Catalytic hydrogenation of organic dyes by Ag nanoparticles on reduced graphene oxide

Bruno C. Mascarenhas,Laudemir C. Varanda 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.103 No.-

Stable, efficient, and reusable catalysts for wastewater treatment, promoting the catalytic elimination ofenvironmental pollutants remains a current challenge. This work shows a one-pot synthesize Agnanoparticles (AgNPs) supported on reduced graphene oxide (rGO/Ag) as a nanocatalyst. Morphological control of AgNPs was achieved by adding NH4OH during the nucleation and growth processesleading to the spherical nanoparticles with average size of 9 ± 3 nm). Temperature increase promotesdecrease of the oxygenated functional groups on rGO sheets, with an ID/IG = 0.57 at 300 C. Catalyticactivity of rGO/Ag was investigated through the catalytic hydrogenation of methylene blue (MB) and rhodamineB (RhB) in the presence of NaBH4 as a reducing agent. The proposed mechanism is based on thetransfer of 2e and 1H+ between the nanocatalyst and the dye molecules. Dyes adsorption on the catalystis a rate-determining step and was accelerated by the rGO support. X-ray photoelectron spectroscopyanalysis before and after successive catalytic cycles indicated that the catalyst integrity was maintained,with a slight decrease in the silver amount from 4.53 to 3.78 at%. The decolorization reaction followed thepseudo-first-order kinetics model for both dyes, and our results showed an efficiency of around 30%higher than similar methods.

Performance Evaluation a Combined Transition System in Slab-Ballasted Railway Track Using a Vehicle-Track-Substructure Interaction Model

Hamidreza Heydari-Noghabi,José Nuno Varandas,Jabbar Ali Zakeri,Morteza Esmaeili 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.9

Abrupt stiffness variations along the railway track may increase the geometrical and mechanical defects of railway lines. The conjunction points of a railway track with concrete and ballast pavements, which are called slab-ballasted track transitions, are one of the main areas where vertical track stiffness changes sharply. Therefore, the potential benefits of a combined transition system along the slab-ballasted transition, made of an approach slab and additional rails, are studied in this paper. For this purpose, a vehicle-track-substructure interaction model, which included three main segments of the railway track (slab track, transition zone, and ballasted track) was programmed based on the finite element method. A test line with the mentioned combined transition system was built to measure the railway track responses through field study. Then, the three-dimensional (3D) numerical model was validated using the results obtained from the experimental tests. Afterwards, a number of parametric studies were performed to analyze the dynamic responses of the combined transition zone. The results indicated that this type of transition system promotes a smoother stiffness transition between the slab track segment and the ballasted track segment by making the transition in three gradual steps. The track displacements in the analyzed case-study gradually increased by about 22%, 28%, and 34% along the combined transition zone in the junction points of the slab and ballasted tracks.

Differences in Gastroprotective and Mutagenic Actions Between Polar and Apolar Extracts of Ananas ananassoides

J.S. Silva,M.A. Andreo,F.R. Tubaldini,E.A. Varanda,L.R.M. Rocha,A.R.M.S. Brito,W. Vilegas,C.A. Hiruma-Lima 한국식품영양과학회 2008 Journal of medicinal food Vol.11 No.1

Several plants are used in folk medicine to treat gastrointestinal disorders. Ananas ananassoides(Baker) L.B.Smith (Family Bromeliaceae) is a medicinal plant commonly used in the central region of Brazil against gastric pain. Weevaluated two extracts (methanol [MeOH] and dichloromethane [DCM]) obtained from the leaves of A. ananassoidesfor theirability to protect the gastric mucosa against injuries caused by necrotizing agents (0.3 M HCl/60% ethanol, absolute ethanol,non-steroidal anti-inflammatory drugs, and pylorus ligation) in mice and rats. The best results were obtained after pretreat-ment with the DCM extract, whereas the MeOH extract did not show any significant anti-ulcerogenic activity but presentedmutagenic action. The mechanism of action of the DCM extract suggested the effective participation of endogenous sulfhydrylgroup in the gastroprotective action. The data, taken together with the absence of acute toxicity and mutagenicity, indicatethe apolar extract, instead of the polar, extract of A. ananassoides as a safe and potential new anti-ulcerogenic drug.

Flavonoid Detection in Hydroethanolic Extract of Pouteria torta (Sapotaceae) Leaves by HPLC-DAD and the Determination of Its Mutagenic Activity

Daryne L.M.G. Costa,Daniel Rinaldo,Eliana A. Varanda,Juliana F. de Sousa,Ana L.M. Nasser,Ana C.Z. Silva,Debora C. Baldoqui,Wagner Vilegas,Lourdes Campaner dos Santos 한국식품영양과학회 2014 Journal of medicinal food Vol.17 No.10

It is well known that phytotherapy has grown in popularity in recent years. Because a drug cannot be administered without ensuring its effectiveness and safety, the standardization and regulation of phytotherapeutic drugs are required by the global market and governmental authorities. This article describes a simple and reliable high-performance liquid chromatography–diode array detection analysis method for the simultaneous detection of myricetin-3-O-b-Dgalactopyranoside, myricetin-3-O-a-L-arabinopyranoside, and myricetin-3-O-a-L-rhaminopyranoside present in the hydroethanolic extract (ethanol/H2O, 7:3, v/v) of Pouteria torta. The mutagenic activity of the extract was evaluated on Salmonella typhimurium and by an in vivo micronucleus test on the peripheral blood cells of Swiss mice. The linearity, sensitivity, selectivity, repeatability, accuracy, and precision of the assay were evaluated. The analytical curves were linear and exhibited good repeatability (with a deviation of less than 5%) and demonstrated good recovery (within the 83–107% range). The results demonstrate that the hydroethanolic extract exhibited a mutagenic activity in both assays, suggesting caution in the use of this plant in folk medicine.

Modulatory Effect of Byrsonima basiloba Extracts on the Mutagenicity of Certain Direct and Indirect-Acting Mutagens in Salmonella typhimurium Assays

Walclecio de Moraes Lira,Fabio Vieira dos Santos,Miriam Sannomiya,Clenilson Martins Rodrigues,Wagner Vilegas,Eliana Aparecida Varanda 한국식품영양과학회 2008 Journal of medicinal food Vol.11 No.1

Byrsonima basiloba A. Juss. species is a native arboreal type from the Brazilian “cerrado” (tropical Americansavanna), and the local population uses it to treat diseases, such as diarrhea and gastric ulcer. It belongs to the Malpighiaceaefamily, and it is commonly known as “murici.” Considering the popular use of B. basilobaderivatives and the lack of phar-macological potential studies regarding this vegetal species, the mutagenic and antimutagenic effect of methanol (MeOH) andchloroform extracts were evaluated by the Ames test, using strains TA97a, TA98, TA100, and TA102 of Salmonella ty-phimurium. No mutagenic activity was observed in any of the extracts. To evaluate the antimutagenic potential, direct and in-direct mutagenic agents were used: 4 nitro-o-phenylenediamine, sodium azide, mitomycin C, aflatoxin B1, benzo[a]pyrene,and hydrogen peroxide. Both the extracts evaluated showed antimutagenic activity, but the highest value of inhibition level(89%) was obtained with the MeOH extract and strain TA100 in the presence of aflatoxin B1. Phytochemical analysis of theextracts revealed the presence of n-alkanes, lupeol, ursolic and oleanolic acid, (. )-catechin, quercetin-3-O-.-L-arabinopyra-noside, gallic acid, methyl gallate, amentoflavone, quercetin, quercetin-3-O-(2.-O-galloyl)-.-D-galactopyranoside, andquercetin-3-O-(2.-O-galloyl)-.-L-arabinopyranoside.

Phytochemical Profile, and Antiproliferative and Proapoptotic Effects of Pouteria ramiflora (Mart.) Radlk. Leaf Extract, and Its Synergism with Cisplatin in HepG2 Cells

Katiuska Tuttis,Daryne Lu Maldonado Gomes da Costa,Juliana Mara Serpeloni,Lourdes Campaner dos Santos,Eliana Aparecida Varanda,Wagner Vilegas,Wilner Martınez-Lopez,Ilce Mara de Syllos Cólus 한국식품영양과학회 2021 Journal of medicinal food Vol.24 No.5

Different species of the genus Pouteria have been used in folk medicine for the treatment of inflammation, fever, ulcers, diabetes, and diarrhea. We analyzed the phytochemical profile of the hydroethanolic extract from Pouteria ramiflora leaves by electrospray ionization ion trap tandem mass spectrometry and high-performance liquid chromatography-diode array detection, and examined whether it alone and in combination with cisplatin interfered with cell proliferation and death processes in HepG2 (human hepatocellular carcinoma) and FGH (human gingival fibroblasts) cells. Five compounds were identified in the extract: gallic acid, myricetin-3-O-α-l-arabinopyranoside, quercetin-3-O-β-d-galactopyranoside, myricetin-3-O-α-l-rhamnopyranoside, and myricetin-3-O-β-d-galactopyranoside. The extract was cytotoxic to both cell lines by inducing apoptotic cell death and acted in synergy with cisplatin; such effect was stronger in HepG2 cells than in FGH cells, demonstrating some selectivity to tumor cells. In HepG2 cells, the extract exerted antiproliferative effect mediated by induction of cell cycle arrest at the S and G2/M phases. Association of the extract with cisplatin enhanced the latter's antiproliferative effect, arrested the cell cycle at the S phase by CDK2 modulation, and reduced the number of anti-cyclin D1-stained HepG2 cells. Simultaneous treatment with the extract and cisplatin increased the latter's cytotoxicity, apoptotic cell death, and BAX expression in HepG2 cells. Altogether, the results reported herein indicate that P. ramiflora extract is a possible adjuvant to cancer therapy, which can circumvent the cisplatin-mediated resistance mechanisms in cancer cells.