Purification and identification of flavonoids from the yellow green cocoon shell (Sasamayu) of the silkworm,Bombyx mori

Three quercetin glycosides, quercetin 5-O-beta-D-glucoside, quercetin 7-O-beta-D-glucoside, and quercetin 4'-O-beta-D-glucoside, and two kaempferol glycosides, kaempferol 5-O-beta-D-glucoside and kaempferol 7-O-beta-D-glucoside, along with their aglycones, quercetin and kaempferol, were isolated from an ethanolic extract of Sasamayu cocoon shells. The chemical structures were characterized by chemical and spectroscopic methods including UV spectrometry and HPLC-ESI-MS. The five flavonol glycosides of the shell are different structurally from those of the leaves of mulberry (Morus alba). It was suggested that potent antioxidative activity in the cocoon is mainly due to flavonoid compounds since free radical scavenging activity was found in the cocoon flavonoids identified here.     

Metabolic profiling of flavonoids in Lotus japonicus using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry

Flavonoids detected from a model legume plant, Lotus japonicus accessions Miyakojima MG-20 and Gifu B-129, were profiled using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR/MS). Five flavonols and two anthocyanidins were detected as aglycones. LC-FTICR/MS facilitated simultaneous detection of 61 flavonoids including compounds that have not been reported previously. Chemical information of the peaks such as retention time, lambdamax, m/z value of the quasi-molecular ion, m/z value of MS/MS fragment ions, and relative intensity of MS/MS fragments was obtained, along with the molecular formulas and conjugate structures. Fourteen were completely identified by comparison with authentic compounds. The high accuracy of m/z values, being 0.081 ppm between observed and theoretical values, allowed prediction of molecular formulas of unknown compounds with the help of isotope peak information for determination of chemical composition. Based on a predicted elemental composition, the presence of a novel nitrogen-containing flavonoid was proposed. A comparison of flavonoid profiles in flowers, stems, and leaves demonstrated that the flowers yielded the most complex profile, containing 30 flower-specific flavonoids including gossypetin glycosides and isorhamnetin glycosides. A comparison of flavonoid profiles between MG-20 and B-129 grown under the same conditions revealed that the accumulation of anthocyanins was higher in B-129 than MG-20, particularly in the stem. Developmental changes in the flavonoid profiles demonstrated that kaempferol glycosides increased promptly after germination. In contrast, quercetin glycosides, predominant flavonoids in the seeds, were not detectable in growing leaves.     

Accumulation of Flavonoid Glycosides and UFGT Gene Expression in Mulberry Leaves (Morus alba L.) before and after Frost

In order to determine the molecular mechanism underlying the influence of frost on chemical changes in mulberry leaves, the UFGT activity, expression level, and accumulation of flavonoid glycosides in mulberry leaves (Morus alba L.) were studied. The expression of UFGT gene was investigated by quantitative real‐time PCR (qRT‐PCR) and the UFGT activity, accumulation of flavonoid glycosides was studied by high performance liquid chromatography. Then, the correlation between the expression level of UFGT, the UFGT activity, and the flavonoid glycosides accumulation with temperature was explored. The accumulation of isoquercitrin and astragalin is significantly positively correlated with UFGT gene expression and UFGT activity. On the contrary, the average temperature was significantly negatively correlated with the level of UFGT gene expression and UFGT activity. The results show that after frost, low temperature can induce the expression of UFGT gene in mulberry leaves, resulting in the accumulation of flavonoid glycosides.     

Purification and Identification of Flavonoids from the Yellow Green Cocoon Shell (Sasamayu) of the Silkworm,Bombyx mori

Three quercetin glycosides, quercetin 5-O-β-D-glucoside, quercetin 7-O-β-D-glucoside, and quercetin 4′-O-β-D-glucoside, and two kaempferol glycosides, kaempferol 5-O-β-D-glucoside and kaempferol 7-O-β-D-glucoside, along with their aglycones, quercetin and kaempferol, were isolated from an ethanolic extract of Sasamayu cocoon shells. The chemical structures were characterized by chemical and spectroscopic methods including UV spectrometry and HPLC-ESI-MS. The five flavonol glycosides of the shell are different structurally from those of the leaves of mulberry (Morus alba). It was suggested that potent antioxidative activity in the cocoon is mainly due to flavonoid compounds since free radical scavenging activity was found in the cocoon flavonoids identified here.     

Changes in citrus leaf flavonoid concentrations resulting from blight-induced zinc-deficiency

Increased flavonoid concentrations were found to correlate with the elevated levels of leaf phenolic compounds occurring in blight-induced zinc-deficient citrus. In orange (Citrus sinensis L.) leaves, the increases occurred primarily in hesperidin and diosmin, whereas in grapefruit (C. paradisi Macf.) the largest increases occurred in naringin and rhoifolin. Zinc-deficiency occurring in the blighted citrus leaves appeared to be the important contributing factor to the increased flavonoid content. Although the leaves from trees with blight were typically smaller than leaves from unaffected trees, the increased flavonoid content was not significantly due to a concentration effect. Large differences occurred in the percent increases in concentrations of certain citrus leaf flavonoids. While large increases occurred for a number of flavanone and flavone glycosides, much smaller percent increases occurred for other minor flavone glycosides, and the polymethoxyflavone aglycones. The parallel increases occurring in the concentrations of certain flavone glycosides and their flavanone analogs provide a further indication that flavanone glycosides are precursors in the biosynthesis of flavone glycosides in citrus.     

Flavonoid glycosides and their p-coumaroyl esters from Campylospermum calanthum leaves

Six new compounds, comprising three flavonoid glycosides and their respective coumaroyl esters, have been isolated and characterized from the methanol extract of the leaves of Campylospermum calanthum, along with three known flavonoid aglycones, 7-O-methyl apigenin (1), 7-O-methyl luteolin (2), and 7-O-methyl quercetin (3). Their structures were elucidated based on chemical evidence as well as spectroscopic analysis including 1D and 2D NMR (1H-1H COSY, HSQC, HMBC, and NOESY) spectroscopy and by comparing their spectral data with those reported for related compounds.     

Application of mass spectrometry for identification and structural studies of flavonoid glycosides

Mass spectrometry is an important tool for the identification and structural determination of flavonoid glycosides. The advantages of mass spectrometry are high sensitivity and possibilities of hyphenation with liquid chromatographic methods for the analysis of mixtures of compounds. Different desorption ionization methods allow the analysis of underivatized glycosides. A review of mass spectrometric techniques applied to the identification and structural studies of flavonoid glycosides is presented.     

Phenolic glycosides of forage legume Onobrychis viciifolia

A chemical examination of the extractives of the leaves of sainfoin was undertaken as part of a programme directed at understanding the factors which may contribute to its nutritive value as animal feed. Among the low molecular weight phenolic compounds characterized were seven cinnamic acid derivatives and nine flavonoid glycosides all of which were identified by NMR spectroscopy. Included among these compounds were two new natural hydroxycinnamic esters namely methyl 6-O-p-trans-coumaroyl-beta-D-glucopyranoside and methyl 6-O-p-cis-coumaroyl-beta-D-glucopyranoside and a novel flavonoid chrysoeriol-4'-O-(6'-O-acetyl)-beta-D-glucopyranoside.     

Flavonoid glycosides from Barringtonia acutangula

Using various chromatographic separation techniques, ten flavonoid glycosides, including six new compounds namely barringosides A?F (1–6), were isolated from a methanol extract of the Barringtonia acutangula leaves. The structure elucidation was confirmed by spectroscopic analyses, including 1D and 2D NMR, and HR ESI MS. Their inhibitory effects on LPS-induced NO production in RAW264.7 cells were also evaluated. Among the isolated compounds, quercetin 3-O-β-d-(6-p-hydroxybenzoyl)galactopyranoside (9) showed significant effect with an IC₅₀ of 20.00 ± 1.68 µM. This is the first report of these flavonoid glycosides from Barringtonia genus and their inhibition on LPS-induced NO production in RAW264.7 cells was reported here for the first time.     

Fragmentation pathways of acylated flavonoid diglucuronides from leaves of Medicago truncatula

Introduction – Flavonoids are important plant compounds occurring in tissues mostly in the form of glycoconjugates. Most frequently the sugar moiety is comprised of mono‐ or oligosaccharides consisting of common sugars like glucose, rhamnose or galactose. In some plant species the glycosidic moiety contains glucuronic acid and may be acylated by phenylpropenoic acids. Methodology – Flavonoid glyconjugates were extracted from leaves of Medicago truncatula ecotype R108 and submitted to analysis using high‐performance liquid chromatography combined with high‐resolution tandem (quadrupole‐time of flight, QToF) mass spectrometry. Results – The studied leaf extracts contained 26 different flavonoid glycosides among which 22 compounds were flavone (apigenin, luteolin, chrysoeriol and tricin) glucuronides and 13 were acylated with aromatic acids (p‐coumaric, ferulic or sinapic). The fragmentation pathways observed in positive and negative ion mass spectra differed substantially between each other and from these of flavonoid glycosides which did not contain acidic sugars. The application of high‐resolution MS techniques allowed unequivocal differentiation between ions with the same nominal m/z values containing different substituents (e.g. ferulic acid or glucuronic acid). Eleven of the identified flavonoids have not been reported previously in this species. Perspectives – The presented unique fragmentation pathways of flavonoid glucuronates enable detection of these compounds in tissue extracts from different plant species. Copyright © 2009 John Wiley & Sons, Ltd.     

The Structures of Two Flavonoid Glycoside from Oxytropis ochrocephala

Two flavonoid glycosides separated from water soluble fraction of Oxytropis ochrocephala Bge. were identified by using IR, NMR, and MS spectroscopic methods. The aglycones and sugars of the two compounds were determined directly from the hydrolytic solutions by using a sugar column and a bonded phase column. The results showed that compound 1 contained two kinds of sugars which have the same retention times as galactose and glucose, compound 2 only contained galactose. The aglycones of the two compounds have the same retention times and UV-spectra of rhamnocitrin. Finally, the structures of the two compounds were elucidated as rhamnocitrin-3-galactoside-4’-glucoside and rhamnocitrin-3-galactoside. The first one is a new flavonoid glycoside and the second one is, for the first time, found in the Oxytropis species.     

A comprehensive investigation of anti-inflammatory diarylheptanoids from the leaves of Alnus formosana

This study was aimed to investigate thoroughly the diarylheptanoids in the n-BuOH soluble fraction of leaves of Alnus formosana in order to examine their anti-inflammatory activities. The application of HPLC-SPE-NMR as a preliminary chemical screening led to characterization of eleven compounds. Further separation resulted in isolation of 28 compounds, of which 10 diarylheptanoids and 2-coumaroylxyloside are new natural products. Compound 1 and alnuside A (27) were found to possess good activities against LPS-induced NO production with respective IC(50) values of 7.99 and 8.08 μM, and which were devoid of significant cytotoxicity.     

An HPLC-PAD method to analyse flavonoid glycosides and styrylpyrones from Cryptocarya species (Lauraceae)

An HPLC-PAD method has been developed in order to evaluate simultaneously the main secondary metabolites, flavonoid glycosides and styrylpyrones, of leaves of Cryptocarya moschata. The sample preparation, consisting of extraction, liquid-liquid extraction and centrifugation, requires minimum sample manipulation but produces high yields with reproducibility, selectivity and simplicity. HPLC on a C18 column presents each class of metabolites grouped and with good resolution of the main compounds. The experimental conditions can be used to study inter- and intra-specific variability of secondary metabolites in Cryptocarya spp.     

红背山麻杆化学成分的研究

采用柱色谱技术从红背山麻杆叶子的60％乙醇提取物中分离得到4个黄酮苷和2个其他类化合物.根据理化性质及波谱方法分别鉴定为:芹菜素-6-C-D-葡萄糖苷(1)、芹菜素-7-O-芸香糖苷(2)、芹菜素-7-O-β-(2″-O-α-鼠李糖基)葡萄糖醛酸苷(3)、木犀草素-7-O-α-L-鼠李糖(1→6)-β-D-葡萄糖苷(4)、没食子酸乙酯(5)、β-胡萝卜苷(6).以上化合物均为首次从该植物中分离得到,其中化合物1～4为首次从山麻杆属中分离得到的黄酮苷.     

Flavonoid glycosides from Salvia moorcroftiana wall

Phytochemical analysis of the whole plant of Salvia moorcroftiana Wall. (Lamiaceae) resulted in the isolation of two new flavonoid glycosides, together with three known compounds. The structures of the new compounds were established as genkwanin 4'-O-alpha-L-arabinopyranosyl-(1-->6)-beta-D-galactopyranoside (1) and genkwanin 4'-O-[alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-galactopyranoside] (2). The structures of all compounds were elucidated by spectroscopic methods, including 2D NMR techniques.     

Studies on the Polyphenolic Composition and the Antioxidant Properties of the Leaves of Poplar (Populus spp.) Various Species and Hybrids

The chemical composition in terms of flavonoid and salicylic compounds of leaves from 6 species and 3 hybrids of poplars (Populus) was identified with the use of TLC and HPLC-DAD/ESI-MS methods. Chromatographic analyses were carried out with 21 standard compounds including salicylic compounds (2), phenolic acids (3) and flavonoids (16). Moreover, on the basis of the obtained chromatographic data from the HPLC-DAD/ESI-MS and TLC separations, the presence of salicortin, tremulacin and chlorogenic acid was confirmed, depending on the analyzed poplar species or hybrid. The content of salicylic compounds was determined by HPLC-UV method and expressed on salicin as free and total fraction. Total flavonoid content was determined by spectroscopic method as quercetin equivalent. Significant qualitative and quantitative differences in the chemical composition of the analyzed leaves were demonstrated. The highest concentration of flavonoids (8.02 mg/g) was found in the leaves of Populus nigra, while the highest content of salicylic compounds (47.14 mg/g) was found in the leaves of P.×berolinensis. The antioxidant and xanthine oxidase inhibition properties of extracts from poplar leaves were investigated by TLC bioautography. It has been shown that the richest set of compounds with antioxidant properties are present in the leaves of P. alba, P.×candicans and P. nigra.     

莲属植物类黄酮代谢产物的研究进展

莲属(Nelumbo)植物既可药用也可食用, 其中荷叶、藕节、莲子、莲子心、莲房和莲须等皆可入药, 但药效各不相同。迄今为止, 从莲的各组织中共检测出类黄酮多达61个, 包括8个花青素苷、2个黄酮醇、29个黄酮醇苷、1个黄酮、16个黄酮苷(内含13个碳苷黄酮)和5个黄烷醇。该文对莲各组织中所含类黄酮的检测方法、组成、含量及药理等方面的研究进展进行了综述。迄今的研究结果表明, 莲中含有丰富的类黄酮化合物, 且具广泛的药理活性(如抗氧化、抗菌、抗HIV、抗动脉粥样化、提高免疫力和减肥降脂等)。这些资料不仅对今后深入研究莲各部位的类黄酮代谢物及其与药效的关系有重要意义, 而且对保健食品和中药的研发也具有重要的参考价值。     

In vivo anti-inflammatory and antinociceptive activity evaluation of phenolic compounds from Sideritis stricta

An acetone extract obtained from aerial parts of S. stricta Boiss. & Heldr. apud Bentham, its fractions and phenolic compounds were investigated for their in vivo anti-inflammatory and antinociceptive activities. For the anti-inflammatory activity and for the antinociceptive activity assessment, carrageenan-induced hind paw edema and p-benzoquinone-induced abdominal constriction tests were used, respectively. The acetone extract of the plant and its phenolic fraction exhibited potent inhibitory activity against both bioassay models in mice. From the active phenolic fraction a well-known phenylethanoid glycoside, verbascoside (acteoside) (1), and two flavonoid glycosides, isoscutellarein 7-O-[6"'-O-acetyl-beta-D-allopyranosyl-(1-->2)]-beta-D-glucopyranoside (2) and isoscutellarein 7-O-[6"'-O-acetyl-beta-D-allopyranosyl-(1-->2)]-6"-O-acetyl-beta-D-glucopyranoside (3), were isolated. During phytochemical studies we also isolated a methoxyflavone, xanthomicrol (4), from the non-polar fraction. The structures of the isolated compounds were established by spectroscopic evidence (UV, IR, 1D- and 2D-NMR, MS). Although antinociceptive and anti-inflammatory activities of the phenolic components were found not significant in the statistical analysis, compounds 1 to 3 showed a notable activity without inducing any apparent acute toxicity as well as gastric damage. Furthermore, a mixture of flavonoid glycosides (2 + 3) exhibited a significant inhibitory effect in both models at a higher dose.     

Neolignan and flavonoid glycosides in Juniperus communis var. depressa

Two neolignan glycosides (junipercomnosides A and B) were isolated from aerial parts of Juniperus communis var. depressa along with two known neolignan glycosides and seven flavonoid glycosides. The structures of the isolated compounds were determined by spectral analysis, in particular by 2D-NMR analysis. The significance of distribution of flavonoids in the chemotaxonomy of genus Juniperus was also discussed.     

Analysis and identification of lignans in Phyllanthus urinaria by HPLC-SPE-NMR

HPLC-SPE-NMR has been applied to the analysis of a number of structurally similar lignans present in Phyllanthus urinaria. A reversed-phase HPLC system, using a C8 column eluted with tetrahydrofuran-water-methanol and detected at 225 nm was developed that gave good resolution for seven lignans from Phyllanthus urinaria. Coupling of this system with SPE-NMR provided clean 1H-NMR spectra for nine lignans present in 4 mg of a lignan-rich fraction, equivalent to ca. 1.0 g of dry plant material. The result demonstrates that HPLC-SPE-NMR is a very efficient and powerful tool for the unambiguous identification of natural products that have been previously characterised.