Systematic Phytochemistry of Legumes
Analysing legume extract using LC-MS
Leguminosae produce a diverse array of secondary metabolites. For this reason, and in view of the economic importance of the family, the phytochemistry of legumes has been investigated intensively. However, most studies have concentrated on economically-important or widely-available species and the results have been interpreted within the traditional concepts of legume systematics based mostly upon morphological characters. Now, with the analysis of DNA sequences providing new hypotheses on relationships for a wide range of legume genera, it is possible to re-examine existing phytochemical data and obtain new data within the context of current ideas of legume systematics.
The aim of this project is to undertake phytochemical investigations on relationships revealed by the new arrangement of legume genera outlined in Legumes of the World. One focus for study is genera currently classified in the tribes Sophoreae and Swartzieae of subfamily Papilionoideae which are now thought to comprise an unnatural assemblage, with several genera having closer affinities with other legume tribes and generic groupings than with core Sophoreae and Swartzieae. Modern analytical techniques, such as the combination of high performance liquid chromatography with mass spectrometry (LC-MS), are used in these studies to examine small fragments of herbarium material. This approach is useful to determine whether an uncommon compound described from a given taxon occurs in other previously unstudied taxa that are now thought to be related (Annex 1). Another approach is to undertake detailed phytochemical characterisation of taxa cultivated at RBG Kew through the isolation of compounds and their structural elucidation, by in-house NMR spectroscopy. This approach may reveal new phytochemical characters that can then be investigated in a systematic framework.
Project Team
Project Leader: Kite, Geoffrey
Herbarium
Barbara Mackinder, Gwilym Lewis, Brian Schrire
HPE
John Sitch
Jodrell Laboratory
Geoffrey Kite, Monique Simmonds, Nigel Veitch
Project Partners and Collaborators
Mexico
Colegio de Postgraduados, Mexico City
The Netherlands
University of Wageningen
UK
National Botanic Garden of Wales
Annex Material
Annex 1: Trace from liquid chromatography-mass spectrometry (LC-MS) of a small fragment of material of Bocoa mollis (Swartzieae) from RBG Kew’s Herbarium collections. (Word document)
Annex 2: Structure of Milbraedin, a new and unusual flavonoid glycoside isolated from the leaves of Mildbraediodendron excelsum (Swartzieae) following detailed phytochemical investigation of material in the living collections of RBG Kew. (Word document)