6-Hydroxy- and 6-methoxyflavonoids from Neurolaena lobata and N. macrocephala

Twelve flavonoids including one new sulfate were isolated from Neurolaena lobata, and six known flavonoids were obtained from N. macrocephala. The new compound isolated from N. lobata is 6-hydroxykaempferol 3-methyl ether 7-sulfate, and the known flavonoids are 6-hydroxykaempferol 3,7-di-dimethyl ether, 6-hydroxykaempferol, 3-methyl ether 7-glucoside, 6-hydroxykaempferol 7-glucoside, quercetagetin and its 7-glucoside, quercetagetin 3,6- and 3,7-dimethyl ethers, quercetagetin 3-methyl ether 7-glucoside and 7-sulfate, 6-hydroxyluteolin 3′-methyl ether and 6-hydroxyluteolin 7-glucoside. The known flavonoids identified from N. macrocephala are quercetagetin 3,6- and 3, 7-dimethyl ethers, quercetagetin 6-methyl ether 7-glucoside, quercetagetin 3,6-dimethyl ether 7-glucoside, quercetagetin 7-glucoside and quercetagetin 3-methyl ether 7-sulfate.     

New 6-hydroxyflavonoids and their methyl ethers and glycosides from Neurolaena oaxacana

Six new and nine known flavonoids were obtained from Neurolaena oaxacana. The known flavonoids are 6-hydroxykaempferol 3,7-dimethyl ether, quercetagetin 3,7-dimethyl ether, quercetin 3-methyl ether, axillarin, nodifloretin, 6-hydroxyluteolin 7-glucoside, kaempferol 3-glucoside, quercetagetin 7-glucoside and patulitrin. The new compounds are 6-hydroxykaempferol 3-methyl ether, quercetagetin 3,7-dimethyl ether 6-galactoside, quercetagetin 3-methyl ether 7-glucoside, the 6- and 7-glucosides of 6-hydroxykaempferol 3-methyl ether and quercetagetin 3-methyl ether 7-sulfate.     

Flavonoids of four species of Parthenium (compositae)

Kaempferol and quercetin 3-O-glycosides were found in the closely related species, Parthenium hysterophorus, P. bipinnatifidum and P. glomeratum; the major aglycone flavonols in P. hypterophorus are quercetagetin 3,7-dimethyl ether and a new flavonoid, 6-hydroxykaempferol 3,7-dimethyl ether. The North-South American species-pair P. glomeratum (Argentina) and P. bipinnatifidum (Mexico) yielded quercetagetin 3,7,3′-trimethyl ether as the major aglycone. The desert species P. rollinsianum yielded five methylated flavonols: quercetin 3,3′-dimethyl ether, penduletin, quercetagetin 3,6,7-trimethyl ether, polycladin and artemetin.     

Geographical variation in the surface flavonoids of Pulicaria dysenterica

Four chemical races were detected in Pulicaria dysenterica, when sampled within Europe, on the basis of the surface flavonoids present. One race uniquely contained quercetagetin 3,7-dimethyl ether and another 6-hydroxykaempferol 3,4'-dimethyl ether. A third race was based on plants having 6-hydroxykaempferol 3,7-dimethyl ether together with quercetagetin 3,7,3'-trimethyl ether. The fourth race contained the above two compounds, as well as quercetagetin 3,7,3',4'-tetramethyl ether and 6-hydroxykaempferol 3,7,4'-trimethyl ether. These lipophilic constituents were variously present on the surfaces of leaf, ray floret, disc floret and fruit. By contrast, the vacuolar flavonoid of all tissues and all races was uniformly quercetin 3-glucuronide. The kaempferol 3-glucoside previously reported in flowers was not detected. Of the lipophilic flavonoids newly reported from this plant, one 6-hydroxykaempferol 3,7,4'-trimethyl ether is new to nature.     

6-methoxyflavonoids from Brickellia laciniata (compositae)

One new and fourteen known flavonoids, including thirteen containing 6-methoxy groups, were isolated from Brickellia laciniata. The new flavonol is quercetagetin 6,4′-dimethyl ether. Among the known compounds identified were the 4′-methyl and 7,4′-dimethyl ethers of eupafolin and luteolin 4′-methyl ether, and the flavonols: patuletin, spinacetin, eupatolitin, eupatin, centaureidin, casticin, patuletin 3-glucoside and 3-galactoside, eupatolitin 3-galactoside, patuletin 3-SO₃K and eupatin 3-SO₃Ca_1/2.     

Evolution of yellow flavonols in flowers of anthemideae

Yellow flavonols have been identified in flowers of Coleostephus myconis, Glossopappus macrotus, Lepidophorum repandum and Leucanthemopsis flaveola. In addition to quercetagetin, gossypetin, patuletin and quercetagetin 3′-methyl ether previously reported in other species of the tribe Anthemideae of the Compositae, spinacetin, the 6,3′-dimethyl ether of quercetagetin, has been found for the first time as a flower pigment. It occurs as the 7-glucoside in flowers of Lepidophorum repandum, the leaves of which contain patuletin 3-rhamnoside. The presence of spinacetin and the 3′-methyl ether of quercetagetin in Lepidophorum fits in with the results of recent taxonomic studies which place this genus closer to Chrysanthemum than to Anthemis. Similarly, the occurrence of quercetagetin and gossypetin in Leucanthemopsis confirms its recently proposed separation from Tanacetum. The chemical data indicate that there is an evolutionary trend in yellow flower pigmentation, with Leucanthemopsis and Chrysanthemum segetum as the two least specialized species and Lepidophorum as the most advanced.     

The flavonoids of Tanacetum parthenium and T. vulgare and their anti-inflammatory properties.

The lipophilic flavonoids in leaf and flower of Tanacetum parthenium and T. vulgaris have been compared. While those of T. parthenium are methyl ethers of the flavonols 6-hydroxykaempferol and quercetagetin, the surface flavonoids of T. vulgare are methyl ethers of the flavones scutellarein and 6-hydroxyluteolin. Apigenin and two flavone glucuronides are surprisingly present in glandular trichomes on the lower epidermis of the ray florets of T. parthenium. The opportunity has been taken to revise the structures of the four 6-hydroxyflavonol methyl ethers of T. parthenium based on NMR measurements. These are now shown to be uniformly 6- rather than 7-O-methylated. Tanetin, previously thought to be a new structure, is now formulated as the known 6-hydroxykaempferol 3,6,4'-trimethyl ether. The vacuolar flavonoids of both plants are dominated by the presence of apigenin and luteolin 7-glucuronides; nine other glycosides were present, including the uncommon 6-hydroxyluteolin 7-glucoside in T. vulgare. When the major flavonol and flavone methyl ethers of the two plants were tested pharmacologically, they variously inhibited the major pathways of arachidonate metabolism in leukocytes. There were significant differences in potency, with the tansy 6-hydroxyflavones less active than the feverfew 6-hydroxyflavonols as inhibitors of cyclo-oxygenase and 5-lipoxygenase.     

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.     

The flavonoids of Cassia renigera stem bark

A new flavanone glycoside 5-hydroxy-6,7,3′,4′,5′-pentamethoxyflavanone 5-O-α-l-rhamnopyranoside along with quercetagetin 3,6-dimethyl ether and an anthraquinone glycoside have been isolated from the stem bark of Cassia renigera. The two flavonoids were characterized by spectral and chemical studies.     

Anthocyanins and flavonols from the flowers of Amherstia nobilis endemic to Myanmar

Three anthocyanins (1–3) and eight flavonols (4–11) were isolated from the flowers of Amherstia nobilis endemic to Myanmar. Anthocyanins were identified as cyanidin 3-O-glucoside (1), 3-O-xyloside (2), and peonidin 3-O-glucoside (3). On the other hand, flavonols were identified as isorhamnetin 3-O-glucoside (4), 7-O-glucoside (5), 3,7-di-O-glucoside (6) and 3-O-rutinoside (7), quercetin 3-O-rutinoside (8) and 3-O-glucoside (9), and kaempferol 3-O-rutinoside (10) and 3-O-glucoside (11). Although an anthocyanin, pelargonidin 3-O-pentoside, has been reported from the flowers of A. nobilis, it was not found in this survey. The presence of flavonols in A. nobilis was reported in this survey for the first time. Flavonoid composition of Amherstia was chemotaxonomically compared with those of phylogenetically related genera Cynometra and Brownea.     

Flavonoids from the leaves and flowers of the Himalayan Cathcartia villosa (Papaveraceae)

Five flavonols, four flavones and one C-glycosylflavone were isolated from the leaves of Cathcartia villosa which is growing in the Himalayan Mountains. They were characterized as quercetin 3-O-vicianoside (1), quercetin 7,4′-di-O-glucoside (3), quercetin 3-O-rutinoside (4), quercetin 3-O-glucoside (5), quercetin 3-O-arabinosylarabinosylglucoside (6) (flavonols), luteolin (7), luteolin 7-O-glucoside (8), apigenin (9), chrysoeriol (10) (flavones), and vicenin-2 (11) (C-glycosylflavone) by UV, LC-MS, acid hydrolysis, NMR and/or HPLC and TLC comparisons with authentic samples. On the other hand, two flavonols 1 and kaempferol 3-O-vicianoside (2) were isolated and identified from the flowers of the species. Flavonoids were reported from the genus Cathcartia in this survey for the first time. Their chemical characters were chemotaxonomically compared with those of related Papaveraceous genera, Meconopsis and Papaver.     

Phenolic compounds from parasitic Sapria himalayana f. albovinosa and Sapria myanmarensis (Rafflesiaceae) in Myanmar

Three anthocyanins, four flavonols, three aromatic acids and five gallotannins were isolated from Sapria himalayana f. albovinosa in Myanmar. They were identified as cyanidin 3-O-glucoside (1), cyanidin 3-O-xyloside (2) and peonidin 3-O-glucoside (3) (anthocyanins), quercetin 3-O-glucoside (4), quercetin 7-O-glucoside (5), quercetin 3-O-glucuronide (6) and isorhamnetin 3-O-glucoside (7) (flavonols), ellagic acid (8), gallic acid (9) and ethyl gallate (10) (aromatic acids), and 1,2,4,6-tetragalloylglucose (11), 1,4,6-trigalloylglucose (12), 1,2,6-trigalloylglucose (13), 1,2,4-trigalloylglucose (14) and 1,6-digalloylglucose (15) (gallotannins) by UV, LC-MS, acid hydrolysis, NMR and/or HPLC comparisons with authentic samples. The chemical composition of S. myanmarensis was qualitatively the same with that of S. himalayana f. albovinosa. Phenolic compounds of the Rafflesiaceae species including Sapria, Rafflesia and Rhizanthes were isolated and identified in this survey for the first time.     

Flavonoids in the leaves of Hillebrandia and Begonia species (Begoniaceae)

The fresh leaves of Hillebrandia sandwicensis and 126 Begonia taxa were chemotaxonomically surveyed for flavonoids. Of their taxa, H. sandwicensis and 119 species, one variety and three hybrids were analyzed for flavonoids for the first time. Ten flavonols and eleven C-glycosylflavones were isolated and characterized as quercetin 3-O-rutinoside (1), kaempferol 3-O-rutinoside (2), isorhamnetin 3-O-rutinoside (3), quercetin 3-O-glucoside (4), quercetin 3-methyl ether 7-O-rhamnosylglucoside (5), quercetin 3,3'-dimethyl ether 7-O-rhamnosylglucoside (6), quercetin glycoside (13), quercetin glycoside (acylated) (14), kaempferol glycoside (17) and quercetin 3-O-rhamnoside (18) as flavonols, and isovitexin (7), vitexin (8), isoorientin (9), orientin (10), luteolin 6-C-pentoside (11), luteolin 8-C-pentoside (12), schaftoside (15), isoschaftoside (16), chrysoeriol 6,8-di-C-pentoside (19), apigenin 6,8-di-C-arabinoside (20) and isovitexin 2''-O-glucoside (21) as C-glycosylflavones. Quercetin 3-O-rutinoside (1) alone was isolated from H. sandwicensis endemic to Hawaii. Major flavonoids of almost Begonia species was also 1. Begonia species were divided into two chemotypes, i.e. flavonol containing type and C-glycosylflavone containing type. Of 14 section of the Begonia, almost species of many section, i.e. sect. Augustia, Coelocentrum, Doratometra, Leprosae, Loasibegonia, Monopteron and Ruizoperonia, were flavonol types. On the other hand, C-glycosyflavone type was comparatively most in sect. Platycentrum.     

Flavonoids in the blue flowers of Parochetus communis Buch.-Ham. ex D. Don (Leguminosae)

A rare anthocyanin, malvidin 3-O-rhamnoside, was isolated from the blue flowers of Parochetus communis Buch.-Ham. ex D. Don along with two known flavonols: kaempferol 3-O-(2-O-glucosyl-6-O-rhamnosyl)-glucoside and kaempferol 3-O-(2,6-di-O-rhamnosyl)-glucoside. These structures were identified using Nuclear Magnetic Resonance (NMR) and Mass Spectrometry (MS).     

Flavonoid constituents of Ephedra alata

Two new flavonol glucosides have been identified in Ephedra alata, namely, herbacetin 8-methyl ether 3-O- glucoside-7-O-rutinoside and herbacetin 7-O-(6″-quinylglucoside). The known flavonoids vicenin II, lucenin III, kaempferol 3-rhamnoside, quercetin 3-rhamnoside and herbacetin 7-glucoside were also found. The structure of the isolated compounds was determined mostly by FABMS and ¹H NMR spectroscopy. The final structure of the new compounds and of herbacetin 7-glucoside was confirmed by ¹³C NMR spectroscopy.     

C-Arabinosylapigenin methyl ethers from Asterostigma riedelianum

The leaves of summer harvested Asterostigma riedelianum were found to contain the following flavonoids all of which are reported for the first time: 6,8-di-C-arabinosylapigenin 7,4′-dimethyl ether, 2″-O-glucosyl-6-C-arabinosylapigenin 7,4′-dimethyl ether and 2″-O-(caffeoyl)glucosyl-6-C-arabinosylapigenin 7,4′-dimethyl ether. Winter harvested A. riedelianum additionally contained the 7-monomethyl ethers of the mono-C-arabinosides.     

Flavonoids and xanthones from the leaves of Amorphophallus titanum (Araceae)

The flavonoids and xanthones in the leaves of Amorphophallus titanum, which has the largest inflorescence among all Araceous species, were surveyed. Eight C-glycosylflavones, five flavonols, one flavone O-glycoside and two xanthones were isolated and characterized as vitexin, isovitexin, orientin, isoorientin, schaftoside, isoschaftoside, vicenin-2 and lucenin-2 (C-glycosylflavones), kaempferol 3-O-robinobioside, 3-O-rutinoside and 3-O-rhamnosylarabinoside, and quercetin 3-O-robinobioside and 3-O-rutinoside (flavonols), luteolin 7-O-glucoside (flavone), and mangiferin and isomangiferin (xanthones). Although the inflorescence of this species has been surveyed for flavonoids, those of the leaves were reported for the first time.     

Distribution of exudate flavonoids in the genus Plectranthus

Thirty-four species of the genus Plectranthus (including species of the former genera Coleus and Solenostemon, fam. Lamiaceae) were surveyed for exudate flavonoids to see whether the distribution of these compounds would support a recent classification of the genus based on molecular and morphological characters. In this classification two major groups had been identified, the Coleus and Plectranthus clades. Only about 40% of the species, predominantly from the Plectranthus clade, were found to produce exudate flavonoids, which were mainly flavones. Flavanones were restricted to five species of the Plectranthus clade, whereas flavonols were only found in two species of the Coleus clade, Plectranthus montanus Benth. (synonyms Plectranthus marrubioides Hochst. ex Benth. and Plectranthus cylindraceus Hochst. ex Benth.) and Plectranthus pseudomarrubioides R.H.Willemse. Four of these flavonols were isolated from P. montanus and identified by NMR spectroscopy as the 3,7-dimethyl ether and 3,7,4′-trimethyl ether of quercetin and the 3,6,7-trimethyl ether and 3,6,7,4′-tetramethyl ether of quercetagetin. The remaining flavonols and flavones were identified by HPLC–UV and LC–MS of crude extracts on the basis of their UV and mass spectra, retention times and comparison with standards. Most flavonols were 3-methyl ethers and many of the flavones and flavonols were oxygenated at the 6-position. The most common flavones, occurring in both clades, were cirsimaritin and salvigenin, which are methoxylated at the 6- and 7-positions. 6-Hydroxylated flavones such as scutellarein and ladanein were restricted to species of the Plectranthus clade.     

The role of lipophilic and polar flavonoids in the classification of temperate members of the Anthemideae

Lipophilic and vacuolar flavonoids were separately identified in representative temperate species of the genera Anthemis, Chrysanthemum, Cotula, Ismelia, Leucanthemum and Tripleurospermum. The four Anthemis species investigated variously produced four main surface constituents, in leaf and flower: santin, quercetagetin 3,6,3′-trimethyl ether, scutellarein 6,4′-dimethyl ether and 6-hydroxyluteolin 6,3′-dimethyl ether. By contrast, surface extracts of disc and ray florets of the species of Chrysanthemum, Cotula, Ismelia, Leucanthemum and Tripleurospermum surveyed yielded five common flavones in the free state: apigenin, luteolin, acacetin, apigenin 7-methyl ether and chrysoeriol. Polar flavonoids were isolated and identified in leaf, ray floret and disc floret of all the above plants. Anthemis species were distinctive in having flavonol glycosides in the leaves, whereas the leaf flavonoids of the other taxa were generally flavone O-glycosides. The 3-glucoside and 3-rutinoside of patuletin were characterised for the first time from Anthemis tinctoria ssp. subtinctoria. Two new flavonol glycosides, the 5-glucuronides of quercetin and kaempferol, were obtained from the leaf of Leucanthemum vulgare, where they co-occur with the related 5-glucosides and with several flavone glycosides. The ray florets of these Anthemideae generally contain apigenin and/or luteolin 7-glucoside and 7-glucuronide, whereas disc florets have additional flavonol glycosides, notably the 7-glucosides of quercetin and patuletin and the 7-glucuronide of quercetin. A comparison of the flavonoid pattern encountered here with those previously recorded for Tanacetum indicate some chemical affinity between Anthemis and Tanacetum. Flavonoid patterns of the other five genera are more distinct from those of Tanacetum and suggest that those genera form a related group. All 14 species surveyed for their flavonoid profiles have distinctive constituents and the chemical data are in harmony with modern taxonomic treatments of the “Chrysanthemum complex” as a series of separate genera.     

Cumarine aus südafrikanischen Pelargonium-arten

From the roots of Pelargonium reniforme 7-hydroxy-5,6-dimethoxycoumarin, its monomethyl ether and its 7-O-glucoside were isolated for the first time. This coumarin, its 7-glucoside and scopoletin were detected chromatographically in the roots of eleven other South African Pelargonium species.