Exkret-Flavonoide bei Höheren Pflanzen arider Gebiete

Flavonoids generally occur in higher plants as water-soluble glycosides. However, lipophilic flavonoid aglycones can be excreted by glandular trichomes or extruded through the cuticle. They are accumulated on the plant surface as constituents of leaf resins or thin epicuticular layers. External flavonoid aglycones are found in various families throughout the higher plants, but appear to be most abundant in theAsteraceae. They occur relatively frequently in plants of (semi-)arid habitats. It is advantageous for chemotaxonomic studies that the structural diversity of exudate flavonoids is normally greater than that of the tissue glycosides in these plants.

Vorgetragen auf der Tagung der Deutschen Botanischen Gesellschaft, Wien, September 1984.     

Neue phloroglucin-derivate aus Leontonyx-arten sowie weitere verbindungen aus vertretern der tribus inuleae

The investigation of several South African species of the tribe Inuleae afforded in addition to known compounds 16 new constituents. From Leontonyx a group of 9 new phloroglucinol derivatives, from Stoebe species two new p-hydroxyacetophenone, two thymol and two coumaric acid derivatives and from Relhania a new euparine-derivative were isolated. The structures are elucidated mainly by spectroscopic methods. The chemotaxonomic aspects are discussed briefly. The phloroglucinol derivatives, which in part are derived from geraniol, seem to be especially characteristic.     

The genus <Emphasis Type="Italic">Lindera</Emphasis>: a source of structurally diverse molecules having pharmacological significance

Lindera plants not only have good ornamental and economic uses but also have great medicinal and therapeutic values. The genus Lindera consists of approximately 100 species that are widely distributed in tropical and subtropical areas throughout the world. This extensive geographical distribution allows Lindera plants to produce diverse secondary metabolites having novel structures. Phytochemical investigations have shown that Lindera plants produce 341 constituents, including sesquiterpenoids, alkaloids, butanolides, lucidones, flavonoids, and phenylpropanoids. Moreover, some Lindera plants show significant chemotaxonomic reference under family Lauraceae and tribe Litseae. Although Lindera plants have various pharmacological and biological properties, their anticancer, antihypertensive, anti-inflammatory, and analgesic properties have been focused in many studies. Butanolides and lucidones have shown great potential in developing anticancer agents while aporphine alkaloids have shown great potential in developing antiarthritic and antinociceptive agents. However, these compounds need to be assessed further by performing in-depth and systematic research.     

Variation in flavonoid pattern in leaves and flowers of Primula veris of different origin and impact of UV-B

Flavonoids can serve as chemotaxonomic markers and play an important role in protection against ultraviolet (UV) radiation. Primula veris originating from two natural field sites in Albania and one cultivar from Austria were used to investigate whether flavonoid pattern may differ between populations and to determine their response to UV. Plants were grown in a common environment and shortly before flowering transferred in two greenhouses with 80% and 4% UV-B transmission, respectively. After two weeks, young leaves and open flowers were harvested and flavonoids analyzed by high performance liquid chromatography. The flavonoid profiles of leaves and flowers were highly distinct for each population, with certain flavonoids occurring only in plants of particular field sites. These flavonoids may be useful biomarkers to identify the origin of plant material. The differences in UV-treatment at that stage had no effect on the total flavonoid contents of both leaves and flowers. However, individual flavonoids of both leaves and flowers responded sensitively to UV, suggesting that they may be involved in protection against UV.     

Chemosystematic value of flavonoids from Crataegus x macrocarpa (Rosaceae) with special emphasis on (R)- and (S)-eriodictyol-7-O-glucuronide and luteolin-7-O-glucuronide

The chemotaxonomic investigation of Crataegus x macrocarpa, a hybrid of C. laevigata and C. rhipidophylla, presents the qualitative and quantitative composition of its flavonoid pattern in relationship to its parent species for the first time. Six flavonoids were identified as vitexin-2'-O-rhamnoside (1), vitexin (2), isovitexin (3), rutin (4), hyperoside (5), and isoquercitrin (6). Furthermore, two flavonoids were isolated from C. x macrocarpa and identified as a diastereoisomeric mixture of (R)- and (S)-eriodictyol-7-O-beta-D-glucuronide (7) and luteolin-7-O-beta-D-glucuronide (8) by means of 1D- and 2D-NMR, MS, and UV experiments. Compounds 7 and 8 were isolated for the first time from Crataegus species. While missing in C. laevigata, their occurrence in C. rhipidophylla additionally emphasizes its chemotaxonomic relationship to C. x macrocarpa.     

Flavonoid races in lasthenia (Compositae)

Nine of the 13 taxa ofLasthenia in which two or more populations were examined for flavonoid constituents exhibited interpopulation variation in these constituents. In certain species entire classes of compounds were present in some races and absent from others. Some of these biochemical differences are due to the failure of certain steps to occur in the biosynthesis of various flavonoids from precursor compounds. Another pattern of variation involves intraspecific differences in the nature of flavonoid glycosides that are produced. In view of the close biosynthetic relationships among all the flavonoids produced byLasthenia, the genetic differences among the flavonoid races of a species may be small. Whether or not these biochemical differences have any adaptive significance is problematical at present.     

Secondary metabolites from Ajania salicifolia and their chemotaxonomic significance

Forty-seven secondary metabolites were isolated from Ajania salicifolia (Mattf.) Poljak, including eight sesquiterpenoids, two diterpenoids, three triterpenoids, four steroids, three flavonoids, five coumarins, five lignans, nine phenylpropanoids, five other phenolic compounds, and three acetylenes. Their chemotaxonomic significance within the genus Ajania (the tribe Anthemideae) of the family Asteraceae is discussed.     

Weitere isocedren-derivate aus Trixis paradoxa

The investigation of two further species from the tribe Mutisieae afforded in addition to known compounds three new sesquiterpene lactones and two further sesquiterpene esters, all closely related to compounds isolated before from other Trixis species. The isolation of these new substances from Trixis further establishes the chemotaxonomic situation in the subtribe Nassauviinae. From the Dinoseris species, among others, 1β-hydroxyalantolactone was isolated, indicating a relationship to the subtribe Gochnatiinae.     

Flavonoid patterns in Leptodactylon and Linanthus

Twenty-seven flavonoids were found among three species of Leptodactylon and sixteen species of Linanthus, of which only three were identical between the two genera. This argues strongly for the maintenance of two genera; however, the underlying similarities in coumarins, flavonol glycosides, chrysoeriol and glycoflavones suggest that the two genera are closely related. The flavonoid data also suggest that Leptodactylon and Linanthus of the tribe Gilieae may actually be closer to Phlox and Microsteris of the tribe Polemonieae, than to other Gilieae.     

New prenylflavanoids from marshallia grandiflora

The investigation of Marshallia grandiflora afforded four new flavanoids, their structures being elucidated by spectroscopic methods. This type of compound is rare in Compositae and similar compounds have only been isolated from species of the tribe Heliantheae and Inuleae. The chemotaxonomic situation is discussed briefly.     

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.     

A new flavonoid from the bark of Ulmus pumila L

A new flavonoid (6), together with eight (1–5 and 7–9) known flavonoids, were isolated from the n-butyl alcohol soluble portion of the EtOH extract of Ulmus pumila L. The chemical structures of the compounds were determined by using spectroscopic methods and further supported by comparison with previously literature values. Among them, flavonoids 4, 6 and 9 were isolated for the first time from the family Ulmaceae. Furthermore, the chemotaxonomic significance of the isolates was also discussed.     

Chemical constituents from Flourensia resinosa S.F. Blake (Asteraceae)

β-eudesmol (1), cryptomeridiol (2), ilicic acid (3), 5,7-dihydroxyflavone (chrysin, 4) and 7-O-methyl-chrysin (tectochrysin, 5) were isolated as the major constituents from the acetone extract of the aerial parts of Flourensia resinosa S.F. Blake (Asteraceae), along with flourensiadiol (6), spathulenol (7), p-acetophenol (8), lupeol (9), β-sitosterol (10), triacontanol (11) and squalene (12). Based on previous studies, this chemical composition for F. resinosa is in accordance with the chemical profile of other species of Flourensia. The profile of flavonoids, sesquiterpenes and benzofurans may have chemotaxonomic significance within this genus.     

Flavonoids from the Turkish endemic plant Rhaponticoides mykalea (Hub.-Mor.) M.V.Agab. & Greuter (Asteraceae)

The genus Rhaponticoides, recently segregated from the genus Centaurea, belongs to the family Asteraceae (tribe Cardueae). Rhaponticoides mykalea (Hub.-Mor.) M.V.Agab. & Greuter is an endemic species narrowly distributed in the Aegean part of Turkey. Owing to the existing anthropogenic impacts (such as urbanization and road construction) throughout its distribution range, the species has been the subject of several conservation studies. Phytochemical research on the aerial parts of R. mykalea led to the isolation of a new flavonoid, namely patuletin 7-O-(6″-E-sinapyl)-β-glucopyranoside, together with four known flavonoids from n-butanol extract. The structures of all isolated compounds were elucidated by spectroscopic analysis (1D and 2D NMR, HR-ESI-MS), as well as by comparison with the relevant literature data. All of the compounds have been isolated from the genus Rhaponticoides for the first time.     

Flavonoids and polyacetylenes from the aerial parts of Bidens tripartita

Fourteen flavonoids (1–14) and two polyacetylenes (15 and 16) were isolated from the aerial parts of Bidens tripartita. Thirteen compounds (1–7, 9, 11, 12, and 14–16) were isolated from this species for the first time, of which a flavonoid (11) was obtained for the first time from the genus Bidens. The chemotaxonomic significance of these compounds was summarized.     

FLORAL PIGMENTATION STUDIES IN THE GENUS GOSSYPIUM. IV. EFFECTS OF DIFFERENT GROWING ENVIRONMENTS ON FLAVONOID PIGMENTATION

Petal extracts of Gossypium were analyzed chromatographically to determine if flavonoid constituents are modified by different environments. In the initial phase, fourteen inbred stocks from four species were grown in a plot that was replicated in five different localities ranging from the Mojave Desert to Raleigh, North Carolina. Petal samples were collected from each stock at each site, and chromatograms developed from these samples looked highly similar regardless of the locality of the growing site. In the second phase, two stocks were phytotron grown under a series of regimes in which daylength, temperature, and mineral nutrition were varied. Each stock showed very little floral flavonoid variation despite the growing conditions. A chromatographic survey of leaf extracts from these same phytotrongrown plants showed them to be much more variable. In cotton, flower petal constituents appear to be less variable than leaf constituents. The chemotaxonomic significance of these results are discussed.     

A chemotaxonomic survey of the tribe psoraleeae in africa

A study of the leaf flavonoids, furanocoumarins and essential oils of 51 species (three genera) of the tribe Psoraleeae (Fabaceae) has provided chemical data to support the recent subdivision of the large worldwide genus Psoralea into a number of segregate genera. The flavonoid patterns in most species were very similar, consisting largely of proanthocyanidins and complex mixtures of flavone O- and C-glucosides. Psoralea repens, the only maritime species to be examined, is unique in containing only rutin. Three isoflavones (daidzein, formononetin and genistein) were of widespread occurrence. The genera Psoralea and Otholobium, which could not be separated on flavonoid data, were clearly demarcated by their essential oils. Furanocoumarin patterns were useful for the characterization of species.     

Caffeic acid ester derivatives and flavonoids of genus Arnaldoa (Asteraceae,Barnadesioideae)

The phytochemical composition of Arnaldoa species is barely known. In this work, the occurrence of caffeic acid ester derivatives and flavonoids in A. argentea, A. macbrideana and A. weberbaueri was established by liquid chromatography associated to high-resolution mass spectrometry analyses and comparison with data from isolated compounds. The distribution of chlorogenic acids in the genus Arnaldoa is herein described for the first time. The metabolite profile of Arnaldoa species was compared to that of Tithonia diversifolia, a known and rich source of chlorogenic acids and sesquiterpene lactones. In addition to the mono- and dicaffeoyl quinic acids present in T. diversifolia, Arnaldoa species exhibited the mono- and dicaffeoyl tartaric acids. Furthermore, mass features correspondent to that of sesquiterpene lactones present in T. diversifolia were not observed in Arnaldoa species. The chemotaxonomic implications of caffeic acid ester derivatives and flavonoid glycosides, as well as the potential absence of sesquiterpene lactones in the genus Arnaldoa and subfamily Barnadesioideae are discussed.     

Triterpene saponins and flavonoids in the seeds of Trifolium species

Seeds of 57 species of the genus Trifolium have been studied for the occurrence and concentration of soyasapogenol B glycosides and flavonoids. It was shown that all tested species contained soyasaponin I and in some species astragaloside VIII and/or 22-O-glucoside and 22-O-diglucoside of soyasaponin I were also present. Total concentration of saponins ranged from trace amounts up to 10 mg/g(DM). It was suggested that soyasapogenol B glycosides could be recognized as chemotaxonomic character of Fabaceae family. All but three tested species contained flavonoids. The majority of species contained quercetin as a sole flavonoid or in the mixture with a number of unidentified flavonoid components. Concentration of quercetine in some species was at the level of about 3 mg/g(DM). This high quercetin concentration and soyasaponin occurrence makes the seeds of some Trifolium species a potential source of health beneficial phytochemicals, to be used in human nutrition.     

Ein neues diterpen und weitere inhaltsstoffe aus Baccharis-arten

The investigation of nine further Baccharis species afforded in addition to known compounds three new p-coumaric acid derivatives, a new eudesmane aldehyde and a clerodane dilactone. The structures are elucidated by spectroscopic methods. The chemotaxonomic situation in this genus is still not very clear. The compounds isolated are not very characteristic, as very similar ones are present in other genera of the tribe to which Baccharis belongs.