Graphene oxide promoted synthesis of <Emphasis Type="Italic">p</Emphasis>-phenylenediamine antioxidants

Three p-phenylenediamine antioxidants (p-phenylenediamine-N,N,N′,N′-tetrapropionic acid tetramethyl ester, p-phenylenediamine-N,N,N′-tripropionic acid trimethyl ester, and p-phenylenediamine-N, N′-dipropionic acid dimethyl ester) were successfully synthesized via atom-economic aza-Michael addition of pphenylenediamine to methyl acrylate p-romoted by graphene oxide in water. The synthesized compounds were characterized by NMR, ESI-MS spectra, and elemental analyses. The effects of the solvent and graphene oxide on the reaction were investigated.     

Synthesis of Bisthiacalix[4]arene: Reaction of Piperazine with Monoacrylamide Derivative of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-Butylthiacalix[4]arene

The reaction of acryloyl chloride with the monoamine derivative of p-tert-butylthiacalix[4]arene was used to synthesize p-tert-butylthiacalix[4]arene monoacrylamide in the 1,3-alternate conformation. The effect of the nature of the amine on the result of its Michael reaction with the synthesized p-tert-butylthiacalix[4]arene monoacrylamide was studied. The latter was reacted with piperazine to obtain bisthiacalix[4]arene with the macrocyclic fragments in the 1,3-alternate conformation.     

Synthesis and antimicrobial activity of novel substituted 4-[3-(1<Emphasis Type="Italic">H</Emphasis>-benzimidazol-2-yl)-4-hydroxybenzyl]-2-(1<Emphasis Type="Italic">H</Emphasis>-benzimidazol-2-yl)phenol derivatives

A series of novel substituted bis-benzimidazole derivatives were synthesized by reaction of 5,5′-methylenebis(2-hydroxybenzaldehyde) with various substituted o-phenylenediamines in glacial acetic acid. The structure of the newly synthesized compounds was elucidated by ¹H and ¹³C NMR, FT-IR, and MS spectra, and their antimicrobial activity against gram positive and gram negative bacteria and antifungal activity were evaluated. The thienyl-substituted derivative showed significant activity against Bacillus licheniformis. Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumonia (bacteria), and Fusarium solani (fungi). The activities of the fluoro-substituted substituted derivative against some bacterial strains and of the thienyl-substituted derivative against fungi were found to be similar to those of standard drugs.     

Synthesis and spectral properties of <Emphasis Type="Italic">meso</Emphasis>-phenyltetrabenzoazaporphyrins containing triphenylmethyl groups

4-(p-Triphenylmethylphenoxy)isoindoline-1,3-diimine was synthesized starting from 4-(p-triphenylmethylphenoxy)phthalodinitrile obtained by the reaction of 4-nitrophthalodinitrile with 4-(triphenylmethyl)phenol. The former was reacted with phenylacetic acid in the presence of zinc oxide to obtain zinc complexes of meso-phenyltetrabenzoazaporphyrins containing triphenylmethyl groups. Spectral properties of the synthesized compounds were studied.     

2-Imino 2<Emphasis Type="Italic">H</Emphasis>-chromene and 2-(phenylimino) 2<Emphasis Type="Italic">H</Emphasis>-chromene 3-aryl carboxamide derivatives as novel cytotoxic agents: synthesis,biological assay,and molecular docking study

The inhibition of AKR₁B₁₀ has been recognized as a potential therapeutic approach to the treatment of various types of cancers. A novel series of compounds with imino-2H-chromen and phenylimino-2H-chromen scaffolds were synthesized by Knoevenagel condensation reaction. The in vitro cytotoxic activity of synthesized compounds was evaluated against MOLT-4 and SK-OV-3 cells. Among the tested compounds, N-(3,4-dimethoxyphenyl)-2-(phenylimino)-2H-chromene-3-carboxamide (8g) demonstrated potent inhibitory activity against both examined cell lines. The results of the molecular docking study suggested that this compound is involved in critical hydrogen-bonding interactions with the Val301 and Lue302 of AKR₁B₁₀ catalytic site.     

Compounds of the menthane series. Synthesis of unsaturated primary alcohols with the <Emphasis Type="Italic">o</Emphasis>- and <Emphasis Type="Italic">p</Emphasis>-menthane skeletons

Precursors to terpene alcohols of the o- and p-menthane series (o-cimen-7-ol and o- and p-cimen-9-ols) were synthesized, and their reduction with lithium in ethylenediamine was studied. The reduction of o- and p-cimen-9-ols in the presence of isopropyl alcohol selectively afforded the corresponding 1,4-dihydro derivatives. Under analogous conditions, o-cimen-7-ol was converted into a mixture of unsaturated hydrocarbons. The reduction with lithium in ethylenediamine in the absence of isopropyl alcohol in all cases gave mixtures of menthene alcohols.     

Modification of silica nanoparticles with stereisomers of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylthiacalix[4]arene containing four 2-oxo-2-{[3-(triethoxysilyl)prop-1-yl]amino}ethoxy substituents at the lower rim

Three stereoisomers (cone, partial cone, and 1,3-alternate) of p-tert-butylthiacalix[4]arene bearing four anchor propyltriethoxysilane substituents at the lower rim were synthesized for the first time. Surface modification of silica nanoparticles (d = 12 nm) with the synthesized macrocycles gave novel hybride thiacalix [4]arene?SiO₂ particles. The obtained nanostructured adsorbents were found to efficiently extract nitroaromatic compounds from aqueous solutions. The partial cone and 1,3-alternate thiacalix[4]arene–SiO₂ hybrid particles showed affinity to nitrophenols.     

Determination of tyrosine using <Emphasis Type="Italic">p</Emphasis>-sulfonated calix[<Emphasis Type="Italic">n</Emphasis>]arene modified electrode

Cyclic voltammetry was used to detect p-sulfonated calix[n]arenas (SCnA) how to immobilize on gold surface. P-sulfonated calix[n]arenes not only increased the specific surface area of the modified electrode, but also improved the enrichment ability of tyrosine. This led to a significant increase in peak current, and improved the sensitivity of tyrosine determination on the p-sulfonated calix[n]arenes-modified electrode. The modified electrode showed good catalytic ability of l-tyrosine oxidation reaction. The peak current of l-tyrosine increased and the oxidation peak potential shifted negatively with cavity size of the SCnA-modified electrode, which indicated that the catalytic ability of the modified electrode to l-tyrosine oxidation reaction was also enhanced. For the tyrosine guest molecule, the order of electrochemical activity and magnitude of catalytic ability of the oxidation reaction of the three modified gold electrodes was as follows: SC4A?>?SC6A?>?SC8A. The electrode had high selectivity and stability for the determination of tyrosine, with a wide linear range, low detection limit and high sensitivity at different concentrations under different pH values. This resulted in an accurate, fast, sensitive electrochemical method for the determination of tyrosine. The sensor was used for the determination of tyrosine in human urine with satisfactory results.     

Selective,metal-free oxidation of sulfides to sulfoxides Using 30% hydrogen peroxide catalyzed with <Emphasis Type="Italic">N</Emphasis>-bromosuccinimide (NBS) under neutral buffered reaction conditions

Various types of aromatic and aliphatic sulfides are selectively oxidized to the corresponding sulfoxides in good to excellent yields using 30% H₂O₂ in the presence of catalytic amounts of N-bromosuccinimide (NBS) in buffered aqueous acetonitrile solution (pH =7.00). The results showed that acid sensitive functional groups such as double bonds, and O,O-acetals remained intact under the described reaction conditions     

Tracing drug release process with dual-modal hyperbranched polymer-gold nanoparticle complexes

Dual-modal surface enhanced Raman spectrum(SERS)-fluorescence polymer/metal hybrid complexes have been prepared for tracing drug release process in tumor cells. Firstly, the hyperbranched poly((S-(4-vinyl) benzyl S′-propyltrithiocarbonate)-co-(poly(ethylene glycol) methacrylate))(HPVBEG) was synthesized via the combination of reversible addition-fragmentation chain-transfer(RAFT) polymerization and self-condensing vinyl polymerization(SCVP). Subsequently, the anticancer drug doxorubicin(DOX) was linked to HPVBEG via pH sensitive Schiff base bonds to form HPVBEG-g-DOX conjugates.Through aminolysis reaction, HPVBEG-g-DOX was coordinated with gold nanoparticles(GNP), resulting in the formation of HPVBEG-g-DOX/GNP complexes. In neutral condition, the HPVBEG-g-DOX/GNP complexes were stable, and DOX was bound to the surface of GNPs. Therefore, the SERS of DOX could be observed, while the fluorescence of DOX was quenched by GNPs. Under an acidic environment, DOX was released from the surface of GNPs with breakage of Schiff base bonds.Thus, the SERS signal of DOX was gradually reduced. Correspondingly, the fluorescence signal of DOX was enhanced.Through dual-modal SERS-fluorescence technique, the DOX delivery and release process was traced in tumor cells. Moreover,the viability of MCF-7 cells incubated with HPVBEG-g-DOX/GNP complexes was investigated by Cell Counting Kit-8(CCK-8) assay. The experimental results showed that HPVBEG-g-DOX/GNP complexes had similar proliferation inhibition effect compared with free DOX. Definitely, the dual-modal SERS-fluorescence complexes for tracing drug delivery and release will have promising prospects on tumor diagnosis and therapy.     

Effect of <Emphasis Type="Italic">Rol</Emphasis> Genes on Polyphenols Biosynthesis in <Emphasis Type="Italic">Artemisia annua</Emphasis> and Their Effect on Antioxidant and Cytotoxic Potential of the Plant

Flavonoids are famous for their antioxidant capacity and redox potential. They can combat with cell aging, lipid peroxidation, and cancer. In the present study, Artemisia annua hybrid (Hyb8001r) was subjected to qualitative and quantitative analysis of flavonoids through HPLC. Rol genes transgenics of A. annua were also evaluated for an increase in their flavonoid content along with an increase in antioxidant and cytotoxic potential. This was also correlated with the expression level of flavonoids biosynthetic pathway genes as determined by real-time qPCR. Phenylalanine ammonia-lyase and chalcone synthase genes were found to be significantly more highly expressed in rol B (four to sixfold) and rol C transgenics (3.8–5.5-fold) than the wild-type plant. Flavonoids detected in the wild-type A. annua through HPLC include rutin (0.31 mg/g DW), quercetin (0.01 mg/g DW), isoquercetin (0.107 mg/g DW) and caffeic acid (0.03 mg/g DW). Transgenics of the rol B gene showed up to threefold increase in rutin and caffeic acid, sixfold increase in isoquercetin, and fourfold increase in quercetin. Whereas, in the case of transgenics of rol C gene, threefold increase in rutin and quercetin, 5 fold increase in isoquercetin, and 2.6-fold increase in caffeic acid was followed. Total phenolics and flavonoids content was also found to be increased in rol B (1.5-fold) and rol C (1.4-fold) transgenics as compared to the wild-type plant along with increased free radical scavenging activity. Similarly, the cytotoxic potential of rol gene transgenics against MCF7, HeLA, and HePG2 cancer cell lines was found to be significantly enhanced than the wild-type plant of A. annua. Current findings support the fact that rol genes can alter the secondary metabolism and phytochemical level of the plant. They increased the flavonoids content of A. annua by altering the expression level of flavonoids biosynthetic pathway genes. Increased flavonoid content also enhanced the antioxidant and cytotoxic potential of the plant.     

Approach to preparative synthesis of <Emphasis Type="Italic">ortho</Emphasis>-(1-methylbut-2-en-1-yl)anilines,precursors of new cytotoxic heterocycles

The reaction of aromatic Claisen rearrangement of N-(1-methylbut-2-en-1-yl)anilines in the presence of p-toluenesulfonic acid was investigated. N-Tosyl-2-(1-iodoethyl)-3-methylindoline derivatives were obtained; one of them exhibited a cytotoxic activity.     

3<Emphasis Type="Italic">H</Emphasis>-Benzo[<Emphasis Type="Italic">a</Emphasis>]imidazo[4,5-<Emphasis Type="Italic">j</Emphasis>]acridine as a new fluorescent heterocyclic system: synthesis,spectral studies,and quantum chemical investigation

The synthesis, spectral studies, and theoretical calculations of a new fluorescent heterocyclic system are described. New 3H-benzo[a]imidazo[4,5-j]acridines were obtained in high yields by the reaction of 1-alkyl-5-nitro-1H-benzimidazoles with (naphthalen-1-yl)acetonitrile via nucleophilic substitution of hydrogen, and their structures were established by spectral (UV-Vis, FT-IR, 1H and 13C NMR) and analytical data. Study of the optical and solvatochromic properties of the dyes revealed their high molar absorption coefficients and high fluorescence quantum yields which in some cases exceeded quantum yields of well-known fluorescent dyes such as fluorescein. Density functional theory (DFT) calculations using the B3LYP hybrid functional and 6-311++G(d,p) basis set were performed to obtain optimized geometries and frontier orbital structures of the synthesized compounds. The electronic absorption spectra were also simulated by the time-dependent density functional theory (TD-DFT) method.     

Synthesis and antimicrobial activity of novel fused [1,2,4]triazino[5,6-<Emphasis Type="Italic">b</Emphasis>]indole derivatives

Synthesis of new fused systems of triazino[5,6-b]indole starting with preparation of 3-amino[1,2,4]-triazino[5,6-b]indole 1 by reaction of isatin with 2-aminoguanidinium carbonate in boiling acetic acid is presented [1]. Intermediate compound 1 reacted with aldehyde, ethyl chloroformate, triethyl orthoformate, and ninhydrine and gave new heterotetracyclic nitrogen systems, such as 3-(N ²-guanidinylimino)indole-2(1H)-one 2, 3-(N-ethoxycarbonylamino)-4H-[1,2,4]triazino[5,6-b]indole 3, 3-(N-ethoxymethyleneamino)-4H-[1,2,4]-triazino[5,6-b]indole 4, 3-(hydrazinothiocarbonylamino)-4H-[1,2,4]triazino[5,6-b]indole 5, respectively. N-(1,3-dioxoindene-2-ylidene)-4H-[1,2,4]triazino[5,6-b]indol-3-amine 6 was synthesized by reaction of compound 1 with aldehyde, ethyl chloroformate, triethyl orthoformate, and ninhydrine. New fused indole systems, pyrimido[2′,1′:3,4][1,2,4]triazino[5,6-b]indol-3(4H)-one 8, 9, 11, 12 and 1H-imidazo[2′,1′:3,4][1,2,4]triazino-[5,6-b]indol-2(3H)-one 10, were synthesized in the reaction of the intermediate 1 with bifunctional compounds. Structures of the products were elucidated from their elemental analysis and spectral data (IR, ¹H and ¹³C NMR and mass spectra). Antimicrobial activity of some synthesized compounds was tested.     

Deactivation of a ruthenium(II) <Emphasis Type="Italic">N</Emphasis>-heterocyclic carbene <Emphasis Type="Italic">p</Emphasis>-cymene complex during transfer hydrogenation catalysis

A ruthenium (II) N-heterocyclic carbene (NHC) complex was synthesized to investigate ligand dissociation as a possible deactivation pathway for the catalytic cycle of a transfer hydrogenation reaction. Diiodo(1,3-dimethylbenzimidazole-2-ylidene)(p-cymene)ruthenium(II) was synthesized for use as the catalytic species and characterized using physico-chemical, spectroscopic methods, and single crystal X-ray diffraction. The transfer of hydrogen from isopropanol to acetophenone was followed using ¹H NMR. We observed 94% conversion of the substrate to the alcohol product after 1 h. We also found that the p-cymene complex decomposed during the catalytic reaction to the extent of 80% deactivation after 1 h, based on ¹H NMR spectrometry. From Gaussian calculations, an ultraviolet–visible spectrum that is in excellent agreement with the actual spectrum was computed, giving insight into the nature of the absorptions observed experimentally.     

Chemiluminescence Determination of Cyanide Ions

It was found that alkaline solutions of luminol exhibit chemiluminescence in the presence of p-nitrobenzaldehyde (p-NBA), hemin, and cyanide ions. Air oxygen dissolved in the solutions is an essential component of the process. The kinetics of luminol chemiluminescence in the presence of p-NBA, hemin, and cyanide ions indicates the catalytic nature of the process. A scheme was proposed for the series of reactions resulting in chemiluminescence and generated by superoxide radicals formed in the p-NBA-catalyzed reaction between hemin-activated air oxygen and hydrated p-NBA species. A procedure was developed with a determination limit of (1.0 ± 0.3) × 10^?7 mg/mL (n = 5, P = 0.95) for cyanide ions.     

<Emphasis Type="SmallCaps">l</Emphasis>-Cysteine-functionalized magnetic nanoparticles (LCMNP): as a magnetic reusable organocatalyst for one-pot synthesis of 9-(1<Emphasis Type="Italic">H</Emphasis>-indol-3-yl) xanthen-4-(9<Emphasis Type="Italic">H</Emphasis>)-ones

l-Cysteine-functionalized magnetic nanoparticles (LCMNP) were introduced as an efficient and magnetically separable organocatalyst for the synthesis of 9-(1H-indol-3-yl) xanthen-4-(9H)-one derivatives. This class of compounds was synthesized via a one-pot three-component coupling reaction of 2-hydroxybenzaldehyde, dimedone, and indole in the presence of catalytic amount of LCMNP under mild and green conditions. High yields, short reaction time, easy workup, using environmental friendly conditions, and magnetic reusable catalyst are the advantages of this synthetic methodology. The LCMNP catalyst was reusable in this reaction at least for 6 times without significant decreasing in its catalytic activity.     

Synthesis and antibacterial activity of new <Emphasis Type="Italic">N</Emphasis>-substituted 7-amino-4-methyl-2<Emphasis Type="Italic">H</Emphasis>-chromen-2-ones

N-Substituted 7-amino-4-methyl-2H-chromen-2-ones containing one or two functionalized azole or azine moieties were synthesized. The structures of all synthesized compounds were confirmed by IR, ¹H NMR, and ¹³C NMR spectroscopy. Some of the synthesized compounds exhibited weak antibacterial activity against Rhizobium radiobacter, Escherichia coli, and Xanthomonas campestris.     

Synthesis and biological activity of arylaliphatic <Emphasis Type="Italic">N</Emphasis>-(2-aminoethyl)-<Emphasis Type="Italic">N</Emphasis>-(2-hydroxy-2-phenylethyl)carboxamides

N-(2-Aminoethyl)-N-(2-hydroxy-2-phenylethyl)carboxamides were synthesized from styrene oxide by ring opening with N,N-disubstituted ethylenediamines followed by N-acylation. Synthesized compounds have pronounced antiarrhythmic activity and low toxicity.     

Catalytic efficiency of cesium and potassium salts of dodecatungstophosphoric acid supported on silica and comparison with H<Subscript>3</Subscript>PW<Subscript>12</Subscript>O<Subscript>40</Subscript>/SiO<Subscript>2</Subscript>

Pure tungstophosphoric acid, potassium tungstophosphate, and cesium tungstophosphate with varying extent of substitution of protons by Cs or K ions x (x = 1, 2, 2.5, and 3) have been prepared and are supported on silica by the wet impregnation method. The extent of loading was fixed at 20 wt %. For the sake of comparison, unloaded Cs _x and K _x (x = 1) salts of tungstophosphoric acid were prepared by the precipitation method. The supported catalysts were characterized by FT-IR, XRD, specific surface area measurements, and catalytic conversion of tert-butanol. The results revealed that the catalytic conversion of tert-butanol proceeds mainly via dehydration yielding isobutene. The Cs₁PW/SiO₂, HPW/SiO₂, and K₁PW/SiO₂ catalysts were more active than their unsupported samples. The previous solids showed greater catalytic activity and stability. Unexpectedly, substitution of one proton of tungstophosphoric acid by a cesium or potassium ion exerted no measurable effect on the catalytic activity of the treated solids, in spite of decreasing the Brønsted acidity of Cs₁PW/SiO₂ and K₁PW/SiO₂ indicating that the acidity of HPW/SiO₂ decrease may be due to the interaction between HPW and the SiO₂ surface. On the other hand, significant decrease in the catalytic activity took place upon increasing the cation content (x) to x = 2, 2.5, and 3.