Development of efficient SPE–TLC method and evaluation of biological interactions of contraceptives with progesterone receptors

TLC–SPE methodologies were developed to ascertain biological interactions of norethindrone acetate and dydrogesterone contraceptives with plasma progesterone receptor proteins. TLC solvent system for plain and Cu(II) impregnated silica gel plates was n-hexane-n-butanol (90:10, v/v), which took 20 min to run up to 10.0 cm. The best separation was on Cu(II) impregnated plates due to maximum difference in R_f values and compact spots. The optimized SPE conditions were pH 2.0 and 3.0 of phosphate buffer (50 mM) for norethindrone acetate and dydrogesterone, respectively. The flow rate of plasma and eluting solvent (methanol) through C₁₈ cartridge was 0.10 mL/min. The interactions of these contraceptives with progesterone receptor proteins were analysed by TLC–SPE results, which were supported by modelling using PyMOL and Autodoc4 softwares. The dydrogesterone was found to be bound strongly than norethindrone acetate. Attempts have been made to discuss the drugs’ interactions at chemo-supramolecular level.     

GC–MS analysis and anti–microbial activity of Prunella vulgaris L. extracts

In this study, the chemical composition of the methanol, hexane and ethyl acetate extracts of Prunella vulgaris L. were investigated by gas chromatography–mass spectrometry (GC–MS) method. 2-hydroxy-5-methylbenzaldehyde (15.70%), linolenic acid (45.50%) and icosane (16.24%) were found to be the most abundant in methanol, hexane and ethyl acetate extracts, respectively. Following the determination of chemical components of the Prunella vulgaris L. extracts, their anti–microbial activities against certain human pathogenic bacteria were tested and minimal inhibitory concentrations (MIC) were determined. While some extracts of Prunella vulgaris L. show anti–microbial activity well above the standards (penicillin and tetracycline), it was determined that in general all the extracts showed good anti–microbial activity against these pathogenic bacteria.     

Formulation and preclinical evaluation of 99mTc–gemcitabine as a novel radiopharmaceutical for solid tumor imaging

The aim of this study is the formulation of a new radiopharmaceutical for imaging solid tumor bearing. Gemcitabine is a nucleoside analogue used as chemotherapeutic agent. Gemcitabine was formulated and radiolabeled with one of the most important diagnostic radioactive isotopes (technetium-99m) to be investigated in solid tumor imaging. The labeling parameters such as gemcitabine amount, stannous chloride amount, pH of the reaction mixture, and reaction time were optimized. ^99mTc–gemcitabine was prepared at pH 9 with a maximum labeling yield of 96 ± 0.3 % without any notable decomposition at room temperature over a period of 8 h. The preclinical evaluation and biodistribution in solid tumor bearing mice showed that ^99mTc–gemcitabine had solid tumor selectivity, preclinical high biological accumulation in tumor cells and high retention. Tumor/normal muscle (T/NT) ratios increased with time showing high T/NT ratio (T/NT = 4.9 ± 0.27 at 120 min post injection) and high Tumor/Blood ratio (3.4 ± 0.06), suggesting ^99mTc–gemcitabine as a novel solid tumor imaging agent.     

GC–MS characterisation and biological activity of essential oils from different vegetative organs of Plectranthus barbatus and Plectranthus caninus cultivated in north Italy

Essential oils (EOs) from the roots, stems and leaves of Plectranthus barbatus (A) and Plectranthuscaninus (B), cultivated in north Italy, were obtained by steam distillation and chemically characterised by gas chromatography–mass spectrometry. The highest yields were obtained from roots (268.15 and 673.60 mg/kg from A and B), followed by leaves (64.34 and 26.65 mg/kg) and stems (19.76 and 18.63 mg/kg). A total of 128 structures were identified in A and 121 in B. Fe⁺⁺ chelating and antiradical activities (DPPH and ABTS) were evaluated: root and stem EOs showed the strongest activities, while EOs from leaves did not show relevant activities. All EOs were tested for their in vitro antimicrobial activity, showing optimal growth-inhibition in antibiogram (?>35 mm) and MIC tests (32–64 μg/mL) against Candida albicans, while EOs from leaves of both species showed a good activity (25 < ? < 34 mm, MIC 64–128 μg/mL) against Escherichia coli.     

Photocatalytic and antibacterial activities of Ag-doped ZnO thin films prepared by a sol–gel dip-coating method

Silver-doped ZnO thin films with various loadings of Ag in the range of 0–10 mol% were prepared by the sol–gel dip-coating method. All prepared films show X-ray powder diffraction patterns that matched with ZnO in its würtzite structure. The grain size decreased as the Ag loading increased. The prepared films, under UV blacklight illumination, produced a photocatalytic degradation of methylene blue, rhodamine B and reactive orange solutions. Furthermore, they inhibited the growth of Escherichia coli bacteria under UV blacklight irradiation and to a lesser extent in dark conditions. The photocatalytic and antibacterial activities of the prepared films increased with Ag loading, presumably because Ag enhanced the efficiency of generation of superoxide anion radicals (^•O₂ ⁻) and hydroxyl radicals (^•OH).     

Dual-functional chitosan–methylisothiazolinone/microfibrillated cellulose biocomposites for enhancing antibacterial and mechanical properties of agar films

In order to enhance the antibacterial and mechanical properties of agar films, the chitosan-methylisothiazolinone (C–MIT) complex was first prepared by the ionic gelation method, and the characterization of the C–MIT complex was carried out by Fourier transform infrared spectroscopy, transmission electron microscopy, and Thermo gravimetry. Chitosan was successfully crosslinked with tripolyphosphate for the nanoencapsulation of methylisothiazolinone, and the C–MIT complex was spherical in shape with a diameter of about 10 nm. The C–MIT/MFC biocomposites obtained through the adsorption of the C–MIT complex on the microfibrillated cellulose (MFC) was then incorporated into the agar films. In comparison with the pure agar films, the tensile strength of the agar composite films was increased by about 19 % at the loading of 10 wt% of C–MIT/MFC biocomposites, and antibacterial tests demonstrated that the agar composite films exhibited remarkable antibacterial activities against both Escherichia coli and Staphylococcus aureus. This work provides a new approach to utilizing multifunctional agar films in the medical field.     

Preparation of palladium nanoparticles–titanium electrodes as a new anode for direct methanol fuel cells

Pd nanoparticle/Ti electrodes are prepared by electroless plating of palladium on titanium plates. The morphology and surface analysis of Pd nanoparticle/Ti electrodes are investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The results indicate that palladium nanoparticles are homogeneously deposited on the surface of titanium plates. The electro-catalytic activity of Pd nanoparticle/Ti electrodes in the methanol electro-oxidation is studied by cyclic voltammetry and chronoamperometry methods. The results show that the electro-catalytic oxidation of methanol on the Pd nanoparticle/Ti electrode improved compare to pure palladium electrode and confirmed the better electro-catalytic activity and stability of these new electrodes.     

Establishment and development of a CZE–UV method for rapid measurement of aprotinin potency

A new method for the measurement of aprotinin potency by CZE–UV detector was established for the first time. The on-line mixing of substrate, trypsin and aprotinin using at-inlet technology was realized by the established method. Enzymatic reaction, separation, and detection of substrate and product can be performed simultaneously online. The aprotinin potency can be measured within 4 min. The response surface methodology was used to optimize the incubation conditions of trypsin and substrate, and the optimized conditions were obtained under 17.39 mM phosphate buffer at pH 7.6, 1.40 min of incubation time. The repeatability of proposed method was evaluated in three different systems of capillary zone electrophoresis: (i) only substrate; (ii) trypsin and substrate; (iii) aprotinin, trypsin and substrate, and the RSDs of migration times and peak areas of substrate were less than 2.7 and 3.1%, respectively. The RSDs of migration times and peak areas of product were less than 2.1 and 3.0%, respectively. A formula was also developed to calculate the aprotinin potency in this method. In a word, the established CZE–UV method was convenient, fast, and environmentally friendly for the measurement of aprotinin potency.     

Characterization of chemical compositions by a GC–MS/MS approach and evaluation of antioxidant activities of essential oils from Cinnamomum reticulatum Hay,Leptospermum petersonii Bailey,and Juniperus formosana Hayata

Essential oils (EOs) are one type of the most significant plant metabolites. Limited works have been conducted on EOs extracted from Cinnamomum reticulatum Hay (CREO), Leptospermum petersonii Bailey (LPEO), and Juniperus formosana Hayata (JFEO), which belong to the Lauraceae, Cupressaceae, and Myrtaceae families, respectively. The present work aimed to characterize and compare EOs chemical compositions of the three aromatic plant species and simultaneously evaluate their antioxidant activities. Using GC–MS/MS techniques, totally 135 volatile organic compounds (VOCs) belonging to nine chemical classes were detected, with 93, 102 and 116 VOCs from and 7, 8 and 16 VOCs unique to CREO, LPEO and JFEO, respecively, and 72 VOCs common to all the three EOs. The main compound identified both in LPEO and JFEO was (?)-bornyl acetate (20.23% and 28.40%, respectively), and the dominated compounds in CREO were L-α-terpineol (16.21%) and 1,2,3,4-tetrahydro-1,6-dimethyl-4-(1-methylethyl)naphthalene (11.68%), all accounting for more than 20% of their total contents. An in-depth dissection of major chemical compositions of the three EOs found that three VOCs were newly identified and biological functions of four VOCs were not yet reported previously. In addition, higher antioxidant capacities, measured with DPPH and ABTS assays, were exhibited in JFEO (IC50 8.37 ± 2.98 and 0.53 ± 3.80 mg/ml, respectively) and in LPEO (IC50 13.93 ± 2.11 and 1.32 ± 0.97 mg/ml) than in CREO (IC50 250.58 ± 1.48 and 4.81 ± 3.23 mg/ml), which may be due to CREO contained more esters and less aromatics than the other two EOs.     

“In situ” extraction of essential oils by use of Dean–Stark glassware and a Vigreux column inside a microwave oven: a procedure for teaching green analytical chemistry

One of the principal objectives of sustainable and green processing development remains the dissemination and teaching of green chemistry in colleges, high schools, and academic laboratories. This paper describes simple glassware that illustrates the phenomenon of extraction in a conventional microwave oven as energy source and a process for green analytical chemistry. Simple glassware comprising a Dean-Stark apparatus (for extraction of aromatic plant material and recovery of essential oils and distilled water) and a Vigreux column (as an air-cooled condenser inside the microwave oven) was designed as an in-situ extraction vessel inside a microwave oven. The efficiency of this experiment was validated for extraction of essential oils from 30 g fresh orange peel, a by-product in the production of orange juice. Every laboratory throughout the world can use this equipment. The microwave power is 100 W and the irradiation time 15 min. The method is performed at atmospheric pressure without added solvent or water and furnishes essential oils similar to those obtained by conventional hydro or steam distillation. By use of GC-MS, 22 compounds in orange peel were separated and identified; the main compounds were limonene (72.1%), β-pinene (8.4%), and γ-terpinene (6.9%). This procedure is appropriate for the teaching laboratory, does not require any special microwave equipment, and enables the students to learn the skills of extraction, and chromatographic and spectroscopic analysis. They are also exposed to a dramatic visual example of rapid, sustainable, and green extraction of an essential oil, and are introduced to successful sustainable and green analytical chemistry.     

Synthesis and preclinical pharmacological evaluation of a novel 99mTc–shikonin as a potential tumor imaging agent

Shikonin was isolated from Ratanjot pigment then the obtained shikonin was well characterized. This study is aimed to optimize radiolabeling yield of shikonin with ^99mTc with respect to factors that affect the reaction conditions such as shikonin amount, SnCl₂·2H₂O amount, reaction time and pH of the reaction mixture. In vitro stability of the radiolabeled complex was checked and it was found to be stable for up to 6?h. Biodistribution studies showed that, ^99mTc?Cshikonin accumulate in tumor sites with higher T/NT than other currently available ^99mTc(CO)₃-VIP, ^99mTc?Cnitroimidazole analogues and ^99mTc?Cpolyamine analogues indicating that shikonin deliver ^99mTc to the tumor sites with a percentage sufficient for imaging and can overcome many drawbacks of other radiopharmaceuticals used for tumor imaging.     

The development of a rapid method for the isolation of four azaspiracids for use as reference materials for quantitative LC–MS–MS methods

The azaspiracids are a family of lipophilic polyether marine biotoxins that have caused a number of human intoxication incidents in Europe since 1995 after consumption of contaminated shellfish (Mytilus edulis). Levels of azaspiracids in shellfish for human consumption are monitored in accordance with EU guidelines: only shellfish with less than 160 μg kg⁻¹ are deemed safe. The limited availability of commercially available standards for azaspiracids is a serious problem, because validated LC–MS methods are required for routine analysis of these toxins in shellfish tissues. The procedure described herein has been used for the separation and the isolation of four azaspiracid (AZA) toxins from shellfish, for use as LC–MS–MS reference materials. Five separation steps have been used to isolate azaspiracids 1, 2, 3, and 6. The purity of the toxins obtained has been confirmed by multiple mass spectrometric methods using authentic azaspiracid standards. The same techniques have been used for quantification of the toxins extracted. The isolation procedure involves several chromatographic purification techniques: solid-phase extraction (diol sorbent, 90% mass reduction, and 95 ± 1% toxin recovery); Sephadex size-exclusion chromatography (87% mass reduction and up to 95 ± 2% toxin recovery), Toyopearl HW size-exclusion chromatography (90% mass reduction and up to 92.5 ± 2.5% toxin recovery), and semi-preparative LC (78 ± 3% toxin recovery). The procedure effectively separates the toxins from the sample matrix and furnishes azaspiracid toxins (AZA1, AZA2, AZA3 and AZA6) of sufficient purity with an average yield of 65% (n = 5). Triple-quadrupole mass spectrometry was used for qualitative and quantitative monitoring of the isolation efficiency after each stage of the process. High-resolution mass spectrometric evaluation of the toxic isolated material in both positive and negative modes suggests high purity.     

Liquid–liquid miscibility and volumetric properties of aqueous solutions of ionic liquids as a function of temperature

The volumetric properties of seven {water + ionic liquid} binary mixtures have been studied as a function of temperature from (293 to 343) K. The phase behaviour of the systems was first investigated using a nephelometric method and excess molar volumes were calculated from densities measured using an Anton Paar densimeter and fitted using a Redlich–Kister type equation. Two ionic liquids fully miscible with water (1-butyl-3-methylimidazolium tetrafluoroborate ([C₁C₄Im][BF₄]) and 1-ethyl-3-methylimidazolium ethylsulfate ([C₁C₂Im][EtSO₄])) and five ionic liquids only partially miscible with water (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C₁C₂Im][NTf₂]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C₁C₄Im][NTf₂]), 1-butyl-3-methylimidazolium hexafluorophosphate ([C₁C₄Im][PF₆]), 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C₁C₄Pyrro][NTf₂]), and butyltrimethylammonium bis(trifluoromethylsulfonyl)imide ([N₄₁₁₁][NTf₂])) were chosen. Small excess volumes (less than 0.5 cm³ · mol^?1 at 298 K) are obtained compared with the molar volumes of the pure components (less than 0.3% of the molar volume of the pure ionic liquid). For all the considered systems, except for {[C₁C₂Im][EtSO₄] + water}, positive excess molar volumes were calculated. Finally, an increase of the non-ideality character is observed for all the systems as temperature increases.     

Thin layer chromatography–spray mass spectrometry: a method for easy identification of synthesis products and UV filters from TLC aluminum foils

A straightforward procedure for direct mass spectrometric (MS) analysis of spots from thin layer chromatography (TLC) plates, without the need of an external ion source, was developed using the aluminum plate backing as spray tip. The spots were cut out shaped as a tip with a 60° angle, mounted in front of the MS orifice, and after addition of a spray solvent spectra were obtained immediately. A high-resolution time-of-flight MS was used since the method is of particular interest for rapid identification or confirmation of spots from TLC plates. The practical benefits of this technique were demonstrated by detection of by-products of organic reactions, by identification of degradation products, and by accurate confirmation of spots when UV filters in sunscreens were analyzed by TLC. Employing the described method TLC spots can be evaluated fast without the need of an external ion source or devices for analyte transfer from TLC to MS, only a basic MS instrument and a high-voltage power supply is required.

A direct relaxation method for calculating eigenfunctions and eigenvalues of the schrödinger equation on a grid

Eigenfunctions and eigenvalues of the Schrodinger equation are determined by propagating the Schrodinger equation in imaginary time. The method is based on representing the Hamiltonian operation on a grid. The kinetic energy is calculated by the Fourier method. The propagation operator is expanded in a Chebychev series. Excited states are obtained by filtering out the lower states. Comparative examples include: eigenfunctions and eigenvalues of the Morse oscillator, the Hénon-Heiles system and weakly bound states of He on a Pt surface.     

Graphene oxides as support for the synthesis of nickel sulfide–indium oxide nanocomposites for photocatalytic,antibacterial and antioxidant performances

NiS (nickel sulfide)–In₂O₃ (indium oxide) nanostructures and NiS–In₂O₃ decorated on graphene oxide (GO) were demonstrated by ultrasonic/hydrothermal method. The structural study demonstrates the preparation of bixbyite and hexagonal phase of In₂O₃ and NiS for all of the synthesized catalysts. The band gap of the synthesized catalyst was determined to be in the range of 2.30–3.00 eV. A morphological evaluation by field emission scanning electron microscopy of NiS–In₂O₃ decorated on graphene oxide shows support for the NiS–In₂O₃ on the graphene oxide layer. Different test parameters were performed to study the phase and morphology. The particle sizes of the In₂O₃, NiS–In₂O₃ and NiS–In₂O₃/GO nanocomposites were 56.0, 62.0 and 66.0 nm, respectively. The photocatalytic performance of NiS–In₂O₃/GO nanocomposites was examined for the degradation of methylene blue dye under a UV lamp. The prepared sample shows 98.25% photocatalytic degradation within 40 min and at pH 9. With the presence the NiS and GO, the photo-degradation capacities of In₂O₃ and NiS–In₂O₃ are improved owing to the low band gap being calculated in UV–vis DRS analysis. The high ratio of NiS causes the highest photocatalytic properties of NiS–In₂O₃ nanocomposites owing to the enhancement of charge separation efficiency and generation of hydroxyl radicals. This study presents a facile and low-cost method to prepare highly active NiS–In₂O₃/GO nanocomposites. The antibacterial data indicate the significant properties of NiS–In₂O₃/GO nanocomposites for this study.     

Development and validation of a fully automated online-SPE–ESI–LC–MS/MS multi-residue method for the determination of different classes of pesticides in drinking,ground and surface water

The present work describes a fully automated method based on online solid phase extraction–liquid chromatography–tandem mass spectrometry for the determination of different classes of pesticides, including acidic and polar pesticides and six thiamethoxam metabolites. Sample preconcentration was performed by extracting 4 mL of the sample with a single styrene-divinylbenzene polymer. Elution of the compounds was done within the high performance liquid chromatography gradient and tandem mass spectrometry determination was performed in the selected reaction monitoring mode, by recording 1–3 transitions per compound. The overall pretreatment and analysis time per sample was less than 15 min. Method validation was performed in drinking, ground and surface water. For nearly all compounds a recovery between 70% and 120% could be achieved. The limit of detection ranges from 1.2 to 18 ng/L in drinking water and 3.0 to 23 ng/L in ground and surface water. The correlation coefficients for a calibration range of 0.05–2 µg/L are between 0.9915 and 0.9999. The limit of quantification (LOQ) for all compounds lies below the required limit of 0.1 µg/L, to fulfil the Council Directive 98/83/EC. Most of the compounds easily reach an LOQ below 0.05 µg/L.