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281.
Yossra A. Trabik Nourhan KH. Al-Afify Amira M. El-Kosasy N. Magdy 《Electroanalysis》2021,33(5):1233-1243
Chitosan (CH) is one of the most abundant biopolymers with multiple applications. Polyvinyl pyrrolidone (PVP) has specific binding and detoxification properties that are of great interest in health care. Hence, it arises a crucial urge to develop economic sensors to analyze CH and PVP in pharmaceutical formulations and biological samples. Two portable sensors were fabricated using precipitation-based technique, and nanoparticles-based technique, for determination of CH and PVP in sensor 1 and 2; respectively. Linear responses of 10−5 to10−7 M and 10−2 to10−7 M at pH 3.6–4.8 and 7.2–8.4, with ideal Nernstian slopes of 60.00 and 59.83 mV /decade, and nanomolar LODs of 94.90 and 81.20 nM were observed for CH and PVP; respectively. The percentage recoveries were 100.40±1.03 and 100.19±0.64 for sensors 1 and 2; respectively. Both sensors were successfully applied in biological fluids without pre-treatment. Accurate results were obtained using sensor 1, in pure form, pharmaceutical formulations, human plasma, rat liver and rat brain, as well as sensor 2, in pure form, pharmaceutical formulations and urine samples. The results were statistically compared with the reported methods and no significant difference was observed. 相似文献
282.
底物,水量对脂肪酶不对称拆分萘普生的影响 总被引:3,自引:2,他引:1
选择了一种便于底物-产物分离的微水-有机两相体系,将对S-(+_萘普生酯有高度对映体选择性的CCL脂肪酶固定于硅藻土上。合成了了一种能提高酶催化反应速度的激活的酯-萘普生氯乙酯。 相似文献
283.
284.
BaO对Pd/Al2O3催化性能的影响 总被引:2,自引:0,他引:2
以 Pd(C2 H3O2 ) 2 为前身 ,制备了系列 Ba O- Al2 O3复合氧化物负载钯的催化剂 .用质量滴定法 ,测定了复合载体的零电荷点 (pzc) .结果表明 ,体系的 pzc随 Ba O含量的增加而增大 ,在 5 %~ 10 %之间存在一拐点 ,并与XRD所测 Ba O在 Al2 O3上的单层分散阈值相对应 .复合载体在制备中发生固相反应 ,所生成的 Ba Al2 O4可以阻止 Al2 O3的相变 ,并极大地提高载体的热稳定性 ,其中 5 % Ba O的作用最为明显 .Ba O的引入 ,增强了 Pd/Al2 O3对 CO的氧化能力 ,同时 ,提高了其热稳定性 相似文献
285.
Wirginia Kukula-Koch Dominik Szwajgier Katarzyna Gawe-Bben Marcelina Strzpek-Gomka Kazimierz Gowniak Henry O. Meissner 《Molecules (Basel, Switzerland)》2021,26(19)
This work aims to assess the recently established anti-inflammatory and antioxidant potential of melatonin of plant origin extracted from the plant matrix as a phytomelatonin complex (PHT-MLT), and compare its activity with synthetic melatonin (SNT-MLT) when used on its own or with vitamin C. For this purpose, a COX-2 enzyme inhibitory activity test, an antiradical activity in vitro and on cell lines assays, was performed on both PHT-MLT and SNT-MLT products. COX-2 inhibitory activity of PHT-MLT was found to be ca. 6.5 times stronger than that of SNT-MLT (43.3% and 6.7% enzyme inhibition, equivalent to the activity of acetylsalicylic acid in conc. 30.3 ± 0.2 and 12.0 ± 0.3 mg/mL, respectively). Higher antiradical potential and COX-2 inhibitory properties of PHT-MLT could be explained by the presence of additional naturally occurring constituents in alfalfa, chlorella, and rice, which were clearly visible on the HPLC-ESI-QTOF-MS fingerprint. The antiradical properties of PHT-MLT determined in the DPPH test (IC50 of 21.6 ± 1 mg of powder/mL) were found to originate from the presence of other metabolites in the 50% EtOH extract while SNT-MLT was found to be inactive under the applied testing conditions. However, the antioxidant studies on HaCaT keratinocytes stimulated with H2O2 revealed a noticeable activity in all samples. The presence of PHT-MLT (12.5, 25 and 50 µg/mL) and vitamin C (12.5, 25 and 50 µg/mL) in the H2O2-pretreated HaCaT keratinocytes protected the cells from generating reactive oxygen species. This observation confirms that MLT-containing samples affect the intracellular production of enzymes and neutralize the free radicals. Presented results indicated that MLT-containing products in combination with Vitamin C dosage are worth to be considered as a preventive alternative in the therapy of various diseases in the etiopathogenesis, of which radical and inflammatory mechanisms play an important role. 相似文献
286.
异丁烷催化脱氢制异丁烯Cr2O3/Al2O3体系催化剂 总被引:2,自引:0,他引:2
对异丁烷催化脱氢催化剂进行了研究。助催化剂K2O,CuO的引入改进了Cr2O3/Al2O3催化剂的活性和抗积炭性能。同时考察了原料气空速、反应温度以及催化剂制备的焙烧温度对K2O-CuO-Cr2O3/Al2O3催化剂反应性能的影响。XRD谱图表明,Cr2O3在催化剂中高分散,700℃焙烧的催化剂中出现的KCuO晶相对催化剂活性不利。用NH3-TPD和CO2-TPD检测了催化剂表面的酸碱中心,表明助 相似文献
287.
Nur Amira Md Amin Siti Hamimah Sheikh Abdul Kadir Akmal Hisyam Arshad Norhaslinda Abdul Aziz Nurul Alimah Abdul Nasir Normala Ab Latip 《Molecules (Basel, Switzerland)》2022,27(6)
Vitamin E is known as an essential vitamin, and many studies had demonstrated the importance of vitamin E throughout the reproductive process, such as miscarriage, premature birth, preeclampsia, and intrauterine growth restriction, which could be caused by a lack of vitamin E during pregnancy. Its potent antioxidant properties can counteract the oxidative stress induced by oxygen free radicals and imbalance of oxidative-antioxidant levels, hence it may play a role in maintaining the normal function of the female reproductive system. Despite the fact that vitamin E is acknowledged as the substance needed for reproduction, its beneficial effects on female fertility, gynaecological health, and diseases are still poorly understood and lacking. Therefore, the goal of this paper is to provide a summary of the known roles of vitamin E supplementation in women for gynaecological health and reproductive-related diseases, as well as its future perspective. 相似文献
288.
Amira Awadalla Mohamed R. Mahdi Mohamed H. Zahran Ahmed Abdelbaset-Ismail Mohamed El-Dosoky Amr Negm 《Molecules (Basel, Switzerland)》2022,27(7)
Cisplatin (CP) is a conventional chemotherapeutic agent with serious adverse effects. Its toxicity was linked to the stimulation of oxidative stress and inflammation. As a result, this study explored the protective effect of baicalein and alpha-tocopherol in nephrotoxicity induced by cisplatin. Until receiving an intraperitoneal injection of CP (3 mg/kg BW), rats were given baicalein orally 100 mg/kg for seven days or/and a single intraperitoneal injection of α-tocopherol 250 mg/kg. Renal function was tested to explore whether baicalein and α-tocopherol have any beneficial effects; blood urea nitrogen (BUN), serum creatinine, malondialdehyde (MDA) content, antioxidant activity biomarkers and histopathology of renal tissue, oxidative stress biomarkers, inflammatory response markers, and histopathological features of kidney architecture were measured. Cisplatin treatment resulted in extreme renal failure, as measured by high serum creatinine and BUN levels and severe renal changes. Cisplatin therapy resulted in increased lipid peroxidation and decreased glutathione and superoxide dismutase levels, reflecting oxidative stress. Upon treatment with α-tocopherol, baicalein, and combined therapy, there was augmentation in the antioxidant status as well as a reduction in IL-6, NF-κB, TNF, TLR2, and TLR4 and a significant increase in Keap-1 and NRF-2. The combined treatment was the most effective and the nearest to the normal status. These findings suggest that baicalein and α-tocopherol may be useful in preventing cisplatin-induced nephrotoxicity. 相似文献
289.
Nourhan M. Abd El-Aziz Ibrahim Khalifa Amira M. G. Darwish Ahmed N. Badr Huda Aljumayi El-Sayed Hafez Mohamed G. Shehata 《Molecules (Basel, Switzerland)》2022,27(9)
COVID-19 is still a global pandemic that has not been stopped. Many traditional medicines have been demonstrated to be incredibly helpful for treating COVID-19 patients while fighting the disease worldwide. We introduced 10 bioactive compounds derived from traditional medicinal plants and assessed their potential for inhibiting viral spike protein (S-protein), Papain-like protease (PLpro), and RNA dependent RNA polymerase (RdRp) using molecular docking protocols where we simulate the inhibitors bound to target proteins in various poses and at different known binding sites using Autodock version 4.0 and Chimera 1.8.1 software. Results found that the chicoric acid, quinine, and withaferin A ligand strongly inhibited CoV-2 S -protein with a binding energy of −8.63, −7.85, and −7.85 kcal/mol, respectively. Our modeling work also suggested that curcumin, quinine, and demothoxycurcumin exhibited high binding affinity toward RdRp with a binding energy of −7.80, −7.80, and −7.64 kcal/mol, respectively. The other ligands, namely chicoric acid, demothoxycurcumin, and curcumin express high binding energy than the other tested ligands docked to PLpro with −7.62, −6.81, and −6.70 kcal/mol, respectively. Prediction of drug-likeness properties revealed that all tested ligands have no violations to Lipinski’s Rule of Five except cepharanthine, chicoric acid, and theaflavin. Regarding the pharmacokinetic behavior, all ligand predicted to have high GI-absorption except chicoric acid and theaflavin. At the same way chicoric acid, withaferin A, and withanolide D predicted to be substrate for multidrug resistance protein (P-gp substrate). Caffeic acid, cepharanthine, chicoric acid, withaferin A, and withanolide D also have no inhibitory effect on any cytochrome P450 enzymes. Promisingly, chicoric acid, quinine, curcumin, and demothoxycurcumin exhibited high binding affinity on SARS-CoV-2 target proteins and expressed good drug-likeness and pharmacokinetic properties. Further research is required to investigate the potential uses of these compounds in the treatment of SARS-CoV-2. 相似文献
290.
在动力学拆分反应中 ,转化率和对映体过量值( ee值 )是经常需要测量的两个重要参数 .传统的测定转化率的方法包括色谱法、分光光度法和滴定法等 .而测定 ee值主要应用手性色谱柱、手性毛细管电泳、核磁以及旋光法等 .在动力学拆分过程中 ,需要对反应进程进行监测 ,而应用传统的方法进行监测需要同时测定两个量 (转化率和 ee值 ) ,工作量较大 ,且使用手性色谱柱进行监测成本也较高 ,不适合大量实验数据的常规分析 .为此 ,需要发展一种快速、灵活、经济的测量方法 ,用以实验前期筛选条件时的常规分析 .基于此思路 ,我们借助于自己编制的计算机… 相似文献