A comprehensive review of anticancer, immunomodulatory and health beneficial effects of the lactic acid bacteria exopolysaccharides.

The employment of nanoparticles obtained through various synthesis routes as novel pesticides recently attracted high research attention. An impressive number of studies have been conducted to test their toxic potential against a wide number of arthropod pests and vectors, with major emphasis on mosquitoes and ticks. However, precise information on the mechanisms of action of nanoparticles against insects and mites are limited, with the noteworthy exception of silica, alumina, silver, and graphene oxide nanoparticles on insects, while no information is available for mites. Here, I summarize current knowledge about the mechanisms of action of nanoparticles against insects. Both silver and graphene oxide nanoparticles have a significant impact on insect antioxidant and detoxifying enzymes, leading to oxidative stress and cell death. Ag nanoparticles also reduced acetylcholinesterase activity, while polystyrene nanoparticles inhibited CYP450 isoenzymes. Au nanoparticles can act as trypsin inhibitors and disrupt development and reproduction. Metal nanoparticles can bind to S and P in proteins and nucleic acids, respectively, leading to a decrease in membrane permeability, therefore to organelle and enzyme denaturation, followed by cell death. Besides, Ag nanoparticles up- and downregulate key insect genes, reducing protein synthesis and gonadotrophin release, leading to developmental damages and reproductive failure. The toxicity of SiO2 and Al2O3 nanoparticles is due to their binding to the insect cuticle, followed by physico-sorption of waxes and lipids, leading to insect dehydration. In the final section, insect nanotoxicology research trends are critically discussed, outlining major challenges to predict the ecotoxicological consequences arising from the real-world use of nanoparticles as pesticides.

Mode of action of nanoparticles against insects

Introduction: In recent years, multidrug resistance (MDR) in bacteria has drastically increased and has posed a great threat to the human health. This problem has generated an urgent need to search alternatives for the treatment of MDR bacteria. It has been proved that metal nanoparticles (MNPs) and metal nanocomposites (MNCs) possess remarkable antimicrobial potential, and hence can be used in alternative therapy. Areas covered: This review is aimed to discuss recent reports on antibacterial activities of MNPs and MNCs against MDR bacteria. Expert opinion: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Serratia marcescens, Streptococcus pneumoniae, and Staphylococcus epidermidis are important pathogenic bacteria which have shown MDR against a wide range of conventional antibiotics. In this context, effects of MNPs and MNCs on these pathogens have demonstrated considerable efficacy. Several mechanisms concerning activity of MNPs and MNCs against pathogenic bacteria which are mainly dependent on type of their precursors and treated bacterium have been investigated. In addition, many studies have been made on antibacterial activities of these nanomaterials with similar and different results.

Recent advances in antibacterial applications of metal nanoparticles (MNPs) and metal nanocomposites (MNCs) against multidrug-resistant (MDR) bacteria

Here, we report the novel fabrication of ZnO nanoparticles using the Costus igneus leaf extract. Gas chromatography-mass spectrometry (GC–MS) and proton nuclear magnetic resonance ( 1 H NMR) spectroscopy to determine the bioactive components present in the plant extract. The synthesis of Ci -ZnO NPs ( C. igneus - coated zinc oxide nanoparticles) was accomplished using a cost-effective and simple technique. Ci -ZnO NPs were specified using UV–visible spectroscopy, FTIR, XRD, and TEM. Ci -ZnO NPs was authenticated by UV–Vis and exhibited a peak at 365 nm. The XRD spectra proved the crystalline character of the Ci -ZnO NPs synthesized as hexagonal wurtzite. The FTIR spectrum illustrated the presence of possible functional groups present in Ci -ZnO NPs. The TEM micrograph showed evidence of the presence of a hexagonal organization with a size of 26.55 nm typical of Ci -ZnO NPs. The α-amylase and α-glucosidase inhibition assays demonstrated antidiabetic activity of Ci -ZnO NPs (74 % and 82 %, respectively), and the DPPH [2,2-diphenyl-1-picrylhydrazyl hydrate] assay demonstrated the antioxidant activity of the nanoparticles (75%) at a concentration of 100 μg/ml. The Ci -ZnO NPs exhibited promising antibacterial and biofilm inhibition activity against the pathogenic bacteria Streptococcus mutans , Lysinibacillus fusiformis , Proteus vulgaris , and Vibrio parahaemolyticus . Additionally, the Ci -ZnO NPs showed biocompatibility with mammalian RBCs with minimum hemolytic activity (0.633 % ± 0.005 %) at a concentration of 200 μg/ml.

Synthesis of ZnO nanoparticles using insulin-rich leaf extract: Anti-diabetic, antibiofilm and anti-oxidant properties.

The emergence of bacterial resistance to antibiotics has led to the search for alternate antimicrobial treatment strategies. Engineered nanoparticles (NPs) for efficient penetration into a living system have become more common in the world of health and hygiene. The use of microbial enzymes/proteins as a potential reducing agent for synthesizing NPs has increased rapidly in comparison to physical and chemical methods. It is a fast, environmentally safe, and cost-effective approach. Among the biogenic sources, fungi and bacteria are preferred not only for their ability to produce a higher titer of reductase enzyme to convert the ionic forms into their nano forms, but also for their convenience in cultivating and regulating the size and morphology of the synthesized NPs, which can effectively reduce the cost for large-scale manufacturing. Effective penetration through exopolysaccharides of a biofilm matrix enables the NPs to inhibit the bacterial growth. Biofilm is the consortia of sessile groups of microbial cells that are able to adhere to biotic and abiotic surfaces with the help extracellular polymeric substances and glycocalyx. These biofilms cause various chronic diseases and lead to biofouling on medical devices and implants. The NPs penetrate the biofilm and affect the quorum-sensing gene cascades and thereby hamper the cell-to-cell communication mechanism, which inhibits biofilm synthesis. This review focuses on the microbial nano-techniques that were used to produce various metallic and non-metallic nanoparticles and their "signal jamming effects" to inhibit biofilm formation. Detailed analysis and discussion is given to their interactions with various types of signal molecules and the genes responsible for the development of biofilm.

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Microbiologically-Synthesized Nanoparticles and Their Role in Silencing the Biofilm Signaling Cascade.

Bacterial exopolysaccharide (EPS)-coated ZnO nanoparticles showed high antibiofilm activity and larvicidal toxicity against malaria and Zika virus vectors.

The objective of the present study was to investigate the presence of various phytochemicals from ethanol, ethyl acetate, methanol and chloroform extracts of Aerva lanata (whole plant) , leaves of Adathoda vasica, Pisonia alba, Sesbania grandiflora and Indigofera aspalathoides . The phytochemical analysis showed the presence of tannins, flavonoids, alkaloids, terpenoids, glycosides, saponins, resins, carbohydrates and proteins. The whole plant of A. lanata showed the presence of flavonoids, terpenoids, glycosides, carbohydrates and proteins. Flavonoids, alkaloids, terpenoids, glycosides, resins, carbohydrates and proteins are found in the leaves of Adathoda vasica . Flavonoids, glycosides and resins were found in the leaves of Pisonia alba . No phytochemical constituents were found in the chloroform extract of Pisonia alba leaves. Ethanol and methanol leaf extracts from Sesbania grandiflora and methanol leaf extract from Indigofera aspalathoides indicated that they contained most of the phytochemical compounds. The different extracts of plants have clearly indicated the presence of all the major phytochemicals, hence these plants can be used for the extraction of bioactive compounds.

Aruna Sharmili

Papers

Bacterial exopolysaccharide (EPS)-coated ZnO nanoparticles showed high antibiofilm activity and larvicidal toxicity against malaria and Zika virus vectors.

PHYTOCHEMICAL ANALYSIS OF Aerva lanata, Adathoda vasica, Pisonia alba, Sesbania grandiflora AND Indigofera aspalathoides