An Electrochemical Sensor Based on Reduced Graphene Oxide,Gold Nanoparticles and Molecular Imprinted Over‐oxidized Polypyrrole for Amoxicillin Determination

An electrochemical sensor for amoxicillin (AMX) detection based on reduced graphene oxide (RGO), molecular imprinted overoxidized polypyrrole (MIOPPy) modified with gold nanoparticles (AuNPs) is described in this work. The electrochemical behavior of the imprinted and non‐imprinted polymer (NIP) was carried out by cyclic voltammetry (CV) and impedance spectroscopy (IS). The structure and morphology of the prepared MIP sensor were characterized by scanning electron microscopy (SEM), UV‐Visible, Fourier transform infrared spectroscopy (FTIR) and its experimental parameters such as monomer and template concentration, pH buffer solution, incubation time of AMX and AuNPs, scan rate as well as electropolymerization scan cycles were optimized to improve the performance of the sensor. The peak current obtained at the MIP electrode was proportional to the AMX concentration in the range from 10^?8 to 10^?3 mol L^?1 with a detection limit and sensitivity of 1.22 10^?6 mol L^?1 (Signal to noise ratio=3) and 2.52×10^?6 μAmol^?1 L, respectively. It was also found that this sensor exhibited reproducibility and excellent selectivity against molecules with similar chemical structures. Besides, the analytical application of the AMX sensor confirms the feasibility of AMX detection in milk and human serum.     

Synthesis and proton NMR stereochemical study of 7,8,9-substituted-7,8-dihydro-4H,9H-furo[2′,3′,4′:4,4a,5]-naphth[2,1-e][1,3]oxazin-4-ones

7,8,9-Substituted-7,8-dihydro-4H,9H-furo[2′,3′,4′:4,4a,5]naphth[2,1-e][1,3]oxazin-4-ones were stereospecifically obtained as a single pair of enantiomers. Their relative trans configuration and the conformation of the dihydro oxazine ring were established by ¹H nmr 2D NOESY experiments.     

Molecular Determinant of DIDS Analogs Targeting RAD51 Activity

RAD51 is the central protein in DNA repair by homologous recombination (HR), involved in several steps of this process. It is shown that overexpression of the RAD51 protein is correlated with increased survival of cancer cells to cancer treatments. For the past decade, RAD51 overexpression-mediated resistance has justified the development of targeted inhibitors. One of the first molecules described to inhibit RAD51 was the 4,4′-diisothiocyanato-stilbene-2,2′-disulfonic acid (DIDS) molecule. This small molecule is effective in inhibiting different functions of RAD51, however its mode of action and the chemical functions involved in this inhibition have not been identified. In this work, we used several commercial molecules derived from DIDS to characterize the structural determinants involved in modulating the activity of RAD51. By combining biochemical and biophysical approaches, we have shown that DIDS and two analogs were able to inhibit the binding of RAD51 to ssDNA and prevent the formation of D-loop by RAD51. Both isothiocyanate substituents of DIDS appear to be essential in the inhibition of RAD51. These results open the way to the synthesis of new molecules derived from DIDS that should be greater modulators of RAD51 and more efficient for HR inhibition.     

Dittrichia viscosa L. Leaves: A Valuable Source of Bioactive Compounds with Multiple Pharmacological Effects

This work focused on the leaves of Dittrichia viscosa, a plant used in Mediterranean folk medicine. Compared to water extract, the methanolic extract had higher antioxidant effects. Moreover, this extract showed potent in vitro inhibitory activity against α-amylase and α-glucosidase and showed an interesting antiglycation effect. Additionally, the evaluation of the cytotoxic activity of the methanolic extract against two human breast cancer cell lines, MCF-7 and MDA-MB-468, was very promising, with no cytotoxicity towards normal cells (peripheral blood mononuclear cells (PBMCs). The antibacterial effect was also assessed and showed potent inhibitory activity against Proteus mirabilis and Bacillus subtilis. On the other hand, Dittrichia viscosa leaves were rich in macro-elements containing appropriate micro-elements and high levels of phenolics and flavonoids such as caffeic acid derivatives. Taken together, the results obtained in this study indicate that Dittrichia viscosa could constitute a valuable source of bioactive molecules and could be used either on the preventive side or for therapeutic applications without toxicity.     

In Vitro and In Vivo Regulation of SRD5A mRNA Expression of Supercritical Carbon Dioxide Extract from Asparagus racemosus Willd. Root as Anti-Sebum and Pore-Minimizing Active Ingredients

Oily skin from overactive sebaceous glands affects self-confidence and personality. There is report of an association between steroid 5-alpha reductase gene (SRD5A) expression and facial sebum production. There is no study of the effect of Asparagus racemosus Willd. root extract on the regulation of SRD5A mRNA expression and anti-sebum efficacy. This study extracted A. racemosus using the supercritical carbon dioxide fluid technique with ethanol and investigated its biological compounds and activities. The A. racemosus root extract had a high content of polyphenolic compounds, including quercetin, naringenin, and p-coumaric acid, and DPPH scavenging activity comparable to that of the standard L-ascorbic acid. A. racemosus root extract showed not only a significant reduction in SRD5A1 and SRD5A2 mRNA expression by about 45.45% and 90.86%, respectively, but also a reduction in the in vivo anti-sebum efficacy in male volunteers, with significantly superior percentage changes in facial sebum production and a reduction in the percentages of pore area after 15 and 30 days of treatment. It can be concluded that A. racemosus root extract with a high content of polyphenol compounds, great antioxidant effects, promising downregulation of SRD5A1 and SRD5A2, and predominant facial sebum reduction and pore-minimizing efficacy could be a candidate for an anti-sebum and pore-minimizing active ingredient to serve in functional cosmetic applications.     

Thermal analysis, Raman spectroscopy and complex impedance analysis of Cu2+-doped KDP

Raman spectroscopy and differential thermal analysis (DTA) and thermogravimetric analysis have been carried out on Cu-doped KH₂PO₄ (Cu-KDP). X-ray diffraction powder data reveal that the structure of the KDP crystal does not change with the additive Cu²⁺ ion. DTA analysis and Raman study of Cu-KDP as a function of temperature reveal that this compound undergoes two phase transitions at about Ttr =453 and 473 K. The electrical conductivity measurements on polycrystalline pellet of Cu-KDP (5) are performed from room temperature (RT) up to 495 K. Only one phase transition is observed at 470 K. The activation energy in the migration is 0.42 eV in the temperature range from RT to 470 K. For temperature above 470 K, the activation energy of the superprotonic phase is 1.87 eV.     

High Pressure Processing Impact on Alternariol and Aflatoxins of Grape Juice and Fruit Juice-Milk Based Beverages

High-pressure processing (HPP) has emerged over the last 2 decades as a good alternative to traditional thermal treatment for food safety and shelf-life extension, supplying foods with similar characteristics to those of fresh products. Currently, HPP has also been proposed as a useful tool to reduce food contaminants, such as pesticides and mycotoxins. The aim of the present study is to explore the effect of HPP technology at 600 MPa during 5 min at room temperature on alternariol (AOH) and aflatoxin B1 (AFB1) mycotoxins reduction in different juice models. The effect of HPP has also been compared with a thermal treatment performed at 90 °C during 21 s. For this, different juice models, orange juice/milk beverage, strawberry juice/milk beverage and grape juice, were prepared and spiked individually with AOH and AFB1 at a concentration of 100 µg/L. After HPP and thermal treatments, mycotoxins were extracted from treated samples and controls by dispersive liquid–liquid microextraction (DLLME) and determined by HPLC-MS/MS-IT. The results obtained revealed reduction percentages up to 24% for AFB1 and 37% for AOH. Comparing between different juice models, significant differences were observed for AFB1 residues in orange juice/milk versus strawberry juice/milk beverages after HPP treatment. Moreover, HPP resulted as more effective than thermal treatment, being an effective tool to incorporate to food industry in order to reach mycotoxins reductions.     

褐铁矿处理水中六价铬

Cr(VI)是土壤和水体中常见的有毒污染物,将Cr(VI)转化为毒性较低的Cr(III)是常用而有效的治理方法.本文采用褐铁矿对水中Cr(VI)进行处理研究,考察了褐铁矿投加量、Cr(VI)初始浓度、pH值、反应温度、铁矿石粒径大小以及添加不同物质等因素对褐铁矿去除效果的影响.结果表明,褐铁矿对Cr(VI)有很好的还原去除效果,Cr(VI)去除效率随褐铁矿用量的增加而增大,随Cr(VI)初始浓度的增加而减小,pH值越低越有利于反应的进行.铁矿石颗粒的直径越小,比表面积越大,也对反应越有利,而温度对Cr(VI)的去除影响不大.100目的褐铁矿颗粒去除Cr(VI)的能力为7.77 mg Cr(VI)/g.使用褐铁矿不仅可以将Cr(VI)还原为Cr(III),还能将Cr(VI)彻底从水中去除.