Isoflavonoids in the Cannabaceae family

Isoflavones (3-phenyl chromones) are biologically active secondary metabolites found in a limited number of taxa with unclear phylogenetic relationships. They are abundant in the Fabaceae family (about 1000 known structures) and a few others, e.g. Iridaceae and Moraceae.

In recent study, we have tested two representatives of the Cannabaceae family, i.e. Humulus lupulus L. cultivars Orion and Magnum and Cannabis sativa L. cultivars Manitoba poison and Duke foot, for the presence of ten metabolites synthesized at the early steps of the isoflavonoid biosynthetic pathway. Six compounds of interest were aglycones (i.e. daidzein, genistein, formononetin, isoformononetin, biochanin A, prunetin) and four were glycosides (i.e. daidzin, genistin, ononin, sissotrin).

Leaves and hops were lyophilized, pulverized and extracted with a mixture methanol/water. The extracts were analyzed by HPLC-MS-SIM and by specific ELISAs. Both approaches revealed a spectrum of isoflavonoids, aglycones as well as glycosides, in all plants under study. The concentrations of individual compounds ranged from units up to hundreds of micrograms per kg (dry weight). Methoxy isoflavones prevailed to non-methylated ones.

Previously small amounts of isoflavonoids have been found in beer, but their origin in this foodstuff was unclear. Mazur [1] detected daidzein and genistein in several samples of barley. Our data indicate that hops may represent an additional source of isoflavonoids in beer. Moreover, this is the first report on isoflavonoids in the Cannabaceae family.

Acknowledgment: This study was supported by the grant GACR 525/06/0864.

Reference: 1. Mazur, W., Adlercreutz, H. (1998), Pure & Appl. Chem. 70: 1759–1776.