Lactucin is a bitter substance that forms a white crystalline solid and belongs to the group of sesquiterpene lactones. It is found in some varieties of lettuce and is an ingredient of lactucarium. It has been shown to have analgesic and sedative properties. It has also shown some antimalarial effects. It is also found in dandelion coffee. Lactucin is a bitter substance that forms a white crystalline solid and belongs to the group of sesquiterpene lactones. It is found in some varieties of lettuce and is an ingredient of lactucarium. It has been shown to have analgesic and sedative properties. It has also shown some antimalarial effects. It is also found in dandelion coffee. It acts as an adenosine receptor agonist.