THE FLAVONOIDS OF LASTHENIA (COMPOSITAE)

Lasthenia (Compositae: Helenieae), a western North American-Chilean genus of 16 species, produces 22 flavonoid glycosides. Flavonoids are the chalcones butein and okanin, the aurones maritimetin and sulfuretin, the flavone luteolin, and the flavonols kaempferol, quercetin, and patuletin. The presence or absence of various of these classes of compounds in general follows sectional alignments in the genus, confirms affinities based on morphological and cytological evidence, and suggests relationships of problematical species. Intraspecific variation in flavonoid constituents occurs in several species, and in one taxon intrapopulation variation seems to exist as well. Evolution within Lasthenia has been associated with a loss of the ability to produce or accumulate luteolin, chalcones, and aurones; an increase in diversity of quercetin glycosides; acquisition of the ability to produce patuletin; and an elaboration of glycosylation patterns of patuletin.     

FLAVONOIDS AND FLAVONOID EVOLUTION IN FUCHSIA (ONAGRACEAE)

A comprehensive survey of 225 populations of 80 taxa of Fuchsia showed flavonol monoglycosides, especially quercetin and kaempferol 3-O-glucosides, to be ubiquitous in all species examined. Flavonol diglycosides are unusual, however, and occur in just eight species in five of the nine sections of the genus. Flavone glycosides were found in only nine species belonging to five sections and are associated with primitive taxa, having been lost in more recently derived species or sections. Flavone sulphates are restricted to species of the disjunct sect. Skinnera from New Zealand. The limited presence of flavone glycosides and flavonol diglycosides in certain species can be effectively employed as chemical markers in determining the parentage of these species in fuchsia cultivars of unknown hybrid origin.     

A taxonomic revision of Crambe section Dendrocrambe (Brassicaceae)

As part of a recent revision of the genus Crambe , based on the morphological study of herbarium and cultivated material, the systematics of section Dendrocrambe DC. are reviewed here. Section Dendrocrambe (including monospecific section Rhipocrambe Svent.) is considered to comprise 14 species, all endemic to Macaronesian archipelagoes: 13 in the Canary Islands and one in the Madeira Islands. Crambe feuilleei A. Santos and C. gomerae subsp. hirsuta Prina are described here, C. fruticosa subsp. pinnatifida (Lowe) Prina & Mart.-Laborde is proposed as a new status, and a key for the identification of all taxa, as well as maps with localities of collection, are provided.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156 , 291–304.     

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.     

Internal transcribed spacer sequence phylogeny of Crambe L. (Brassicaceae): molecular data reveal two Old World disjunctions

Crambe L. (Brassicaceae) is an Old World genus with a disjunct distribution among four major centers of species diversity. A phylogenetic analysis of nucleotide sequences of the internal transcribed spacers (ITS) of the nuclear ribosomal repeat was conducted with 27 species of Crambe and 18 related genera. Cladistic analyses using weighted and unweighted parsimony support Crambe as a monophyletic genus with three major lineages. The first comprises those taxa endemic to the Macaronesian archipelagos. Taxa with a predominant Mediterranean distribution form the second assemblage, and a disjunction between east Africa (C. abyssinica) and the Mediterranean (C. hispanica) occurs in this clade. The third lineage includes all Eurosiberian-Asian taxa and C. kilimandscharica, a species from the highlands of east Africa. A basal biogeographic split between east Africa and Eurasia is present in the third clade. The patterns of relationships in the ITS tree are concordant with known climatic events in northern Africa and southwestern Asia since the middle Miocene. The ITS trees are congruent with the current sectional classification except for a few members of sections Crambe, Leptocrambe, and Orientecrambe (C. cordifolia, C. endentula, C. kilimandscharica, and C. kotschyana). Low levels of support in the basal branches do not allow resolution of which genera of the subtribes Raphaniae or Brassicinae are sister to Crambe. Both subtribes appear to be highly polyphyletic in the ITS trees.     

Chemotaxonomy of Geranium

The species of Geranium show a wide range of flavonoid pattern, from one in which ail the regular (primitive) constituents are present to one where only quercetin and kaempferol are present. The primitive pattern predominates in the central Eurasian area, radiating eastward and westward from which the flavonoid constituents become progressivley impoverished. A "flavonoid score" providing a numerical estimate of this impoverishment is proposed. The results are presented and discussed in relation to Knuth's arrangement of the genus.     

Flavonoid distribution patterns in Leucanthemum and related species from North Africa

Flavonoid data is reported for 16 species including eight species of Leucanthemum from North Africa, four from Europe and related species in the Chrysanthemum-Leucanthemum complex. Flavonols, especially quercetin, isorhaamnetin, kaempferol, patuletin and spinacetin, are predominant in the North African species. Flavones, which are common in Leucanthemum species in Europe, are of very rare occurrence in the North African species. The relationship of the species based on the distribution of flavonoid glycosides and aglycones from the ray florets is discussed.     

Flavonoid chemistry of arceuthobium (viscaceae)

Flavonoid compounds from 36 of the 38 known taxa of the genusArceuthobium (dwarf mistletoes) were examined. The flavonoid chemistry of the genus is rather uniform, all taxa producing 3-O-glycosides of the flavonols quercetin and myricetin. No infraspecific chemical variation was encountered, and in those instances where subspecific taxa are recognized, their chemistry was uniform. At the subgeneric level, members of subgenusArceuthobium synthesize primarily glucosides, whereas galactosides are more common in subgenusVaginata. In two of the four Old World species of subgenusArceuthobium (A. juniperi- procerae andA. oxycedri) only myricetin 3-O-glucoside was detected. There are no absolute flavonoid differences between subgenera, sections, or series. On the other hand, flavonoids are useful in several instances at the species level. In several cases, chemical data lend support to the recognition of species which in the past have been considered doubtfully distinct on the basis of morphology.     

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.     

Flavonoids and the taxonomy of Cercis

Flavonoids of 11 samples of Cercis, comprising seven species, were isolated and identified. Only 3-O-monoglycosides of kaempferol, quercetin and myricetin were obtained. Bauhinia (the largest genus in tribe Cercideae) is akin to Cercis because flavones are rarely found in the former. On the other hand, species of Bauhinia often present glycosides of isorhamnetin and a wider diversity of glycosides, and only rarely present myricetin. The frequent occurrence of this flavonol and the simpler flavonoid profile of Cercis may reflect a greater antiquity of Cercis as compared with Bauhinia. With the exception of C. canadensis var. mexicana, Cercis taxa from xerophytic habitats did not yield kaempferol glycosides in detectable amounts, as opposed to taxa from mesophytic habitats. The results obtained are consistent with proposals of merging C. reniformis into synonymy of C. occidentalis, as well as the recognition of two North American species, C. canadensis and C. occidentalis, and the recognition of the Asian C. gigantea.     

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 phylogenetic relationship of Solanum flavonols

Flavonoid profiles of Solanum sections Petota, Basarthrum, Solanum and Androceras have all proved to be useful in the delineation of species and series boundaries. A total of sixty-four flavonols have been isolated from these four sections, forty of which have been fully characterized. Flavonol glycosides of kaempferol and quercetin are confirmed as the flavonoids characteristic of this genus but in addition methylated and acylated compounds have also been isolated. By combining existing data, it is possible to develop a phylogenetic scheme illustrating the relationship between each section on the basis of the biosynthetic complexity of their flavonol substitution patterns. Sections Petota and Basarthrum appear to be more ‘primitive’ than sections Solanum and Androceras.     

The flavonoids of ferns in the isolated genera Loxsoma and Loxsomopsis

Kaempferol and quercetin 3-O-glucosides and 3-O-rhamnoglucosides are common to both Loxsoma cunninghamii and Loxsomopsis costaricensis, but in the former the new flavonoid glycosides, kaempferol and quercetin 3-O-glucoside-7-O-arabinoside have also been identified. The data are consistent with the proposed taxonomic relationship between these geographically isolated genera. Comparative flavonoid chemistry indicates that the Loxsomaceae may be a primitive family, not closely related to the Hymenophyllaceae or the Cyatheaceae.     

Chemosystematic studies in the chrysobalanaceae. I. Flavonoids in Parinari

A survey of flavonoids in 31 Asian, African and Neotropical species of Parinari showed a predominance of flavonol glycosides based on myricetin, quercertin, and kaemp-ferol. The African taxa split into two groups based on the presence or absence of myricetin glycosides. The Neotropical taxa, a complex of closely related species, are chemically very similar to each other and lack myre?etin, as does one group of African species. The Asian taxa are similar to the Neotropical ones in their flavonoid patterns and lack of myricetin glycosides. The presence of myricetin considered a primitive flavonoid character, suggest that te African species pro-ducing this flavonol represent a primitive nucleus eastward and westward ex-pansion to two myricetin-lacking phytogeographic lines. This hypothesis is in agreement with current proposals for geographic evolution in the Chrysobalanaceae.     

Phenolic chemotaxonomy and phytogeography of Adiantum

The occurrence of flavonoid glycosides and hydroxycinnamic acid esters has been examined in the fronds of 58 species of Adiantum , covering the morphological and geographical range of the genus. The genus may be divided into five sections on the basis of their flavonoid patterns. The correspondence of these patterns with the major existing systems of classification is discussed. The A. capillus-veneris group is the least homogeneous, both morphologically and chemically, and requires further study. However, the flavonoid patterns of extracts of the fronds of thirteen samples of the cosmopolitan species A. capillus-veneris from different geographical areas were found to be qualitatively similar, suggesting this species has probably spread relatively recently. Adiantum species which are restricted to the Old World have a basically different flavonoid pattern from those species which are exclusive to the New World. The phytogeographical and phylogenetic implications of these results are outlined and it is concluded that the Old World species represent more ancient stocks than those in the New World.     

Anthochlors and other flavonoids as honey guides in the compositae

Anthochlor pigments have been recorded for the first time in three species of Helianthus and in Viguiera laciniata. Yellow flavonols based on quercetagetin or gossypetin have been found in yellow flowered species of Eriophyllum and Geraea. In Eriophyllum, all seven species studied contain quercetagetin and/or patuletin 7-glucosides. In those species containing UV honey guides, either yellow flavonoid or colourless quercetin glycosides can be responsible for producing strongly UV absorbent zones on the flowers. Thus in Helianthus, honey guides in some species result from UV absorbance by the chalcone coreopsin and the aurone sulphurein, whilst in H. annuus they result from absorbance by quercetin 3- and 7-glucosides. Furthermore, the occurrence of yellow flavonoids in flowers is not directly correlated with the presence of UV nectar guides. A detailed study of the distribution of chalcone in Coreopsis bigelovii flowers revealed that the anthochlor was present in epidermal cells on both upper and lower surfaces.     

The unique occurrence of the flavone aglycone tricetin in Myrtaceae pollen

In pollen, flavonoids are usually found as glycosides and in particular, flavonol 3-O-diglycosides. However, in members of the Myrtaceae, subfamily Leptospermoideae, the rare flavone aglycone tricetin, along with other flavonoid aglycones including 3-O-methyl quercetin and luteolin, have been found to comprise a significant portion of the constituent flavonoids.     

Leaf flavonoids from Croton urucurana and C. floribundus (Euphorbiaceae)

Flavonoids were isolated by PVPP column chromatography of leaf extracts of Croton floribundus Spreng and C. urucurana Baill. and identified by NMR and co-chromatography with standards. The two species revealed highly distinct flavonoid profiles. C. urucurana, belonging to the phylogenetically basal section Cyclostigma, yielded the flavone C-glycosides vitexin and orientin, quercetin and the O-glycosides quercetin 7-O-rhamnoside, rhamnitrin and rutin, in addition to tiliroside. Instead, C. floribundus, from the more derived section Lasiogyne, yielded no C-glycosides, but a high diversity of classes of flavonols, including kaempferol, three flavonol O-methyl ethers, isoquercitrin, three tri-O-galactosides, in addition to tiliroside and an isorhamnetin-coumaroyl-O-glycoside. The present work is the first report for Croton of two rhamnosides (isolated from C. urucurana). It is also the first report for Euphorbiaceae of two tri-O-glycosides obtained from C. floribundus. The distribution of flavonoids in the two species as determined by HPLC-DAD of extracts of small leaf samples of herbarium specimens is highly similar with the profiles resulting from isolation of compounds from bulky leaf samples. Differences among specimens of the same species were restricted to relative proportions of individual constituents. The results indicate that flavonoid profiles are effective to characterize and distinguish the two species. The present results, combined with literature data, supports the condition of tiliroside as a marker of Croton and the hypothesis of an evolutionary trend in the genus toward the loss of C-glycosides and a progressive complexity of flavonoid profiles.     

The leaf flavonoids of the Zingiberales

A survey of flavonoids in the leaves of 81 species of the Zingiberales showed that, while most of the major classes of flavonoid are represented in the order, only two families, the Zingiberaceae and Marantaceae are rich in these constituents. In the Musaceae (in 9 species), Strelitziaceae (in 8 species) and Cannaceae (1 of 2 species) flavonol glycosides were detected in small amount and in the Lowiaceae no flavonoids were fully identified. In the Zingiberaceae kaempferol (in 22%), quercetin (72%) and proanthocyanidins (71%) are distributed throughout the family. The two subfamilies of the Zingiberaceae may be distinguished by the presence of myricetin (in 26%), isorhamnetin (10%) and syringetin (3%) in the Zingiberoideae and of flavone $\text{C-}\text{glycosides}$ (in 86% of taxa) in the Costoideae. A number of genera have distinctive flavonol profiles: e.g. Hedychium species have myricetin and quercetin. Roscoea species isorhamnetin and quercetin and Alpinia species kaempferol and quercetin glycosides. A new glycoside, syringetin 3-rhamnoside was identified in Hedychium stenopetalum. In the Zingiberoideae flavonols were found in glycosidic combination with glucuronic acid, rhamnose and glucose but glucuronides were not detected in the Costoideae or elsewhere in the Zingiberales. The Marantaceae is chemically the most diverse group and may be distinguished from other members of the Zingiberales by the occurrence of both flavone $\text{O-}$ and $\text{C-}\text{glycosides}$ and the absence of kaempferol and isorhamnetin glycosides. The distribution of flavonoid constituents within the Marantaceae does not closely follow the existing tribai or generic limits. Flavonols (in 50% of species). flavones (20%) and flavone $\text{C-}\text{glycosides}$ (40%) are found with similar frequency in the two tribes and in the genera Calathea and Maranta both flavone and flavonol glycosides occur. Apigenin- and luteolin-7-sulphates and luteolin-7,3′-disulphate were identified in Maranta bicolor and M. leuconeura var. kerchoveana and several flavone $\text{C-}\text{glycosides}$ sulphates in Stromanthe sanguinea. Anthocyanins were identified in those species with pigmented leaves or stems and a common pattern based on cyanidin-and delphinidin-3-rutinosides was observed throughout the group. Finally the possible relationship of the Zingiberales to the Commelinales, Liliales, Bromeliales and Fluviales is discussed.     

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.