One step selective 5'-O-allylation of thymidine using microwave or ultrasound activation

An improved procedures for the synthesis of 5'-O-allylthymidine via one step selective allylation of thymidine using either ultrasound or microwave activation is described.     

微波免疫组织化学技术在宫颈癌涂片快速诊断中的应用

本文应用微波免疫组化ＡＢＣ技术检测了６７例宫颈涂片细胞中ＥＭＡ的分布。结果,Ｉ～Ｖ级宫颈涂片ＥＭＡ阳性率分别为３０％（３／１０）、５０％（５／１０）、７０％（７／１０）、９３．７％（１５／１６）和９５．２％（２０／２１）。Ⅰ、Ⅱ级与Ⅲ级,Ⅲ级与Ⅳ、Ⅴ级ＥＭＡ阳性率均有显著差异性（Ｐ＜０．０５）。结果提示：ＥＭＡ可作为宫颈涂片细胞的分化标志,有助于良恶性细胞的鉴别。同时对形态学不够恶性而ＥＭＡ呈强阳性者,有潜在恶变的物质基础。在抗体稀释度相同时,微波免疫组化较常规免疫组化具有特异性染色深。背景浅,反应时间显著缩短等特点。     

On the Use of Microwave Radiation Energy for Brain Tissue Fixation

Abstract: Focused microwave irradiation (MWR) is an increasingly accepted method of sacrifice of laboratory animals such as the mouse or rat. By fixing the brain within a fraction of a second with heat inactivation, the investigation of fast neurochemical events may be obtained. Even though the technique is widely utilized, its application is inconsistent. This report illustrates some of the requirements necessary for the proper application of MWR for the sacrifice of animals, particularly those related to the length of time MWR is applied and the efficiency with which generated MWR power is coupled to the brain tissue. Studies were performed on the mouse, using either a 2.5 KW or 6.3 KW generator with a focused, closed system waveguide at time intervals of 350 or 500 ms or 1.4 s. During each of these intervals MWR was varied so that core brain temperatures for all groups were held between 83 and 95°C. In contrast with reported studies that used full animal restraint, all animals were minimally restrained for less than 1 s before sacrifice. Tissue content of cyclic AMP, an index of neuronal activity grossly affected by subtle changes in the activity of adenylate cyclase and/or phosphodiesterases, was monitored. No differences in tissue cyclic AMP content in any of 12 brain regions were detected after MWR, either at 350 or 500 ms. A substantial increase in cyclic AMP content occurred in 8 of 12 brain regions examined following microwave irradiation for 1.4 s. On the basis of these experiments, accurate determination of cyclic AMP in rodent brain requires that the maximum time interval of MWR exposure should not exceed 500 ms.     

A facile access to novel steroidal 17-2′-(1′,3′,4′)-oxadiazoles,and an evaluation of their cytotoxic activities in vitro

Novel types of 17-exo-heterocycles in the Δ⁵ androstene series carrying an 1,3,4-oxadiazole moiety were efficiently synthesized via aldehyde N-acylhydrazone intermediates, obtained from the microwave-assisted condensation of 3β-hydroxy- or 3β-acetoxyandrost-5-ene-17β-carbaldehyde with different acylhydrazides. The subsequent phenyl iodonium diacetate-induced oxidative cyclization proceeded under mild conditions. The synthesized compounds were subjected to in vitro pharmacological studies to investigate their antiproliferative activities on four malignant adherent cell lines (HeLa, MCF7, A2780 and A431), and exhibited the highest potency against HeLa cells, some of them revealing action comparable to that of the reference agent cisplatin.     

Microwave assisted synthesis of naphthopyrans catalysed by silica supported fluoroboric acid as a new class of non purine xanthine oxidase inhibitors

A series of naphthopyrans was synthesized employing silica supported fluoroboric acid under solvent free conditions in a microwave reactor. The catalytic influence of HBF₄–SiO₂ was investigated in detail to optimize the reaction conditions. The synthesised compounds were evaluated for in vitro xanthine oxidase inhibitory activity for the first time. Structure–activity relationship analyses have also been presented. Among the synthesised compounds, NP-17, NP-19, NP-20, NP-23, NP-24, NP-25 and NP-26 were the active inhibitors with an IC₅₀ ranging from 4 to 17 μM. Compound NP-19 with a thiophenyl ring at position 1 emerged as the most potent xanthine oxidase inhibitor (IC₅₀ = 4 μM) in comparison to allopurinol (IC₅₀ = 11.10 μM) and febuxostat (IC₅₀ = 0.025 μM). The basis of significant inhibition of xanthine oxidase by NP-19 was rationalized by its molecular docking at MTE binding site of xanthine oxidase.     

InCl3 as a powerful catalyst for the acetylation of carbohydrate alcohols under microwave irradiation

Indium(III) chloride catalyzed microwave assisted acetylation of different carbohydrates is an efficient synthesis of per-O-acetyl derivatives and provides the products in good to excellent yields.     

Salt-assisted acid hydrolysis of chitosan to oligomers under microwave irradiation

The effect of inorganic salts such as sodium chloride on the hydrolysis of chitosan in a microwave field was investigated. While it is known that microwave heating is a convenient way to obtain a wide range of products of different molecular weights only by changing the reaction time and/or the radiation power, the addition of some inorganic salts was shown to effectively accelerate the degradation of chitosan under microwave irradiation. The molecular weight of the degraded chitosan obtained by microwave irradiation was considerably lower than that obtained by traditional heating. Moreover, the molecular weight of degraded chitosan obtained by microwave irradiation assisted under the conditions of added salt was considerably lower than that obtained by microwave irradiation without added salt. Furthermore, the effect of ionic strength of the added salts was not linked with the change of molecular weight. FTIR spectral analyses demonstrated that a significantly shorter time was required to obtain a satisfactory molecular weight by the microwave irradiation-assisted inorganic salt method than by microwave irradiation without inorganic salts and conventional technology.     

Piperazine-azole-fluoroquinolone hybrids: Conventional and microwave irradiated synthesis,biological activity screening and molecular docking studies

A series of new 1,2,4-triazole and 1,3,4-oxadiazole derivatives was obtained via several steps sequential reactions of phenyl piperazine. Then, these compounds were converted to the corresponding fluoroquinolone hybrids via one pot three component Mannich reaction. All the reactions were examined under conventional and microwave mediated conditions, and optimum conditions were determined. The effect of different solvents and microwave power on microwave prompted reactions was investigated as well. All the newly synthesized compounds were characterized by FTIR, ¹H NMR, ¹³C NMR and EI MS spectral techniques. The antimicrobial activity, DNA gyrase and Topoisomerase IV inhibition potentials were performed. The results obtained showed that fluoroquinolone hybrids possess good antimicrobial activity. Moreover, Fluoroquinolone-azole-piperazine hybrids synthesized in the present study displayed excellent DNA gyrase inhibition. To unveil the interaction mode of compounds to receptor, a molecular docking study was performed. With an average least binding energy of −9.5 kcal/mol, all compounds were found to have remarkable inhibitory potentials against DNA gyrase (E. coli).     

Rapid microwave-assisted synthesis and characterization of cellulose-hydroxyapatite nanocomposites in N,N-dimethylacetamide solvent

Preparation of nanocomposites was carried out using microcrystalline cellulose, CaCl₂, and NaH₂PO₄ in N,N-dimethylacetamide (DMAc) solvent by a microwave-assisted method at 150 °C. XRD results showed that the nanocomposites consisted of cellulose and hydroxyapatite (HA). The cellulose existed as a matrix in the nanocomposites. SEM and TEM analysis showed that HA nanorods were homogeneously dispersed in the cellulose matrix. The effects of the microwave heating time on the products were investigated. This method has advantages of being simple, rapid, low-cost, and environmentally friendly.