Diterpenoids and Sesquiterpene Lactones from Helianthus tuberosus

Helianthus tuberosus L. (Asteraceae), commonly known as Jerusalem artichoke, is a sunflower species that may be found in the Ohio and Mississippi River valleys in the United States. The plant has been cultivated worldwide in temperate areas for acquiring its tubers, which are a rich source of carbohydrates and have been utilized not only as foods but also as raw materials in the bioethanol industry. H. tuberosus has also been reported as a folk medicine for the treatment of diabetes and rheumatism [1,2]. Up to the present, phytochemical studies on the plant are comparatively limited [3,4]. In the present cytotoxicity-guided study using the MCF-7 human breast cancer cell line to monitor fractionation, six known compounds have been isolated from an active fraction of the chloroform-soluble partition prepared from the aerial part of H. tuberosus collected in Ohio. These compounds include three ent-kaurane diterpenes, a norlabdane diterpene, and two germacrolide-type sesquiterpene lactones. In addition to the MCF-7 cytotoxicity assay, a soybean defense bioassay has also been employed to evaluate the isolates. This is the first time that diterpenes have been isolated and identified from H. tuberosus. Acknowledgements: Funding by the Consortium for Plant Biotechnology Research, Inc./Ohio Plant Biotechnology Symposium is gratefully acknowledged. References: [1] James, A.D. (1983) Handbook of Energy Crops. Further information available at http://www.hort.purdue.edu/newcrop/duke_energy/Helianthus_tuberosus.html [2] Ohio Agricultural Research and Development Center. Further information available at http://www.oardc.ohio-state.edu/weedguide/singlerecordframe2.asp?id=870 [3] Pearce J, et al. (1986) Phytochemistry 25: 159–165 [4] Matsuura H, et al. (1993) Biosci. Biotechnol. Biochem. 1, 57: 1492–1498