Essential metals and phenolic acids in commercial herbs and spices. Multivariate analysis of correlations among them

Abstract

Abstract The purpose of this study was to show relationships among the levels of essential metals (zinc, iron, sodium, magnesium, calcium and potassium) and phenolic acids (caffeic, chlorogenic, ferulic, gallic, rosmarinic and syringic) in commercial herbs (lemon balm, thyme, rosemary, mint, sage and angelica) and spices (caraway, lovage, hyssop and oregano). In the herbs higher quantities of metals and phenolic compounds were found than in spices. All plants contained high levels of calcium, potassium and rosmarinic acid, but low levels of zinc and gallic acid. By using principal component and hierarchical cluster analyses several clusters were identified grouping samples originating from a plant of a particular botanical species. Multivariate analysis has also shown that the contents of phenolic acids had a stronger impact on the scattering of herbs and spices than the metals levels. Furthermore, statistically significant correlations were found between calcium and ferulic, gallic, rosmarinic and syringic acids as well as between zinc and sodium and caffeic acid. This suggests co-operate between these biologically active constituents in metabolic processes occurring in plants.