Poster: Secondary metabolism

Abs # 275: Metabolomics Approach to Analysis of Bioactive Constituents of Echinacea Genotypes

Presenter:	Wu, Lankun , lkwu@iastate.edu
Authors	Wu, Lankun  (A) (C)  Beth, Fatland L (B) (C)  Nikolau, Basil J (B) (C)  Wurtele, Eve Syrkin (A) (C)
Affiliations:	(A): Department of Genetics, Development, and Cell Biology, Iowa State University (B): Department of Biochemistry, Biophysics and Molecular Biology (C): NIH Center for Research on Dietary Botanical Supplements, Iowa State University

Historically, Echinacea was used by Native Americans as an herbal medicine to treat colds, coughs and snake bites. Currently, Echinacea extracts are a popular herbal-remedy used for general enhancement of the immune system. However, the specific compounds responsible for immunostimulatory properties of Echinacea are still unknown and commercial Echinacea products are not standardized. As part of a larger NIH-funded study on the efficacy and mechanism of action of Echinacea, we are investigating the accumulation of potentially bioactive compounds in the context of developmental, environmental and genetic diversity. Our long-term goal is to explore the metabolic network of alkamides (a group of putatively bioactive compounds) in Echinacea. Using HPLC and GC-MS, we have characterized developmental and genetic factors affecting the accumulation of the alkamides. Analysis of five stages of flowers of E. purpurea indicates that two tetraene alkamides predominate: N-isobutyl-(2E,4Z,8Z,10E/Z)-dodecatetraenamide; concentrations are up to 3-fold higher in mature flowers than in flower buds. An analysis of 120 individual plants from 40 accessions from nine Echinacea genotypes indicates that at least six species (E. angustifolia, E. sanguinea, E. simulata, E. tennesseensis, E. atrorubens and E. laevigata) accumulate three 3 diacetylenic isobutylamides (E-N-isobutyl undeca-2-ene-8,10-diynamide, Z-N-isobutyl undeca-2-ene-8,10-diynamide and E-N-isobutyl dodeca-2-ene-8, 10-diynamide). Interestingly, the qualitative distribution of alkamides among different accessions of E. pallida, one of the major medicinally used species, varies greatly. These studies will facilitate our understanding of how potentially bioactive metabolites change during development and across genotypes.