中草药和天然植物有效成分提取新技术——微波协助萃取

中草药和天然植物有效成分的提取分离是天然药物生产过程中最为关键的环节之一。近年来 ,随着中药现代化进程的加速 ,越来越多的新技术正被逐步采用 ,其中 ,微波协助萃取 (microwave assistedextraction ,MAE)是在传统有机溶剂萃取的基础上发展而来的 ,无论是萃取速度、萃取效率还是萃取物质量均优于常规工艺 ,并以其投资少、设备简单、适用范围广、选择性高、重现性好、无污染等特点而受人瞩目。作者综述了MAE技术的作用原理、特点及其在黄酮类、苷类、多糖、萜类、挥发油等天然产物提取中的最新研究进展 ,并展望了其发展前景。     

GC/MS-screening analyses of valuable products in the aqueous phase from microwave-assisted hydrothermal processing of Lemna minor

Microwave-assisted hydrothermal treatment of Lemna minor plant material was studied under subcritical conditions. The water phases of this process were extracted with polar and nonpolar solvents and the extracts were investigated by GC/MS screening analyses for value added products. The polar extracts were dominated by compounds known as flavouring agents and partly as platform chemicals, e.g. hydroxyacetone, 1-hydroxybutan-2-one, furfural, cyclotene and pyrrolidone. Pyridinol, an important educt for heterocyclic chemistry, was another interesting product. Benzaldehyde and oleamide were detected as main products in nonpolar n-hexane extracts. An essential aspect is that a large proportion of compounds like aldehyds and ketones were obtained when mild hydrothermal processing was applied.     

Antiangiogenic evaluation of ZnWO4 nanoparticles synthesised through microwave-assisted hydrothermal method

Angiogenesis, the complex process of formation of new blood vessels from pre-existing blood vessels, which involves the participation of several pro- and anti-angiogenic factors, is implicated in many physiological and pathological conditions. Nanoparticle-based anti-angiogenic activity at the tumour tissue, harnessed by the Enhanced Permeability and Retention Effect (EPR effect), could potentially become a breakthrough therapy to halt tumour progression. Herein, we evaluate the anti-angiogenic effect of ZnWO₄ nanoparticles (NPs). The nanoparticles were obtained by microwave-assisted hydrothermal synthesis (MAHS) at 120?°C for 60?min and were structurally characterised by X-ray diffraction (XRD) and micro-Raman (MR) spectroscopy. The mean size and polydispersity index were estimated by Zeta potential analysis. The XRD analysis revealed structural organisation at a long-range order, with an average crystallite size of around 3.67?nm, while MR revealed short-range order for ZnWO₄. The anti-angiogenic potential of zinc tungstate nanoparticles was investigated through the chorioallantoic membrane assay (CAM) using fertilised chicken eggs. We demonstrate, in an unprecedented way, that nanocrystalline ZnWO₄ NPs obtained by MAHS, at low reaction temperatures, showed excellent anti-angiogenic properties even at low concentrations. The ZnWO₄ NPs were further evaluated for its cytotoxicity in vitro.     

Improving placental block morphology using microwave-assisted fixation

ABSTRACT

The histopathologic assessment of placenta is often marred by poorly fixed and processed sections. An audit conducted in the department resulted in 21% of placental blocks showing features of poor processing. A microwave-assisted fixation procedure was introduced using the Micromed KOS microwave oven (ABACUS-ALS, Brisbane, Australia) for 2 h at 45°C. This resulted in an improvement in the quality of the sections with a zero failure rate on a subsequent audit.     

中药刺五加中总皂苷的微波辅助提取方法研究

目的:建立中药刺五加中总皂苷微波辅助提取方法。方法:用微波辅助提取法提取中药刺五加中总皂苷。利用正交实验,考察了微波提取条件(包括溶剂、微波辐射时间、提取压力和料液比)对刺五加中总皂苷提取率的影响规律,优化了最佳提取条件。结果:在所选因素水平下,溶剂为70%乙醇、提取压力为700kPa、提取时间为10min、料液比为1:30时,刺五加中总皂苷提取效率最佳。与传统的索氏提取法进行了比较研究,微波辅助提取效率可提高34%。结论:微波辅助提取法提取中药刺五加中总皂苷,提取时间短,提取效率高。     

香豆素类基本骨架化合物的微波辐射辅助合成

目的 合成香豆素基本骨架化合物.方法 在微波辐射和氨基磺酸的催化作用下经Pechmann反应得到相应产物,其结构经IR、1H-NMR波谱确证.结果与结论 合成了8个苯并吡喃酮类化合物,反应收率74%～95%.微波辐射辅助可以缩短反应时间,提高反应效率,减少溶剂的使用.实验结果显示,氨基磺酸是Pechmann反应的良好固体酸催化剂.     

Investigation on Crystallization and Magnetic Properties of (Nd,Pr, Ce)2Fe14B/α-Fe Nanocomposite Magnets by Microwave Annealing Treatment

In the present work, the structures and magnetic properties of (Nd, Pr, Ce) ₂Fe₁₄B/α-Fe nanocomposite magnets were thoroughly investigated. The microwave annealing was applied to achieve a uniform heating effect and uniform grains. Microwave annealing is more favorable to obtain α-Fe phase than conventional annealing, which leads to the enhanced coercivity of hysteresis loops. The coercivity of nanocomposite magnets was 245 kA/m after annealing at 2000 W for 10 min.     

微波辅助萃取-高效液相色谱-串联质谱法测定辣椒中3种辣椒素

目的:建立微波辅助萃取-高效液相色谱-串联质谱法测定辣椒中3种辣椒素类化合物(辣椒素、二氢辣椒素、降二氢辣椒素)含量。方法:辣椒样品经微波辅助萃取甲醇稀释后分析。色谱分离采用C18反相色谱柱(150 mm×2.1 mm,3.5μm),流动相为0.1%甲酸水溶液和乙腈,梯度洗脱。串联质谱在多反应监测模式下检测目标分析物,以保留时间和特征离子对(母离子和2个碎片离子)信息比较进行定性和定量分析。结果:3种辣椒素的检出限为0.01～0.11 ng.mL-1,定量限为0.03～0.36 ng.mL-1,辣椒素、二氢辣椒素、降二氢辣椒素平均回收率分别为95.4%,94.3%,93.1%;RSD分别为2.1%,2.5%,2.7%。结论:该方法简便、准确、灵敏,可用于辣椒中3种辣椒素的分析。     

微波辅助合成红霉素环11,12-碳酸酯

在无相转移催化剂存在的条件下,红霉素、碳酸乙撑酯及碳酸钾（物质的量之比为1:5:1.5）于溶剂二氧六环中,经微波照射直接合成了红霉素环11,12-碳酸酯,其结构经MS和¹H-NMR谱确证。与常规的制备方法相比,该方法更加简便、有效。     

微波辅助萃取葛根和刺五加微观机制的研究

目的 研究微波辅助萃取葛根和刺五加的微观机制。方法 通过透射电子显微镜对葛根和刺五加药材细胞内液泡膜的变化进行观察。结果 微波辅助萃取与传统提取对液泡膜的影响是不同的。结论 微波辅助萃取工艺较传统提取工艺更易使细胞内的有效物质溶出。