Natural diversity of hydroxycinnamic acid derivatives, flavonoid glycosides, carotenoids and chlorophylls in leaves of six different amaranth species

Amaranth species are globally grown food crops. However, knowledge about the composition of their secondary metabolites is insufficient. Here, selected hydroxycinnamic acid derivatives, flavonoid glycosides, carotenoids and chlorophylls in the leaves of 14 genotypes from six different amaranth species were identified and quantified. For the first time, caffeic acid esters of isocitric and several aldaric acids were isolated and quantified in a leafy food matrix. High concentrations of hydroxycinnamic acid derivatives and chlorophylls, and moderate amounts of flavonoids and carotenoids were detected. A hierarchical clustering method of the metabolic profiles followed by Random Amplification of Polymorphic DNA (RAPD)-PCR fingerprinting was used to group the genotypes. Using this combined approach, three main groups of amaranth species were assigned. The information provided in this study increases the attractiveness of the amaranth genus as a food crop due to its strong diversity of plant secondary metabolites that are associated with numerous health-promoting benefits.