Flavonol glycosides in the leaves ofTrillium apetalon Makino andT. kamtschaticum pallas

Seven flavonol glycosides were isolated from the leaves ofT. apetalon. They were identified chromatographically and spectrally to be: quercetin/kaempferol 3-O-α-arabinopyranosyl-(1→6)-β-galactopyranoside (TQ and TK), quercetin/kaempferol 3-O-[2‴-O-acetyl-α-arabinopyranosyl]-(1→6)-β-galactopyranoside (TAQ and TAK), quercetin 3-O-β-glucoside (ISQ), isorhamnetin 3-O-α-arabinopyranosyl-(1→6)-β-galactopyranoside (TI) and isorhamnetin 3-O-[2‴-O-acetyl-α-arabinopyranosyl]-(1→6)-β-galactopyranoside (TAI). TQ, TAQ, TI and TAI were major constituents. This is the first report on two new isorhamnetin-type glycosides, TI and TAI. The seven flavonol glycosides identical to those ofT. apetalon were isolated and identified in the leaves ofT. kamtschaticum; TQ and TAQ were also major components, but TI and TAI were only minor components. TI and TAI were not detected in the leaves ofT. tschonoskii. These leaf-flavonoid patterns were discussed from a chemosystematic point of view. Part 3 in the series “Studies of the flavonoids of the genusTrillium”. For Part 2 see Yoshitamaet al., (1997) J. Plant Res.110: 379–381.     

Flavonoid chemistry ofBlennospermatinae, a trans-Pacific disjunct subtribe ofSenecioneae (Asteraceae)

The flavonoid profiles of seven species ofAbrotanella and one species ofIschnea have been shown to be based upon kaempferol 3- and quercetin 3-O-glycosides and a delphinidin glycoside. Glucosides, glucuronides, arabinosides, diglucosides, and rutinosides of the flavonols were identified. The profile ofIschnea consisted solely of quercetin 3-O-glucoside and 3-O-arabinoside whereas the profiles of theAbrotanella species were more varied. Although infraspecific variation was not investigated in this study, the flavonoid chemistry of the two genera is in accordance with the flavonoid variation described for other members ofSenecioneae which are primarily flavonol producers. Based on the known phylogeny and biogeography, the flavonoid distribution from the perspective of long-distance dispersals across the Pacific is discussed. Such events should lead to genetic bottle-neck situations and depauperate flavonoid profiles. A summary of current flavonoid knowledge in theSenecioneae is supplied.     

Flavonoids in the leaves ofTrillium undulatum willdenow

Three flavonol glycosides were identified in the leaves ofTrillium undulatum. The main glycoside was kaempferol 3-O-α-rhamnosyl-(1→2)-O-[α-rhamnosyl-(1→6)]-β-glucoside; the glycosidic sugars and their linkage pattern were quite different from those of the leaf flavonoids ofT. tschonoskii, T. apetalon, T. Kamtschaticum, T. erectum andT. grandiflorum. Two minor compounds were kaempferol/quercetin 3-O-rutinoside. Part 2 in the series “Studies of the flavonoids of genusTrillium”. For Part 1, see Yoshitamaet al., (1992) Bot. Mag. Tokyo105: 555.     

Flavonoids from Zea mays pollen

The flavonol glycosides of quercetin, isorhamnetin and kaempferol were isolated from Zea mays pollen. The most prominent flavonols were diglycosides of quercetin and isorhamnetin. Flavonol 3-O-glucosides of quercetin, isorhamnetin and kaempferol, and triglucosides of quercetin and isorhamnetin, were minor components. The flavonoid pattern of maize pollen is characterized by the accumulation of quercetin and isorhamnetin diglycosides and by the absence of flavones, which are common in other maize tissues.     

Flavonoids in translucent bracts of the Himalayan<Emphasis Type="Italic"> Rheum nobile</Emphasis> (Polygonaceae) as ultraviolet shields

UV-absorbing substances were isolated from the translucent bracts of Rheum nobile, which grows in the alpine zone of the eastern Himalayas. Nine kinds of the UV-absorbing substances were found by high performance liquid chromatography (HPLC) and paper chromatography (PC) surveys. All of the five major compounds are flavonoids, and were identified as quercetin 3-O-glucoside, quercetin 3-O-galactoside, quercetin 3-O-rutinoside, quercetin 3-O-arabinoside and quercetin 3-O-[6-(3-hydroxy-3-methylglutaroyl)-glucoside] by UV, ¹H and ¹³C NMR, mass spectra, and acid hydrolysis of the original glycosides, and direct PC and HPLC comparisons with authentic specimens. The four minor compounds were characterised as quercetin itself, quercetin 7-O-glycoside, kaempferol glycoside and feruloyl ester. Of those compounds, quercetin 3-O-[6-(3-hydroxy-3-methylglutaroyl)-glucoside] was found in nature for the first time. The translucent bracts of R. nobile accumulate a substantial quantity of flavonoids (3.3–5 mg per g dry material for the major compounds). Moreover, it was clarified by quantitative HPLC survey that much more of the UV-absorbing substances is present in the bracts than in rosulate leaves. Although the flavonoid compounds have been presumed to be the important UV shields in higher plants, there has been little characterisation of these compounds. In this paper, the UV-absorbing substances of the Himalayan R. nobile were characterised as flavonol glycosides based on quercetin.     

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.     

Flavonoid glycosides from the leaves of Aphananthe aspera (Thunb.) Planch. (Cannabaceae) and their chemotaxonomic significance

From the leaves of Aphananthe aspera (Thunb.) Planch. (Family: Cannabaceae), six flavonol glycosides, such as quercetin 3-O-β-glucopyranoside (1), kaempferol 3-O-β-glucopyranoside (2), quercetin 3-O-rutinoside (3), kaempferol 3-O-rutinoside (4), quercetin 3-O-neohesperidoside (5) and kaempferol 3-O-neohesperidoside (6) were isolated and identified. Structure elucidation of these compounds was performed on the basis of NMR spectral data. All these compounds were isolated for the first time from the genus Aphananthe. Chemotaxonomic significance and distribution of these flavonoid derivatives among the genera of Cannabaceae are explained in detail.     

Flavonoids of Heterogaura (Onagraceae)

Heterogaura is a monotypic genus of the tribe Onagreae of the Onagraceae. It is endemic to south western Oregon and California. Four flavonol glycosides, kaempferol 3-O-rhamnoside, quercetin 3-O-glucoside, quercetin 3-O-rhamnoglucoside and myricetin 3-O-glucoside, were found to occur in methanolic leaf extracts of each of the populations sampled. The presence of only flavonols is consistent with flavonoid analyses from other genera of the Onagreae, including Clarkia, the closest relative of Heterogaura.     

Flavonoid analysis of<Emphasis Type="Italic">Heloniopsis orientalis</Emphasis> (Thunb.) by high performance liquid chromatography

We have isolated and identified seven flavonoid compounds from the foliar extracts ofHeloniopsis orientalis, a member of Liliaceae, which is habituated at Namhansanseong and Maranggol (Jinburyung). All are glycosylated derivatives of the flavonols isorhamnetin, kaempferol, and quercetin. Among them, quercetin 3-O-galactoside is the major compound, while isorhamnetin 3-O-arabinosylgalactoside, isorhamnetin 3-O-digalactoside, kaempferol 3,7-O-galactoside, kaempferol 3-O-arabinosylgalactoside, kaempferol 3-O-glycoside, and quercetin 3-O-arabinosylgalactoside are present in smaller amounts. Although the two populations do not differ significantly in their overall flavonol profiles, their relative amounts indicate that flavonoid levels, especially for isorhamnetin, are geographically controlled and specifically depend on the origin of the individual population.     

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.     

Differences in flavonoid constituents among the species ofFagonia sinaica complex (Zygophyllaceae)

Eight flavonol glycosides were detected in the three species of theFagonia sinaica complex. They were fully characterized as the 3-glucosides of kaempferol, quercetin and isorhamnetin, 3-rutinoside of quercetin and 3,7-diglucoside of quercetin and isorhamnetin. Two additional glycosides were partially characterized as a kaempferol 3,7-diglycoside and quercetin 3-diglycoside.     

Flavonoids of Mayaca fluviatilis (Mayacaceae)

Mayaca is an aquatic monocot of the monogeneric family Mayacaceae. The flavonol glycosides quercetin 3-O-glucoside, quercetin 3-O-rutinoside, and kaempferol 3-O-glucoside, and the flavone luteolin 5-O-glucoside were found in methanolic leaf extracts. The presence of flavonol and flavone O-glycosides sets the Mayacaceae apart from the Commelinaceae, which accumulates predominantly flavone C-glycosides.     

Further studies of flavonols of Clibadium (compositae)

The flavonoids of an additional eight species of Clibadium have been determined. The compounds are derivatives of kaempferol, quercetin and quercetagetin. O-Methylated quercetagetin derivatives were found in several taxa with the possibility that 6-methoxykaempferol may also exist in one collection. Kaempferol and quercetin exist as 3-O-glucosides, galactosides, rhamnosides, rutinosides and diglucosides although not all glycosides occur in each taxon. Quercetagetin derivatives occur as 7-O-glucosides. Observations on these newly investigated species confirm previous work in the genus that three types of flavonoid profiles exist: (1) kaempferol and quercetin 3-glycosides; (2) kaempferol and quercetin 3-glycosides plus quercetagetin 7-glucoside; and (3) kaempferol and quercetin 3-glycosides plus quercetagetin 7-glucoside and O-methylated derivatives of quercetagetin.     

Acylated flavonol diglucosides from Lotus polyphyllos

Three acylated flavonol diglucosides, kaempferol 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside; quercetin 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside; isorhamnetin 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside were isolated from the whole plant aqueous alcohol extract of Lotus polyphyllos. The known 3,7-di-O-glucosides of the aglycones kaempferol, quercetin and isorhamnetin were also characterized. All structures were established on the basis of chemical and spectral evidence.     

Flavonol tetraglycosides from the leaves of Prunus cerasus and P. Avium

Four new flavonol glycosides have been identified from fresh leaves and fruits of sweet and sour cherries (Prunus avium and P. cerasus) as minor flavonoids: quercetin 3-O-rutinosyl-7,3′-O-bisglucoside; two quercetin 3-O-rutinosyl-4′-di-O-glucosides; kaempferol 3-O-rutinosyl-4′-di-O-glucoside.     

Acylated flavonol glycosides from Delphinium staphisagria

An ethanolic extract of the aerial parts of Delphinium staphisagria L. from Tenerife yielded four new flavonol glycosides 2″-acetylastragalin, 2″-acetylpaeonoside, quercetin 3-O-(2-acetyl-β-glucopyranoside)-7-O-β-glucopyranoside and 2″-acetylpetiolaroside in addition to astragalin, isoquercitrin, paeonoside, kaempferol 3-O-β-glucopyranoside-7-O-α-rhamnopyranoside, petiolaroside and rutin.     

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.     

Flavonoids of Abies amabilis needles

Seventeen flavonol glycosides were identified from needles of Abies amabilis and these were based on 6 aglycone types: syringetin, isorhamnetin, kaempferol, quercetin, laricytrin and myricetin. Glycosides were 3-O-rutinosides, 3-O-glucosides, 3-O-galactosides or 3-O-rhamnosides. Also identified as needle constituents were rhamnosylvitexin and dihydroquercetin.     

Leaf flavonoid glycosides as chemosystematic characters in Ocimum

Thirty-one accessions of nine species belonging to three subgenera of Ocimum (basil, family Lamiaceae) were surveyed for flavonoid glycosides. Substantial infraspecific differences in flavonoid profiles of the leaves were found only in O. americanum, where var. pilosum accumulated the flavone C-glycoside, vicenin-2, which only occurred in trace amounts in var. americanum and was not detected in cv. Sacred. The major flavonoids in var. americanum and cv. Sacred, and also in all other species investigated for subgenus Ocimum, were flavonol 3-O-glucosides and 3-O-rutinosides. Many species in subgenus Ocimum also produced the more unusual compound, quercetin 3-O-(6″-O-malonyl)glucoside, and small amounts of flavone O-glycosides. The level of flavonol glycosides produced was reduced significantly in glasshouse-grown plants, but levels of flavone glycosides were unaffected. A single species investigated from subgenus Nautochilus, O. lamiifolium, had a different flavonoid glycoside profile, although the major compound was also a flavonol O-glycoside. This was identified as quercetin 3-O-xylosyl(1‴→2″)galactoside, using NMR spectroscopy. The species investigated from subgenus Gymnocimum, O. tenuiflorum (=O. sanctum), was characterised by the accumulation of flavone O-glycosides. These were isolated, and identified as the 7-O-glucuronides of luteolin and apigenin. Luteolin 5-O-glucoside was found in all nine species of Ocimum studied, and is considered to be a key character for the genus.     

Sulphated flavonoid glycosides from leaves of Atriplex hortensis

Two flavonoid sulphates, i.e. quercetin 3-O-sulphate-7-O-α-arabinopyranoside and kaempferol 3-O-sulphate-7-O-α-arabinopyranoside, were isolated from leaves of Atriplex hortensis L. The structures of these compounds were established by UV, ¹H and ¹³C NMR, 2D NMR and MS spectra. The compounds were isolated for the first time from plant material.