Echinacea alkylamide transport kinetics in Caco-2 monolayers. ■ (2E,4E,8Z,10Z)-N-isobutyldodeca-2,4,8,10-tetraenamide mw = 247 (1); □ (2E,4E,8Z)-N-isobutyldodeca-2,4,8-trienamide mw = 249 (2); ● (2E)-N-isobutylundeca-2-ene-8,10-diynamide mw = 231 (3); ○ (2E)-N-(2-methylbutyl)dodeca-2-ene-8,10-diynamide mw = 259 (4). Values are means ± sd for 5 monolayers.