Rotenoid and isoflavone metabolites from an antioxidant seed extract of Dalbergia lanceolaria subsp. paniculata (roxb.) thoth

Abstract

A new rotenoid named 12-O-methylrotenolol along with five known rotenoid and isoflavone metabolites were isolated from the seeds of Dalbergia lanceolaria subsp. paniculata, collected from Egypt. The structures of these compounds were identified by physical and spectroscopic data measurements ([α]_D, UV, 1D- and 2D-NMR and MS). The methanol extract of the seeds exhibited strong antioxidant activity with IC₅₀ value 0.7?µg/µl against DPPH radical, in respect to quercetin as antioxidant reference (IC₅₀ 1.5?μM), while the tested compounds from this extract showed weak activities with IC₅₀ values ranged from 19.6 to 33.0?µM.     

Geranyl Acetate Emulsions: Surfactant Association Structures and Stability

The phase diagram of fragrance oil, geranyl acetate, water, and a surfactant, Laureth 4, was used to calculate the surfactant association structures present in emulsions with constant O/W ratio for increased fractions of surfactant. The liquid crystal appeared in the emulsion at a critical value of the surfactant fraction and additional surfactant caused an approximately linear increase of it, while the fraction of the aqueous phase experienced a corresponding reduction. The result of the calculations was confirmed by optical microscopy observation with the samples between crossed polarizers. The calculations revealed the formation of vesicles from the liquid crystal to result in a drastic reduction of the “free” aqueous phase, due to the amount of the aqueous liquid forming the core of the vesicle.     

Some experiments on complex spontaneous emulsification in the system water–benzene–ethanol

The system water–benzene–ethanol was used to illustrate the complexity of spontaneous emulsification, when water-poor emulsions are brought in contact with water. In the first case, an O/W emulsion located close to the plait point in the system was used. The aqueous phase in the emulsion was incompatible with water, and a strong spontaneous emulsification to an O/W between the two liquids took place in the water layer close to the interface between layers. In the second case, a W/O emulsion, also close to the plait point, was brought in contact with water. Now, the spontaneous emulsification between the water and the oil phase of the original emulsion to an O/W emulsion also took place in the water layer forming a distinct emulsion layer beneath the interface.     

2-Pyridyl-benzimidazole-Pd(II)/Pd(0) Supported on Magnetic Mesoporous Silica: Aerobic Oxidation of Benzyl Alcohols/Benzaldehydes and Reduction of Nitroarenes

Catalysis Surveys from Asia - 2-(2-Pyridyl)benzimidazole (PyBzIm) was supported onto magnetic mesoporous silica, Fe3O4@SiO2@SBA-15 via the click chemistry. The supported ligand was treated with...     

Preparation of Cationic Mixed-Mode Acrylamide-Based Monolithic Stationary Phases for Capillary Electrochromatography

A series of amphiphilic macroporous mixed-mode acrylamide-based continuous beds bearing positively charged quaternary ammonium groups is synthesized for capillary electrochromatography (CEC) under variation of the concentration of the cationic monomer in the polymerization mixture. Positively charged mixed-mode monolithic stationary phases are synthesized in pre-treated fused silica capillaries of 100 µm I.D via single step free radical copolymerization of cyclodextrin-solubilized N-tert-butylacrylamide, a hydrophilic crosslinker (piperazine diacrylamide), a hydrophilic neutral monomer (methacrylamide), and a positively charged monomer ([2-(methacryloyloxy)ethyl]trimethyl ammonium methyl sulfate) in aqueous solution containing the lyotropic salt ammonium sulfate as a pore-forming agent. The synthesized monolithic stationary phases contain hydrophobic, hydrophilic, and charged functionalities. They can be employed for the CEC separations of different classes of neutral and charged solutes (with varied polarity) in the reversed-phase mode, in the normal-phase mode, in the ion-exchange mode, in a mixed-mode, or in the hydrophilic interaction liquid chromatography (HILIC) mode. The influence of the concentration of the cationic monomer in the polymerization mixture on retention factor, electroosmotic mobility, and methylene selectivity (α_meth) is studied under isocratic conditions for alkylphenones in the reversed-phase mode by capillary electrochromatography (CEC). Scanning electron microscopy (SEM) micrographs demonstrate that the morphology of the synthesized monoliths (i.e., the domain size) is strongly influenced by the variation of the concentration of the cationic monomer in the polymerization mixture.     

High performance liquid chromatography separation of structurally related enkephalins on quaternary ammonium-embedded stationary phase in isocratic mode

Separation of twelve enkephalins was investigated on a quaternary ammonium-embedded stationary phase (Stability BS-C23). Variation of buffer pH of the mobile phase highlighted the complex relationship between repulsive/attractive electrostatic interactions and the reversed-phase partitioning mechanism. The effect of three different anions employed as additives (phosphate, chloride and perchlorate) was examined at various concentrations and two pH values (acidic and neutral). At pH 2.5, an increase in the anion eluent concentration resulted in a higher retention factors of positively charged enkephalins. This effect was more pronounced when perchlorate ions were added to the mobile phase rather than phosphate and chloride ions, due to chaotropic and ion-pairing effects. In contrast, at pH 7.5, retention factors of negatively charged enkephalins decreased when these salts were added, due to an anion-exchange mechanism. Perchlorate caused a sharper decrease than chloride and phosphate anions did. The results presented here provide insight into the possible adjustment of retention and separation of peptides on a mixed-mode stationary phase (BS-C23) by a careful control of the buffer pH, the nature and concentration of anions, added to the buffer, and organic modifier content.     

Experimental investigation on the effect of natural gas premixed ratio on combustion and emissions in an IDI engine

Journal of Thermal Analysis and Calorimetry - Usage of natural gas in an internal combustion engine that has different combustion technologies is considered a possible solution to reduce engine...     

Equilibration in a geranyl acetate emulsion

Water and a geranyl acetate solution of a non-ionic surfactant, a commercial C₁₂EO₄, were brought into contact in amounts to give a combination of a lamellar liquid crystal and an oil phase of equal weights at equilibrium and the equilibration transport between the layers was followed by measuring the change in layer heights with time. The initial reaction, lasting approximately two months, transferred surfactant from the oil phase to combine with water to form a birefringent layer initially containing excess water over the fraction in the liquid crystal in equilibrium with both water and oil phase. After this period the composition of the oil phase had reached a level corresponding to equilibrium with both water and a lamellar liquid crystal, while the birefringent phase, although a liquid crystal, still contained less water fraction than required for equilibrium. The final equilibration process of transferring the excess water to the formed liquid crystal was extremely slow with an estimated time to reach equilibrium of several years.     

Kinetics and mechanism of ligand substitution reactions in [cis-M(CO)4(amine)(EPh3)] complexes (M = Mo,W; amine = pyridine,piperidine; E = As,Sb)

Group 6 metal carbonyls [cis-M(CO)₄(amine)(EPh₃)] (M = Mo, W; amine = piperidine (pip), pyridine (py); E = As, Sb) have been prepared and characterized. These complexes react thermally in chlorobenzene solutions with phosphine or phosphite ligands (= L) to give cis- and trans-M(CO)₄(L)(EPh₃) products. Kinetics of amine substitution by L in these complexes, under pseudo-first-order conditions, indicate that these reactions proceed by a rate law that is first-order in concentration of the metal complex. Rate constants and activation parameters for these reactions have been determined and are discussed. Competition studies for the [M(CO)₄(EPh₃)] intermediates show that these intermediates are highly reactive and react almost indiscriminately with various incoming nucleophiles with slight preference for more basic ones.     

Antioxidant,Antimicrobial Activities and Characterization of Polyphenol-Enriched Extract of Egyptian Celery (Apium graveolens L., Apiaceae) Aerial Parts via UPLC/ESI/TOF-MS

Medicinal plant extracts are increasingly considered a major source of innovative medications and healthcare products. This study focused on preparing a polyphenol enriched water extract of Egyptian celery “Apium graveolens L., Apiaceae” aerial parts (TAE) in an endeavor to accentuate its antioxidant capacity as well as its antimicrobial activity. (TAE) of celery was partitioned against different organic solvents to yield dichloromethane (DCM), ethyl acetate (EAC), and butanol (BUOH) fractions. (TAE) and the organic fractions thereof besides the remaining mother liquor (ML) were all screened for their antioxidant capacity using various protocols viz. monitoring the reducing amplitudes for ferric ions (FRAP), and radical scavenging potentials of oxygen (ORAC), 2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and metal chelation assays. The examination procedure revealed both (TAE) extract and (DCM) fraction, to pertain the highest antioxidant potentials, where the IC₅₀ of the (TAE) using ABTS and metal chelation assays were ca. 34.52 ± 3.25 and 246.6 ± 5.78 µg/mL, respectively. The (DCM) fraction recorded effective results using the FRAP, ORAC, and DPPH assays ca. 233.47 ± 15.14 and 1076 ± 25.73 μM Trolox equivalents/mg sample and an IC₅₀ 474.4 ± 19.8 µg/mL, respectively. Additionally, both (TAE) and (DCM) fraction exerted antimicrobial activities recording inhibition zones (mm) (13.4 ± 1.5) and (12.0 ± 1.0) against Staphylococcus aureus and (11.0 ± 1.2) and (10.0 ± 1.3) against Escherichia coli, respectively, with no anti-fungal activity. Minimum inhibitory concentration (MIC) of (TAE) and (DCM) fraction were 1250 and 2500 µg/mL, respectively. UPLC/ESI/TOF-MS unveiled the chemical profile of both (TAE) and (DCM) fraction to encompass a myriad of active polyphenolic constituents including phenylpropanoids, coumarins, apigenin, luteolin, and chrysoeriol conjugates.