Flavonoids in Parahebe and Veronica: a chemosystematic study

Flavone glycosides are the main flavonoid leaf constituents in the related genera Parahebe and Veronica (Scrophulariaceae), in agreement with former chemical studies of the family. In Parahebe there are groups of species in which there are mainly luteolin glycosides, and groups in which 6-hydroxyluteolin dominates. Small amounts of apigenin occur in many taxa. Glycosylation is usually in the 7-position but 4′- and 5-glycosides were also found. In Veronica a larger variety of flavone aglycones was found: e.g. luteolin, apigenin, chrysoeriol, tricin and three different 6-hydroxyflavones. They are often present in the plants in the form of glucuronides. Glycosylation is in the 7-or-5-position. Most species of both genera have a distinctive pattern of flavonoid glycosides in their leaves which can be used for identification. Populations of P. catarractae are an exception in showing three different patterns, but here the variety in flavone profiles corresponds to the pattern of morphological and geographic variation within this taxon. Anthocyanins are responsible for the blue, mauve and pink colours of the flowers in the two genera. In Veronica they are based on delphinidin, whereas in Parahebe catarractae on both delphinidin and cyanidin.     

A chemosystematic study of Veronica: Iridoid glucosides

Caffeoyl-catalpol, isoferuloyl-catalpol, protocatechuoyl-catalpol, benzoyl-catalpol, p-hydroxybenzoyl catalpol (catalposide), vanilloyl-catalpol and cinnamoyl-aucubin have been isolated from several Veronica species (Scrophulariaceae) in a more or less pure state. The first four compounds have never been recorded in plants before. A PC survey of forty-three species of the genus sensu lato has shown a general presence of aucubin and catalpol. They are accompanied in many of the species by a complex mixture of esters, especially esters of catalpol with aromatic acids. In only one species have aucubin esters been found. Loganin has been identified in five species, this being the first time that this compound has been found in the Scrophulariaceae. Loganin is accompanied by unidentified loganin esters in the same five species. From the systematic point of view the complex mixtures of esters of catalpol in Veronica seem to be noteworthy. Species of Globularia, Erinus, Scrophularia Verbascum, Wulfenia, Catalpa and Plantago investigated either totally lacked ester glucosides in leaves or contained mainly different types of esters. The possible systematic meaning of these results is briefly discussed.     

Phytoalexin induction and its chemosystematic significance in the genus Trigonella

Using the drop-diffusate technique, a number of isoflavonoid phytoalexins have been obtained from the excised, fungus-inoculated leaflets of 41 species belonging to the legume genus Trigonella. Leaf diffusates variously contained pterocarpan (medicarpin and maackiain) and isoflavan (vestitol and sativan) derivatives previously associated with genera closely allied to Trigonella. In diffusates from T. calliceras, medicarpin was accompanied by a phytoalexin (designated TC-1) provisionally identified as a new hydroxylated pterocarpan. Most of the Trigonella species were also examined for their ability to release coumarin upon tissue maceration. The combined phytoalexin/coumarin data suggest that three major intrageneric chemical divisions occur in Trigonella; two of these apparently link the genus to Medicado/Factorovskya and Melilotus respectively, whilst the third provides some evidence for a connection with Trifolium. The taxonomic aspects of these findings are discussed in the light of earlier morphological studies which provided evidence for a distinct floral dichotomy amongst Trigonella species.     

Terpenoid chemosystematic studies of Abies grandis

Cortial essential oil from 395 typical Abies grandis and Abies grandis-Abies concolor intermediate trees collected in 48 locations was analyzed for composition of its monoterpenoids. The monoterpenoids were composed primarily of α-pinene, camphene, β-pinene, β-phellandrene and bornyl acetate, with tricyclene, 3-carene, myrcene and limonene in secondary quantities. Camphene, present in larger amounts in A. grandis and in smaller amounts in A. concolor var. lowiana, was used as a marker for studying intergradation of the two species in western and northwestern United States. A. grandis from northern Montana, Idaho and Washington, from British Columbia and Oregon and from Washington coastal areas could be classified as typical while the rest of the populations showed various degrees of intermediacy. The variability patterns agreed with the hypothesis that introgressive hybridization was the main reason for the intermediacy. Compared with morphological evaluations, the intermediate populations were chemically significantly more A. concolor-like. Typical A. grandis exhibited little population-to-population variability, in spite of its large geographic range. The results are correlated with and explained on the basis of existing paleobotanical records.     

A chemosystematic investigation on Ipomopsis

The diminutive North American desert annual species of Ipomopsis, Section Microgilia, I. depressa and I. polycladon, agree with other members of the genus in having a flavonoid syndrome based upon 6-methoxyflavonols. Patuletin is the predominant aglycone present but traces of eupatolitin and eupalitin were detected. In I. polycladon, four glycosides of patuletin and one of eupalitin were isolated and identified.     

A chemosystematic study of some geraniaceae

The flavonoids of five Geranium, fourteen Erodium and four Monsonia species were studied. Quercetin was the most common aglycone with lesse     

Flavonoid variation in Xanthisma texanum: Infrapopulation and interpopulation variation

Fourteen flavonoids were isolated from Xanthisma texanum. Chemosystematic interpretations are made concerning the origin and distribution of the infraspecific taxa of the species.     

2-deoxy-3-epiecdysone from the fern Blechnum vulcanicum

2-Deoxy-3-epiecdysone and ecdysone were isolated from fronds of the fern Blechnum vulcanicum. The structure and stereochemistry of the epiecdystero     

Flavonol derivatives of the genus Clibadium (compositae)

The flavonoids of eleven species of Clibadium are all based on the flavonols kaempferol, quercetin and quercetagetin. Glucose and galactose sugar substitutions occur in all taxa, while rhamnosides, arabinosides, xylosides, rutinosides and diglucosides are less widely distributed. O-Methylated compounds provide the most meaningful taxonomic information and serve to divide the species into two groups. Infraspecific variation of flavonoids is commonplace. This is the first report of flavonoids in Clibadium.     

Systematic implicationsofflavonoid patterns in Haplopappus segregates

Complex flavonoid patterns are correlated with primitive woody taxa and high base chromosome numbers among Haplopappus segregates. Variability among flavonoid complements supports the polyphyletic interpretation of the genus.     

A comparative study of the flavonoids of Medicago radiata with other Medicago and related Trigonella species

The flavonoid glycosides of Medicago radiata as well as M. arabica, M. polymorpha, M. sativa, Trigonella coerulescens, T. foenum-graecum and T. spicata were studied in detail. Major glycosides identified were the 7-glucuronides of apigenin, luteolin, chrysoeriol and tricin, as well as lesser amounts of di- and triglucuronides of chrysoeriol and tricin. Also identified were the 3-robinobioside and 3,7-diglucoside of kaempferol, along with lesser amounts of quercetin-3,7-diglucoside, 4′,7-dihydroxyflavone, 3′,4′,7-trihydroxyflavone, formononetin and daidzein. Twelve other Medicago and Trigonella species were also studied for their flavonoid aglycones. The systematic position of M. radiata is discussed.     

Hamamelose and its derivatives as chemotaxonomic markers in the genus Primula

About 550 species of vascular plants as well as a few mosses were checked for the occurrence of hamamelose, the corresponding alcohol hamamelitol and a galactoside of the latter, clusianose. Hamamelose was found in most of the species investigated. It provides therefore no useful character for chemotaxonomic purposes. Hamamelitol, however, could only be detected in the genus Primula and was therefore more useful. Small amounts of hamamelitol were found in the leaves of species from the subgenera Auganthus, Aleuritia and Auricula but not from Primula and Sphondylia. Clusianose and large amounts of hamamelitol are produced by species of 4 subsections of the section Auricula, but not by species of the subsections Auricula and Erythrodrosum. A taxonomic separation of the two latter from the 4 former subsections is suggested. The taxonomic position of Primula allionii should be reconsidered, since neither clusianose nor hamamelitol could be demonstrated in this species, whereas the other species of the subsection Rhopsidium do contain these carbohydrates.     

Isoflavonoid phytoalexins of the genus Medicago

Detached leaves of 25 annual and perennial Medicago species have been inoculated with the fungus, Helminthosporium carbonum, and examined for subsequent production of isoflavonoid phytoalexins. Hydroxylated pterocarpan (medicarpin) and isoflavan (vestitol, sativan and isosativan) phytoalexins were obtained from most of the species investigated. Although large quantities of two flavonoid derivatives, isoliquiritigenin and liquiritigenin, were isolated from leaves of M. lupulina, this species was apparently unable to produce isoflavonoid compounds. Traces of 7-hydroxy-2′,4′-dimethoxyisoflavanone (a substance not previously recorded in the tribe Trifolieae) were obtained (together with medicarpin, vestitol and sativan) from M. sativa cv Du Puits. Some taxonomic aspects of phytoalexin induction are discussed with reference to the generic location of certain controversial Medicago species including M. (Trigonella) radiata.     

Chemosystematic implications of flavonoids in Aniba riparia

The trunk wood of Aniba riparia (Nees) Mez (Lauraceae) contains flavokawin-B, (2S)-pinostrombin, (2S)-5, 7-di-O-methylpinocembrin, (2R, 3R)-5, 7-di-O-methylpinobanksin, izalpinin and 3,5, 7-tri-O-methylgalangin. Structural comparison of these flavonoids with the pyrones and neolignans, which characterized all previously examined Aniba spp., leads to a chemical classification of the genus.     

A permineralized species of mangrove fern Acrostichum L. from Deccan Intertrappean beds of India

Acrostichum intertrappeum sp. nov., a permineralized aerial stem with helically arranged petioles and roots in organic connection, is described from the Deccan Intertrappean beds of Nawargaon, District Wardha, Maharashtra, India and forms the first and the oldest record of its kind. The stem is covered with a thick ramentum of large multicellular scales and is characterized by a three angled dictyostele enclosing a few medullary bundles. The petioles are helically arranged and the vascular morphology is distinct with abaxial horseshoe-shaped ring, adaxial linear row and central dorso-ventrally elongated ring. The roots have hexarch steles and aerenchymatous cortex with large air cavities in rings. Occurrence of Acrostichum along with coastal palms, mangroves and marsh plants described earlier from this region and nearby locations suggests the north-western shore of the Deccan was linked to the equatorial ocean (South Western Tethys Sea) probably through the Narmada Valley during the deposition of Intertrappean sediments. Morphological features and anatomical characters of the fossil reveal that Acrostichum grew in marsh swamp environment or on mud flats of back water areas of the coastal environment prevailing a tropical humid climate when the Deccan region was almost at an equatorial position during the Late Cretaceous period. This new record further adds to a growing body of data on the diversification of polypodiaceous ferns that point to a much earlier crown group radiation of the group than previously thought.     

Molecular phylogeny and biogeography of the fern genus Pteris (Pteridaceae)

Background and Aims

Pteris (Pteridaceae), comprising over 250 species, had been thought to be a monophyletic genus until the three monotypic genera Neurocallis, Ochropteris and Platyzoma were included. However, the relationships between the type species of the genus Pteris, P. longifolia, and other species are still unknown. Furthermore, several infrageneric morphological classifications have been proposed, but are debated. To date, no worldwide phylogenetic hypothesis has been proposed for the genus, and no comprehensive biogeographical history of Pteris, crucial to understanding its cosmopolitan distribution, has been presented.

Methods

A molecular phylogeny of Pteris is presented for 135 species, based on cpDNA rbcL and matK and using maximum parsimony, maximum likelihood and Bayesian inference approaches. The inferred phylogeny was used to assess the biogeographical history of Pteris and to reconstruct the evolution of one ecological and four morphological characters commonly used for infrageneric classifications.

Key Results

The monophyly of Pteris remains uncertain, especially regarding the relationship of Pteris with Actiniopteris + Onychium and Platyzoma. Pteris comprises 11 clades supported by combinations of ecological and morphological character states, but none of the characters used in previous classifications were found to be exclusive synapomorphies. The results indicate that Pteris diversified around 47 million years ago, and when species colonized new geographical areas they generated new lineages, which are associated with morphological character transitions.

Conclusions

This first phylogeny of Pteris on a global scale and including more than half of the diversity of the genus should contribute to a new, more reliable infrageneric classification of Pteris, based not only on a few morphological characters but also on ecological traits and geographical distribution. The inferred biogeographical history highlights long-distance dispersal as a major process shaping the worldwide distribution of the species. Colonization of different niches was followed by subsequent morphological diversification. Dispersal events followed by allopatric and parapatric speciation contribute to the species diversity of Pteris.     

Flavonoid glycosides of Tribulus pentandrus and T. Terrestris

Twenty-five flavonoid glycosides were detected in Tribulus pentandrus and T. terrestris. The glycosides belong to the common flavonols, kaempferol, quercetin and isorhamnetin, with the 3-gentiobiosides as the major glycosides. Traces of a flavone (tricin) glycoside was also present in T. pentandrus. The separation of Tribulaceae as a distinct family from Zygophyllaceae is discussed.     

Flavonoid chemistry of the generic segregates Ascyrum and Crookea of Hypericum

Leaf flavonoids were isolated and characterized from the seven taxa of Hypericum, formerly segregated as Ascyrum and Crookea. These included flavonol 3-glycosides based on quercetin and kaempferol and flavone-O-glycosides and C-glycosides based on apigenin and luteolin. The flavonoid data do not indicate that the taxe of Ascyrum and Crookea form a single coherent group and hence support their merger with Hypericum.     

Sesquiterpenoids of Riccardia and Pallavicinia species

Riccardia species (Metzgeriales) contain various types of sesquiterpenes. R. jackii produces ent-selinane-, ent-aromadendrane-and ent-bicyclogermacrane-type sesquiterpenes together with (R)-cuparene and α-barbatene. Aneura pinguis (= Riccardia pinguis) is chemically quite different from R. multifida and R. jackii. The former produces a large amount of pinguisone. R. multifida contains 6-(3-methyl-2-butenyl)-indole and (+)-β-elemene as the major components. Pallavicinia longispina (Dilaenaceae; Metzgeriales) produces mainly spathulenol. The chiral properties of the sesquiterpenes isolated from R. jackii are quite similar to those of red algae, Laurencia species.     

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.