Chemosystematics of the hydrophyllaceae: Flavonoids of three species of eriodictyon

Eleven flavonoids, nine aglycones and two glycosides were isolated from Eriodictyon tomentosum, E. angustifolium and E. Californicum. Aglycones included the flavanone homoeriodictyol, the flavones apigenin, luteolin, chrysoeriol, 6-methoxyapigenin, 6-methoxyapigenin 7-methyl ether, 6-methoxyapigenin 4′-methyl ether, 6-methoxyluteolin and 6-methoxyluteolin 3′-methyl ether, glycosides were the 3-O-glucosides of quercetin and kaempferol.     

Leaf surface flavonoids of Eriodictyon trichocalyx

Extraction of the leaf resin of Eriodictyon trichocalyx var. trichocalyx ether, yielded naringenin, eriodictyol, eriodictyol 3′-methyl ether, apigenin, 6-methoxy-apigenin, luteolin, 6-methoxyluteolin, chrysoeriol, luteolin 3′,7-dimethyl ether and isorhamnetin. The flavonoid profile agrees weil in most respects with the types of compounds exhibited by other Eriodictyon species, particularly with regard to the presence of 6-substituted flavones and a moderate level of O-methylation. Flavonoid variation in E. californicum is briefly discussed.     

The chemosystematics of local members of the subtribe gnaphaliinae (Compositae)

Eight species belonging to the genera Filago, Ifloga, Achyrocline, Helichrysum and Pseudognaphalium, subtribe Gnaphaliinae, tribe Inuleae (Compositae), were investigated for their flavonoid glycosides. All glycosides were found to belong to the aglycones kaempferol, quercetin, apigenin and luteolin. Calycopterin and its 3'-methyl ether were present in the free form.     

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.     

Chemotaxonomic significance of flavonoids and phenolic acids in the Hieracium rohacsense group (Hieracium sect. Alpina; Lactuceae, Compositae)

Five apomictic taxa from the Hieracium rohacsense group were studied for their phenolic constituent composition. The following substances represent dominant compounds in the leaves: chlorogenic acid, 3,5-dicaffeoylquinic acid, luteolin 7-O-β- -glucopyranoside, luteolin 4′-O-β- -glucuronopyranoside and apigenin 4′-O-β- -glucuronopyranoside. Within the group only quantitative differences were found, luteolin 7-O-glucoside being the most important chemotaxonomic marker. Each taxon has its own specific quantitative pattern, invariable within the taxon. Based on these characteristic profiles, H. rohacsense can be distinguished from a closely related and still undescribed taxon from Mt. Pip Ivan. The proportion of luteolin 7-O-glucoside to apigenin 4′-O-glucuronoside also clearly separates the individuals of two morphologically close species—H. ratezaticum and H. pseudocaesium, which corresponds to a few slight but recognisable morphological and phenological characteristics. The ontogenetic stage of leaf development and seasonal variation are also important factors, which must be taken into consideration, as the quantity of the substances changes during leaf ontogeny and with season.     

Flavonoid similarities among five species of Isocoma

The flavonoid profiles of the leaf resins from Isocoma veneta, I. tenuisecta, I. acradenia, I. drummondii, and I. eremophila were identified by TLC co-chromatography with authentic samples. Thirty flavonoid aglycones were identified, most of which are methylated, based on apigenin, luteolin, kaempferol, quercetin, scutellarein (I. veneta)only, and 6-OH-kaempferol (I. tenuisectaonly). Cluster analyses were performed using Jaccard similarities of both presence/absence data and of biosynthetic step indices. The latter method yielded consistently higher similarity coefficients and is believed to be a truer indication of the chemical similarities among Isocoma species.     

Flavonoids of Helianthus series Microcephali

Ray flower and leaf flavonoids were investigated for the three species of Helianthus series Microcephali. Ray flowers of all species contain coreopsin, sulphurein, and quercetin 7-O-glucoside; those of H. microcephalus also contain quercetin 3-O-glucoside. A mixture of flavonoid aglycones, mostly methoxylated flavones, occurs in leaves of H. microcephalus, but not in H. glaucophyllus or H. laevigatus which also lack the glandular trichomes that in Helianthus are typically associated with flavonoid aglycones. The presence of compounds with the 6,8,4′ pattern of methoxylation in H. microcephalus suggests that the series is more similar in flavonoids to series Angustifolii than to series Corona-solis.     

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.     

Systematic implications of flavonoids in Hazardia

The flavonoid patterns in Hazardia species support species delimitations and relationships based on morphology and geography. The compounds thus far elucidated are glycosides of quercetin, kaempferol, isorhamnetin, luteolin, and apigenin, glycoflavones of apigenin, and methoxylated flavonol aglycones.     

Flavonoid patterns in leaves of the gramineae

In a leaf survey of 274 species from 121 genera of the Gramineae, flavone C-glycosides and tricin were found to be the major flavonoids in 93% of the samples. By contrast, apigenin and luteolin O-glycosides were comparatively rare, as were the flavonols, kaempferol and quercetin. In only one species, Rottboellia exaltata were flavonols the sole flavonoids. 7.3′.4′-Trihydroxyflavone, which has been detected in the Juncaceae, was found in 3 of 5 samples of the species Bothriochloa bladhii. Flavonoid sulphates were present in 16% of the species examined. While in most of these plants tricin glycosides were conjugated with sulphate, in Paspalum convexum quercetin mono- and di-sulphates and 1-caffeylglucose sulphate were identified. Flavonoid sulphates are present in the tropical-subtropical subfamilies: Panicoideae (in 18% of species). Chloridoideae (15%) and Arundinoideae (40%) but were not found at all in tribes of the cool temperate regions. Proanthocyanidins were found in only 3% of the species surveyed. The flavan-4-ol, luteoforol and its apigenin analogue were detected only in the subfamilies Panicoideae and Chloridoideae, where they occured in 12 and 6% of species respectively.     

Biosystematics of the monocotyledoneae—flavonoid patterns in leaves of the liliaceae

In a leaf survey of 168 species of the Liliaceae, most of the major flavonoid classes were found to be represented in the family. Flavonols occurred most frequently: quercetin and kaempferol were detected in 40% and 42% of the sample respectively, while the flavones luteolin and apigenin were present in only 24% and 20% of the sample. Methylated derivatives, i.e. isorhamnetin, diosmetin and tricin were rare. Procyanidins were present in 17 species, flavonoid sulphates in only one species and flavone C-glycosides in only three species. Anthraquinone pigments were identified in species of Aloe Asphodeline and Asphodelus. Three new flavonoid glycosides were characterised during the course of the survey: diosmetin 7-diglucoside in Colchicum byzanthinum and tricin 7-fructosylglucoside and tricin 7-rutinoside-4′-glucoside in Hyacinthus orientalis cv. ‘Quean of the Pinks’. On the basis of the flavonoid survey, the subfamilies of the Liliaceae may be grouped into those containing flavonols only, those with flavones only or those having both flavonols and flavones. Members of the related families: Amaryllidaceae (17 species), Agavaceae (1 species) and Xanthorrhoeaceae (1 species) contained only flavonols. The subfamilies Scilloideae, Asphodeloideae and Melanthioideae show the most chemical variation whilst the Wurmbaeoideae and Lilioideae are the most homogeneous groups. The tribe Scilleae is unusual in that both flavone- and flavonol-containing genera occur and a wide variety of flavonoid types are represented. A comparison of the leaf flavonoids of the Liliaceae with those found in families related to the grasses showed that all except two classes of flavonoid compound (5-methylated flavones and 5-deoxyflavonoids) found in the Juncaceae. Cyperaceae, Palmae and Gramineae are present in the Liliaceae thus supporting the view that all four families could have arisen from Liliaceae-like ancestors.     

Flavonoid variation in Arnica cordifolia: an Apomictic polyploid Complex

Thirty-three populations of A. cordifolia, a wide-ranging apomictic polyploid complex, were examined for flavonoid content. A total of ten compounds, including simple and methylated flavone and flavonol glycosides as well as methylated aglycones, were isolated and identified. The number of compounds per population varies from two to nine. With the exception of luteolin 7-O-glucoside and its 6-methyl ether, which are restricted to northern populations, the remaining compounds are randomly distributed. This distribution pattern is probably the result of a combination of factors including founder effect, genetic drift and a general reduction of flavonoid profile as a result of reproductive isolation.     

The chemosystematics of Egyptian Trigonella species

Flavonoid glycosides of eight Trigonella species belonging to four sections of the Leguminosae [Gamal El Din, E.M. and Hassan, A.E. (1995) Taeckholmia, in press] were investigated. Fifteen glycosides were found based on the aglycones kaempferol, quercetin and the less common 7,4′-dihydroxyflavone and 7,3′,4′-trihydroxyflavone. One isoflavone (formononetin) was found in all Trigonella species. Chemosystematic relationships are discussed.     

Flavonoids of five Hieracium species of British Columbia

Five Hieracium species were examined for flavonoid constituents: H. albertinum, H. albiflorum, H. cynoglossoides, H. gracile and H. umbellatum. The major compounds present in all species were mono- and diglycosides, of apigenin and luteolin. Chrysoeriol occurred per se in several species. Quercetin-3-O-glucoside was seen only in H. umbellatum. Species specific patterns of flavonoid glycosides were evident in all five taxa; H. albertinum and H. cynoglossoides showed the greatest similarity which reflects their morphological similarity. Limited examination of artificial hybrids showed additivity of flavonoid glycoside patterns.     

Flavonoids and isoflavonoids of chemotaxonomic significance from Glycyrrhiza pallidiflora (Leguminosae)

Chemical studies were carried out on the root of Glycyrrhiza pallidiflora (Leguminosae), a licorice of no medicinal or commercial value. Two isoflavone glycosides, wistin and ononin, were isolated as major constituents from the methanol extract. A series of chromatographic separations of the acetone extract yielded isoflavone aglycones (afromosin, 2′,7-dihydroxy-4′-methoxyisoflavone and formononetin), flavanones (liquiritigenin and 4′,7-dihydroxy-6,8-diprenylflavanone), an isoflavan [(-)-vestitol], a pterocarpan [(-)-medicarpin], chalcones (echinatin and isoliquiritigenin), dibenzoylmethanes (licodione and 2′-O-methyl-licodione), a flavone (4′,7-dihydroxyflavone), a 3-arylcoumarin (2′-7-dihydroxy-4′-methoxy-3-arylcoumarin), and a new isoflav-3-ene (2′-7-dihydroxy-4′-methoxyisoflav-3-ene). The co-occurrence of the retrochalcone echinatin and the biogenetically related licodione and 2′-O-methyl-licodione is of particular interest, and suggests that this species is closely related to G. echinata and G. inflata. The biogenesis of the retrochalcone is also discussed in relation to its significance in the chemotaxonomy of sects Echinatae and Bucharicae of the genus Glycyrrhiza.     

C-GLYCOSYLFLAVONES IN THE GNETOPSIDA: A PRELIMINARY REPORT

C-Glycosylflavones appear to be the only detectable flavonoids in representative species of Gnetum, Ephedra and Welwitschia. Ephedra antisyphilitica contains mixed 6,8-di-C-glycosides of apigenin and luteolin and Welwitschia mirabilis produces 6-C-glycosylchrysoeriol and 6,8-di-C-glycosylchrysoeriol. Recently it was reported that Gnetum gnemon contains 6-C-, 8-C and 6,8-di-C-glucosyl derivatives of apigenin, luteolin and their 7-0-methyl ethers. Based on the present preliminary survey the apparent absence of other flavonoid types indicates that C-glycosylflavones may be a unifying characteristic of the Gnetopsida.     

Flavonoids of the Muhlenbergia montana complex

Specimens from natural populations of Muhlenbergia montana (Nutt.) Hitch. and related species were analysed for their flavonoid content. Twenty-four flavonoids from 14 species were separated and 22 of the compounds identified. Most were glycosylated derivatives of luteolin, apigenin and tricin. Two flavonols, quercetin 3-O-rutinoside and quercetin 3-O-glycoside, and two flavanones were also identified. Flavonoid patterns were distinct for all perennial species and identical for the two annual species examined. Phenetic analysis of the flavonoid characters does not support the inclusion of the annual species M. crispiseta and M. peruviana as part of the M. montana complex.     

Further studies of flavonoids in Saxifraga

The flavonoid composition of Saxifraga cernua, S. micranthidifolia, S. tolmiei, and S. tricuspidata has been determined. The major proportion of the profiles comprise a complex mixture of flavonol 3-O-glycosides, including mono-, di-, and triglycosides. Kaempferol, quercetin, isorhamnetin, and myricetin were observed although not all taxa had all aglycones. The monoglycoside fraction of S. tolmiei was unusual in that it consisted only of quercetin 3′-O-glucoside and myricetin 7-O-glucoside; both compounds are unusual for the family. Saxifraga tricuspidata exhibited an unusually complex array of monoglycosides which was comprised of glucosides, galactosides, xylosides, several isomeric arabinosides, and acylated derivatives of some of the arabinosides. The diversity of biosynthetic capacity observed for Saxifraga (present and earlier data) reflect the complexity described for the Saxifrageae.     

Flavonoid variation in Melampodium

Five species of Melampodium have been studied for their flavonoid components. Melampodium aureum, M. divaricatum and M. longipilum exhibited simple arrays of kaempferol and quercetin 3-O-mono-and diglycosides. Melampodium bibracteatum afforded the same simple glycosides plus quercetagetin 3-methyl ether. Melampodium americanum had the most complex pattern with simple flavonol glycosides being accompanied by five O-methylated derivatives of quercetagetin plus 6-hydroxykaempferol 3-methyl ether. Three populations of M. bibracteatum gave identical flavonoid profiles as did 15 collections of M. bibracteatum.     

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.