From the hairy roots of Lobelia inflata, two new polyacetylene compounds lobetyolin (9-O-beta-D-glucopyronosyl-2,10-tetradecadien-4,6-diyne-8,14-diol) and lobetyol (2,10-tetradecadien-4,6-diyne-8,9,14-triol) were isolated and their structures established on the basis of chemical and spectroscopic evidence.