A chemotaxonomic survey of flavonoids in leaves of the Oleaceae

Leaves of 97 taxa representing all the genera at present recognized in the family Oleaceae were surveyed for flavonoids. Four flavonol glycosides were found to be common, the 3-glucmides and 3-rutinosides of quercetin and kaempferol, as were four flavone glycosides, namely the 7-glurosides arid 7-rutinosides of luteolin and apigenin. Among rarer constituents detected were luteolin 4'-glucoside, eriodictyol 7-glucoside, chrysoeriol 7-glucoside, an apigenin-di-C-glycoside and several higher glycosides of quercetin. The species and genera surveyed fell into two groups: those with flavonol glycosides alone; and those with both flavonol and flavone glycosides. The most striking correlation was with chromosome number (and subfamily division) since almost all taxa with a basic number of 11, 13 and 14 had only flavonol glycosides, whereas most taxa with x = 23 had both types of flavonoid. Evolutionary advancement in the family appears to involve the gradual replacement of flavonol by flavone glycosides. Indeed, a few tam, notably Nestegis apelala, Picconia excelsa and Tesserandra fluminense , lacked flavonol glycosides in the leaves completely. At the lower levels of classification, the distribution of flavonoids is of less interest. However, the patterns in Linociera and Chionanthus , two taxa recently made congeneric, are sufficiently different to suggest that this decision might have to be reconsidered when more is known of their chemistry. Otherwise leaf patterns generally fit in with the existing generic classification in the family.     

Structurally different flavonol glycosides and hydroxycinnamic acid derivatives respond differently to moderate UV-B radiation exposure

The aim of this study was to investigate the modifying influence of moderate ultraviolet-B (UV-B) radiation exposure on structurally different flavonol glycosides and hydroxycinnamic acid derivatives during pre-harvest using kale, a leafy Brassica species with a wide spectrum of different non-acylated and acylated flavonol glycosides. Juvenile kale plants were treated with short-term (1 day), moderate UV-B radiation [0.22-0.88 kJ m?2 day?1 biologically effective UV-B (UV-B(BE))]. Twenty compounds were quantified, revealing a structure-specific response of flavonol glycosides and hydroxycinnamic acid derivatives to UV-B radiation. A dose- and structure-dependent response of the investigated phenolic compounds to additional UV-B radiation was found. The investigated quercetin glycosides decreased under UV-B; for kaempferol glycosides, however, the amount of sugar moieties and the flavonol glycoside hydoxycinnamic acid residue influenced the response to UV-B. Monoacylated kaempferol tetraglucosides decreased in the investigated UV-B range, whereas the monoacylated kaempferol diglucosides increased strongly with doses of 0.88 kJ m?2 day?1 UV-B(BE) . The UV-B-induced increase in monoacylated kaempferol triglucosides was dependent on the acylation pattern. Furthermore, the hydroxycinnamic acid glycosides disinapoyl-gentiobiose and sinapoyl-feruloyl-gentiobiose were enhanced in a dose-dependent manner under UV-B. While UV-B radiation treatments often focus on flavonol aglycones or total flavonols, our investigations were extended to structurally different non-acylated and acylated glycosides of quercetin and kaempferol.     

Flavonol glycoside production in callus cultures of Epimedium diphyllum.

Callus cultures of Epimedium diphyllum produced a large amount of epimedoside A in addition to a small amount of diphylloside B, ikarisoside C, epimedoside E, diglycosides of des-O-methylanhydroicaritin (8-gamma, gamma-dimethylallylkaempfero). Icariin, epimedins A-C, which are glycosides of anhydroicaritin, were also produced in the callus cultures. Contents of the flavonol glycosides in callus tissue were higher than those of mother plants, but the composition of each flavonol glycoside mixture in the callus cultures was different from that of the original plants. The time-course experiments showed that an inverse relationship existed between cell growth and flavonol glycoside production. Effects of hormonal factors on cell growth and flavonol glycoside production indicated that 2,4-dichlorophenoxyacetic acid was needed for the production of flavonol glycosides.     

Analysis of supercooling-facilitating (anti-ice nucleation) activity of flavonol glycosides

Deep supercooling xylem parenchyma cells (XPCs) of katsura tree (Cercidiphyllum japonicum) contain four kinds of flavonol glycosides with high supercooling-facilitating (anti-ice nucleation) activities. These flavonol glycosides have very similar structures, but their supercooling-facilitating activities are very different. In this study, we analyzed the supercooling-facilitating activities of 12 kinds of flavonol glycosides in order to determine the chemical structures that might affect supercooling-facilitating activity. All of the flavonol glycosides tested showed supercooling-facilitating activity, although the magnitudes of activity differed among the compounds. It was clear that the combination of the position of attachment of the glycosyl moiety, the kind of attached glycosyl moiety and the structure of aglycone determined the magnitude of anti-ice nucleation activity. However, there is still some ambiguity preventing the exact identification of features that affect the magnitude of supercooling-facilitating activity.     

Investigation of biologically active components in ginkgo leaf products on the Japanese market

The rapid and highly separative ultra high-performance liquid chromatography (UHPLC)-UV method was adopted and validated to investigate the flavonol glycoside compositions in ginkgo leaf products on the Japanese market. The result indicates that certain products contained amounts of flavonol glycosides approximately equivalent to the medicinal product. Additionally, we examined the correlations between the total amount of flavonol glycosides and of terpene lactones in various ginkgo leaf products.     

Change of supercooling capability in solutions containing different kinds of ice nucleators by flavonol glycosides from deep supercooling xylem parenchyma cells in trees

Deep supercooling xylem parenchyma cells (XPCs) in Katsura tree contain flavonol glycosides with high supercooling-facilitating capability in solutions containing the ice nucleation bacterium (INB) Erwinia ananas, which is thought to have an important role in deep supercooling of XPCs. The present study, in order to further clarify the roles of these flavonol glycosides in deep supercooling of XPCs, the effects of these supercooling-facilitating (anti-ice nucleating) flavonol glycosides, kaempferol 3-O-β-d-glucopyranoside (K3Glc), kaempferol 7-O-β-d-glucopyranoside (K7Glc) and quercetin 3-O-β-d-glucopyranoside (Q3Glc), in buffered Milli-Q water (BMQW) containing different kinds of ice nucleators, including INB Xanthomonas campestris, silver iodide and phloroglucinol, were examined by a droplet freezing assay. The results showed that all of the flavonol glycosides promoted supercooling in all solutions containing different kinds of ice nucleators, although the magnitudes of supercooling capability of each flavonol glycoside changed in solutions containing different kinds of ice nucleators. On the other hand, these flavonol glycosides exhibited complicated nucleating reactions in BMQW, which did not contain identified ice nucleators but contained only unidentified airborne impurities. Q3Glc exhibited both supercooling-facilitating and ice nucleating capabilities depending on the concentrations in such water. Both K3Glc and K7Glc exhibited only ice nucleation capability in such water. It was also shown by an emulsion freezing assay in BMQW that K3Glc and Q3Glc had no effect on homogeneous ice nucleation temperature, whereas K7Glc increased ice nucleation temperature. The results indicated that each flavonol glycoside affected ice nucleation by very complicated and varied reactions. More studies are necessary to determine the exact roles of these flavonol glycosides in deep supercooling of XPCs in which unidentified heterogeneous ice nucleators may exist.     

Flavonols in the Pollen of Tea Flowers

A new flavonol and its glycosides were isolated from the pollen of tea flowers. Their UV, IR, MS, and NMR spectra, alkaline degradation and color reactions have supported that the chemical structure of the flavonol is 3,5,8,4’-tetrahydroxy-7-methoxyflavone and that two glycosides were its 3-rhamnoglucoside and 3-monoglucoside, respectively. But another glycoside remained unidentified as to the sugar moiety. This flavonol, its rhamno-glucoside, monoglucoside and undetermined glycoside were named pollenitin, pollenin a, b, and c, respectively.     

Comprehensive analysis of flavonols in Ginkgo biloba products by ultra-high-performance liquid chromatography coupled with ultra-violet detection and time-of-flight mass spectrometry

The aim of this study was to survey the flavonol compositions of Ginkgo biloba products, especially those on the Japanese market. Sixteen food products, six medicinal products, and raw Ginkgo biloba leaves were examined by ultra-high-performance liquid chromatography coupled with ultra-violet detection and time-of-flight mass spectrometry. Eleven flavonol glycosides, three biflavones, and a flavonol aglycone were qualified by analysis of accurate mass spectra. The quantitative data obtained were then applied to multivariate data analysis, and the flavonol compositions of the food and medicinal products were classified into four groups. Most of the food products were classified into the same group as the medicinal products, which contained high percentages of flavonol glycosides. On the other hand, some food products contained high percentages of biflavones or an aglycone.     

Flavonol glycosides from Epimedium sagittatum

Two new flavonol glycosides were isolated from Epimedium sagittatum besides the known flavonol glycosides, icariin and icarisid I. On the basis of spectral analyses, the structures of the compounds were determined to be anhydroicaritin-3-O-α-rhamnoside and icaritin-3-O-α-rhamnoside.     

Isolation and antioxidant activity of galloyl flavonol glycosides from the seashore plant, Pemphis acidula

Four kinds of galloyl flavonol glycosides were found in the leaf extract of Pemphis acidula, a plant growing on the subtropical seashore. Their chemical structures were elucidated to be quercetin or kaempferol 6"-O-galloyl-beta-D-glycosides by using spectroscopic and chemical analyses. One of the flavonols, kaempferol-3-O-(6-O-galloyl-beta-D-galactopyranoside), was newly isolated from natural sources and its structure was completely determined in this investigation. The antioxidant-related activities of the galloyl flavonoids were examined by the DPPH antiradical activity, inhibition of methyl linoleate oxidation, and inhibition of oxidative cell death. These results were compared with those of the corresponding non-galloylated flavonol glycosides and their aglycones. The galloyl flavonoids showed more efficient activity than that of the corresponding flavonol glycosides, but not more than that of the corresponding aglycones in the three assays applied.     

Flavonoid glycosides and saponins from Astragalus shikokianus

A new flavonol glycoside, kaempferol 3-O-alpha-L-rhamnopyranosyl -(1-->6)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-galactopyranosyl-7-O-a lpha-L-rhamnopyranoside, named astrasikokioside I, was isolated from aerial part of Astragalus shikokianus, together with two flavonol glycosides, kaempferol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-galactopyranosyl-7-O-alpha-L- rhamnopyranoside, robinin, and three triterpenoid glycosides, soyasaponin I, sophoraflavoside II and robinioside E.     

4种蔷薇属植物叶片黄酮含量的季节性变化

采用ＨＰＬＣ法对刺梨（Ｒｏｓａ ｒｏｘｂｕｒｇｈｉｉ Ｔｒａｔｔ．）等４种蔷薇属植物在不同生长季节叶片的总黄酮甙含量和甙元配比进行了分析测定。结果表明,不同采摘期的华西蔷薇（Ｒ．ｍｏｙｅｓｉｉ Ｈｅｍｓｌ．ｅｔ Ｗｉｌｓ．）绣球蔷薇（Ｒ．ｇｉｏｍｅｒａｔａ Ｒｅｈｄ．ｅ Ｗｉｌｓ．）和峨嵋蔷薇（Ｒ．ｏｍｅｉｅｎｓｉｓ Ｒｏｌｆｅ）的叶片总黄酮甙含量有较大的差异,一般在展叶期黄酮含量较低,随后叶片黄     

Camellianoside, a novel antioxidant glycoside from the leaves of Camellia japonica

A novel flavonol glycoside named camellianoside and three known flavonol glycosides were isolated from the leaves of Camellia japonica. The structure of camellianoside was established as quercetin-3-O-beta-D-xylopyranosyl-(1-->3)-O-alpha-L-rhamnopyranosyl-(1-->6)-O-beta-D-glucopyranoside by spectroscopic and chemical methods. The antioxidant activities of these glycosides evaluated by the diphenylpicrylhydrazyl (DPPH) radical scavenging reaction was higher than those of L-cysteine and L-ascorbic acid used as the reference antioxidants.     

6-Methoxyflavonols from disjunct populations of Brickellia cylindracea (compositae)

Eight identical 6-methylated flavonols including aglycones and glycosides were isolated from two geographically disjunction population of Brickellia cylindracea from Mount Livermore and Austin, Texas, suggesting that they are best treated as a single taxon. Among the flavonol aglycones identified were patuletin, centaureidin, quercetagetin 3,6,3′,4′-tetramethyl ether and artemetin. The flavonol glycosides were patuletin and its 3-galactoside, 3-galactogalactoside, 3-rhamnogalactoside and a 3-rhamnogalactoside derivative.     

Flavonol glycosides from flowers of Crocus speciosus and C. antalyensis.

From the flower extracts of Crocus speciosus and C. antalyensis nine flavonol glycosides have been isolated. One of these products is a new flavonol glycoside identified as kaempferol 3-O-alpha-(2,3-di-O-beta-D-glucopyranosyl)rhamnopyranoside by UV, mass and NMR spectroscopy.     

Effects of total flavonoids and flavonol glycosides from Epimedium koreanum Nakai on the proliferation and differentiation of primary osteoblasts.

In a bioassay-guided drug screening for anti-osteoporosis activity, eight flavonol glycosides were isolated from Epimedium koreanum Nakai, which is traditionally widely used in China for the treatment of impotence and osteoporosis. The effects of total flavonoids and flavonol glycosides on the proliferation and differentiation of rat calvarial osteoblast-like cells were evaluated by the MTT method and measuring the activity of alkaline phosphatase (ALP activity). Total flavonoids (1.2 x10(-2) to 6.0 x10(-7) mg/ml) and flavonol glycosides (2.0 x10(-5) to 1.0 x10(-9) mol/l) exhibited a strong inhibition on the proliferation of primary osteoblasts at most concentrations. However, the total flavonoids and icariin significantly promoted the differentiation of primary osteoblasts. The results suggested that flavonoids from E. koreanum Nakai may improve the development of osteoblasts by promoting the ALP activity; and icariin might be one of the active constituents facilitating the differentiation of osteoblasts.     

Temporal lag between gene expression and metabolite accumulation in flavonol biosynthesis of Arabidopsis roots

The temporal lag between gene expression and metabolite accumulation has been estimated in flavonol biosynthesis, but the time difference between these events is unclear. In the present study, we investigated the expression of flavonol biosynthetic genes ELONGATED HYPOCOTYL5, MYELOBLASTOSIS PROYEIN12/PRODUCTION OF FLAVONOL GLYCOSYDES1, CHALCONE SYNTHASE, CHALCONE ISOMERASE, FLAVANONE 3-HYDROXYLASE, and FLAVONOL SYNTHASE1, and the accumulation of flavonol glycosides (kaempferol and quercetin glycosides) in time-series samples of Arabidopsis thaliana roots. All genes started to be expressed within 3 h after sequential light irradiation (HAS) and reached their maximum expression levels at 12 HAS, and the accumulation of the flavonol glycosides started at 6 HAS. Metabolome analysis using liquid chromatography-mass spectrometry showed that the accumulation of kaempferol 3-O-glucoside-7-O-rhamnoside and kaempferol 3-O-rhamnosyl (1 → 2) glucoside-7-O-rhamnoside reached their maximum levels at 48 HAS, whereas other flavonol glycosides, such as kaempferol/quercetin 3-O-rhamnoside-7-O-rhamnoside, quercetin 3-O-glucoside-7-O-rhamnoside and quercetin 3-O-rhamnosyl (1 → 2) glucoside-7-O-rhamnoside, increased gradually until 96 HAS. These results show that the expression of the flavonol genes is an early response against light exposure, and that the accumulation of the flavonol glycosides is a late response.     

Chalcone and flavonol glycosides from Asarum canadense (Aristolochiaceae)

Two chalcone glycosides were isolated, together with seven known flavonol glycosides, from the leaves of Asarum canadense. The structures of the chalcone glycosides were established as chalcononaringenin 2',4'-di-O-glucoside and chalcononaringenin 2'-O-glucoside-4'-O-gentiobioside by chemical, UV, FAB MS, 1H and 13C NMR evidence.     

Adulteration of Ginkgo biloba products and a simple method to improve its detection

Extracts of ginkgo (Ginkgo biloba) leaf are widely available worldwide in herbal medicinal products, dietary supplements, botanicals and complementary medicines, and several pharmacopoeias contain monographs for ginkgo leaf, leaf extract and finished products. Being a high-value botanical commodity, ginkgo extracts may be the subject of economically motivated adulteration. We analysed eight ginkgo leaf retail products purchased in Australia and Denmark and found compelling evidence of adulteration with flavonol aglycones in three of these. The same three products also contained genistein, an isoflavone that does not occur in ginkgo leaf.Although the United States Pharmacopeia – National Formulary (USP-NF) and the British and European Pharmacopoeias stipulate a required range for flavonol glycosides in ginkgo extract, the prescribed assays quantify flavonol aglycones. This means that these pharmacopoeial methods are not capable of detecting adulteration of ginkgo extract with free flavonol aglycones.We propose a simple modification of the USP-NF method that addresses this problem: by assaying for flavonol aglycones pre and post hydrolysis the content of flavonol glycosides can be accurately estimated via a simple calculation. We also recommend a maximum limit be set for free flavonol aglycones in ginkgo extract.     

La variation flavonique chez les sous-especes de l'Anthyllis vulneraria

Nine infraspecific taxa of Anthyllis vulneraria have been investigated for leaf flavonoids. The distribution of 35 flavonol glycosides within 26 populations, indicated the presence of four chemical taxa, each based on different glycosides of 7-methylkaempferol.