Central composite design with the help of multivariate curve resolution in loadability optimization of RP‐HPLC to scale‐up a binary mixture

Chromatographic method development for preparative targets is a time‐consuming and subjective process. This can be particularly problematic because of the use of valuable samples for isolation and the large consumption of solvents in preparative scale. These processes could be improved by using statistical computations to save time, solvent and experimental efforts. Thus, contributed by ESI‐MS, after applying DryLab software to gain an overview of the most effective parameters in separation of synthesized celecoxib and its co‐eluted compounds, design of experiment software that relies on multivariate modeling as a chemometric approach was used to predict the optimized touching‐band overloading conditions by objective functions according to the relationship between selectivity and stationary phase properties. The loadability of the method was investigated on the analytical and semi‐preparative scales, and the performance of this chemometric approach was approved by peak shapes beside recovery and purity of products.     

Noscapine Prevents Rotenone-Induced Neurotoxicity: Involvement of Oxidative Stress,Neuroinflammation and Autophagy Pathways

Parkinson’s disease is characterized by the loss of dopaminergic neurons in substantia nigra pars compacta (SNpc) and the resultant loss of dopamine in the striatum. Various studies have shown that oxidative stress and neuroinflammation plays a major role in PD progression. In addition, the autophagy lysosome pathway (ALP) plays an important role in the degradation of aggregated proteins, abnormal cytoplasmic organelles and proteins for intracellular homeostasis. Dysfunction of ALP results in the accumulation of α-synuclein and the loss of dopaminergic neurons in PD. Thus, modulating ALP is becoming an appealing therapeutic intervention. In our current study, we wanted to evaluate the neuroprotective potency of noscapine in a rotenone-induced PD rat model. Rats were administered rotenone injections (2.5 mg/kg, i.p.,) daily followed by noscapine (10 mg/kg, i.p.,) for four weeks. Noscapine, an iso-qinulinin alkaloid found naturally in the Papaveraceae family, has traditionally been used in the treatment of cancer, stroke and fibrosis. However, the neuroprotective potency of noscapine has not been analyzed. Our study showed that administration of noscapine decreased the upregulation of pro-inflammatory factors, oxidative stress, and α-synuclein expression with a significant increase in antioxidant enzymes. In addition, noscapine prevented rotenone-induced activation of microglia and astrocytes. These neuroprotective mechanisms resulted in a decrease in dopaminergic neuron loss in SNpc and neuronal fibers in the striatum. Further, noscapine administration enhanced the mTOR-mediated p70S6K pathway as well as inhibited apoptosis. In addition to these mechanisms, noscapine prevented a rotenone-mediated increase in lysosomal degradation, resulting in a decrease in α-synuclein aggregation. However, further studies are needed to further develop noscapine as a potential therapeutic candidate for PD treatment.     

An efficient and facile ultrasonic‐accelerated one‐pot synthesis of N‐acetyl‐2‐aryl‐1, 2‐dihydro‐(4H)‐3,1‐benzoxazin‐4‐ones

An application of ultrasonic irradiation in the one‐pot synthesis of N‐acetyl‐2‐aryl‐1,2‐dihydro‐(4H)‐3,1‐benzoxazin‐4‐ones from the condensation reaction between aromatic aldehydes and anthranilic acid in the presence of excess amount of acetic anhydride has been explored. The reactions proceed smoothly under mild and solvent‐free conditions at room temperature in the absence of any catalyst to afford the products in good to excellent yields. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:106–113, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20663     

An experimental and in situ IR spectroscopic study of the lithiation-substitution of N-Boc-2-phenylpyrrolidine and -piperidine: controlling the formation of quaternary stereocenters

A general and enantioselective synthesis of 2-substituted 2-phenylpyrrolidines and -piperidines, an important class of pharmaceutically relevant compounds that contain a quaternary stereocenter, has been developed. The approach involves lithiation-substitution of enantioenriched N-Boc-2-phenylpyrrolidine or -piperidine (prepared by asymmetric Negishi arylation or catalytic asymmetric reduction, respectively). The combined use of synthetic experiments and in situ IR spectroscopic monitoring allowed optimum lithiation conditions to be identified: n-BuLi in THF at -50 °C for 5-30 min. Monitoring of the lithiation using in situ IR spectroscopy indicated that the rotation of the tert-butoxycarbonyl (Boc) group is slower in a 2-lithiated pyrrolidine than a 2-lithiated piperidine; low yields for the lithiation-substitution of N-Boc-2-phenylpyrrolidine at -78 °C can be ascribed to this slow rotation. For N-Boc-2-phenylpyrrolidine and -piperidine, the barriers to rotation of the Boc group were determined using density functional theory calculations and variable-temperature (1)H NMR spectroscopy. For the pyrrolidine, the half-life (t(1/2)) for rotation of the Boc group was found to be ～10 h at -78 °C and ～3.5 min at -50 °C. In contrast, for the piperidine, t(1/2) was determined to be ～4 s at -78 °C.     

Estimation of the power scintillation probability density function in free-space optical links by use of multicanonical Monte Carlo sampling

Free-space optics (FSO) can provide cost-effective, high-bandwidth, wireless connections. However, atmospheric turbulence may degrade the performance of FSO links by causing intensity and power scintillations at the receiver. Multicanonical Monte Carlo sampling is used in conjunction with the phase screen method to calculate the statistics, and particularly the probability density function (PDF), of the power fluctuations at an FSO receiver. This allows the efficient calculation of the PDF even for very small values with a limited number of iterations. The obtained PDF can be used to characterize the performance of the system in terms of the error probability.     

Poly(DEAEMa-co-PEGMa): a new pH-responsive comb copolymer stabilizer for emulsions and dispersions

Stimulus responsive copolymers are an important class of surfactants that are attracting growing attention in the literature. When used to stabilize colloids, they confer responsiveness to an otherwise nonresponsive system. In this work, a new pH-responsive comb copolymer surfactant, poly(DEAEMa-co-PEGMa), where DEAEMa and PEGMa are diethylaminoethyl methacrylate and poly(ethylene glycol) methacrylate, is introduced and used to stabilize emulsions and particulate dispersions. The copolymer contained 70 mol % of DEAEMa. Turbidity versus pH measurements and photon correlation spectroscopy of the copolymer solutions revealed pH-triggered collapse of the chains above the pK(a). The surface activity of the copolymer increased with pH. The minimum surface tension measured was 33.6 mN/m at pH = 10. These data enabled identification of the pK(a) for poly(DEAEMa-co-PEGMa) as 6.8. The emulsions consisted of tetradecane-in-water and had a droplet size in the range 5-11 mum. They were slightly flocculated when the pH value was close to the isoelectric point. The emulsions phase separated at low pH values. The particulate dispersions were based on carbendazim, which is a fungacide, and had an average size of 1.8 mum. The data for the emulsions and carbendazim dispersions show that the extent of flocculation decreases with decreasing size of the dispersed phase. Analysis of the data suggest that optimum emulsion stability occurs in the pH region of 5.3-6.8 as judged by turbidity measurements. Electrophoretic mobility measurements as a function of pH for the emulsions and carbendazim dispersions reveal a similar isoelectric point in the range of 8.5-9.0, which is about two pH units higher than the pK(a) of the copolymer. A mechanism that explains the pH-responsive stability of the emulsions and dispersions is presented and discussed.     

Determination of organochlorine and pyrethroid pesticides in fruit and vegetables using solid phase extraction clean-up cartridges

A method to determine six organochlorine and three pyrethroid pesticides in grape, orange, tomato, carrot and green mustard based on solvent extraction followed by solid phase extraction (SPE) clean-up is described. The pesticides were spiked into the sample prior to analysis, extracted with ethyl acetate, evaporated and reconstituted with a solvent mixture of acetone:n-hexane (3:7). Three different sorbents (Strong Anion Exchanger/Primary Secondary Amine (SAX/PSA), Florisil and C18) were used for the clean-up step. Pesticides were eluted with 5mL of acetone:n-hexane (3:7, v/v) and determined by gas chromatography and electron-capture detection (GC-ECD). SAX/PSA was the sorbent, which provided chromatograms with less interference and the mean recoveries obtained were within 70-120% except for captafol. The captafol recoveries for grape were within acceptable range with C18 clean-up column.     

PEG Coated Biocompatible Cadmium Chalcogenide Quantum Dots for Targeted Imaging of Cancer Cells

Cancer stands as a leading cause of mortality worldwide and diagnostics of cancer still faces drawbacks. Optical imaging of cancer would allow early diagnosis, evaluation of disease progression and therapy efficiency. To that aim, we have developed highly biocompatible PEG functionalized cadmium chalcogenide based three differently luminescent quantum dots (QDs) (CdS, CdSe and CdTe). Folate targeting scheme was utilized for targeting cancer cell line, MCF-7. We demonstrate the biocompatibility, specificity and efficiency of our nanotool in detection of cancer cells sparing normal cell lines with retained fluorescence of functionalized QDs as parental counterpart. This is the first time report of utilizing three differently fluorescent QDs and we have detailed about the internalization of these materials and time dependent saturation of targeting schemes. We present here the success of utilizing our biocompatible imaging tool for early diagnosis of cancer.     

The Potential Role of Nigella sativa Seed Oil as Epigenetic Therapy of Cancer

Nigella sativa oil, commonly known as black seed oil (BSO), is a well-known Mediterranean food, and its consumption is associated with beneficial effects on human health. A large number of BSO’s therapeutic properties is attributed to its pharmacologically active compound, thymoquinone (TQ), which inhibits cell proliferation and induces apoptosis by targeting several epigenetic players, including the ubiquitin-like, containing plant homeodomain (PHD) and an interesting new gene, RING finger domains 1 (UHRF1), and its partners, DNA methyltransferase 1 (DNMT1) and histone deacetylase 1 (HDAC1). This study was designed to compare the effects of locally sourced BSO with those of pure TQ on the expression of the epigenetic complex UHRF1/DNMT1/HDAC1 and the related events in several cancer cells. The gas chromatographs obtained from GC-MS analyses of extracted BSO showed that TQ was the major volatile compound. BSO significantly inhibited the proliferation of MCF-7, HeLa and Jurkat cells in a dose-dependent manner, and it induced apoptosis in these cell lines. BSO-induced inhibitory effects were associated with a significant decrease in mRNA expression of UHRF1, DNMT1 and HDAC1. Molecular docking and MD simulation showed that TQ had good binding affinity to UHRF1 and HDAC1. Of note, TQ formed a stable metal coordinate bond with zinc tom, found in the active site of the HDAC1 protein. These findings suggest that the use of TQ-rich BSO represents a promising strategy for epigenetic therapy for both solid and blood tumors through direct targeting of the trimeric epigenetic complex UHRF1/DNMT1/ HDAC1.     

Copper Schiff base complex immobilized on magnetic graphene oxide: Efficient heterogeneous nanocatalyst for treating environmental pollutants and synthesis of chromenes

Herein, a new Cu(II) Schiff base complex was immobilized onto the magnetic graphene oxide surface through a stepwise procedure. The as-synthesized nanostructure (GO/Fe₃O₄/CuL) was characterized by various techniques including Fourier transform infrared (FT-IR), Raman spectroscopies, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), energy-dispersive X-ray (EDX) and inductively coupled plasma (ICP) spectroscopies, N₂ adsorption–desorption analysis, vibrating sample magnetometry (VSM), and X-ray diffraction (XRD). The catalytic activity of the synthesized nanocatalyst was examined in 4-nitrophenol (4-NP), Congo red (CR), and methylene blue (MB) reduction using NaBH₄ in an aqueous solution at room temperature. The reaction progress was monitored by UV–Vis spectroscopy. Also, the synthesized nanostructure was evaluated as an efficient catalyst for the synthesis of 2-amino-4H-benzopyrans via three-component reactions of 1-naphthol, malononitrile, and various aldehydes in ethanol/water at 50°C. The use of green solvents, the short reaction time, the high product yield, and easy separation from the reaction environment are the main benefits of this catalytic system. By covalent grafting of the complex on the graphene oxide surface, its catalytic performance significantly increased compared with graphene oxide; this is probably related to the chemical change of the graphene oxide surface. The results show the high chemical stability and the improved reusability of the synthesized nanocatalyst (six times) without significant loss in the catalytic activity of GO/Fe₃O₄/CuL nanocomposite.