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Isoflavonoids of the Leguminosae

Provision of an authoritative reference work on isoflavonoids of the Leguminosae with an emphasis on their chemosystematic, ecological, and economic significance.

Ateleia herbert-smithii, a new source of novel isoflavones. Photo: G.P. Lewis.

The isoflavonoids are one of the most distinctive and important classes of the naturally occurring flavonoids. Their distribution in plants is restricted compared to other flavonoids, and they are found predominantly in subfamily Papilionoideae of the Leguminosae. Well-known examples that have attracted interest because of their biological properties include the isoflavones of soy and red clover (oestrogenic), rotenones (insecticidal) and induced compounds with anti-fungal activity produced under stress conditions (phytoalexins). A recent focus of research in this area at Kew has been on the isoflavonoids of Ateleia (Annex 1) and Cicer.

The initial aim of the project was to produce a reference work entitled ‘Isoflavonoids of the Leguminosae’, covering the literature from 1997 to 2004. This was commissioned by the Royal Society of Chemistry for publication in their high impact journal, Natural Product Reports. Earlier reviews of the scientific literature relating to isoflavonoids to the end of 1991 appeared in four volumes of the ‘Advances in Flavonoids’ series, edited by the late Jeffrey Harborne and others. Subsequently, the literature from 1992 to 1996 was reviewed in two articles by Boland and Donnelly in Natural Product Reports (1995, 12, 321 and 1998, 15, 241). Two contributions to ‘Isoflavonoids of the Leguminosae’ have now been published as part of the current project, the first deals with the literature from 1997 to 2004 [1], and the second, with 2005–2007 [2].

All the major isoflavonoid subclasses are surveyed, including glycosides, dimers, heterodimers and oligomers. Points of interest relating to the source, biosynthesis, identification and biological properties of new compounds are emphasised, together with wider issues such as chemosystematic, ecological, and economic significance. Chemical syntheses of new isoflavonoids introduced in the reviews are cited, but general procedures for isoflavonoid synthesis and the production of well-known compounds are not included. Advances in the biosynthesis of Leguminosae isoflavonoids are described, together with new applications of hyphenated analytical techniques such as LC-MS and LC-NMR. The reviews are fully illustrated by structure drawings, and 570 new isoflavonoids have been described to date. Species names under which the compounds were published have been checked using currently available databases, and with colleagues in the Legume Team at Kew. Accepted names of legume taxa are quoted together with any synonyms used in original publications. Each published review includes a species checklist for new Leguminosae isoflavonoids in order to provide other researchers with easy access to phytochemical data on taxa of interest. Baseline data from these reviews are used in other Legume Team projects such as ‘Importance of Legumes and Legume-Derived Compounds in Medicine and Agriculture’ and ‘Systematic Phytochemistry of Legumes’. A third article in the series is intended for publication in 2012, covering the literature from 2008–2011.

 

Publications 2006-2011

  • [1] Veitch, N.C. (2007). Isoflavonoids of the Leguminosae. Natural Product Reports 24: 417–464.
  • [2] Veitch, N.C. (2009). Isoflavonoids of the Leguminosae. Natural Product Reports 26: 776–802.
     

Annex 1: Isoflavones from the leaves of the tropical forest tree, Ateleia herbert-smithii (Leguminosae; tribe Swartzieae). (Word doc)

Project team

Herbarium, Library, Art & Archives

Gwilym Lewis, Brian Schrire

Jodrell LaboratoryNigel Veitch