A New LC Method for Determination of Some Aminoglycoside Antibiotics in Dosage Forms and Human Plasma Using 7-Fluoro-4-nitrobenz-2-oxa-1,3-diazole as a Fluorogenic Pre-Column Label

A validated, selective and sensitive pre-column derivatization chromatographic method for determination of some aminoglycoside antibiotics, namely, amikacin (AMK), gentamicin and neomycin sulphates, has been developed. Determination was obtained by pre-column reaction of the samples with 7-fluoro-4-nitrobenz-2-oxa-1,3-diazole and separating the corresponding derivatives on a reversed phase LC column (ultrasphere C₁₈, 250 × 4.6 mm) and fluorescence detection (λ _ex 465 nm, λ _em 531 nm). Linear quantitative response curve was generated over a concentration range of 0.05–10 μg mL⁻¹ with a correlation coefficient of more than 0.999 with all studied compounds. The accuracy and precisions were satisfactory for determination of all drugs in dosage forms within- and between-run assay. Furthermore, the method was extended to the determination of AMK in spiked human plasma. The method is specific for the intact drugs, and can be adopted in the presence of co-formulated drugs.

     

Flow injection ion-exchange preconcentration for the determination of iron(II) with chemiluminescence detection

Summary Flow injection analysis with on-line ion-exchange preconcentration using a mini-column loaded with 8-quinolinol immobilized on controlled-pore glass, is described for the determination of iron(II)-enhanced chemiluminescent oxidation of luminol in alkaline hydrogen peroxide. The detection limit for iron(II) is 10^–13 mol/l (in 3 ml of sample). The operating conditions are optimized, and the effect of interferents is studied. The analysis time was 5 min for each sample, including 2 min for sample loading.     

Investigation of the Optical Properties of a Novel Class of Quinoline Derivatives and Their Random Laser Properties Using ZnO Nanoparticles

Quinoline Schiff bases display potential applications in optoelectronics and laser fields because of their unique optical properties that arise from extensive delocalization of the electron cloud, and a high order of non-linearity. In this context, a new class of conjugated quinoline-derivative viz. N-(quinolin-3-ylmethylene)anilines were synthesized from 2-hydroxyquinoline-3-carbaldehyde in two good yielding steps. The ability of these imines to accept an electron from a donor is denoted by their electron acceptor number and sites, which is calculated using density functional theory (DFT). The optical properties such as FT-IR, Raman, UV-VIS, and EDS spectra were calculated using TD-DFT, which also provided the energy gap, HOMO-LUMO structure. The optical properties of the synthesized imino quinolines were experimentally studied using photoluminescence and absorption spectroscopy. The properties such as Stokes shift and quantum yield were calculated using experimental data. Furthermore, the compound bearing a methyl group on the aryl ring and ZnO nanoparticles (hydrothermally synthesized) were dissolved in toluene, and optically excited with a 355 nm nanosecond laser, which produced a random laser.     

Simplified Method the Determination of Multiple Pesticides Residues in Water by Capillary Column Chromatography

Pesticides occur trace levels in water. The determination of pesticide residues involves complex methodologies composed of different analytical steps. Multiresidue analysis has been applied successfully to analyses for Pyrethroids, Organohalogens, Organophosphates, and Carbamatesl561 in agricultural products.     

Determination of lactate and lactic dehydrogenase by biamperometric monitoring of hexacyanoferrate(II) in a flowing stream

Summary Open tubular carbon electrodes were used to monitor the biamperometric current of hexacyanoferrate(II) ion produced by the LDH catalyzed reaction between hexacyanoferrate(III) ion and lactate, and that produced from the diaphorase catalyzed reaction between hexacyanoferrate(III) ion and NADH, product from the LDH catalyzed reaction between lactate and NAD. Reagents and samples were mixed in a flow stream. Reaction takes place between the mixing point and the electrodes, and measurements are taken after a constant time interval. Lactate and LDH standards in serum control solutions were measured using the NAD dependent reaction.

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Bestimmung von Lactat und Lactatdehydrogenase durch biamperometrische Messung von Hexacyanoferrat(II) im Durchfluß

Zusammenfassung Kohlenstoff-Röhrenelektroden wurden zur Messung des biamperometrischen Stromes des Hexacyanoferrat(II)-ions eingesetzt, das aus der LDH-katalysierten Reaktion zwischen Hexacyanoferrat(III) und Lactat bzw. der Diaphorase-katalysierten Reaktion zwischen Hexacyanoferrat(III) und NADH (Produkt der LDH-katalysierten Reaktion zwischen Lactat und NAD) stammte. Die Reagentien wurden mit den Proben im Durchfluß vermischt. Die Reaktion fand zwischen der Mischungsstelle und den Elektroden statt und die Messungen wurden nach einem Bestimmten Zeitintervall durchgeführt. Mit Hilfe der NAD-abhängigen Reaktion wurden Lactat- und LDH-Standards in Serumkontrollösungen bestimmt.

     

Spinodal Decomposition in Ternary Systems with Significantly Different Component Diffusivities

A numerical method for simulating spinodal decomposition in ternary systems with order‐of‐magnitude differences in diffusion coefficients is presented. The method has been partially verified by molecular dynamic simulations and gives results equivalent to the standard technique when the diffusivities are equal. A two‐dimensional simulation of an asymmetric polymer/polymer/polymer system reproduces an experimentally observed bimodal distribution of dispersed‐phase particle sizes. The ripening exponent for the larger particles is near the expected value of 0.33, but that for the smaller particles is only about 0.1. The method was also used for a polymer/polymer/solvent system.

     

Activation of IGF-1/GLP-1 Signalling via 4-Hydroxyisoleucine Prevents Motor Neuron Impairments in Experimental ALS-Rats Exposed to Methylmercury-Induced Neurotoxicity

Amyotrophic lateral sclerosis (ALS) is a severe adult motor neuron disease that causes progressive neuromuscular atrophy, muscle wasting, weakness, and depressive-like symptoms. Our previous research suggests that mercury levels are directly associated with ALS progression. MeHg+-induced ALS is characterised by oligodendrocyte destruction, myelin basic protein (MBP) depletion, and white matter degeneration, leading to demyelination and motor neuron death. The selection of MeHg+ as a potential neurotoxicant is based on our evidence that it has been connected to the development of ALS-like characteristics. It causes glutamate-mediated excitotoxicity, calcium-dependent neurotoxicity, and an ALS-like phenotype. Dysregulation of IGF-1/GLP-1 signalling has been associated with ALS progression. The bioactive amino acid 4-hydroxyisoleucine (HI) from Trigonella foenum graecum acts as an insulin mimic in rodents and increases insulin sensitivity. This study examined the neuroprotective effects of 4-HI on MeHg+-treated adult Wistar rats with ALS-like symptoms, emphasising brain IGF1/GLP-1 activation. Furthermore, we investigated the effect of 4-HI on MBP levels in rat brain homogenate, cerebrospinal fluid (CSF), blood plasma, and cell death indicators such as caspase-3, Bax, and Bcl-2. Rats were assessed for muscular strength, locomotor deficits, depressed behaviour, and spatial learning in the Morris water maze (MWM) to measure neurobehavioral abnormalities. Doses of 4-HI were given orally for 42 days in the MeHg+ rat model at 50 mg/kg or 100 mg/kg to ameliorate ALS-like neurological dysfunctions. Additionally, neurotransmitters and oxidative stress markers were examined in rat brain homogenates. Our findings suggest that 4-HI has neuroprotective benefits in reducing MeHg+-induced behavioural, neurochemical, and histopathological abnormalities in ALS-like rats exposed to methylmercury.     

Green Synthesized Zinc Oxide Nanoparticles Based on Cestrum diurnum L. of Potential Antiviral Activity against Human Corona 229-E Virus

SARS-CoV-2 has caused more than 596 million infections and 6 million fatalities globally. Looking for urgent medication for prevention, treatment, and rehabilitation is obligatory. Plant extracts and green synthesized nanoparticles have numerous biological activities, including antiviral activity. HPLC analysis of C. dirnum L. leaf extract showed that catechin, ferulic acid, chlorogenic acid, and syringic acid were the most major compounds, with concentrations of 1425.16, 1004.68, 207.46, and 158.95 µg/g, respectively. Zinc nanoparticles were biosynthesized using zinc acetate and C. dirnum extract. TEM analysis revealed that the particle size of ZnO-NPs varied between 3.406 and 4.857 nm. An XRD study showed the existence of hexagonal crystals of ZnO-NPs with an average size of 12.11 nm. Both ZnO-NPs (IC₅₀ = 7.01 and CC₅₀ = 145.77) and C. dirnum L. extract (IC₅₀ = 61.15 and CC₅₀ = 145.87 µg/mL) showed antiviral activity against HCOV-229E, but their combination (IC₅₀ = 2.41 and CC₅₀ = 179.23) showed higher activity than both. Molecular docking was used to investigate the affinity of some metabolites against the HCOV-229E main protease. Chlorogenic acid, solanidine, and catchin showed high affinity (−7.13, −6.95, and −6.52), compared to the ligand MDP (−5.66 Kcal/mol). Cestrum dinurum extract and ZnO-NPs combination should be subjected to further studies to be used as an antiviral drug.     

Reactions of some sterically-hindered organosilicon hydrides and iodides with halogens

The reaction of TsiSiMe₂H (I) (Tsi = (Me₃Si)₃C) with I₂ or with a molar equivalent of ICl gives the iodide TsiSiMe₂I (II) in hydroxylic media (MeOH, CH₃CO₂H, CF₃CO₂H) as it does in CCl₄. The reaction with I₂ is very fast in CF₃CO₂H, but in MeOH is only about as fast as in CCl₄. The iodide II reacts with ICl in MeOH to give a mixture of TsiSiMe₂OMe (III) and TsiSiMe₂Cl (IV), but the reaction is markedly slower than that in CCl₄ (in which IV is formed). The hydride I also reacts with INO₃ in MeOH to give II, and the latter reacts with INO₃ to give III. The reactions of TsiSiPh₂H (V) and TsiSiPh₂I (VI) with ICl in MeOH are markedly slower than those of I and II; even with one equivalent of ICl in MeOH, V gives a mixture of VI and the (rearranged) methoxide (Me₃Si)₂C(SiPh₂Me)(SiMe₂OMe) (VII). Reaction of VI with ICl in MeOH gives VII and the rearranged chloride (Me₃Si)₂C(SiPh₂Me)(SiMe₂Cl). The formation of methoxides in the reactions of the iodides II and VI with ICl in MeOH, and the rearrangements observed in the case of VI, are consistent with a mechanism involving an intermediate silicocation. Other mechanistic aspects are discussed.