Leguminosae flavonoids structure

A characteristic structural feature of all Leguminosae flavonoids, regardless of subfamily, is the presence of 5-deoxy compounds. In the Papilionoideae, both 5-deoxyflavonoids and 5-deoxyisoflavonoids are found. A previous survey by Hegnauer and Grayer-Barkmeijer (1993) based on aglycone structures reported up to the end of 1985 showed that 5-OH groups... 

As part of the series Topics in Heterocyclic chemistry, this volume titled Bioactive Heterocycles II presents comprehensive and up-to-date reviews on selected topics concerning mainly the usefulness for human health of flavonoids and related compounds, Sophora flavonoids and their functions in Sophora species (Leguminosae), the relationship of biological activity with the diverse structures of heterocycles by quantum chemical calculation, advances in bioactive mesoionic heterocycles, and the spectroscopic properties and application of bioactive phenothiazines including also benzo[a]phenothiazines. 

The full characterization of some flavonoid and isoflavonoid structures found in the Leguminosae requires determination of absolute configuration, principally by CD spectroscopy (Slade et al, 2005). This information cannot be obtained from the hyphenated analyses involving MS and NMR described in the preceding sections, yet it is crucial to... 

More chemistry has been carried out on the heartwood flavonoids of the Leguminosae than on those of any other plant family. This is not surprising considering that there are many tree species in what is a very large family and also that these trees are used as timber, for furniture, or as a source of tannin. But it also reflects the fact that there are an enormous variety of chemical structures present, particularly of isoflavonoids. The discovery of interesting and novel structures in one tree inevitably encourages investigation of related species for further novelties. 

The majority of the plant pigments hitherto isolated from woods in pure form are the flavonoids, such as flavone, flavanone, isoflavone, isoflavanone, pterocar-pane, and chalcone derivatives, along with the phenols stilbene and xanthone, which are almost white or yellow in color. Other flavonoids such as aurone and neoflavone derivatives (orange pigments) have a limited distribution and sometimes occur as wood extractives in species of the Anacardiaceae and Leguminosae (4, 7). The presence of the typical anthocyanin derivatives of flowers and fruits is extremely rare in wood, but their leuco-compounds such as flavan-3-ol and flavan-3,4-diol have been found to occur in the wood of a considerable number of tree species (14). Besides anthocyanidin, the few other deep-colored (red, purple, or blue) pigments from woods usually possess a quinone structure. 

Closely related both structurally and biogenetically to the flavonoids are two groups of natural products—the isoflavonoids and neoflavonoids. In contrast to the flavonoids however, these groups are of a more limited taxonomic distribution in higher plants and are found primarily in the Leguminosae. Isoflavonoids have in common the 1,2-diphenyl propane skeleton (11) and include many classes of natural product such as the isoflavones, isoflava-nones, rotenoids, pterocarpans and coumestans. The term neo-flavonoid was introduced by Ollis and his associates to cover the third group of compounds which possess the 1,1-diarylpropane skeleton (12) and includes such compounds as the 4-phenyl-coumarins and the various dalbergiones. 

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