Diversity of antioxidant ingredients among Echinacea species

Abstract

Echinacea species are important medicinal plants with significant therapeutic potential and are widely used in the pharmaceutical industry. Different Echinacea species exhibit various chemical compositions and bioactivities. In the present study, the chemical differences, antioxidant ingredients, and diversity mechanisms of Echinacea species were studied. The aerial parts and roots of six different Echinacea species (E. purpurea (L.) Moench; E. pallida (Nutt.) Nutt.; E. angustifolia DC.; E. atrorubens (Nutt.) Nutt.; E. paradoxa (Norton) Britton var. paradoxa; E. sanguinea Nutt.) were collected for investigation. Through non-target metabolomics following targeted quantitative analysis, chicoric acid, caftaric acid, and echinacoside were found to be the main different components of Echinacea species. Coincidentally, these three chemicals were also the dominant antioxidant ingredients of Echinacea extracts, as determined by correlation analysis between chemical contents and in vitro antioxidant activities. Based on the cloning, sequencing, and measurement of the identified chicoric acid biosynthetic genes, the diversity of chicoric acid and caftaric acid among Echinacea species was determined by the precursor content, as well as by the expression levels of key biosynthetic genes. Overall, these results clarified the chemical differences and the possible mechanisms, as well as the bioactive ingredients, in Echinacea species and can guide the selection of Echinacea species for different industrial applications.