improved. These enhanced biological activities were accompanied by improved seed chemical composition at the primary and secondary metabolic levels. Therefore, eCO2 treatment represents an efficient strategy to increase the hypocholesterolaemic, antioxidant and antibacterial activities of fenugreek seeds.

Silicon dioxide nanoparticles ameliorate the phytotoxic hazards of aluminum in maize grown on acidic soil.

Aluminum (Al) toxicity is a major constraint for crop production in acid soils. Therefore, looking for sustainable solutions to increase plant tolerance to Al toxicity is needed. Although several studies addressed the potential utilization of silica or silicon dioxide nanoparticles (SNPs) to ameliorate heavy metal phytotoxicity, the exact mechanisms underlying SNPs-induced stress tolerance are still unknown. The current study investigated how SNPs could mitigate Al toxicity in maize plants grown on acidic soil. The impact of Al alone or in combination with SNPs on Al accumulation and detoxification, plant growth, photosynthetic C assimilation and redox homeostasis has been investigated. Al accumulation in stressed-maize organs reduced their growth, decreased photosynthesis related parameters and increased production of reactive oxygen species, through induced NADPH oxidase and photorespiration activities, and cell damage. These effects were more pronounced in roots than in leaves. SNPs ameliorated Al toxicity at growth, physiological and oxidative damage levels. Co-application of SNPs significantly reduced the activities of the photorespiratory enzymes and NADPH oxidase. It stimulated the antioxidant defense systems at enzymatic (superoxide dismutase, catalase, ascorbate and glutathione peroxidases) and non-enzymatic (ascorbate, glutathione, polyphenols, flavonoids, tocopherols, and FRAP) levels. Moreover, SNPs increased organic acids accumulation and metal detoxification (i.e. glutathione-S-transferase activity) in roots, as a protective mechanism against Al toxicity. The SNPs induced-protective mechanisms was dependent on the applied Al concentration and acted in organ-specific manner. Overall, the current study suggests the promising application of SNPs as an innovative approach to mitigate Al phytotoxicity in acidic soils and provides a comprehensive view of the cellular and biochemical mechanisms underlying this mitigation capacity.

Actinobacterium isolated from a semi-arid environment improves the drought tolerance in maize (Zea mays L.).

Drought represents a major constraint for agricultural productivity and food security worldwide. Plant growth promoting actinobacteria have attracted the attention as a promising approach to enhance plant growth and yield under stressful conditions. In this regard, bioprospecting in arid and semi-arid environments could reveal uncommon bacteria with improved biological activities. In the present study, the ability of actinobacteria isolated from a semi-arid environment (Saudi Arabia) to mitigate the negative impact of drought on growth and physiology of maize, a drought-sensitive crop, has been investigated. Among the different actinobacterial isolates screened for secondary metabolites production and biological activities, isolate Ac5 showed high ability of flavonoid, phytohormones and siderophores production. Moreover, Ac5 improved the growth and photosynthesis and induced a global metabolic change in the bacterized plants under water-deficit conditions. Interestingly, Ac5 treatment significantly mitigated the detrimental effects of drought stress on maize. Reduced H2O2 accumulation and lipid peroxidation accompanied with higher levels of molecular antioxidants (total ascorbate, glutathione, tocopherols, phenolic acids and flavonoids) were observed in the bacterized plants. From the osmoregulation point of view, drought-stressed bacterized maize accumulated higher levels of compatible solutes, such as sucrose, total soluble sugars, proline, arginine and glycine betaine, as compared with the non-bacterized plants. Therefore, this study highlights the comprehensive impact of actinobacteria on the global plant metabolism and suggests the potential utilization of actinobacteria isolated from semi-arid environments to mitigate the negative impact of drought on crop plants.