黄酮类化合物的1H NMR研究

报道了某些黄酮、黄烷酮及查耳酮的¹H NMR光潜特点及其规律以及取代基对化学位移的影响。     

大孔吸附树脂分离纯化巫山淫羊藿总黄酮

筛选适合分离纯化巫山淫羊藿总黄酮的大孔吸附树脂并确立纯化工艺参数。以对总黄酮的吸附容量、解吸附率、吸附速率为指标,筛选D101、DM301、AB-8 3种大孔吸附树脂,并对最适树脂进行洗脱液浓度和洗脱液用量的工艺参数考察。结果AB-8型大孔树脂对巫山淫羊藿总黄酮的吸附容量、解吸附率、吸附速率均大于其他两种树脂,洗脱液以50%乙醇最佳,洗脱液用量3.6BV即可,纯化后总黄酮含量可达70.20%。该工艺简便、成本低,可用于工业化生产。     

大青叶提取物中总黄酮含量测定

建立大青叶中总黄酮含量测定方法.以超声辅助、70％乙醇提取大青叶总黄酮,采用紫外可见分光光度法对大青叶总黄酮进行测定.芦丁标准溶液线性方程为:A=0.01087C-0.0005833,r=0.9999.加标回收率为98.00％,相对标准偏差为1.45％.方法简便、快速、准确,且稳定性好,适用于测定大青叶总黄酮的含量.     

Regioselective 6-iodination of 5,7-dioxygenated flavones by benzyltrimethylammonium dichloroiodate

The iodination of 5,7-dioxygenated flavones with 1 equiv of benzyltrimethylammonium dichloroiodate (BTMA·ICl₂) in the system CH₂Cl₂-MeOH-CaCO₃ at room temperature is presented in this note. Flavones with a free phenol group at C5 and an alkoxy or a peracylglycosyloxy at C7 lead to the 6-iodoflavones with a good regioselectivity (ratio 6-iodination/8-iodination about 9).     

Preparative separation of five flavones from flowers of Polygonum cuspidatum by high‐speed countercurrent chromatography

A preparative high‐speed countercurrent chromatography method was successfully used for the isolation of five minor flavones from Polygonum cuspidatum flowers. Among them, three compounds were obtained from P. cuspidatum for the first time. A twin two‐phase solvent system composed of n‐hexane/ethyl acetate/ethanol/water (1:6:3:6, v/v/v/v) and petroleum ether/ethyl acetate/methanol/water (2:4:3:3, v/v/v/v) was developed. Compounds were obtained from the fraction B and fraction C prepurified by silica gel column chromatography. Five minor compositions, 6.8 mg of hesperidin, 11.2 mg of phloridzin, 4.9 mg of luteolin, 5.3 mg of hyperin, and 3.7 mg of luteoloside were obtained from 140 mg of the fraction B and 110 mg of fraction C with a purity of 95.3, 96.4, 98.0, 96.8, and 95.3%, respectively, as determined by high‐performance liquid chromatography. The structures of these compounds were identified by ¹H and ¹³C NMR spectroscopy.     

黄酮化合物的合成研究进展

黄酮化合物是一类具有多种生物活性的天然产物,其经典的合成方法主要为查耳酮路线和β-丙二酮路线.近年来出现了许多新技术、新方法.本文介绍了2'-羟基查尔酮的氧化关环法、黄烷酮氧化法、改进的Baker-Venkataraman法及其他合成黄酮化合物的方法.     

基于正交试验法优选红枣中总黄酮的提取工艺研究

采用正交试验优化红枣中总黄酮的提取,以芦丁的含量为评价指标。用12倍原料药的70%乙醇提取2次,每次1h,提取效果最好。该工艺可充分提取红枣中的总黄酮类成分,提高了药材利用率,为进一步研究红枣的有效成分奠定基础。     

一种新型循环微波萃取装置及其应用

介绍了一种自行设计制作的循环微波萃取装置 ,具有自动化程度高的特点 ,适用于实验室复杂样品的前处理 ,对改进样品前处理方法具有一定实用价值。该装置已用于提取银杏叶中的总黄酮测定其高效液相色谱指纹图谱。     

In memory of Prof. Venkataraman: Recent advances in the synthetic methodologies of flavones

Flavones are present in a variety of medicines and natural products and are important structural motif due to their unique mode of physiological action. Hence the structural importance of flavone moiety has elicited a great deal of interest in the field of organic synthesis and chemical biology to develop some new and improved synthesis of this molecular skeleton. Herein, we have described an up to date overview on the recent advances in the diverse synthetic methodologies of flavones. The review covers the basic conceptual and practical catalytic synthesis like carbonylative annulation, cyclodehydration, Suzuki Miyaura coupling, Heck coupling, green methodologies, metal catalyzed reactions, organocatalytic transformations, microwave irradiation, etc. which are significant for constructing flavone skeleton. This review will satisfy the expectations of readers who are interested in the development of the field and looking for an update. It will stimulate researchers to develop new and creative synthetic access to this heterocyclic system, which will be instrumental in the advancement of flavone chemistry.     

Dimethylsulfoxide-iodine catalysed deprotection of 2′-allyloxychalcones: synthesis of flavones

A new one-pot method is described for the removal of O-allyl protecting groups under oxidative conditions at neutral pH. 2′-Allyloxychalcones undergo deprotection and subsequent oxidative cyclisation to give flavones. The general applicability of the reagent has been studied.