LC–MS–MS determination of ibuprofen, 2-hydroxyibuprofen enantiomers,and carboxyibuprofen stereoisomers for application in biotransformation studies employing endophytic fungi

The purpose of this study was the development and validation of an LC–MS–MS method for simultaneous analysis of ibuprofen (IBP), 2-hydroxyibuprofen (2-OH-IBP) enantiomers, and carboxyibuprofen (COOH-IBP) stereoisomers in fungi culture medium, to investigate the ability of some endophytic fungi to biotransform the chiral drug IBP into its metabolites. Resolution of IBP and the stereoisomers of its main metabolites was achieved by use of a Chiralpak AS-H column (150 × 4.6 mm, 5 μm particle size), column temperature 8 °C, and the mobile phase hexane–isopropanol–trifluoroacetic acid (95: 5: 0.1, v/v) at a flow rate of 1.2 mL min⁻¹. Post-column infusion with 10 mmol L⁻¹ ammonium acetate in methanol at a flow rate of 0.3 mL min⁻¹ was performed to enhance MS detection (positive electrospray ionization). Liquid–liquid extraction was used for sample preparation with hexane–ethyl acetate (1:1, v/v) as extraction solvent. Linearity was obtained in the range 0.1–20 μg mL⁻¹ for IBP, 0.05–7.5 μg mL⁻¹ for each 2-OH-IBP enantiomer, and 0.025–5.0 μg mL⁻¹ for each COOH-IBP stereoisomer (r ≥ 0.99). The coefficients of variation and relative errors obtained in precision and accuracy studies (within-day and between-day) were below 15%. The stability studies showed that the samples were stable (p > 0.05) during freeze and thaw cycles, short-term exposure to room temperature, storage at −20 °C, and biotransformation conditions. Among the six fungi studied, only the strains Nigrospora sphaerica (SS67) and Chaetomium globosum (VR10) biotransformed IBP enantioselectively, with greater formation of the metabolite (+)-(S)-2-OH-IBP. Formation of the COOH-IBP stereoisomers, which involves hydroxylation at C3 and further oxidation to form the carboxyl group, was not observed.     

Trace analysis of uranium ore concentrates using laser ablation inductively coupled plasma mass spectrometry for nuclear forensics

Journal of Radioanalytical and Nuclear Chemistry - We present a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method for trace-element analysis of uranium ore concentrates...     

Dinitriles Bearing AIE‐Active Moieties: Synthesis,E/Z Isomerization,and Fluorescence Properties

Dinitriles bearing aggregation‐induced emission (AIE)‐active moieties [tetraphenylethylene (TPE) or diphenylphenanthrene (DPP)] were prepared. Compounds 4 (TPE‐linked) and 8 (DPP‐linked) showed considerably redshifted emission resulting from their large Stokes shifts and also strong fluorescence in the aggregated and solid states. Pure E and Z stereoisomers of both dinitriles were easily separated, and their isomerization equilibria and fluorescence properties were investigated. In addition to their pronounced AIEE behavior, 4 and 8 also showed various reversible chromic responses to external stimuli, namely, solvato‐, piezo‐, vapo‐, and thermochromism, which make them potential candidates for smart materials.     

High Solids Content,Soap‐Free,Film‐Forming Latexes Stabilized by Laponite Clay Platelets

High solids content film‐forming poly[styrene‐co‐(n‐butyl acrylate)] [poly(Sty‐co‐BuA)] latexes armored with Laponite clay platelets have been synthesized by soap‐free emulsion copolymerization of styrene and n‐butyl acrylate. The polymerizations were performed in batch in the presence of Laponite and a methyl ether acrylate‐terminated poly(ethylene glycol) macromonomer in order to promote polymer/clay association. The overall polymerization kinetics showed a pronounced effect of clay on nucleation and stabilization of the latex particles. Cryo‐transmission electron microscopy observation confirmed the armored morphology and indicated that the majority of Laponite platelets were located at the particle surface. The resulting nanostructured films displayed enhanced mechanical properties.

     

Antifungal Activity of Microgramma vacciniifolia Rhizome Lectin on Genetically Distinct Fusarium oxysporum f. sp. lycopersici Races

Fusarium oxysporum f. sp. lycopersici races 1, 2, and 3 deteriorate tomato crops since they cause a vascular wilt. Lectins are carbohydrate-binding proteins with hemagglutinating and antifungal activities. This work reports that Microgramma vacciniifolia rhizome lectin (MvRL) inhibits F. oxysporum f. sp. lycopersici race 3 growth (61 %) more intensely than of races 1 (55 %) and 2 (45 %). The hemagglutinating activity of MvRL was inhibited by glycoprotein preparations from mycelia of races 1, 2, and 3, and these data indicate that lectin carbohydrate-binding sites recognized glycosylated molecules from races. Inter-simple sequence repeat (ISSR) marker system showed that race 3 is genetically distinct from races 1 and 2, and thus the highest sensitiveness of F. oxysporum f. sp. lycopersici race 3 to MvRL may be due to molecular characteristics of this race.     

In vitro antibacterial and time-kill assay of ethanolic extract of Davilla nitida bark on multidrug resistant bacteria isolated from diabetic foot lesions

This study reported the antimicrobial activity of the bark extract of Davilla nitida on multidrug resistant bacteria isolated from Diabetic Foot Infections. Antibacterial activity of the bark extract was evaluated by agar Disk-Diffusion (DD), Broth Dilution (BD), Checkerboard and Time-kill methods. The extract showed a significant antibacterial activity against all groups of bacteria tested. BD was more sensitive for determining the antibacterial activity of the bark extract than the DD method. The bark extract inhibited the growth of bacteria with high-levels of antibiotic-resistance, such as Pseudomonas spp. (100.0%), Enterobacer spp. (88.89%), Staphylococcus aureus (54.55%), Streptococcus pneumoniae (75.0%), Staphylococcus saprophyticus (92.86%). The combination of extract with antibiotics resulted in an additive effect against most of the strains tested. Time-kill kinetics profiles of bark extract showed bactericidal and time-dependent properties. Our results suggest that the bark extract of Davilla nitida is a source of bioactive compounds, which may be useful against antibiotic-resistant bacteria.     

Effect of the AL-MCM-41 catalyst on the catalytic pyrolysis of atmospheric petroleum residue (ATR)

Thermogravimetry (TG) was used in this study to evaluate thermal and catalytic pyrolysis of Atmospheric Petroleum Residue (ATR) which can be found in the state of Rio Grande do Norte/Brazil, after a process of atmospheric distillation of petroleum. The utilized sample in the process of catalytic pyrolysis was Al-MCM-41, a mesoporous material. The procedures for obtaining the thermogravimetric curves were performed in a thermobalance with heating rates of 5, 10, and 20 °C min⁻¹. From TG, the activation energy was determined using the Flynn–Wall kinetic method, which decreased from 161 kJ mol⁻¹, for the pure ATR, to 71 kJ mol⁻¹, in the presence of the Al-MCM-41, showing the efficiency of the catalyst in the pyrolysis of Atmospheric Petroleum Residue.     

Real-Time pH-Dependent Self-Assembly of Ionisable Lipids from COVID-19 Vaccines and In Situ Nucleic Acid Complexation

Ionisable amino-lipid is a key component in lipid nanoparticles (LNPs), which plays a crucial role in the encapsulation of RNA molecules, allowing efficient cellular uptake and then releasing RNA from acidic endosomes. Herein, we present direct evidence for the remarkable structural transitions, with decreasing membrane curvature, including from inverse micellar, to inverse hexagonal, to two distinct inverse bicontinuous cubic, and finally to a lamellar phase for the two mainstream COVID-19 vaccine ionisable ALC-0315 and SM-102 lipids, occurring upon gradual acidification as encountered in endosomes. The millisecond kinetic growth of the inverse cubic and hexagonal structures and the evolution of the ordered structural formation upon ionisable lipid-RNA/DNA complexation are quantitatively revealed by in situ synchrotron radiation time-resolved small angle X-ray scattering coupled with rapid flow mixing. We found that the final self-assembled structural identity, and the formation kinetics, were controlled by the ionisable lipid molecular structure, acidic bulk environment, lipid compositions, and nucleic acid molecular structure/size. The implicated link between the inverse membrane curvature of LNP and LNP endosomal escape helps future optimisation of ionisable lipids and LNP engineering for RNA and gene delivery.     

Surfactant self-assembly objects as novel drug delivery vehicles

The past decade has been witness to a new impetus in surfactant self-assembly objects as agents for drug delivery that are an alternative to micellar, lamellar (liposome, niosome and transfersome) or microemulsion-based vehicles. The review focus herein is on the application of hexagonal, cubic, ‘intermediate’ (viz. rhombohedral, tetragonal and monoclinic) and L₃ (‘sponge’) mesophases.     

Membrane‐permeable Triphosphate Prodrugs of Nucleoside Analogues

The metabolic conversion of nucleoside analogues into their triphosphates often proceeds insufficiently. Rate‐limitations can be at the mono‐, but also at the di‐ and triphosphorylation steps. We developed a nucleoside triphosphate (NTP) delivery system (TriPPPro‐approach). In this approach, NTPs are masked by two bioreversible units at the γ‐phosphate. Using a procedure involving H‐phosphonate chemistry, a series of derivatives bearing approved, as well as potentially antivirally active, nucleoside analogues was synthesized. The enzyme‐triggered delivery of NTPs was demonstrated by pig liver esterase, in human T‐lymphocyte cell extracts and by a polymerase chain reaction using a prodrug of thymidine triphosphate. The TriPPPro‐compounds of some HIV‐inactive nucleoside analogues showed marked anti‐HIV activity. For cellular uptake studies, a fluorescent TriPPPro‐compound was prepared that delivered the triphosphorylated metabolite to intact CEM cells.