The interactions between lipase and pyridinium ligands investigated by electrochemical and spectrophotometric methods

The interaction between pyridinium ligands derived from 4,4’-bipyridine (N,N’-bis(p-bro-mophenacyl)-4,4’-bipyridinium dibromide – Lr) and (N,N’-bis(p-bromophenacyl)-1,2-bis (4-pyridyl) ethane dibromide – Lm) with lipase enzyme was evaluated. The stability of the pyridinium ligands, having an essential role in biological systems, in 0.1 M KNO3 as supporting electrolyte is influenced by the lipase concentration added. The pH and conductometry measurements in aqueous solution suggest a rapid ionic exchange process. The behavior of pyridinium ligands in the presence of lipase is investigated by cyclic voltammetry and UV/Vis spectroscopy, which indicated bindings and changes from the interaction between them. The voltammograms recorded on the glassy carbon elec-trode showed a more intense electronic transfer for the Lr interaction with lipase com-pared to Lm, which is due to the absence of mobile ethylene groups from Lr structure

FLUORESCENT N-HETEROCYCLES VIA ONE-POT TANDEM REACTIONS

Substituted indolizines are very attractive heterocyclic units. On developing efficient methods toward differently substituted indolizines, we were particularly interested in elaborating efficient approaches toward three-component reaction of these compounds which are very interested from the point of view fluorescent properties. The microwave-mediated three component reaction of acyl bromide, bipyridine and dipolarophyl is catalyzed by basic alumina to give corresponding bis-indolizines in excellent yields in a one –pot reaction

Characterization of blast furnace dust for reintroduction into the agglomeration process

Significant amounts of dust from the processing of cast iron in the furnace can be considered as by-products for the technological flow from the agglomeration, having an adequate chemical and structural composition. Blast furnace dust contains significant amounts of metals and non-metals that can be recovered by various processing methods. The transformation of these recyclable materials for reuse into metal producing units is essential not only for the conservation of mineral resources but also for the protection of the environment. This paper presents the chemical and mineralogical characterization of blast furnace dust resulting from the processing of cast iron, a useful analysis for this material to be reintroduced into the agglomeration process. From the obtained results it was found that the blast furnace dust contains significant amounts of SiO2 in fine granular form (<1 mm) which determines a fluidization of the slag resulting from the production of cast iron in the blast furnace, as well as the fact that it helps to form the binder phases in the agglomerate due to the fact that the powders have a high thermo-chemical activity that can be considered a first phase of formation of the initial liquid melt that triggers the reaction between melt and solid

Pyrrolidinium octanoate carboxylate as PIL agent in the growth mechanism of lysozyme spherulites

International audienceIn this research the impact of pyrrolidinium octanoate carboxylate (PyO) on Lysozyme (Ly) spherulite forms using the method of vapour diffusion with hanging drops (HDVD) was investigated. Two different stock solutions at low alkaline pH were tested: 0.1 M NaAc (the first one) and 0.1 M TRIS hydrochloride contained 0.2 M ammonium sulfate and 25 % wt. PEG 3450 as crystallant agents (the second one). The experiments were performed at 18°C using two PyO concentrations (0.4 M and 1.6 M) in each stock solution. PyO of booth concentrations lead to the formation of Ly - SNLC (Ly single needle-like crystals), observed by optical microscopy one day after the droplets deposition, excepted the stock solution of 0.1 NaAc based on 0.4 M PyO where Ly microspheres were identified by electron scanning microscopy. The growth mechanism of the Ly spherulites of type I obtained using 0.4 M PyO in 0.1 M TRIS/crystallant agent could be summarised as follows: Ly-SNLC → Ly-like axialites → Ly spherulites of type I. The growth mechanism of the Ly spherulites of type II using 1.6 M PyO in 0.1 M TRIS/crystallant agent can be summarised as follows: Ly-SNLC → Ly-like axialites → Ly spherulites of type II

Antibiofilm and Anti-Quorum Sensing Potential of Cycloartane-Type Triterpene Acids from Cameroonian Grassland Propolis: Phenolic Profile and Antioxidant Activity of Crude Extract

Propolis is very popular for its beneficial health properties, such as antimicrobial activity and antioxidant effects. It is one of the most long-serving traditional medicines to mankind due to its interesting chemical diversity and therapeutic properties. The detailed chemical information of propolis samples is very necessary to guarantee its safety and for it to be accepted into health care systems. The phenolic profile of the hydroethanolic extract was determined using HPLC-DAD, and the antioxidant was evaluated using five complementary methods. Triterpenoids were isolated using column chromatography and characterized using 1H NMR and 13C NMR. The effects of the extract and the isolated compounds on quorum sensing mediated processes and biofilm formation in bacteria were evaluated. Protocatechic acid (40.76 ± 0.82 µg/g), 4-hydroxybenzoic acid (24.04 ± 0.21 µg/g), vanillic acid (29.90 ± 1.05 µg/g), quercetin (43.53 ± 1.10 µg/g), and luteolin (4.44 ± 0.48 µg/g) were identified and quantified. The extract showed good antioxidant activity in the DPPH•, ABTS•+, CUPRAC, and metal chelating assays, and this antioxidant effect was confirmed by cyclic voltammetry. 27-Hydroxymangiferonic acid (1), Ambolic acid (2), and Mangiferonic acid (3) were isolated from anti-quorum sensing activity at MIC, and it was indicated that the most active sample was the extract with inhibition diameter zone of 18.0 ± 1.0 mm, while compounds 1, 2, and 3 had inhibition zones of 12.0 ± 0.5 mm, 9.0 ± 1.0 mm, and 12.3 ± 1.0 mm, respectively. The samples inhibited the P. aeruginosa PA01 swarming motility at the three tested concentrations (50, 75, and 100 μg/mL) in a dose-dependent manner. The propolis extract was able to inhibit biofilm formation by S. aureus, E. coli, P. aeruginosa, C. albicans, and C. tropicalis at MIC concentration. Compound 1 proved biofilm inhibition on S. aureus, L. monocytogenes, E. faecalis, E. coli, and C. tropicalis at MIC and MIC/2; compound 2 inhibited the formation of biofilm at MIC on S. aureus, E. faecalis, E. coli, S. typhi, C. albicans, and C. tropicalis; and compound 3 inhibited biofilm formation on E. faecalis, E. coli, C. albicans, and C. tropicalis and further biofilm inhibition on E. coli at MIC/4 and MIC/8. The studied propolis sample showed important amounts of cycloartane-type triterpene acids, and this indicates that there can be significant intra-regional variation probably due to specific flora within the vicinity. The results indicate that propolis and its compounds can reduce virulence factors of pathogenic bacteria

Antioxidative activity and stability of the extracts of liquorice root (Glycyrrhiza glabra)

The active principles from the aqueous liquorice plant extracts were investigated and quantified by evaluation of bioactive compounds (saponins) through phytochemical reactions. The presence of saponins was evaluated by measuring the foam index, which was around 500. A major component was Glycyrrhizic acid, responsible for the antioxidant activity, found in concentration of 5.82 % at plant maturity. A time-dependent decrease in concentration of the bioactive compounds from aqueous liquorice extracts was observed. The antimicrobial activity of the extracts was tested by the agar diffusion method, showing a moderate inhibitory activity against Bacillus sp. and strong inhibitory activity against coliforms. A liquorice syrup was obtained and subsequently could be used as nutraceutical additive in bread with good results, showing characteristic, optical and antimicrobial properties and good stability in time. Adding liquorice syrup in food products could be an alternative to improve nutraceutical potential

Flavonoid Profiles of Two New Approved Romanian Ocimum Hybrids

Basil (Ocimum spp.) is a traditional herbal medicine abundant in antioxidants such as phenolic compounds. As part of a diet, this herb is proved to have some roles in decreasing the risk of cancer, and in the treatment of inflammation and neurodegenerative diseases. This study aims to explore the total phenolic and flavonoid content of two new basil hybrids growing in Romania, namely “Aromat de Buzau” (AB) and “Macedon” (MB). The antioxidant capacity of those two species was also analyzed by DPPH and cyclic voltammetry. Six different flavonoids, such as catechin (+), rutin, hyperoside, naringin, naringenin, and genistein, were separated, identified, and quantified by HPLC–DAD chromatography, for the first time, from romanian basil hybrids. The main flavonoid of the extracts was found to be naringin which is present in the highest amount (26.18 mg/kg) in “Aromat de Buzau” (O. basilicum) methanolic extract. These results suggest that dietary intake of these new hybrids can be a source of antioxidant compounds

Bridging the Chemical Profile and Biological Activities of a New Variety of <i>Agastache foeniculum</i> (Pursh) Kuntze Extracts and Essential Oil

This study investigated the phytochemical content of alcoholic extracts and essential oil of a new variety of medicinal plants, Agastache foeniculum (Pursh), which Kuntze adapted for cultivation in Romania, namely “Aromat de Buzău”. The essential oil was investigated by GC-MS, while the identification and quantification of various compounds from alcoholic extracts were performed by HPLC-DAD. The total phenol and flavonoid contents of the extracts were evaluated by using standard phytochemical methods. The antioxidant activities of ethanol, methanol extracts, and essential oil of the plant were also assessed against 2,2′-diphenyl-1-picrylhydrazyl (DPPH•), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS•+), and by ferric reducing power (FRAP) using spectroscopic methods. Cyclic voltammetry was used to evaluate the antioxidant capacity of the essential oil. The concentrations of phenolic compounds were higher in methanolic extract compared to ethanolic extract. A significant correlation was found between total phenol and total flavonoid contents (r = 0.9087). Significant high correlations were also found between the total phenolic compounds and the antioxidant activities of the extracts (r ≥ 0.8600, p A. foeniculum as a potential source of bioactive compounds and a good candidate for pharmaceutical plant-based products