The World Botanical Associates Web Page
Prepared by Richard W. Spjut
May 2004

Conyza canadensis
Peninsular Ranges, CA
Spjut & Marin 15384A, May 2003



Pacciaroni A. V. , E. Mongelli, L. Ariza Espinar, A. Romano, G. Ciccia and G. L. Silva.  2000. Bioactive constituents of Conyza albida. Planta Med. 66(8): 720723. The bioactivity-guided fractionation of an active chloroform extract of Conyza albida led to the isolation of three alkenynes, deca-4,6-diyn-2-(Z)-enoic methyl ester (1), deca-4,6-diyn-2-(Z)-enoic ethyl ester (2) and deca-2,4-diene-4-hydroxy-6-yn-1,4-olide (3), and the terpenoid spathulenol (4), as the active toxic metabolites in the Artemia sp. lethality test. When tested in the KB cell cytotoxicity assay, compounds 1-4 demonstrated IC50 values of 52.2, 38.4, 117.9, and 83.8 microM, respectively. All compounds studied were inactive in the DNA methyl green and DNA strand scission assays, while compounds 3 and 4 showed moderate activity as inhibitors of human topoisomerase I. Compound 2 is reported here for the first time.