Approach to the study of C-glycosyl flavones acylated with aliphatic and aromatic acids from Spergularia rubra by high-performance liquid chromatography-photodiode array detection/electrospray ionization multi-stage mass spectrometry

The use of mass spectrometry (MS) coupled to liquid chromatography (LC) as working tool for the study of the C-glycosyl flavones acylated with aliphatic and aromatic acids has allowed the tentative characterization of these compounds in Spergularia rubra and the establishment of the position of the acylation on the sugar moiety of the C-glycosylation by use of MS data. The combination of retention time (Rt), ultraviolet (UV) and MS(n) data of the compounds revealed their C-glycosyl flavone nature, being luteolin, apigenin and chrysoeriol derivatives. Ten non-acylated flavones were identified, from which six are described for the first time (one 7-O-glycosyl-6,8-diC-glycosyl flavone, four 6,8-diC-glycosyl flavones and one 2"-O-glycosyl-6-C-glycosyl flavone). Twenty-six acylated derivatives were also found for the first time. These compounds are grouped in three classes, namely, C-glycosyl flavones acylated with aliphatic acids, with aromatic acids or with a mixed acylation. The first group is characterized by the presence of one 6,8-diC-(acetyl)glycosyl flavone, four 6,8-diC-(malonyl)glycosyl flavones and two 7-O-glycosyl-6,8-diC-(malonyl)glycosyl flavones, while in the second one twelve 6,8-diC-(acyl)glycosyl flavones and two 7-O-glycosyl-6,8-diC-(acyl)glycosyl flavones are described. The last class contained five 6,8-diC-(malonyl,acyl)glycosyl flavones. No previous work has described the presence of C-glycosyl flavones acylated with aliphatic acids in this genus.     

Determination of flavones in Crataegus pinnatifida by capillary zone electrophoresis

A capillary electrophoretic method for the separation of four flavones in Crataegus pinnatifida is developed. The four flavones in Crataegus pinnatifida are separated on baseline within 15 min using 50mM borax buffer containing 15% acetonitrile and adjusted to pH 8.15 with phosphoric acid. The detection limits of vitexin-2"-rhamnoside, hyperside, rutin, and vitexin are 0.35, 0.30, 0.40 and, 0.29 microg/mL, respectively. The recovery of these flavones is as follows: vitexn-2"-rhamnoside 96.8%, hyperside 99.9%, rutin 97.1%, and vitexin 97.8%. The results are in accordance with those obtained in the high-performance liquid chromatography system. The content of flavones is higher in Crataegus pinnatifida leaves than in its fruits, and hyperside is not detected in either Crataegus pinnatifida fruits or flowers.     

Analysis of antioxidant compounds in sweet orange peel by HPLC-diode array detection-electrospray ionization mass spectrometry

HPLC-diode array detection-electrospray ionization mass spectrometry was used to determine qualitatively and quantitatively the flavonoid content of several fractions and residues of extracts of Greek navel sweet orange peel (Citrus sinensis) from the region of southern Greece (Leonidi-Tripoli). The main groups of flavonoids found according to HPLC retention times, spectral data and literature references were polymethoxylated flavones, C-glycosylated flavones, O-glycosylated flavones, O-glycosylated flavanones, flavonols and phenolic acids and their derivatives. The ethyl acetate fraction which has been shown in previous work to possess the best radical scavenging activity among the others was found to contain C-glycosylated flavones, polymethoxylated flavones, O-glycosylated flavones, O-glycosylated flavanones, two phenolic acid derivatives and two unknown compounds, all in low concentrations. The group of C-glycosylated flavones was reported for the first time in the peel of Navel sweet orange. The C-glycosylated flavones found according to their spectral characteristics and literature were 6-C-beta-glucosyldiosmin, 6,8-di-C-glucopyranosylapigenin, 6,8-di-C-beta-glucosyldiosmin and two unknown. The results suggest that the ethyl acetate fraction of navel Citrus sinensis peel consists of significant antioxidant compounds and can be used as a food additive of natural origin or a pharmaceutical supplement using as a source of peel the byproducts of the orange juice industry.     

毛细管电泳技术在天然黄酮类物质测定中的应用评述

综述了近年来毛细管电泳技术在天然黄酮类物质分离中的应用,简要概括了不同分离模式的应用情况,并列举了部分黄酮物质的分离实例.     

黄酮化合物的合成新方法

黄酮类化合物具有广泛而重要的生物活性和药理作用,其化学合成研究受到普遍重视.经典的合成方法主要是查耳酮路线和β-丙二酮路线.近年来有很多新技术、新方法在黄酮化合物合成中得到了巧妙的应用.对近年来出现的新的改进的Baker-Venkataraman法、催化羰基化闭环法以及其他合成黄酮化合物的新方法作了介绍.     

基于浊点提取悬铃木球叶中黄酮化合物的研究

采用微波辅助浊点提取悬铃木球叶中的黄酮类化合物。在单因素试验的基础上,0.6%吐温-80的乙醇溶液作为浊点萃取剂,通过响应面法优化确立悬铃木黄酮类化合物的最佳提取工艺条件：微波功率410 W,提取时间7 min,液料比49:1 mL?g_^-1,实际测得黄酮平均得率1.480 mg?g_^-1。并对黄酮类化合物进行了分离纯化,得到2个化合物,经理化常数测定和波谱解析鉴定,化合物1为3,5,7-三羟基黄酮,分子式为C₁₅H₁₀O₅;化合物2为山奈酚,分子式为C₁₅H₁₀O₆。     

A New Method for the Facile Synthesis of Hydroxylated Flavones by Using Allyl Protection

The iodine‐induced oxidative cyclization of 2′‐hydroxychalcones provides a simple, highly efficient approach to various hydroxy flavones and analogues. This process is run under mild conditions, tolerates various functional groups, and provides hydroxy flavones in good to excellent yield. The allyl‐protected acetophenones and benzaldehydes were smoothly deallylated under similar conditions.     

黄芪中黄酮类组分的高效液相色谱分离条件的快速优化

以黄芪为研究对象,对黄芪中乙酸乙酯部位的化学成分进行了高效液相色谱分析并对其色谱操作条件进行了快速优化。根据几个线性梯度下的保留时间来计算各组分的保留参数,然后利用重叠分辨图法确定其最佳分析条件。在选定的最佳条件下各组分分离情况良好。利用梯度保留时间计算保留参数比较方便快速,并可以有效地避免以往等度线性回归法遇到的峰识别问题。该方法更适用于实际复杂样品色谱分析条件的优化。     

超临界CO_2萃取桑叶总黄酮工艺的研究

采用超临界CO2萃取桑叶总黄酮,以得率为指标,对萃取压力、萃取温度、夹带剂乙醇的浓度和流量等影响因素进行正交试验。结果表明最佳工艺条件为:萃取压力35 MPa,温度55℃,乙醇质量分数90%,乙醇流量0.01 mL/min。此条件下桑叶总黄酮得率2.28%。该方法简便、可靠、选择性高,适于工业化生产。     

Retention behavior of silica-bonded and novel polymeric reversed-phase sorbents in studies on flavones as chemotaxonomic markers of Scutellaria L. genus

In this study, the effectiveness of both classical and novel polymeric sorbents used in solid-phase extraction (SPE) for isolation of pharmacologically active flavones (baicalin, luteolin, apigenin, wogonin and chrysin) from aerial parts of 13 species of Scutellaria L. (Skullcap) genus was assessed. The highest recoveries of hydrophilic (baicalin, luteolin) flavones for Oasis HLB were obtained, whereas for medium hydrophobic (apigenin) and hydrophobic (wogonin, chrysin) flavones better quantitative results for BakerBond phenyl cartridges were stated. Eluates were analysed using reversed-phase high-performance liquid chromatography with diode array detection (RP-HPLC-DAD). For the five target compounds the determined concentrations ranged from approximately 4 to approximately 15,500 microg/g dry wt. Very good linearities (r(2)>0.9995) of calibration curves were achieved for each flavone. The accuracy was below 5% for most compounds examined. This is the first method reported that enabled simultaneous qualification and quantitation of five flavones (being chemotaxonomic markers) in 13 species of Scutellaria L. genus.     

茅莓黄酮液相色谱-电喷雾质谱与薄层色谱-表面增强拉曼光谱研究

采用紫外光谱定性定量分析野生植物茅莓主要有效成分黄酮化合物,并对其进行液相色谱-电喷雾质谱联用、薄层色谱原位表面增强拉曼散射研究。液相色谱流动相A:CH3OH,B:H2O 1%乙酸,液相色谱流出时间16.21 m in的化合物为六羟基双氢黄酮醇二聚体形式,分子量640,占总黄酮的91.71%;流出时间19.61 m in的化合物分子量448,为槲皮甙,占总黄酮的8.29%。茅莓总黄酮经聚酰胺薄层色谱板分离,获得两个斑点:R f1=0.14,R f2=0.47;分别制备灰银胶和溴化银光致还原银溶胶表面增强基底,在样品薄层色谱两个斑点原位分别获得2种黄酮化合物的表面增强拉曼光谱,在2种表面增强基底作用下,都能观察到μg量黄酮化合物特征拉曼光谱,并比较了2种色谱分离与指纹检测联用技术。     

Synthesis of novel flavonoid derivatives as potential HIV‐ Integrase inhibitors

Eighteen novel flavonoid derivatives ‐ substituted chalcones and flavones were synthesized and characterized by using NMR, IR, UV/Vis spectroscopy and elemental analysis. The target compounds were achieved by using a sequence of simple and effective reactions starting from phloroglucinol. The initial hydroxyl groups were protected by methylation and in the final flavones the 5‐OH group was selectively demethylated by means of AlBr₃. 5‐methoxy flavones exhibit a strong fluorescence, which was quenched after the removal of the methyl group.     

羟丙基-β-环糊精与五种黄酮类物质的包合作用

采用溶液搅拌法制备了羟丙基-β-环糊精(HP-β-CD)与5种黄酮类物质(橙皮素、依普黄酮,新黄酮、刺芒柄花素、黄芩素)的包合物;利用红外光谱、X射线衍射等分析了包合物的组成,利用相溶解度法研究了羟丙基-β-环糊精与黄酮类物质的包合作用.结果表明,HP-β-CD与5种黄酮类物质均产生理想的包合作用,增溶顺序为:依普黄酮...     

Studies on inhibitors of skin tumor promotion. XI. Inhibitory effects of flavonoids from Scutellaria baicalensis on Epstein-Barr virus activation and their anti-tumor-promoting activities.

To search for possible anti-tumor-promoters, fourteen flavones obtained from the root of Scutellaria baicalensis were examined for their inhibitory effects on the Epstein-Barr virus early antigen (EBV-EA) activation by a short-term in vitro assay. Among these flavones, 5,7,2'-trihydroxy- and 5,7,2',3'-tetrahydroxyflavone showed remarkable inhibitory effects on the EBV-EA activation, and the effect of the latter on Raji cell cycle was also examined by flow cytometer. These two flavones exhibited remarkable inhibitory effects on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test.     

柑桔果皮中多甲氧基黄酮的LC-APCI-MS定性分析

黄酮化合物是具有多种生物活性的物质,广泛存在于自然界中。单纯为甲氧基取代的多甲氧基黄酮PMF是芸香科多种桔类所特有的,特别是在其果皮中有较高的含量。近年来有关桔皮PMF抗癌的研究取得了很大进展。PMF作为桔皮中的抗癌活性成分,对多种癌细胞有较强的抑制作用,受到国内外的广泛关注。由于桔皮中PMF的主要成分随柑桔种类和产地的不同而有较大差异,所以,筛选含有较强抗癌活性的PMF成分的桔皮种类,是一项非常有意义的工作。文献报道的PMF的分析检测方法主要有液相色谱法、气相色谱-质谱法等。本文利用液相色谱-大气压化学电离化质谱联用技术定性分析了3种柑桔果皮中PMF的主要成分,并结合紫外吸收光谱进一步确证。     

树脂吸附法分离纯化桑叶总黄酮——（Ⅱ）动态法分离桑叶总黄酮的工艺条件及数学模拟

考察了H103树脂固定床吸附分离桑叶总黄酮的工艺参数,并对吸附工艺进行了数学模拟和比较.实验结果表明,H103树脂固定床吸附分离桑叶总黄酮在上样浓度6.05mg/mL时,以9mL/min上样,吸附完全后用60%乙醇以4.5mL/min流速洗脱,桑叶总黄酮产品的回收率为90.57%,纯度为76.33%,建立的固定床吸附模型为预测固定床吸附桑叶水提液中桑叶黄酮达到穿透点时间及固定床吸附容量提供了准确、快捷的方法.     

聚（对乙烯基苄基脲）大孔吸附树脂对银杏叶黄酮的吸附性能

通过静态吸附平衡和动态柱吸附试验,研究了自制大孔交联聚（对乙烯基苄基脲）树脂（简称PMVBU树脂）对银杏叶黄酮的吸附性能．结果表明,在pH=5．00时,该树脂对银杏叶黄酮有较好的吸附性能;PMVBU树脂对黄酮的吸附等温线符合Langmuir吸附等温方程,相关系数R^2〉0．99．308K时,PMVBU干树脂对黄酮的静态饱和吸附量达293．3mg／g．298K时,干树脂的动态吸附穿透容量为180mg／g．用75％的乙醇溶液对吸附在PMVBU树脂上的黄酮可进行有效洗脱．银杏叶提取液经过该树脂吸附柱吸附纯化后,黄酮纯度提高了18．6％,且树脂具有良好的重复使用性．     

A novel method for extraction and separation of total flavones and total astragalosides from <Emphasis Type="Italic">Radix astragali</Emphasis>

In this paper a novel method for extraction and separation of total flavones and total astragalosides from Radix astragali using a resin method is suggested. Ethanol is used as the extractant, the macroporous absorption resin modeled H-107 is used to enrich the astragalus extract, and the macroporous strong base anion resin D-280 is used to separate the total flavones and the total astragalosides. This method allows a good yield of total flavones of 600 mg/100 g Radix astragali, a purity of 94.2%, and a yield of total astragalosides of 28 mg/100 g Radix astragali. Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 26–29, January–February, 2007.     

Bioflavonoid profile of citrus juices from Greece

High‐performance liquid chromatography with confirmation by UV–visible photodiode array detector–positive electrospray ionization–mass spectrometry [HPLC‐UV–vis‐DAD‐(+ESI)‐MS] with enhanced fragmentation by appropriate adjustment of the cone voltage was used to determine bioflavonoid content of five citrus species (tangerine, sanguine, sour orange, lemon and grapefruit) cultivated in Greece which come from citrus varieties analyzed for the first time. The main groups of bioflavonoids found in the juice of the citrus species according to HPLC retention times, spectral data and literature references were O‐glycosylated flavanones and flavones, C‐glucosylated flavones, O‐glucosylated flavones, O‐C‐glucosylated flavones like saponarin and a phenolic derivative. Copyright © 2012 John Wiley & Sons, Ltd.     

Intramolecular excited-state proton-transfer studies on flavones in different environments

The absorption and fluorescence spectra of some biologically active flavones have been studied as a function of the acidity (pH/H0) of the solution. Dissociation constants have been determined for the ground and first excited singlet states. The results are compared with those obtained from Forster-Weller calculations. The acidity constants obtained by fluorimetric titration method are in complete agreement (in most of the systems) with ground state data indicating a excited state deactivation prior to prototropic equilibration. Compared to umbelliferones, flavones are only weakly fluorescent in alkaline solution. This behaviour is explained by the small energy difference between the singlet excited state and triplet excited state giving rise to more efficient intersystem crossing. Most of the flavones studied here undergo adiabatic photodissociation in the singlet excited state indicating the formation of an exciplex or a phototautomer.