Lactucin n. : A white, crystalline substance, having a bitter taste and a neutral reaction, and forming one of the essential ingredients of lactucarium.

Example:


Taxonomy
Lactucin, free encyclopedia, crystalline solid, search, 3aR, 4R, Hydroxy, hydroxymethyl, methyl, methylene, 4,5, 9a, 9b, tetrahydro, azuleno, 4-d, furan, 2,7.

Defination from the web:
Lactucin is a bitter substance that forms a white crystalline solid and belongs to the group of sesquiterpene lactones. ... Analgesic and sedative activities of lactucin and some lactucin-like guaianolides in mice". J Ethnopharmacol 107 (2): 254–8. doi:10.1016/j.jep.2006.03.003. PMID 16621374. ...