Flavonoids as chemosystematic markers for the genus Adenocarpus

Abstract Twenty-four species of the genus Adenocarpus (Leguminosae), sampled in Mediterranean and tropical African regions, were surveyed for their flavonoids by means of high performance liquid chromatography with diode array detection and atmospheric pressure chemical ionization-mass spectrometry. For ten of these species, 2–8 samples were examined to investigate a possible infraspecific variation in flavonoids. Nineteen flavonoids belonging to various different classes (flavone C - and O -glycosides, flavonol glycosides, isoflavone glycosides and flavanones) were detected. Previous DNA sequence analyses have resulted in the grouping of Adenocarpus species into four different clades, so that the results of the flavonoid survey could be compared with that of molecular studies. A good correlation was found in that each of the clades could also be characterised by a combination of flavonoids. For example, the species in clade 4, which are distributed in South and South-East Europe and tropical Africa, are characterised by the presence of flavonol O -glycosides and 5-hydroxyisoflavone O -glycosides. In contrast, flavonol O -glycosides were absent from all but one species of the other three clades, which have a mainly North Africa distribution, and these species produce flavone mono- C -glycosides and/or flavone 7- O -glycosides instead. In addition flavone 4′- O -glycosides were only found in species of clade 1 and flavanones were mainly restricted to clade 3. The relationships among species of Adenocarpus suggested by flavonoid profiles and DNA sequence analyses provide a framework that can be used as a basis for a new classification of the genus.