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Biosynthesis of metal oxide nanoparticles via the green approach is an effective and eco-friendly method. The proposed investigation is focused on Zinc oxide nanoparticles (ZnO-NPs) synthesis from methanolic extract of Lawsonia inermis L. seeds. The seed extract contains phytoactive compounds which act as a reductant and stabilizer for the biosynthesis of ZnO-NPs followed by calcination. ZnO-NPs are characterized by different analytical techniques which provide information regarding its surface morphology, the average crystallite size (19 nm), estimation of the functional group involved in nanoparticles (NPs) synthesis. Gas chromatography-mass spectroscopy is helpful in the investigation of variant phytoactive compounds in the methanolic plant extract. UV-visible absorption spectra at 400 nm substantiate the formation of ZnO-NPs. ZnO-NPs is applicable in a wide range which includes fabrication of biosensor, optoelectronics, bio-medicals, etc. [ABSTRACT FROM AUTHOR]

Green synthesis of silver nanoparticles (AgNPs) from Hibiscus sabdariffa (HS) and cytotoxicity was performed. The characteristic UV-Vis. absorption maximum of the material was found at 426 nm. Energy dispersive X-ray analysis ensures the presence of elemental silver. The X-ray diffraction confirms the formation of a face-centered cubic crystal lattice of silver. The transmission electron microscopy along with XRD revealed the nano-dimension of the material (∼24 nm). The Fourier transform infrared analysis depicted the secondary structure of proteins and amino acids in the leaf extract as responsible factors for the reduction of Ag+ to form biomolecules encapsulated stable AgNPs. The results of the cell viability study showed that HSAgNPs didn't bring out any cytotoxicity in PC12 cells until 10 ppm for 48 h of incubation of the nanoparticles, which was further confirmed by the lactate dehydrogenase assay. Thereby, this study may encourage the low-cost production of green-AgNPs and their safe usages. [ABSTRACT FROM AUTHOR]

An ultrasonic irradiation-assisted green approach was developed for the facile preparation of xanthenones and chromenopyrimidinediones using copper chromite nanoparticles (CuCr2O4 NPs) as an efficient heterogeneous catalyst. The desired products were formed by a one-pot three-component reaction of aromatic aldehydes, 3,4-methylenedioxyphenol, and C-H activated acidic compounds including dimedone and 1,3-dimethylbarbituric acid. Various aromatic aldehydes extended the scope and generality of the presented route. Using water as green and nonvolatile solvent and ultrasonic irradiation as an innocuous energy resource, high yields of products within a short reaction time increase the current protocol's economic and environmental superiority. Compounds were evaluated for their antimicrobial inhibition against some selected Gram-positive and Gram-negative bacterial strains. The results showed that the growth of Gram-positive bacteria was highly inhibited by only compounds 5a, 5b, 6d, and 6e, while the rest of test compounds show moderate effects on microbial growth. All test compounds, aside compound 6d, did not display any remarkable growth inhibitory activity against the Gram-negative bacteria. The present study introduces a ground work for the application prospects of ultrasound-based novel, green, and sustainable method for the preparation of some xanthenone and chromenopyrimidinedione derivatives. Copper chromite nanoparticles have appeared as efficacious and reusable catalyst for ultrasonic irradiation treatment in the synthesis of the above-mentioned compounds. The present study establishes that several synthesized compounds show good antimicrobial effects against the standard Gram-positive bacteria Staphylococcus aureus and Streptococcus pyogenes and Gram-negative bacterium Serratia marescens. Due to the best of our knowledge for these previously known compounds, this study is the first report of their promising antimicrobial activity. [ABSTRACT FROM AUTHOR]

Knoevenagel condensation was optimized through the eco-friendly condition as a binary mixture of ethanol:water (3:7, v/v) associated with NaCl salt as the promoter of the reaction between different aldehydes or isatins and malononitrile at room temperature. Due to its high efficiency and low toxicity, the proposed system provides easy isolation of products by simple filtration and optimal yields ranging between 83 and 97% in a short-time reaction at room temperature. [ABSTRACT FROM AUTHOR]

Context:Marrubium vulgareLinn (Lamiaceae) was generally extracted by conventional methods with low yield of marrubiin; these processes were not considered environment friendly. Objective:This study extracts the whole plant ofM. vulgareby microwave assisted extraction (MAE) and optimizes the effect of various extraction parameters on the marrubiin yield by using Central Composite Design (CCD). Materials and methods:The selected medicinal plant was extracted using ethanol: water (1:1) as solvent by MAE. The plant material was also extracted using a Soxhlet and the various extracts were analyzed by HPTLC to quantify the marrubiin concentration. Results:The optimized conditions for the microwave-assisted extraction of selected medicinal plant was microwave power of 539 W, irradiation time of 373 s and solvent to drug ratio, 32 mL per g of the drug. The marrubiin concentration in MAE almost doubled relative to the traditional method (0.69 ± 0.08 to 1.35 ± 0.04%). The IC50for DPPH was reduced to 66.28 ± 0.6 μg/mL as compared to conventional extract (84.14 ± 0.7 μg/mL). The scanning electron micrographs of the treated and untreated drug samples further support the results. Discussion and conclusion:The CCD can be successfully applied to optimize the extraction parameters (MAE) forM. vulgare. Moreover, in terms of environmental impact, the MAE technique could be assumed as a ‘Green approach’ because the MAE approach for extraction of plant released only 92.3 g of CO2as compared to 3207.6 g CO2using the Soxhlet method of extraction. [ABSTRACT FROM PUBLISHER]

A green method for the solvothermal synthesis of copper sulphide nanoparticles (CuS NPs) using xanthan gum as a capping agent was developed. The CuS NPs were characterised by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, Brunauer–Emment–Teller, zeta analysis, thermal gravimetric– differential thermal analysis, Fourier transform infrared and UV–visible absorption spectra. These characterisations together determine the composition, structural, thermal and optical properties. The UV–visible spectrum had a broad absorption in the visible range. The particle size of the products was observed by TEM in the range of 8–20 nm. The photocatalytic performance of the CuS NPs was evaluated for the degradation of organic dyes (methylene blue, rhodamine B, eosin Y and congo red) under irradiation of solar, visible and UV lights. The CuS NPs showed good photocatalytic activity. Kinetic analyses indicate that the photodegradation rates of dyes usually follow pseudo-first-order kinetics for degradation mechanisms. [ABSTRACT FROM AUTHOR]

In recent years, the green approach of nanoparticle synthesis by biological entities has been gaining great interest over various other physico-chemical methods, which are laden with many disadvantages. The important challenging issues in current nanotechnology include the development of reliable experimental techniques for the synthesis of nanoparticles of different compositions and sizes along with high monodispersity. Biological systems offer unique promising features to tailor nanomaterials with predefined properties. Fungi are the favorite choice of microorganisms due to the wide variety of advantages they offer over bacteria, yeast, actinomycetes, plants, and other physico-chemical techniques. The use of microorganisms for the deliberate synthesis of nanoparticles is a fairly new and exciting area of research with considerable potential for further development. This review describes an overview of the current green approaches for the synthesis of nanoparticles with particular emphasis on fungi, which are gaining worldwide popularity as nano-factories for the green synthesis of nanoparticles. [ABSTRACT FROM AUTHOR]

The effect of aqueous ethanol medium on the outcome of a Diels-Alder (DA) reaction with regard to yields, reaction time, and the stereoselectivity observed has been studied. When the reaction between anthrone and (R)-(+)-N-α-methylbenzylmaleimide was carried out in aqueous ethanol in presence of achiral base no diastereoselectivity could be obtained. Moderate diastereoselectivity could be achieved in presence of chiral bases. Use of biodegradable aqueous ethanol solvent for the reaction and stereoselective nature of the reactions studied provide a greener approach. [ABSTRACT FROM AUTHOR]