Bruce A. Bohm

Flavonoids of the sunflower family (Asteraceae)

Section I. Introduction to the Sunflower Family.- 1. Biology and Distribution.- 2. Classification, Phylogeny and Biogeography.- Section II. Introduction to the Flavonoids.- 3. The Use of Flavonoids as Taxonomic Markers.- 4. Structural Variation of the Flavonoids of Asteraceae.- 5. Biosynthesis of Flavonoids.- 6. Biological Functions of Flavonoids.- Section III. Flavonoid Data.- 7. Flavonoids of Anthemideae.- 8. Flavonoids of Astereae.- 9. Flavonoids of Calenduleae and Cardueae.- 10. Flavonoids of Eupatorieae.- 11. Flavonoids of Heliantheae s.l.- 12. Flavonoids of Inuleae s.l.- 13. Flavonoids of Lactuceae.- 14. Flavonoids of Mutisieae and Barnadesioideae.- 15. Flavonoids of Senecioneae.- 16. Flavonoids of Tageteae.- 17. Flavonoids of Vernonieae and Liabeae.- Section IV. Efficacy of Flavonoids at Different Taxonomic Levels.- 18. Flavonoids at the Subfamilial Level.- 19. Flavonoids at the Tribal Level.- 20. Flavonoids at the Subtribal Level.- 21. Flavonoids at the Generic Level.- 22. Flavonoids at the Specific Level.- 23. Flavonoids at Infraspecific Levels.- Section V. Flavonoids as Indicators of the Evolutionary Process.- 24. Flavonoids and Populational Variation.- 25. Flavonoids and Hybridization and Introgression.- Section VI. Flavonoids and Phylogeny.- 26. Flavonoid Relationships with other Families.- 27. Evolution of the Flavonoid System in Asteraceae.- Addendum.- References.- Common Names of Flavonoids Used in This Book and Their Equivalents.- Chemical Index.- Taxon Index.

Ellagitannins from Tellima grandiflora

Abstract Three ellagitannins present in Tellima grandiflora have been isolated and partly identified. Two are 2,3-digallyl-4,6-hexahydroxydiphenoyl -β- d -glucopyranose and 1,2,3-trigallyl-4,6-hexahydroxydiphenoyl-β- d -glucopyranose. The third is complex, with five gallyl and two hexahydroxydiphenyl residues; hydrolysis yielded glucose, gallic acid and ellagic acid.

Angiosperm Flavonoid Evolution: A Reappraisal

Critical review of the distribution of flavonoids in the angiosperms, combined with considerations of their biosynthesis has led to a reappraisal of existing dicta on the phylogenetic status of the various structural types. Caution is necessary when attempting evolutionary interpretations because there seem to be two trends operating within the angiosperms. The major one involves reduction in structural complexity, following a reverse direction down the biosynthetic pathway. Reduction in the actual number of flavonoid structures produced is also part of the trend. A secondary trend, often superimposed on the first, involves diversification whereby the flavonoid nucleus undergoes progressive elaboration (extra oxygenation, 0-methylation, etc.). The complications engendered by these two trends require the recognition of at least three evolutionary grades: primitive, advanced and highly advanced. It is very difficult to distinguish between the primitive and highly advanced conditions because in many cases the flavonoid phenotype is identical: in the first case the simplicity is primary and in the second it is secondary by reduction. Correlations in distribution of the different flavonoid structures can not only be interpreted in phylogenetic terms but also in terms of adaptive complexes. Many structures and groups of structures have never been reported from nature-are these ill-adaptive? On the other hand, there are several combinations which do appear regularly and it is suggested that they contribute to adaptive peaks. These flavonoid combinations are shown, within the limits of their definition, to characterize many orders and superorders (with increased precision of definition, the combinations can also be used to characterize families and lower taxa). The flavonoid profiles of the orders show a remarkable correlation with the occurrences of other secondary metabolites such as benzyl isoquinoline alkaloids, tannins, iridoids, sesquiterpenes and polyacetylenes. It is possible that flavonoids are not independent in their efficiency of action but rather act in functional consort not only with other metabolites and physiological processes, but also with morphological and anatomical

Edaphic races and phylogenetic taxa in the Lasthenia californica complex (Asteraceae: Heliantheae): an hypothesis of parallel evolution

Lasthenia californica sensu Ornduff consists of two races that differ in their flavonoid pigments and edaphic tolerances. Recent phylogenetic studies of Lasthenia have revealed that members of L. californica sensu Ornduff belong to two phylogenetic species. The relationship of the edaphic races to these new species and to each other is the focus of this study. Characterization of flavonoid profiles and phylogenetic placement of 33 populations demonstrates that races and phylogenetic taxa are not concordant, suggesting that one or both edaphic races evolved in parallel in the two clades. We hypothesize an edaphically linked ecological role for flavonoid differences that first revealed the existence of two races.

Intraspecific flavonoid variation

This review is concerned with variation of flavonoid patterns within species. Many examples of species with invariant flavonoid patterns are known; there are at least as many examples where complex arrays of pigments are known. Eight categories of variation are discussed: 1) qualitatively invariant pigment profiles, 2) quantitative variation, 3) flavonoid races that do not correspond to recognized taxonomic groups, 4) flavonoid races that do correspond to recognized taxonomic groups, 5) flavonoid profile differences between different ploidy levels, 6) differences between organs or between tissues, 7) differences between developmental stages, and 8) environmentally influenced flavonoid profiles. These types of variation seem to occur randomly in the plant kingdom. Members of the same family, or in some cases, the same genus, can display different types of variation. Careful attention to these sources of variation is necessary before flavonoid characters can be used in taxonomic studies.RésuméCette revue s’occupe du phénomène de la variation infraspécifique dans la répartition des flavonoïdes. On peut trouver plusieurs exemples de constitution flavonique invariable; on trouve autant d’exemples de constitution flavonique très variable. Les catégories suivantes de variation sont discutées: 1) répartition qualitative constante, 2) variation quantitative, 3) races flavoniques qui ne correspondent pas aux cercles taxonomique reconnus, 4) races flavoniques qui correspondent aux cercles taxonomique reconnus, 5) différences entre les cytotypes diploïdes et polyploides, 6) différences entre les organs et entre les tissus, 7) différences entre les différents stades du développement, et 8) différences qu’on peut attribuer aux influences de l’environnement. Il n’existe pas de modèle constante pour cette espèce de variation. Les membres de la même famille ou en certain cas du même genre montrent des modèles de variation différentes. Donc, il faut faire très attention au degré de variabilité avant d’utiliser les caractères flavoniques pour la taxonomie.

Inhibition of tomato ringspot virus by flavonoids

Abstract When applied in a mixed inoculum with tomato ringspot nepovirus (TomRSV), flavonoids and related compounds inhibited infectivity in Chenopodium quinoa . Compounds that showed strong anti-viral activity were: quercetin, quercetin 3-methyl ether, quercetin 7-methyl ether, quercetin 3,7,3′4′-tetramethyl ether, galangin 3-methyl ether, morin, robinin, quercetin 3,7,4′-trimethyl ether, quercetin 7,4′-dimethyl ether, 7,4′-di- O -benzol-quercetin 7-hydroxy-3,4′-dimethyl flavone, 6,3′-dihydroxy-4′-methyl aurone and fisetin 4′-methyl ether. Quercetin applied at a concentration of 5 μg ml −1 caused 70% inhibition of local lesion development. When quercetin was applied to leaves prior to inoculation, there was only slight induced resistance to infection. Quercetin at 5 μg ml −1 did not affect virus multiplication in protoplasts prepared from cucumber cotyledons and transfected with viral-RNA. In meristematic tip cultures, quercetin reduced virus titre by up to 89% over a period of 36 weeks whereas ribavirin caused a 25% reduction over the same period. It is proposed that flavonoids interfere with an early event in the virus life cycle resulting in decreased infectivity and titre in tissue culture.

Adaptive Differentiation in Response to Water Stress by Edaphic Races of Lasthenia californica (Asteraceae)

Two edaphic races of Lasthenia californica sensu Ornduff (races A and C) grow in parapatry on a serpentine outcrop at Jasper Ridge Biological Preserve, California. The races occupy distinct edaphic habitats that have different water‐holding capacities. We predict that the two races will show differentiation in reproductive strategies related to their response to water stress. In order to test this hypothesis, we performed a greenhouse experiment to characterize the reaction norms of the two races exposed to a gradient in water availability. We measured the response of five variables to the watering treatments: early survivorship, days to flowering, root/shoot dry mass ratio, total dry mass, and a measure of reproductive fitness, number of flower heads. We found that the races differ in their allocation patterns to roots compared with shoots and in days to flowering, indicating genetic differentiation for these traits. Race A consistently allocates relatively more biomass to roots while race C flowers earlier. However, the reaction norms of the two races for all nonreproductive traits are parallel, indicating that races do not differ in their plastic response to drought stress. The number of flower heads, our measure of reproductive fitness, did, however, exhibit differential response to water availability between the two races. Under low watering treatment, race C plants are able to maintain flower head production, while race A plants show a monotonic decrease in head production as water stress increases. Results indicate that race C plants are better adapted to drought; they are able to maintain a high reproductive output under low water availability. However, as the phenotype of race A is affected by drought, reproductive output decreases, as we would predict for plants that rarely experience drought in their natural environment.

Biosystematics and Evolution of Cultivated Coca (Erythroxylaceae)

ABSTRAcr. Erythroxylum coca vars. coca and ipadu and E. novogranatense vars. novogranatense and truxillense are closely related taxa cultivated in South America for their cocaine-bearing leaves. Taxonomically they have been variously treated, ranging from one to three separate species. Erythroxylum novogranatense var. truxillense is morphologically somewhat intermediate between E. c. var. coca and E. n. var. novogranatense and has been suggested to be a hybrid between the two. Evidence from artificial hybridizations, leaf flavonoid chemistry, and breeding system studies was used to clarify the taxonomic and evolutionary relationships of these plants. This evidence suggests that E. n. var. truxillense is intermediate between E. coca and E. n. novogranatense but it is not a hybrid between them. These three taxa represent a linear evolutionary series, with E. c. var. coca the ancestral taxon, E. n. var. truxillense derived from it, and E. n. var. novogranatense derived from E. n. var. truxillense. Eythroxylum c. var. ipadu was independently derived from E. c. var. coca. All of the taxa are partially isolated genetically except E. c. var. coca and E. c. var. ipadu. The taxonomic treatment that best reflects their relationships is to regard E. novogranatense var. novogranatense and E. n. var. truxillense as varieties of a species distinct from E. coca. Only limited material of E. c. var. ipadu was available for study, but it might better be regarded as a cultivar of E. coca.

Flavonoids of Wyethia angustifolia and W. helenioides

Abstract Seventeen flavonoids, including seven new natural products, were isolated from a dichloromethane extract of Wyethia angustifolia . Known compounds are:8- C -prenyleriodictyol, 6- C -prenyleriodictyol, 8- C -prenylnaringenin, 6-C-prenylnaringenin, orobol 7-methyl ether, orobol 3′-methyl ether, naringenin 4′-methyl ether, orobol, eriodictyol and naringenin. The new compounds are 6- C -prenylorobol, 6- C -prenylorobol 3′-methyl ether, orobol 7,3′-dimethyl ether, 8- C -prenyldihydroisorhamnetin, 7,8-dihydrooxepinocriodictyol, 7,8-dihydrooxepinodihydroquercetin and 3′,4′-dihydrooxepino-6′-hydroxybutein. A dichloromethane extract of Wyethia heleniodes yielded eleven compounds only five of which were previously reported from the species. All these compounds appear to occur on the leaf surface.

The proanthocyanidin polymers in some species of Onobrychis

Abstract Proanthocyanidin (PA) polymers (condensed tannins) were isolated and purified from the leaves of 26 accessions and species of sainfoin (Onobrychis). Analysis of the degradation products by HPLC revealed that epicatechin, gallocatechin and epigallocatechin were present as both terminal and extension units in all the samples studied while catechin was a terminal unit only. Quantitative analysis showed that epigallocatechin was the dominant extension unit in all of these polymers (52–63% total units). A mean degree of polymerization (DP) of 6.5 (by HPLC) and 9 (by Gel Permeation Chromatography) was obtained. The PA polymers consist principally (73–85%) of delphinidin units and 78–87% of cis-isomer units in all the samples studied.