Comprehensive mass spectrum analysis of two flavone-6,8-C-di-glycosides and its application by high resolution electrospray ionization tandem mass spectroscopy in both negative and positive ion modes / 中国中药杂志

The tandem mass spectrum of apigenin-6,8-C-di-glucoside( 1) and apigenin-6-C-glucose-8-C-rhamnoside( 2) were obtained by high resolution electrospray ionization mass spectrometry( HR-ESI-MS/MS) in both positive and negative ion modes. The elemental composition of each ion was determined according to its accurate mass-to-charge,hence,the fragmentation pathways of each compound were proposed in both negative and positive ion modes. Comprehensive analysis of each ion and its proposed fragmentation pathways of the two compounds was initially conducted in both negative and positive ion mode HR-ESI-MS/MS to explore the diagnostic ions for flavone-6,8-C-di-glycosides and the characteristic ions for each compound and their cleavage rules. The results showed that a family of fragmentation ions with m/z 353,325,311,297 in ESI(-)-MS and m/z 355,325,307,295 in ESI( +)-MS could be the diagnostic ions of flavone-6,8-C-di-glycoside,and characteristic neutral loss could be assigned to glycosyl substitution,for example,neutral losses of C_4H_8O_4( 120),C_3H_6O_3( 90),C_2H_4O_2( 60) for glucoside substitution while neutral losses of C_4H_8O_3(104),C_3H_6O_2( 74),C_2H_4O( 44) for rhamnoside substitution. Furthermore,only one H_2O loss from mother ion( [M-H]-) was observed for 1 & 2 in ESI(-)-MS while five to six H2 O loss from mother ion( [M+H]+) was observed for 1 & 2 in ESI( +)-MS to produce a family of ions by subsequent loss of H_2O,which could be applied for glucosyl difference. The flavone-6,8-C-di-glycosides in both ESI( +)-MS and ESI(-)-MS showed the cleavage similarity at sugar substitutions. However,there were much more differences by the fragmentation pathways and neutral losses between ESI( +)-MS and ESI(-)-MS as following,hyperconjugation ions by subsequent loss of H_2O from precursor ions of flavone-6,8-C-di-glycosides in ESI( +)-MS were not observed in ESI(-)-MS; the subsequent neutral loss of CH_2O in ESI( +)-MS were rarely observed in ESI(-)-MS; the loss of CO only happen at C-ring of flavone ESI( +)-MS other than glycosyl position in ESI(-)-MS; the C4-chain neutral loss of flavone-6,8-C-di-glycosides happened at 8-C-glycosyl position other than at 6-C-glycosyl position. The above cleavage rules and diagnostic ions of ESI( +)-MS were successfully applied for the structure identification of 4 flavone-6 C,8 C-diglycosides from the stem extract of Dendrobium officinale as vicenin Ⅱ,vicenin Ⅰ,isoschaftoside,schaftoside as well as one flavone-O-glysoside named rutin,which were supported by ESI(-)-MS data as well.

13C NMR spectral data and molecular descriptors to predict the antioxidant activity of flavonoids / Dados espectrais de RMN 13C e descritores moleculares para prever a atividade antioxidante dos flavonóides

Tissue damage due to oxidative stress is directly linked to development of many, if not all, human morbidity factors and chronic diseases. In this context, the search for dietary natural occurring molecules with antioxidant activity, such as flavonoids, has become essential. In this study, we investigated a set of 41 flavonoids (23 flavones and 18 flavonols) analyzing their structures and biological antioxidant activity. The experimental data were submitted to a QSAR (quantitative structure-activity relationships) study. NMR 13C data were used to perform a Kohonen self-organizing map study, analyzing the weight that each carbon has in the activity. Additionally, we performed MLR (multilinear regression) using GA (genetic algorithms) and molecular descriptors to analyze the role that specific carbons and substitutions play in the activity.

Danos aos tecidos devido ao estresse oxidativo estão diretamente ligados ao desenvolvimento de muitos, senão todos, os fatores de sedentarismo e de doenças crônicas. Neste contexto, a busca de moléculas naturais, que participam da nossa dieta e que possuam atividade antioxidante, flavonóides, torna-se de grande interesse. Neste estudo, nós investigamos um conjunto de 41 flavonóides (23 flavonas e 18 flavonóis), relacionando suas estruturas e atividade antioxidante. Os dados experimentais foram submetidos à análise de QSAR (relações quantitativas estrutura-atividade). Dados de RMN 13C foram utilizados para realizar um estudo do mapa auto-organizável de Kohonen, analisando o peso que cada carbono tem na atividade. Além disso, realizamos uma MLR (regressão múltipla) usando GA (algoritmos genéticos) e descritores moleculares para avaliar a influência de carbonos e substituições na atividade.

Two triglycoside flavonols from Lotus corniculatus legumes

Two new triglycoside flavonols, kaempferol 3-o-beta-xylopyranosyl [1['"]-2["]]-o-beta-galactopyranoside 7-O-alpha- rhamnopyranoside and quercetine 3-0-beta-xylopyranosyl [1["']- >[2]"]-O-beta-galactopyranoside 7-0-alpha-rhamnopyranoside were isolated and identified from aqueous alcoholic extract of Lotus corniculatus legumes, together with seven known flavonoids. All structures were established on the basis of chemical and spectral evidence, including ESI-MS, [1]H, [13]C, DEPT, COSY, HMQC and HMBC NMR

new flavonol glycoside from polygonum bellardu all: growing in Egypt

A new flavonol glycoside named myricetin-3-O-[5"-acetyl alpha-arabinofuranoside] has been isolated from Polygonum bellardii All F. Polygonaceae growing in Egypt, together with quercetin-3-O-[5"-acetyl alpha -arabinofuranoside], quercetin-3-O-rutinoside [rutin], alpha-amyrin, beta sitosterol and beta-sitosterol-3-O-beta glucoside. Their structures were elucidated using different spectral techniques

Antioxidant flavonols from fruits, vegetables and beverages: measurements and bioavailability

Flavonols are polyphenolic secondary plant metabolites that are present in varying levels in commonly consumed fruits, vegetables and beverages. Flavonols have long held an interest for nutritionists, which has increased following a Dutch study in the early 1990's showing that dietary intake of flavonols was inversely correlated with the incidence of coronary heart disease. The main factors that have hindered workers in the field of flavonol research are (i) the accurate measurement of these compounds in foods and biological samples, and (ii) a dearth of information on their absorption and metabolism. This review aims to highlight the work of the authors in attempting to clarify the situation. The sensitive and selective HPLC procedure to identify and quantify common flavonols and their sugar conjugates is described. In addition, the results of an on-going screening program into the flavonol content of common produce and beverages are presented. The bioavailability of dietary flavonols is discussed with reference to an intervention study with onions, as well as pilot studies with tea, red wine and cherry tomatoes. It is concluded that flavonols are absorbable and accumulate in plasma and that consuming high flavonol-containing varieties of fruits and vegetables and particular types of beverages could increase their circulatory levels.

Hplc method for the determination of hesperidin and diosmine in flavonoid extract and capsules

A high performance liquid chromatographic procedure was developed for the determination of hesperidin and diosmine in the flavonoid extract of rutaceae and in dosage forms. The method utilized a reversed phase chromatography with UV detection. The mobile phase comprised of 38% methanol and 62% 0.005 M heptane sulfonic acid sodium salt pumped at a flow rate of 1.5 ml/min and the column was at ambient temperature. The detection wavelength was 278 nm and the quantitation was performed by measuring the peak area. It was also determined that the excipients in the commercial soft gelatin capsule preparations containing these flavonoids did not interfere with the assay. The method was linear in the range 5-40 mug/ml. In all cases, the coefficient of variation did not exceed 2%

Actividad antioxidante de los flavonoides / Antioxidizer activity of the flavonoids

Los flavonoides son substancias de origen vegetal, ampliamente distribuidas en la naturaleza. Se sintetizan principalmente en las plantas superiores especialmente en las familias de las Poligonáceas, Rutáceas, Leguminosas, Umbelíferas y compuestas. En la actualidad se conocen más de 2000 de estos compuestos, que, generalmente, se encuentran glicosilados con uno o más azúcares unidos a los grupos hidroxilos de su estructura, o no, llamados en este caso agliconas. Los flavonoides contribuyen a dar color a numerosos vegetales y poseen, como característica estructural básica, un esqueleto carbonado C6-C3-C6, formando tres anillos de los cuales los de C6 son de tipo aromático. El núcleo central, por lo general, posee una estructura de tipo gama-pirona. Otra de las características es que la estructura básica del flavonoide puede tener modificaciones en pasos subsiguientes a su síntesis, tales como hidroxilaciones o reducciones adicionales, metilaciones, isoprenilaciones, metilenaciones, sulfonaciones y glicosilaciones (por unión de diversos azúcares) y dimerizaciones (para producir biflavonoides), dando múltiples variaciones. Por esta razón, se los califica como el grupo más numeroso de los heterósidos fenólicos naturales. Los flavonoides constituyen, en la actualidad, un campo de continuas investigaciones. Es muy probable que diversas plantas medicicnales cuyos principios activos son, hasta ahora, desconocidos, deban su acciónfarmacológica a los flavonoides. Desde los primeros informes acerca de la capacidad de los flavonoides para reducir la fragilidad capilar, hasta la fecha, se han descripto múltiples trabajos sobre diversas propiedades farmacológicas, principalmente acciones antiinflamatorias, antihepatotóxicas, sobre el sistema vascular central, antitumoral, antibacteriana y antiviral

C-glycosylflavones from prosopis chilensis

Five apigenin-based C-glycosylflavones were isolated from the leaves and pods of Prosopis chilensis and identified as vicenin-1, 6-O-acetylvicenin-1, vicenin-2, vitexin and isovitexin. 6-O-acetylvicenin-1 could be a new acylated di-C-glycosylflavone and vicenin-1 is reported here for the first time in the genus Prosopis. The structures of the isolated compounds were established through spectroscopic analyses including 2D-NMR [HMQC, HMBC]

New flavonoid glycosides from euphorbia dracunculoidea

The ethyl acetate fraction of the alcoholic extract aerial parts of Euphorbia dracunculoides afforded kaempferol and two new glycosides identified through their UV, IR, 1H-NMR, 13C-NMR, 13C-NMR [APT] COESY and HETCOR spectral data as kaempferol 3-0-beta-methyl glucouronide and kaempferol 3-0-beta-glucosyl [1-4] beta-methyl glucouronide

Studies on the anthocyanin-flavonoid complex in coleus blumei infested by the mealy bug icerya aegyptiaca

Leaves and inflorescences of Coleus blumei from healthy, and from plants infested with Icerya aegyptiaca were analysed to study the changes in flavonoid and anthocyanin complexes associated with the visible changes in the infested leaves, for 6 weeks following infestation. Anthocyanins and flavonoids remained unchanged or increased slightly following infestation compared to healthy leaves. The aglycones of some anthocyanins and flavonoids were detected after the 3rd and 4th week of infestation and increased slightly thereafter. Anthocyanins and flavonoids in the inflorescence were somewhat those in the leaves of healthy plants, and did not change following infestation. The biosynthetic and transport pathways causing changes in anthocyanin-flavonoid complex during infestation of the investigated plant are discussed