Flavonoid chemistry and plant geography in the Cyperaceae

A leaf survey of 59 tropical (43 African, and 16 South American) Cyperaceae showed that in addition to the expected flavonoid constituents, i.e. glycoflavones and tricin derivatives, a representative number of them (33%) contained luteolin 5-methyl ether. An equal sample of temperate Cyperaceae failed to show any species with this substance. Thus it appears that this rare 5-methylated flavone is restricted to tropical members of the family. In four species of the South American genus, Lagenocarpus, 6-hydroxyluteolin 7-glucoside was identified. This is the first report of this 6-hydroxyflavone in the Cyperaceae and in the monocotyledons. A new glycoside of iso-orientin, the 3'-glucuronide, was identified in Rhynchospora eximia. The new data have been collected in a revised summary of the leaf flavonoid pattern of the Cyperaceae and compared with those of the Gramineae and Juncaceae. The discovery of luteolin 5-methyl ether in the Cyperaceae brings it closer in chemical terms to the Juncaceae, from which family this compound was first isolated     

Flavonoids in leaves and inflorescences of australian Cyperus species

A survey of the flavonoids of some 92 species of Australian Cyperus, mainly of subtropical or tropical origin, has confirmed a correlation previously reported in this family between flavonoid pattern and plant geography. The pattern found was similar to that of African and South American Cyperaceae, particularly in the occurrence of the rare marker substance, luteolin 5-methyl ether. Tricin and luteolin are relatively common, in glycosidic form, in the leaves while the flavonol quercetin is infrequent. When present, quercetin occurs either in glycosidic form or free as a methyl ether. The 3-monomethyl and 3, 7-dimethyl ethers of kaempferol and quercetin and the 3, 7, ?-trimethyl ether of quercetin are reported for the first time from the Cyperaceae. The flavonoid pattern of inflorescences is distinct from that of the leaves in that tricin is not detectable and that luteolin 5-methyl ether appears to be replaced by 7, 3′, 4′-trihydroxyflavone. In addition, the aurone aureusidin is more commonly present than in the leaves and is occasionally accompanied by two further aurones. The glycoxanthones mangiferin and isomangiferin occur rarely in all three species examined in the section Haspani, i.e. in C. haspan, C. prolifer and C. tenuispica. In general, however, the flavonoid data do not offer any markers which separate off different sections within the genus; there are, however, some significant correlations between the frequency of the flavonoid classes and subgeneric groupings.     

The leaf flavonoids of the orchidaceae

In a leaf survey of 142 species from 75 genera of the Orchidaceae, flavone C-glycosides (in 53%) and flavonols (in 37 %) were found to be the most common constituents. However, since these compounds are not found uniformly and their distribution shows a strong correlation with plant geography, it is not possible to represent the Orchidaceae by a single flavonoid profile. Thus, flavone C-glycosides are most common in tropical and subtropical species of the Epidendroid and Vandoid tribes (in 63%) and flavonol glycosides are more characteristic of temperate species of the Neottioid tribes (in 78%). By contrast 6-hydroxyflavones (in 6 species), luteolin (in 2 species) and tricin as the 5-glucoside (in 1 species) are all rare. Three new glycosides were characterised: scutellarein 6-methyl ether 7-rutinoside from Oncidium excavatum and O. sphacelatum, pectolinarigenin 7-glucoside from 0. excavatutn and Eria javanica, and luteolin 3′,4′-diglucoside from Listera ovata. The xanthones, mangiferin and isomangiferin were found in Mormolyca ringens, Maxillaria aff. luteo-alba and 5 Polystachya species and a mangiferin sulphate tentatively identified in P. nyanzensis. Other unusual phenolic constituents include 6,7-methylenedioxy- and 6,7-dimethoxycoumarins from Dendrobium densiflorum and D. farmeri, formed by the rearrangement during the extraction process from the corresponding O-glucosyloxycinnamic acids. The origin and relationship of the Orchidaceae to other monocot groups are discussed in the light of the flavonoid evidence.     

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.     

Flavonoids in leaves and inflorescences of australian cyperaceae

A survey of 170 Australian species of Cyperaceae belonging to 35 genera has confirmed that this family has a highly characteristic flavonoid pattern in leaf and inflorescence. Aurone pigments, the most distinctive family constituents, were found in the leaves of 25% of the sample and in the inflorescences of 40%. Sulphuretin was found for the first time in the family, in Carex appressa. Flavones, such as tricin and luteolin, are very common; in addition, a variety of methyl ethers were detected. Luteolin 5-methyl ether was found in further genera, while luteolin 7-methyl ether, diosmetin and acacetin were detected for the first time in the Cyperaceae. Flavonols and their methyl ethers occurred in over one-third of the species, particularly in the leaves, being especially well represented in the genera Fuirena, Gahnia, Lepidosperma and Mesomelaena. Myricetin was found only twice, in two Baumea species. The 3-desoxyanthocyanidin carexidin was found in the inflorescences of eight species, i.e. in 5% of the sample. Taxonomically, the results are mainly of interest at the generic and specific level, where the patterns sometimes show useful correlations with morphology. At the tribal level, the Sclerieae are the most distinctive, with higher than average frequency of flavone C-glycosides, flavonols, proanthocyanidins and aurones, and lower than average frequency of flavones.     

Occurrence of sulphated flavones and caffeic acid esters in members of the fluviales

A survey of 50 species of the Fluviales showed that over 50% have either flavone or caffeic acid sulphates present. Flavone sulphates were detected in 16% of the sample and the 7-sulphates of luteolin, apigenin, diosmetin and chrysoeriol and the 7,3′-disulphate of luteolin were identified variously in Thalassia, Zannichellia and Zostera species. Anionic caffeic esters were found in 46% of the sample; preliminary studies indicate the presence of sulphated caffeylquinic acids in these plants. In confirmation of earlier studies, glycoflavones were found to be widespread and flavonols and proanthocyanidins to be rare. The taxonomic and ecological significance of these results are discussed.     

Chemotaxonomic consideration of flavonoids from the leaves of Chrysanthemum arcticum subsp. arcticum and yezoense,and related species

We examined the foliar flavonoids of Chrysanthemum arcticum subsp. arcticum and yezoense, and related Chrysanthemum species. Five flavonoid glycosides (luteolin 7-O-glucoside and 7-O-glucuronides of luteolin, apigenin, eriodictyol and naringenin) were isolated from these taxa. Luteolin 7-O-xylosylglucoside, luteolin, apigenin and quercetin 3-methyl ether were found in subsp. yezoense as very minor compounds that were not recognised by high-performance liquid chromatography/photodiode array (HPLC/PDA). The related species C. yezoense contained acacetin 7-O-rutinoside and some methoxylated flavone aglycones as major compounds. Thus, C. arcticum was distinguished from C. yezoense according to their flavonoid profiles.     

Methylated Chalcones from Bidens torta

Four new natural products, all methylated chalcones, including an acetylated glycoside, were isolated from Bidens torta. Their structures were determined by spectroscopic methods as okanin 3,4,3′,4′-tetramethyl ether, okanin 3,4,3′-trimethyl ether 4′-glucoside, okanin 4-methyl ether 4′-glucoside and okanin 4-methyl ether 4′-glucoside monoacetate. Okanin 3,4-dimethyl ether 4′-glucoside was also isolated.     

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.     

Flavone 5-O-glucosides from Daphne sericea

The aerial parts of Daphne sericea yielded two new flavonoids, luteolin 7-methyl ether 5-β-d-glucoside and luteolin 7,3′-dimethyl ether 5-β-d-glucoside, as well as luteolin 7-methyl ether, isovitexin, apigenin and its 7-β-d-glucoside.     

Flavonoids from Haplophyllum pedicellatum, H. robustum AND H. glabrinum

Haplophyllum pedicellatum, H. robustum and H. glabrinum all yielded the known compound gossypetin 8,3′-dimethyl ether 3-rutinoside. In addition the first two species afforded isorhamnetin and its 3-rutinoside. A new glycoside, gossypetin 8,3′-dimethyl ether 3-glucoside was obtained from H. pedicellatum together with the 3-malonylrutinoside, 3-malonylglucoside and 3-galactoside of isorhamnetin plus kaempferol 3-malonylglucoside. H. robustum yielded isorhamnetin 7-glucoside and 3-glucoside and quercetin 3-galactoside, while H. glabrinum was found to contain gossypetin 8-methyl ether 3-malonylrutinoside in addition to kaempferol and isorhamnetin 3-glucoside.     

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.     

Leaf flavonoid and other phenolic glycosides as indicators of parentage in six ornamental Fuchsia species and their hybrids

In a leaf flavonoid analysis of six Fuchsia species and seven Fuchsia hybrids, flavonols were found to be abundant in all taxa except F. procumbens. Flavone glycosides were found in only three species: luteolin 7-glucoside in F. splendens; and luteolin and apigenin 7-glucuronides and 7-glucuronidesulphates, tricin 7-glucuronidesulphate and diosmetin 7-glucuronide from one or both of the New Zealand species F. procumbens and F. excorticata. Luteolin 7- glucuronidesulphate is reported for the first time. Other less common phenolics identified include the flavanone, eriodictyol 7-glucoside from F. excorticata, a galloylglucose from F. triphylla, and a galloylglucosesulphate present in all taxa. Eight of the flavonoid glycosides proved useful as marker substances for particular Fuchsia species: quercetin 3- rhamnoside, 3-glucuronide and 3-rutinoside for F.fulgens; quercetin and kaempferol 3-galactosides for F. boliviana var. luxurians; diosmetin 7-glucuronide for F. excorticata and apigenin 7-glucuronide and 7-glucuronidesulphate for F. procumbens. The chemical results on the hybrids support the view that the cultivar ‘Mary’ is a hybrid of F. boliviana var. luxurians and F. triphylla and that both F.fulgens and F. triphylla are involved as parents of the cultivars ‘Koralle’ and ‘Traudchen Bondstedt’.     

The flavonoids of tetragonotheca (compositae)

Fifteen flavonols, five aglycones and ten glucosides were isolated from the four species of Tetragonotheca, T. repanda, T. helianthoides, T. texana and T. ludoviciana. Included among the isolated flavonols are four previously unreported 7-O-glucosides, 6-hydroxykaempferol 7-O-glucoside, 6-hydroxykaempferol 6-methyl ether 7-O-glucoside, quercetagetin 6,3′-dimethyl ether 7-O-glucoside and quercetagetin 3,6-dimethyl ether 7-O-glucoside.     

Distribution of charged flavones and caffeylshikimic acid in Palmae

Identification of the phenolic constituents in flowers of nine palm species has revealed that charged C-glycosylflavones and caffeylshikimic acid are characteristically present. Flavonol glycosides are also common; the 3-glucosides, 3-rutinosides and 3,4′-diglucosides of quercetin and isorhamnetin and the 7-glucoside and 3,7-diglucoside of quercetin are all variously present. Tricin 7-glucoside, luteolin 7-rutinoside and several unchanged C-glycosylflavones were also detected. Male flowers of Phoenix canariensis differ from female flowers in having flavonol glycosides. As expected, in most species studied, flavonoid patterns in the flowers vary considerably from those found in the leaves.     

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.     

Negatively charged flavones and tricin as chemosystematic markers in the palmae

A survey of 125 species of the Palmae revealed a complex pattern of flavonoids in the leaf. C-Glycosylflavones, leucoanthocyanins and tricin, luteolin and quercetin glycosides were common, being present in 84, 66, 51, 30 and 24% of the species respectively. Apigenin and kaempferol were recorded in only a few species and isorhamnetin only once. Eighteen flavonoids were identified: the 7-glucoside, 7-diglucoside and 7-rutinoside of both luteolin and tricin, tricin 5-glucoside, apigenin 7-rutinoside, quercetin 3-rutinoside-7-galactoside, isorhamnetin 7-rutinoside, orientin, iso-orientin, vitexin, isovitexin and vitexin 7-O-glucoside. Many of the C- and O-flavonoid glycosides were present as the potassium bisulphate salts and negatively charged compounds were detected in 50% of the species. The distribution patterns are correlated with the taxonomy of the family in several ways. Thus, the Phoenicoideae and Caryotoideae have distinctive flavonoid patterns, there is evidence to support the separation of the subfamilies Phytelephantoideae and Nypoideae, and tricin is a useful marker at tribal level. At the generic level, Cocos is clearly separated from Butia, and other Cocoseae and Mascarena and Chamaedorea form well defined groups within the Arecoideae. A numerical analysis of these biochemical data, together with morphological characters, produces a new classification which suggests that the flavonoid data may have more systematic value than is indicated when they are applied to the traditional classification.     

Flavonol glycosides of Limnanthes douglasii

Eighteen flavonol glycosides were isolated from petal and leaf-stem of Limnanthes douglasii. There were six aglycones: kaempferol, quercetin, isorhamnetin, myriectin, syringetin and a new flavonol, myricetin 3′-methyl ether. Each occurred as the 3-rutinoside, 3-rhamnosylrutinoside and 3-rutinoside-7-glucoside.     

A chemosystematic study of the phenolics of Sonchus

Thirty-three Sonchus, one Embergeria, one Babcockia and five Taeckholmia species were surveyed for their phenolic constituents. The coumarins scopoletin and aesculetin were found as major constituents of Embergeria, Babcockia and Taeckholmia species, and in lesser amount in some Sonchus species. Six flavone glycosides were identified: apigenin 7-glucuronide, apigenin 7-rutinoside, luteolin 7-glucoside, luteolin 7-glucuronide, luteolin 7-rutinoside and luteolin 7-glucosylglucuronide and the systematic significance of their distribution is discussed.     

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.