Evaluation of the Antioxidant and Antiradical Properties of Some Phyto and Mammalian Lignans

In this study, the antioxidant and antiradical properties of some phyto lignans (nordihydroguaiaretic acid, secoisolariciresinol, secoisolariciresinol diglycoside, and α-(-)-conidendrin) and mammalian lignans (enterodiol and enterolactone) were examined by different antioxidant assays. For this purpose, radical scavenging activities of phyto and mammalian lignans were realized by 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) radical (ABTS^•+) scavenging assay and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging assay. Additionally, the reducing ability of phyto and mammalian lignans were evaluated by cupric ions (Cu²⁺) reducing (CUPRAC) ability, and ferric ions (Fe³⁺) and [Fe³⁺-(TPTZ)2]³⁺ complex reducing (FRAP) abilities. Also, half maximal inhibitory concentration (IC₅₀) values were determined and reported for DPPH^• and ABTS^•+ scavenging influences of all of the lignan molecules. The absorbances of the lignans were found in the range of 0.150–2.320 for Fe³⁺ reducing, in the range of 0.040–2.090 for Cu²⁺ reducing, and in the range of 0.360–1.810 for the FRAP assay. On the other hand, the IC₅₀ values of phyto and mammalian lignans were determined in the ranges of 6.601–932.167 µg/mL for DPPH^• scavenging and 13.007–27.829 µg/mL for ABTS^•+ scavenging. In all of the used bioanalytical methods, phyto lignans, as secondary metabolites in plants, demonstrated considerably higher antioxidant activity compared to that of mammalian lignans. In addition, it was observed that enterodiol and enterolactone exhibited relatively weaker antioxidant activities when compared to phyto lignans or standard antioxidants, including butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), Trolox, and α-tocopherol.     

Antioxidant,Antidiabetic, Anticholinergic,and Antiglaucoma Effects of Magnofluorine

Magnofluorine, a secondary metabolite commonly found in various plants, has pharmacological potential; however, its antioxidant and enzyme inhibition effects have not been investigated. We investigated the antioxidant potential of Magnofluorine using bioanalytical assays with 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^•+), N,N-dimethyl-p-phenylenediamine dihydrochloride (DMPD^•+), and 1,1-diphenyl-2-picrylhydrazyl (DPPH^•) scavenging abilities and K₃[Fe(CN)₆] and Cu²⁺ reduction abilities. Further, we compared the effects of Magnofluorine and butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), α-Tocopherol, and Trolox as positive antioxidant controls. According to the analysis results, Magnofluorine removed 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals with an IC₅₀ value of 10.58 μg/mL. The IC₅₀ values of BHA, BHT, Trolox, and α-Tocopherol were 10.10 μg/mL, 25.95 μg/mL, 7.059 μg/mL, and 11.31 μg/mL, respectively. Our results indicated that the DPPH· scavenging effect of Magnofluorine was similar to that of BHA, close to that of Trolox, and better than that of BHT and α-tocopherol. The inhibition effect of Magnofluorine was examined against enzymes, such as acetylcholinesterase (AChE), α-glycosidase, butyrylcholinesterase (BChE), and human carbonic anhydrase II (hCA II), which are linked to global disorders, such as diabetes, Alzheimer’s disease (AD), and glaucoma. Magnofluorine inhibited these metabolic enzymes with Ki values of 10.251.94, 5.991.79, 25.411.10, and 30.563.36 nM, respectively. Thus, Magnofluorine, which has been proven to be an antioxidant, antidiabetic, and anticholinergic in our study, can treat glaucoma. In addition, molecular docking was performed to understand the interactions between Magnofluorine and target enzymes BChE (D: 6T9P), hCA II (A:3HS4), AChE (B:4EY7), and α-glycosidase (C:5NN8). The results suggest that Magnofluorine may be an important compound in the transition from natural sources to industrial applications, especially new drugs.     

Synthesis and spectroscopic properties of (N/O) mono- and dispirocyclotriphosphazene derivatives with benzyl pendant arms: study of biological activity

The Cl replacement reactions of hexachlorocyclotriphosphazene (trimer; N ₃ P ₃ Cl ₆ ) with sodium (N-benzyl)- aminopropanoxides (1 and 2) produced monospiro- (3 and 4), cis-, and trans-dispirocyclotriphosphazenes (13–16). The monospiro tetrakis-aminocyclotriphosphazenes (5–12) were obtained by the Cl substitutions of 3 and 4 with different secondary amines. The cis- (13 and 14) and trans-dispirophosphazenes (15 and 16) possessed 2 chiral P centers, and they were able to present meso and racemic forms, respectively. Moreover, the structures of compounds 5 and 14 were designated using X-ray data. The absolute configuration of compound 14 was found as SR in the solid state. Analytical and spectroscopic data of the phosphazenes were consistent with their suggested structures. Antimicrobial activities of the benzyl-pendant-armed cyclotriphosphazenes were scrutinized against G(+) and G(−) bacteria and yeast strains. The bacterium most affected by the synthesized compounds was Pseudomonas aeruginosa . Minimum inhibitory concentrations and minimal bacterial concentrations were in the range of 125–500 μM. Interactions between the phosphazenes (3–12 and 15) and plasmid DNA were studied with agarose gel electrophoresis. The phosphazene- DNA interaction studies of the cyclotriphosphazenes revealed that phosphazenes 3, 4, and 15 had a substantial effect on supercoiled DNA by cleavage of the double helix.     

Applications of Mitsunobu Reaction in total synthesis of natural products

The Mitsunobu Reaction allows the conversion of primary and secondary alcohols to esters, phenyl ethers, thioethers and some other compounds. The nucleophile employed should be acidic, since one of the reagents, diethylazodicarboxylate (DEAD) must be protonated during the course of the reaction, preventing from the formation of unwanted side products. In this review, we try to focus on the scope and preparative synthetic applications of Mitsunobu reaction as a key step in the total synthesis of biologically active natural products.     

Experimental and modeling study on production of activated carbon from pistachio shells in rotary reactor

In this study, activated carbons were prepared by physical activation from pistachio shell with steam in a rotary reactor. Experiments were performed based on the central composite design (CCD) in DX8 software. A quadratic model for prediction of iodine number and a quadratic model for burn-off were developed using CCD in the activation process. The optimum iodine number and burn-off for physical activation were, respectively, 1,478.17 mg/g and 22.09 wt%, which showed good agreement with the experimental values. The optimum values were achieved at the activation temperature of 816.5 °C, dwell time of 40 min, and gas flow rate of 47.4 l/min.     

Synthesis,characterization, and electrical properties of a diazodiphenylene‐bridged Cu–phthalocyanine polymer

A diazodiphenylene‐bridged Cu–phthalocyanine polymer was synthesized from the diazonium salt of bensidine and the Cu(II) 1,8,15,22‐tetraaminophthalocyanine complex and characterized with Fourier transform infrared, ultraviolet–visible spectroscopy, and elemental analysis. The polymer was partially soluble in organic solvents such as dimethylformamide and tetrahydrofuran. The molecular weight of the soluble part of the polymer was investigated with ebullioscopy and viscosimetry methods in tetrahydrofuran. Both methods showed that the molecular weight of the polymer was much larger than that of the complex. The conductivity of the samples was measured with a four‐prop conductivity measuring device. Iodine and hydrogen chloride were doped to the polymer, and an increase of about 10⁴ S cm^?1 in the electrical conductivity was observed. The cyclic voltammogram of the diazodiphenylene‐bridged Cu–phthalocyanine polymer in contact with a LiClO₄ electrolyte exhibited two reductions and two reoxidations with high reversibility and electrochemical stability. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5692–5698, 2006     

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.     

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.     

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.