N‐(Substituted benzyl)‐3,5‐bis(benzylidene)‐4‐piperidones: Synthesis and Preliminary Anti‐leukemia Activity (I)

A series of novel N‐(substituted benzyl)‐3,5‐bis(benzylidene)‐4‐piperidones 5a – 5o were synthesized with substituted benzylamines as raw materials via a series of Michael addition, Dieckmann condensation, hydrolysis decarboxylation and aldol condensation. The structures were confirmed by ¹H NMR, IR, MS techniques and elemental analysis. Assay‐based antiproliferative activity study using leukemic cell lines K562 revealed that most of the title compounds have high effectiveness in inhibiting leukemia K562 cells proliferation, among which the compounds 5g (IC₅₀=7.81 µg·mL⁻¹), 5k (IC₅₀=6.35 µg·mL⁻¹), 5l (IC₅₀=7.20 µg·mL⁻¹), and 5o (IC₅₀=5.79 µg·mL⁻¹) have better inhibition activities than standard 5‐fluorouracil (IC₅₀=8.56 µg·mL⁻¹).     

Cytotoxic activity of two polyaspartamide‐ based monoamineplatinum(II) conjugates against the HeLa cancer cell line

In this screening study in vitro, two polymer‐conjugated, square‐planar platinum(II) complexes bound to the carrier via a single primary amine ligand were tested for antineoplastic activity against the HeLa human cervical epithelioid carcinoma cell line. In the first of these conjugates, 1‐Pt , the spacer connecting the metal complex with the carrier backbone is a short oligo(ethylene oxide) segment, whereas a long poly(ethylene oxide) chain represents the spacer unit in the second conjugate, 2‐Pt . IC₅₀ data, expressed as conjugate concentration at 50% cell growth inhibition, are 48 µg Pt ml⁻¹ for 1‐Pt and 120 µg Pt ml⁻¹ (estimated) for 2‐Pt , the long tether in the latter conjugate presumably causing retarded enzymic release and lysosomal membrane crossing of the monomeric complex. The IC₅₀ value of 1‐Pt is close to that (44 µg Pt ml⁻¹) of a similar conjugate of an earlier investigation, 3‐Pt , in which the metal is chelated by two carrier‐attached, cis‐oriented amino groups in conformance with the ligand arrangement in cisplatin. It thus appears that, in the carrier‐bound state, both monoamine‐ and cis‐diamine‐coordinated platinum(II) complexes of suitable structures may well show similar biological performance patterns. Copyright­© 1999 John Wiley & Sons, Ltd.     

Extraction and Determination of Quercetin and Myricetin from Chamaecyparis obtusa by Ionic Liquids‐based Monolithic Cartridge

A short ionic liquids (ILs)‐based monolithic cartridge was prepared and used as the selective extraction sorbent. After the material was evaluated by field emission‐scanning electron microscopy (FE‐SEM), a new approach for the extraction and determination of quercetin and myricetin from Chamaecyparis obtusa (C. obtusa) by using ILs‐based, monolithic cartridge system was developed. Chromatographic analysis was conducted on a C₁₈ column with UV detection at 372 nm, an eluting solution consisting of acetonitrile‐water (25/75,V/V) as the mobile phase, and a flow rate of 0.7 mL·min⁻¹. A good linear relationship was demonstrated when the concentrations of quercetin and myricetin were in the range of 0.5–100.0 µg·mL⁻¹. The recoveries ranged from 101.6% to 104.6% and the inter‐ and intra‐day relative standard deviations (RSD) were less than 5.0%. This method effectively removed the impurities and avoided tedious pretreatment. It provided a fast, economic and effective method for assaying trace drugs from natural plants.     

Poly(amidoamine) Conjugates Containing Doxorubicin Bound via an Acid‐Sensitive Linker

Poly(amidoamine)s with amino pendant groups were prepared by hydrogen‐transfer polyaddition of primary and secondary amines to bis‐acrylamines. Dansyl cadaverine (DC) doxorubicin (Dox) were bound to the polymers via a cis‐aconityl spacer to give conjugates containing 3 µg of DC per mg of polymer and 28 to 35 µg of Dox per mg of polymer. Release of DC and Dox at physiological and acidic pH varied from 0 to 35% over 48 h and was pH dependent. Although the ISA1Dox conjugate (IC₅₀ = 6 µg Dox · mL^?1) presented similar toxicity as the parent polymer without Dox, ISA23Dox showed increased toxicity (IC₅₀ = 10 µg Dox · mL^?1). These results suggest that ISA23Dox is able to release biologically active Dox in vitro and that this conjugate might be suitable for further development.

     

Simple and selective extraction of quercetin with microextraction in packed syringe method using modified glass powder by a molecularly imprinted polymer followed by spectrophotometric determination

A new sample preparation method based on microextraction in packed syringe was developed for preconcentration of quercetin prior to its spectrophotometric determination. Molecularly imprinted polymers as packing material was used for higher extraction efficiency. First, glass powder as support material because of low cost and available substrate was modified, and then molecularly imprinted polymers were synthesized by the sol–gel method using 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as cross-linker agent. The combination of a molecularly imprinted polymers and microextraction in packed syringe increased the selectivity and sensitivity. The surface morphology and functionality of the prepared molecularly imprinted polymers was characterized using Fourier-transform infrared spectroscopy, Field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and thermogravimetric analysis. Different influencing parameters on extraction efficiency such as effect of the number of sample sorption/desorption cycles, type and volume of desorption solvent, pH of the sample solution, and molecularly imprinted polymers amounts were optimized. Under the optimum condition, the proposed method displayed a linear range from 0.01 to 5 µg mL⁻¹ and limit of detection 3.68 ng mL⁻¹. Relative standard deviation for three replicate determination of 1 µg mL⁻¹ quercetin was 2.1 %. The proposed method was applied successfully for the selective extraction of quercetin from tea and coffee samples.     

Hydrogels based on schiff base formation between an amino‐containing polyphosphazene and aldehyde functionalized‐dextrans

Hydrogels generated by the interaction of two different water‐soluble polymers offer access to a new group of soft materials. A prototype amino‐functionalized polyphosphazene with both tyramine and ferulic acid‐based side groups was coupled to aldehyde functionalized‐dextrans to form hydrogels crosslinked via Schiff base chemistry. Synthesis of the polyphosphazene was accomplished by macromolecular substitution and protection‐deprotection chemistry, with characterization by ¹H NMR, ³¹P NMR, solid state ¹³C NMR, and DSC techniques. Combination of the aqueous polyphosphazene and aldehyde functionalized‐dextran solutions at room temperature caused gelation with different gelation times and crosslink densities dependent on the aldehyde content of the dextran. The hydrogel properties were evaluated using rheology, thermal characterization, and cryo‐microscopy. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2984–2991     

Simultaneous Determination and Drug Dissolution Testing of Combined Amlodipine Tablet Formulations Using RP-LC

In the proposed work, the simultaneous analysis of amlodipine–rosuvastatin and amlodipine–atorvastatin in their dosage forms was achieved. Simultaneous dissolution profiles of the amlodipine–rosuvastatin and amlodipine–atorvastatin tablets are realized using Apparatus II with a simple, accurate and precise RP-LC method. The mobile phase consisting of 0.2 % H₃PO₄ and pH 5:methanol:acetonitrile (46:27:27) was used. The samples of 10 µL were injected onto a Zorbax SB C18 (100 mm, 4.6 mm, 3.5 µm particle size) column with 1.2 µL min⁻¹ flow rate. The samples were detected at 236 nm. By plotting peak area ratios vs. concentration, the linearity for amlodipine–rosuvastatin and amlodipine–atorvastatin was determined. With the developed RP-LC method, AML, ROS and ATOR were detected within the range of 0.25–10, 0.5–10 and 0.25–25 µg mL⁻¹, respectively. LOD and LOQ values were also calculated as 0.028, 0.058, 0.021 and 0.095 µg mL⁻¹, 0.195 µg mL⁻¹, 0.070 µg mL⁻¹ for AML, ROS and ATOR, respectively. System suitability tests parameters, such as capacity factor, selectivity to previous peak, selectivity to next peak, resolution to previous peak, resolution to next peak, tailing factor, theoretical number of plates, were performed and found coherent with the ICH guideline parameters. The proposed method has been extensively validated in terms of recovery, and recovery results were between 99 and 101 %. For proving the precision, between-day and within-day repeatability results of the method were proposed. The method can be used for the simultaneous determination of amlodipine–rosuvastatin and amlodipine–atorvastatin.

     

Immunoassay for the detection of lead ions in environmental water samples

A rapid, simple, and reliable competitive immunoassay was developed for measurement of lead ions Pb(II) in environmental samples. Avian antibodies were produced against Pb(II). Since lead ions are too small to elicit an immune response, the metal was coupled to protein carrier Bovine serum albumin (BSA) using a bifunctional chelator 1-(4-isothiocyanobenzyl) ethylenediamine N,N,N′,N′-tetra acetic acid (ITCBE). Poultry birds (layers) were immunised with this Pb(II)–ITCBE–BSA immunoconjugate and the avian antibodies (IgY) isolated from egg yolk recognised Pb(II)-ITCBE complexes as capture reagent and a Pb(II)–ITCBE conjugate of Alkaline phosphatase as an enzyme label. Antibody reaction was optimised for different concentrations of antigen and antibody dilutions. Cross reactivity with other metals were below 1% in competitive ELISA. The IC₅₀ value of this avian antibody was 0.19?µg?mL^?1. The detection range and the detection limit were 0.02–1000?µg?mL^?1and 0.2?µg?mL^?1, respectively.     

Determination of Amantadine Residue in Honey by Solid‐phase Extraction and High‐performance Liquid Chromatography with Pre‐column Derivatization and Fluorometric Detection

Amantadine (AMA) is an anti‐viral drug used in apiculture to protect honeybee against the sacbrood virus (Morator aetatulae). This study described a reliable high‐performance liquid chromatographic (HPLC) method for analyzing AMA in honey using a solid‐phase extraction (SPE) cartridge (Plexa PCX) for purification, 4‐fluoro‐7‐nitro‐2,1,3‐benzoxadiazole (NBD‐F) as a pre‐column derivatization agent, and fluorometric detection (λ_ex=470 nm, λ_em=530 nm). The chromatographic separation was performed on an XDB C18 column (150×4.6 mm i.d.) using 0.1% trifluoroacetic acid/acetonitrile (35:65,V/V) as the mobile phase at a flow rate of 1.0 mL·min⁻¹ with a run time of 20 min. Under these optimal conditions, a linear relationship was observed in the range of 0.025–1.0 µg· mL⁻¹ with a good correlation coefficient (0.998) and low limit of detection (0.0080 µg·g⁻¹), the recoveries were all above 90%, and the intra‐day and inter‐day precision (RSD) ranged from 3.4%–5.1%.     

Determination of Aflatoxin M1 in Milk by a Magnetic Nanoparticle-Based Fluorescent Immunoassay

A sensitive and rapid magnetic nanoparticle-based fluorescent immunoassay for the determination of aflatoxin M1 in raw milk was developed. Aflatoxin M1 was converted to aflatoxin M1-o-carboxymethyl oxime. The aflatoxin M1-oxime was used for the preparation of aflatoxin M1-oxime-fluoresceinamine conjugate through the carbodiimide reaction. The aflatoxin M1-oxime-fluoresceinamine conjugate was characterized by ultraviolet–visible and infrared spectroscopy. Magnetic nanoparticles (Fe₃O₄) were synthesized and modified by 3-(aminopropyl)triethoxysilane. The size of initial (139?nm) and functionalized magnetic nanoparticles (147?nm) was determined by particle analysis. The optimal mass of immobilized antibody (25?µg) and optimal concentration of aflatoxin M1-oxime-fluoresceinamine conjugate (15?µg?mL^?1) for magnetic nanoparticle-based fluorescent immunoassay were determined. The developed immunoassay provided a linear aflatoxin M1 concentration range from 3.0 to 100?pg?mL^?1 in bovine milk. The detection limit was 2.9?pg?mL^?1. The results of aflatoxin M1 magnetic nanoparticle-based fluorescent immunoassay in heat-treated milk and phosphate-buffered saline at pH 6.6 were compared. The influence of the somatic cell count, pH, and fat concentration in bovine milk on the aflatoxin M1 immunoassay was investigated. The influence of the milk species on the immunoassay was also characterized. The high fat concentration ovine milk depressed the sensitivity of the aflatoxin M1 immunoassay.     

Direct functionalization of polyisobutylene by living initiation with α‐methylstyrene epoxide

This article describes the synthesis and characterization of polyisobutylene (PIB) carrying one primary hydroxyl head group and a tertiary chloride end group, [Ph? C(CH₃)(CH₂OH)–PIB–CH₂? C(CH₃)₂Cl] prepared with direct functionalization via initiation. The polymerization of isobutylene was initiated with the α‐methylstyrene epoxide/titanium tetrachloride system. Living conditions were obtained from ?75 to ?50 °C (198–223 K). Low molecular weight samples (number‐average molecular weight ～ 4000 g/mol) were prepared under suitable conditions and characterized by Fourier transform infrared and ¹H NMR spectroscopy. The presence of primary hydroxyl head groups in PIB was verified by both methods. Quantitative Fourier transform infrared with 2‐phenyl‐1‐propanol calibration and ¹H NMR performed on both the hydroxyl‐functionalized PIB and its reaction product with trimethylchlorosilane showed that each polymer chain carried one primary hydroxyl head group. The synthetic methodology presented here is an effective and simple route for the direct functionalization of PIB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1005–1015, 2002     

Quantification of Thiram in Honeybees: Development of a Chemiluminescent ELISA

Abstract

A Chemiluminescence Enzyme‐Linked Immuno‐Sorbent Assay (CL‐ELISA) for determination and quantification of the fungicide thiram in honeybees was developed in an indirect competitive format. The assay was optimized by determining: the optimal coating conjugate concentration and anti‐thiram antiserum dilution, the effect of the incubation time on the competitive step, the tolerance to organic solvents. The IC₅₀ and the limit of detection (LOD) values were 60 ng mL^?1 and 9 ng mL^?1, respectively, similar to those of colorimetric ELISA with a calibration range of 9–15,000 ng mL^?1. Cross reactivity of some related compounds such as some dithiocarbamates, a thiocarbamate, the ethylenethiourea and the tetramethylthiourea were tested. The assay was then applied to honeybees sample extracts obtained by using the liquid‐liquid extraction or the graphitized carbon‐based solid phase extraction.

The calibration curves in honeybee extracts from liquid‐liquid procedure gave an IC₅₀ of 141 ng mL^?1 and a LOD of 17 ng mL^?1. In case of extracts obtained by SPE these values were 139 ng mL^?1 and 15 ng mL^?1, respectively. The average recovery value from honeybee extracts spiked with 75 ng mL^?1 of thiram was 72% for SPE, higher than for liquid‐liquid extraction (60%). On the opposite, when the honeybees were directly spiked with 2 and 10 ppm the average recovery was higher for liquid‐liquid extraction (54%), than for SPE (31%). Finally, the assay was applied to honeybee samples collected during monitoring activities in Italy and Russia.     

Nonextractive Trace Level Simultaneous Determination of Mercury(II) and Zinc(II) in Environmental Samples with 2‐(5‐Bromo‐2‐pyridylazo)‐5‐diethylaminophenol and Cetylpyridinium Chloride

Abstract

A simple, rapid, selective, and sensitive method for the derivative spectrophotometric determination of Hg(II) and its simultaneous determination in the presence of Zn(II) using 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol in the presence of cetylpyridinium chloride, a cationic surfactant, has been developed. The molar absorption coefficient and analytical sensitivity of the 1∶1 Hg(II) complex at 558 nm (λ_max) are 5.78×10⁴ L mol^?1 cm^?1 and 0.67 ng mL^?1, respectively. The detection limit of Hg(II) is 1.40×10^?2 ng mL^?1, and Beer's law is valid in the concentration range 0.05–2.40 µg mL^?1. Overlapping spectral profiles of Hg(II) and Zn(II) complexes in zero‐order mode interfere in their simultaneous determination. However, 0.10–2.00 µg mL^?1 of Hg(II) and 0.065–0.650 µg mL^?1 of Zn(II), when present together, can be simultaneously determined at zero cross point of the derivative spectrum, without any prior separation. The relative standard deviation for six replicate measurements of solutions containing 0.134 µg mL^?1 of Hg(II) and 0.620 µg mL^?1 of Zn(II) is 1.72 and 1.47%, respectively. The proposed method has successfully been evaluated for trace level simultaneous determination of Hg(II) and Zn(II) in environmental samples.     

Study on the Synthesis and Bioactivity of Novel Mahkoside A Derivatives

Abstract

A series of novel Mahkoside A derivatives was synthesized, and their in vitro cytotoxic activities were evaluated against the human cancer cell line Ec‐9706. A Preliminary structure–activity relationship study showed compounds 7 and 8 have obvious cytotoxic activities (IC₅₀: 30.0 and 12.5 µg · mL^?1, respectively).     

Simultaneous HPLC–DAD Determination of Retinol and Eight Vitamin E Isomers in Human Serum

An efficient, high-performance liquid-chromatographic method with diode-array detection (HPLC–DAD) has been established for simultaneous determination of retinol, α, (β + γ), and δ-tocopherols, and α, β, γ, and δ-tocotrienols in human serum. After deproteinization, the target vitamins in serum were extracted with n-hexane and the extract was evaporated under weak nitrogen flow. The residue was redissolved in methanol and the resulting solution was used for HPLC analysis. Retinol acetate and α-tocopherol acetate were used as internal standards. The internal standard calibration curves were linear over the range of 0.010–50.0 µg mL⁻¹, with correlation coefficients >0.999. Mean recoveries of the method were 86.3–110 %, with intra-day and inter-day relative standard deviations less than 12.2 and 14.9 %, respectively. The detection limits of the method ranged from 0.001 to 0. 002 µg mL⁻¹, and the quantification limits ranged from 0.002 to 0.008 µg mL⁻¹. The method was successfully applied to analysis of the target vitamins in 50 human serum samples; all the analytes were detected at concentrations ranging from <0.002–23.0 µg mL⁻¹.

     

Voltammetric Method for the Simultaneous Determination of Melatonin and Pyridoxine in Dietary Supplements Using a Cathodically Pretreated Boron‐doped Diamond Electrode

The simultaneous voltammetric determination of melatonin (MT) and pyridoxine (PY) has been carried out at a cathodically pretreated boron‐doped diamond electrode. By using cyclic voltammetry, a separation of the oxidation peak potentials of both compounds present in mixture was about 0.47 V in Britton‐Robinson buffer, pH 2. The results obtained by square‐wave voltammetry allowed a method to be developed for determination of MT and PY simultaneously in the ranges 1–100 μg mL⁻¹ (4.3×10⁻⁶–4.3×10⁻⁴ mol L⁻¹) and 10–175 μg mL⁻¹ (4.9×10⁻⁵–8.5×10⁻⁴ mol L⁻¹), with detection limits of 0.14 μg mL⁻¹ (6.0×10⁻⁷ mol L⁻¹) and 1.35 μg mL⁻¹ (6.6×10⁻⁶ mol L⁻¹), respectively. The proposed method was successfully to the dietary supplements samples containing these compounds for health‐caring purposes.     

Speciation Analysis of Osmium(VIII) and Osmium(IV) by UV‐VIS Spectrophotometry Using Quercetin as the Reagent

Abstract

The UV‐VIS spectrophotometric methods for the determination of Os(VIII) (as OsO₄) and Os(IV) (as OsCl₆ ^2? complex) in their mixtures were developed. Quercetin (Q), a flavonoid compound, was used as a chromogenic reagent. Both direct and derivative spectrophotometry can be employed for the determination of Os(VIII). The calculation of the first‐derivative spectrum of the examined mixture and the use of the signal at 285.1 nm allows reaching a better detection limit (0.01 µg mL^?1 Os) as compared with direct spectrophotometry (0.1 µg mL^?1 Os). Relative standard deviations of the results are in the range of 0.87%–4.65% and 0.45%–1.15% for direct and derivative mode, respectively. Selective redox reaction of OsO₄ with Q under the conditions used (0.05 M HCl, 1×10^?4 M Q, 15 min heating at 70°C) makes the basis of its determination in mixtures with the OsCl₆ ^2? complex. Quercetin does not react with the OsCl₆ ^2? complex. The signals of the OsCl₆ ^2? complex can be isolated from the examined mixtures by the calculation of the third‐order derivative spectra and the use of the values at 340.0 nm. The effectiveness of the reduction of OsO₄ in chloride solutions has been studied by the developed method.     

Statistical optimization of an RP‐HPLC method for the determination of selected flavonoids in berry juices and evaluation of their antioxidant activities

An isocratic RP‐HPLC method for the separation and identification of selected flavonoids (quercetin, rutin, luteolin‐7‐O‐glucoside, kaempferol and kaempferol‐3‐O‐glucoside) in commercial berry juices (blackcurrant, blueberry, red raspberry and cherry) was developed with the aid of central composite design and response surface methodology. The optimal separation conditions were a mobile phase of 85:15 (% v/v) water–acetonitrile, pH 2.8 (adjusted with formic acid), flow rate 0.5 mL min⁻¹ and column temperature 35°C. The obtained levels of bioflavonoids (mg per 100 mL of juice) were as follows: for quercetin, ca. 0.21–5.12; for kaempferol, ca. 0.05–1.2; for rutin, ca. 0.4–6.5; for luteolin‐7‐O‐glucoside, ca. 5.6–10.2; and for kaempferol‐3‐O‐glucoside, ca. 0.02–0.12. These are considerably lower than the values in fresh fruits. Total phenolic, flavonoid and anthocyanin contents were determined spectrophotometrically. Total flavonoid content varied as follows: blackcurrant > blueberry > red raspberry > cherry. The antioxidant activity of juice extracts (DPPH and ABTS methods) expressed as IC₅₀ values varied from 8.56 to 14.05 mg L⁻¹. These values are ~2.5–3 times lower than quercetin, ascorbic acid and Trolox®, but compared with rutin and butylhydroxytoluene, berries show similar or better antioxidant activity by both the DPPH and ABTS methods.     

The Development and Validation of a Stability-Indicating UHPLC-DAD Method for Determination of Perindopril l-Arginine in Bulk Substance and Pharmaceutical Dosage Form

A stability-indicating ultra-high-performance liquid chromatography (UHPLC) method with a diode array detector was developed and validated for the determination of cis/trans isomers of perindopril l-arginine in bulk substance and pharmaceutical dosage form. The separation was achieved on a Poroshell 120 Hilic (4.6 × 150 mm, 2.7 µm) column using a mobile phase composed of acetonitrile–0.1 % formic acid (20:80 v/v) at a flow rate of 1 mL min⁻¹. The injection volume was 5.0 µL and the wavelength of detection was controlled at 230 nm. The selectivity of the UHPLC-DAD method was confirmed by determining perindopril l-arginine in the presence of degradation products formed during acid–base hydrolysis and oxidation as well as degradation in the solid state, at an increased relative air humidity and in dry air. The method’s linearity was investigated in the ranges 0.40–1.40 µg mL⁻¹ for isomer I and 0.40–2.40 µg mL⁻¹ for isomer II of perindopril l-arginine. The UHPLC-DAD method met the precision and accuracy criteria for the determination of the isomers of perindopril l-arginine. The limits of detection and quantitation were 0.1503 and 0.4555 µg mL⁻¹ for isomer I and 0.0356 and 0.1078 µg mL⁻¹ for isomer II, respectively.