Asian Journal of Green Chemistry

Abstract In this work, ZnO nanoparticles were synthesized via a simple green method using just plant extract. The synthesized ZnO nanoparticles were characterized using UV–vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence measurements (PL), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Photocatalytic activities of the ZnO nanoparticles were evaluated by degradation of methylene blue under UV radiation. Moreover, the antibacterial activity of the synthesized ZnO nanoparticles against S. aureus, S. paratyphi, V. cholerae, and E. coli were screened.

Abstract Pure anatase TiO₂ nanoparticles with various Ag and Sn contents were synthesized by hydrothermal and sol-gel low-temperature methods. Structural and morphological characterizations of synthesized nanoparticles were performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and N₂ adsorption/desorption isotherm and brunauer-emmett-teller (BET) techniques. The effect of synthesis procedure on the crystalline structure, crystal size, surface area, pore size distribution and photocatalytic activity of synthesized samples were studied. The photocatalytic activity was tested vs. degradation of methylene blue (MB) under black light radiation. Ag/Sn-TiO₂ nanoparticles synthesized by hydrothermal method showed higher photoactivity during the degradation of MB under black light irradiation because of being enhanced in the specific surface area, total pore volume, and its reduction in the crystallite size. An artificial neural network (ANN) comprising four input variables (mol% of dopant ions, photocatalyst dosage, initial dye concentration, and pH of the solution), eight neurons and an output variable (degradation efficiency %) was optimized, tested and validated for MB degradation by Ag/Sn-TiO₂ nanoparticles synthesized via hydrothermal method. The results showed that the predicted data from the designed ANN model are in good agreement with the experimental data with a correlation coefficient (R²) of 0.979. A 98.9% photodegradation efficiency of MB was achieved by utilizing 0.07 mol% Ag and 0.03 mol% Sn co-doped TiO₂ at pH = 12.

Abstract The plant sources can act as potential precursors for the synthesis of nanoparticles in non-hazardous ways as plants contain various secondary metabolites, acting as reducing and stabilizing agents for the reduction reaction to synthesize novel metallic nanoparticles. The green synthesized nanoparticles have been proven to control various diseases with less adverse effect. Thus, in this study, the green method for the preparation of cadmium sulfide nanoparticles using Panicum sarmentosum has been adopted. The synthesized CdSNPs were evaluated for their optical, structural, surface morphological and antibacterial properties. The CdSNPs were characterized by different techniques including UV–vis spectrophotometry, fourier transmission infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), X-ray fluorescence (XRF) and thermal gravimetric analysis (TGA). The antibacterial activity against Staphylococcus aureus and Escherichia coli was also carried out. The XRD pattern revealed the crystalline structure of CdSNPs. The SEM analysis showed the size and shape of the nanoparticles. XRF analysis confirmed the presence of cadmium and sulphur in nanoparticles. The presence of (OH), (NH) and carboxylic functional groups were confirmed by FTIR analysis. TGA results prove that CdSNPs are more thermally stable than plant material. The ecological friendly methods can generate simple, easy and cost-effective nanoparticles than chemical and physical approaches and have a potential to be used as antibacterial agents.

Abstract This work describes the synthesis of complex small molecules spirooxindoles using imidazole as an efficient organocatalyst. The three components coupling reactions of isatin, malononitrile and enolizable 4-hydroxycoumarin were performed in water as a green solvent. The reaction is done with imidazole an amphoteric organocatalyst to construct spiro-molecules in high yields. The significant features of this protocol are neutral reaction condition, readily available low cost catalyst, metal free, strong acid/base free, and reusable reaction medium with no column chromatography separation. This methodology is useful for the easy access of structurally complex, highly functionalized spirooxindole molecules with important medicinal chemistry applications.

Abstract A convenient and environmentally-friendly protocol for the preparation of imidazol-1-yl-acetic acid hydrochloride is described via solvent-free N-alkylation of imidazole by tert-butyl chloroacetate,  the obtained imidazol-1-yl-acetic acid tert-butyl ester was hydrolyzed in water and treated with hydrochloric acid to get imidazol-1-yl-acetic acid hydrochloride in good yields. Unlike the previously reported methods, this two step process is completely free from the use of hazardous solvents, besides, it has high yielding and been characterized by simple and easy work-up procedure. Imidazol-1-yl-acetic acid hydrochloride produced by the described method is converted into zoledronic acid monohydrate of medicinal use.

Abstract The present communication warrants the presence of significant anti-melanoma bioefficacy in the native bark ethanolic extract (65.15%) of the plant Madhuca longifolia. A family of seven flavonoids has been ascertained in the bark ethanolic extract of the target plant using HPLC-ESI-QTOF-MS analysis as bioactive constituents. Statistically, significant (p <0.05)enhancement in the anti-melanoma bioefficacy (85.15%) has been successfully attempted, reaching near to the level of reference (Cyclophosphamide drug) using bioactive principle (flavonoid) loaded gold nanoparticles (F@AuNp). In vitro anti-melanoma bioefficacy has been measured against two melanoma cell lines (B16F10 and A375) using MTT and SRB bioassays. Noticeably, the native bark extract and F@AuNp  did not show any toxicity towards normal lymphocyte cells, highlighting their safe and non-toxic nature. The pathway of observed anti-melanoma efficacy of (F@AuNp) has been discussed based on our experimental findings on percent inhibition in mice and human melanoma cell lines, production of intracellular reactive oxygen species, the release of nitric oxide, and increase caspase-3 activities. The native bark extract of the plant M. longifolia and its bioactive principle loaded gold nanoparticles possess bright prospects for the development of complimentary herbal nanomedicine for scaling-up the anti-melanoma bioefficacy.

Abstract A series of azomethine and aminomethyl phenol derivatives has been synthesized and characterized by mass, IR, and NMR spectral techniques.In vitro antimicrobial activities of all these compounds were evaluated against different gram-positive and gram-negative bacterial and fungal strains by measuring zone of inhibition using agar diffusion method. Results of antimicrobial screening indicated that the compound 4a was the most active antimicrobial agent (100 µg/mL). The compounds 3a, 4e, 4f were exhibited best in vitro anti-microbial activity against the gram positive bacterial strains such as Bacillus subtilis, Micrococcus luteus and gram negativebacterialstrain Salmonella typhi andfungalstrain Candida albicans.

Abstract The hemagglutination assay is a simple and easy method to specify a lectin. An activelectinagglutinates erythrocytes by recognizing a carbohydrate on the cell surface and forming a cross-linked network in suspension. The assay is traditionally performed on a microtiter plate, where the lectin solution is serially diluted and the minimum concentration of a lectin causing agglutination is detected. The crude extract of Senna occidentalis and Sesbania bispinosa seedscontain considerable amount of protein. It was found that 10 gm of Sesbania bispinosaand Senna occidentalis seeds contain about 12.6 mg/mL and 9.8 mg/mL of protein and minimum agglutination concentration was found to be 0.393 mg/mL for Sesbania bispinosa in each group of human erythrocytes (A, B, O and AB) and 0.613 mg/mL for Senna occidentalis in chicken erythrocytes. Finally, the hemagglutination assay confirmed that possible lectins have been presented in the Sesbania bispinosa and Senna occidentalisplant sources.

Abstract Fe₃O₄ magnetic nanoparticles (Fe₃O₄ MNPs) were prepared and used as an eco-friendly, reusable, low-cost and efficient catalyst for the synthesis of 2,4,5-trisubstituted imidazoles via three-component reaction of aromatic aldehydes with benzil and ammonium acetate under low power microwave irradiation and solvent-free condition. This one-pot procedure is very simple with good to excellent yields. Easy separation of Fe₃O₄ MNPs from the reaction mixture by an external magnet and the reusability of the catalyst are the considerable points of the reaction.

Abstract A new sorbent was provided and exerted for separation and preconcentration of Pb (II) before the determination of lead ions by flame atomic absorption spectrometry. The normative studies on extraction, separation and preconcetration of Pb (II) were represented in the present work. This novel method was based on new sorbent by adding diethylenetriamine to sawdust and increasing incidence exterior. The effect of different parameters were studied; such as pH, ligand concentration and sample volume, type and volume of eluent and ligand effect. The optimum pH and preconcentration factor and limit of detection for Pb (II) were 4, 100 and 0.48 µg/L, respectively. Furthermore, in this approach calibration curve was linear in the range of 0.05-100 mg mL^-1 with R² = 0.995. The vertical and horizontal confines of calibration diagrams in 500 mL solution were calculated about 0-0.5 mg L^-1 and 0-0.6. The results of applying the present  method to determinate the separated lead ions in water samples were prosperous and harmonious. Precision of the method was investigated by comparing them with observations from previous similar researches.