Combined HPLC-CUPRAC (cupric ion reducing antioxidant capacity) assay of parsley, celery leaves, and nettle

This study aims to identify the essential antioxidant compounds present in parsley (Petroselinum sativum) and celery (Apium graveolens) leaves belonging to the Umbelliferae (Apiaceae) family, and in stinging nettle (Urtica dioica) belonging to Urticaceae family, to measure the total antioxidant capacity (TAC) of these compounds with CUPRAC (cupric ion reducing antioxidant capacity) and ABTS spectrophotometric methods, and to correlate the TAC with high performance liquid chromatography (HPLC) findings. The CUPRAC spectrophotometric method of TAC assay using copper(II)-neocuproine (2,9-dimethyl-1,10-phenanthroline) as the chromogenic oxidant was developed in our laboratories. The individual antioxidant constituents of plant extracts were identified and quantified by HPLC on a C18 column using a modified mobile phase of gradient elution comprised of MeOH-0.2% o-phosphoric acid and UV detection for polyphenols at 280 nm. The TAC values of HPLC-quantified antioxidant constituents were found, and compared for the first time with those found by CUPRAC. The TAC of HPLC-quantified compounds accounted for a relatively high percentage of the observed CUPRAC capacities of plant extracts, namely 81% of nettle, 60-77% of parsley (in different hydrolyzates of extract and solid sample), and 41-57% of celery leaves (in different hydrolyzates). The CUPRAC total capacities of the 70% MeOH extracts of studied plants (in the units of mmol trolox g⁻¹ plant) were in the order: celery leaves > nettle > parsley. The TAC calculated with the aid of HPLC-spectrophotometry did not compensate for 100% of the CUPRAC total capacities, because all flavonoid glycosides subjected to hydrolysis were either not detectable with HPLC, or not converted to the corresponding aglycons (i.e., easily detectable and quantifiable with HPLC) during the hydrolysis step.     

Synthesis,Characterization and Crystal Structures of 1,2,4‐Triazole based Schiff‐Bases and their Copper(I) Complexes

The reaction of of 4‐amino‐5‐ethyl‐2H‐1,2,4‐triazole‐3(4H)‐thione (AETT, L ) with furfural in methanol led to the corresponding Schiff‐Base ( L1 ). The reaction of L1 with [Cu(PPh₃)₂]Cl in methanol gave to the neutral compound [( L1 )Cu(PPh₃)₂Cl] ( 1 ). By recrystallization of 1 from CH₃CN the complex [( L1 )Cu(PPh₃)₂Cl]·CH₃CN ( 1a ) was obtained. All compounds were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for L1 at ?80 °C: space group with a = 788.4(1), b = 830.3(2), c = 928.8(2) pm, α = 84.53(1)°, β = 65.93(1)°, γ = 72.02(1)°, Z = 2, R₁ = 0.0323; for 1 at ?100 °C: space group with a = 1166.3(1), b = 1423.8(2), c = 1489.1(2) pm, α = 62.15(1)°, β = 72.04(1)°, γ = 88.82(1)°, Z = 2, R₁ = 0.0338 and for 1a at ?100 °C: space group P2₁/c with a = 1294.1(1), b = 1019.8(2), c = 3316.9(4) pm, β = 94.73(1)°, Z = 4, R₁ = 0.0435.     

Bidirectional switching of near IR emitting boradiazaindacene fluorophores

Two novel distyryl-boradiazaindacene dyes with dimethylaminostyryl and pyridylethenyl substituents display opposite spectral shifts on protonation with TFA in organic solvents. This bidirectional switching of the dyes can be shown to be directly related to ICT donor and acceptor characteristics of the substituents attached to the BODIPY core. The observed spectral response of these dyes could be very useful in the design of novel NIR fluorescent ratiometric probes for pH.     

Picomolar Detection of Hydrogen Peroxide at Glassy Carbon Electrode Modified with NAD+ and Single Walled Carbon Nanotubes

Potential cycling was used for oxidation of NAD⁺ and producing an electroactive redox couple which strongly adsorbed on the electrode surface modified with single walled carbon nanotubes (SWCNTs). Modified electrode shows a pair of well defined and nearly reversible redox peaks at pH range 1–13 and the response showed a surface‐controlled electrode process. The surface coverage and heterogeneous electron transfer rate constant (k_s) of adsorbed redox couple onto CNTs films were about 6.32×10^?10 mol cm^?2 and 2.0 (±0.20) s^?1, respectively, indicating the high loading ability of CNTs toward the oxidation product of NAD⁺ (2,8‐dihydroxy adenine dinucleotide) and great facilitation of the electron transfer between redox couple and CNTs immobilized onto electrode surface. The modified electrode exhibited excellent electrocatalytic activity for H₂O₂ reduction at reduced overpotential. The catalytic rate constant for H₂O₂ reduction was found to be 2.22(±0.20)×10⁴ M^?1 s^?1. The catalytic reduction current allows the amperometric detection of H₂O₂ at an applied potential of ?0.25 V vs. Ag/AgCl with a detection limit of 10 pM and linear response up to 100 nM and resulting analytical sensitivity 747.6 nA/pM. The remarkably low detection limit (10 pM) is the lowest value ever reported for direct H₂O₂ determination on the electrodes at pH 7. The modified electrode can be used for monitoring H₂O₂ without the need for an enzyme or enzyme mimic. The proposed method for rapid amperometric detection of H₂O₂ is low cost and high throughput. Furthermore, the sensor can be used to any detection scheme that uses enzymatically generated H₂O₂ as a reactive product in biological systems.     

Energies,Landé <Emphasis Type="Italic">g</Emphasis>-factors,and lifetimes for some excited levels of doubly ionized lanthanum

Using the relativistic Hartree-Fock (HFR) method developed by Cowan, we calculated the energy levels, Landé g-factors, and lifetimes for nd (n = 5–25), ns (n = 6–24), ng (n = 5–25), nf (n = 4–22), and np (n = 6–25) excited levels of doubly ionized lanthanum (La III, Z = 57). We compared the results with previously reported calculations and experiments.     

Quadrature formulas on the unit circle with prescribed nodes and maximal domain of validity

In this paper we investigate the Szeg?-Radau and Szeg?-Lobatto quadrature formulas on the unit circle. These are (n+m)-point formulas for which m nodes are fixed in advance, with m=1 and m=2 respectively, and which have a maximal domain of validity in the space of Laurent polynomials. This means that the free parameters (free nodes and positive weights) are chosen such that the quadrature formula is exact for all powers z^j, −p≤j≤p, with p=p(n,m) as large as possible.     

A genetic algorithm for a single product network design model with lead time and safety stock considerations

We consider a two-stage supply chain with a production facility that replenishes a single product at retailers. The objective is to locate distribution centers in the network such that the sum of facility location, pipeline inventory, and safety stock costs is minimized. We explicitly model the relationship between the flows in the network, lead times, and safety stock levels. We use genetic algorithms to solve the model and compare their performance to that of a Lagrangian heuristic developed in earlier work. A novel chromosome representation that combines binary vectors with random keys provides solutions of similar quality to those from the Lagrangian heuristic. The model is then extended to incorporate arbitrary demand variance at the retailers. This modification destroys the structure upon which the Lagrangian heuristic is based, but is easily incorporated into the genetic algorithm. The genetic algorithm yields significantly better solutions than a greedy heuristic for this modification and has reasonable computational requirements.     

Synthesis,Crystal Structure and Spectroscopic Characterization of {6-[2-(2-chlorophenyl)-1,3-thiazol-4-yl]-2-oxo-1,3-benzothiazol-3(2<Emphasis Type="Italic">H</Emphasis>)-yl}acetic acid

Abstract  

The title compound {6-[2-(2-chlorophenyl)-1,3-thiazol-4-yl]-2-oxo-1,3-benzothiazol-3(2H)-yl}acetic acid was prepared and characterized by elemental analyses, FT-IR, ¹H NMR spectroscopy, X-ray diffraction. A quantum-chemical calculation was performed using the CNDO method. In the title compound, C₁₈H₁₁ClN₂O₃S₂, the crystal structure is stabilized by intermolecular hydrogen bonds (C–H···O=C) to form centrosymmetric R₂² R_{2}^{2} (16) dimers and the C–H···O, O–H···N, and C–H···N interactions generating the graph set motifs R₂² R_{2}^{2} (9) and R₂² R_{2}^{2} (22).