Variation of polyphenols and betaines in aerial parts of young, field-grown Amaranthus genotypes.
Amaranthus hybridus  and  Amaranthus mantegazzianus  are commonly cultivated and the entire young fresh plants consumed as vegetables in regions of Africa and Asia. A. hybridus and A. mantegazzianus were cultivated at four sites in three climate regions of the world: Santa Rosa, Argentina; Lleida, Spain; and Prague and Olomouc, both in the Czech Republic. The contents of flavonoids (isoquercitrin, rutin, nicotiflorin), hydroxybenzoic acids (protocatechuic acid, 4-hydroxybenzoic acid, vanillic acid), hydroxycinnamic acids (caffeic acid, p-coumaric acid, ferulic acid), hydroxycinnamyl amides (N-trans-feruloyltyramine, N-trans-feruloyl-4-O-methyldopamine), and betaines (glycinebetaine, trigonelline) were determined. The variation in phytochemical content due to species and cultivation site was analyzed utilizing the multivariate statistical methods of principal component analysis (PCA) and graphical model (GM). The Argentinean samples differed from the three other locations due to higher contents of most compounds. The samples from Spain and the Czech Republic differed from each other in the content of the negatively correlated metabolites trigonelline and the flavonoids. The two amaranth species were separated primarily by a higher content of trigonelline and the two hydroxycinnamyl amides in A. mantegazzianus. The GM showed that the quantities of the different analytes within each compound group were intercorrelated except in the case of the betaines. The betaines carried no information on each other that was not given through correlations with other compounds. The hydroxycinnamic acids were a key group of compounds in this analysis as they separated the other groups from each other (i.e., carried information on all of the other groups). This study showed the contents of polyphenols and betaines in the aerial parts of vegetable amaranth to be very dependent on growth conditions, but also revealed that some of the compounds (trigonelline and the two hydroxycinnamyl amides) may be useful as features of a taxonomic classification.
Department of Chemistry, Faculty of Science, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
Stine Krogh
SK
Steffensen
Hans Albert
HA
Pedersen
Rodrigo
R
Labouriau
Anne G
AG
Mortensen
Bente
B
Laursen
Rosa M
RM
de Troiani
Elke J
EJ
Noellemeyer
Dagmar
D
Janovska
Helena
H
Stavelikova
Andreu
A
Taberner
Carsten
C
Christophersen
Inge S
IS
Fomsgaard
D027721:Amaranthus / Q000737:chemistry* / Q000235:genetics / Q000254:growth & development; D001622:Betaine / Q000032:analysis*; D005838:Genotype; D010936:Plant Extracts / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D059808:Polyphenols / Q000032:analysis*; D014675:Vegetables / Q000737:chemistry*
D010936:Plant Extracts; D059808:Polyphenols; D001622:Betaine