Khellin is a furanochrome in which the basic tricyclic skeleton is substituted at positions 4 and 9 with methoxy groups and at position 7 with a methyl group. A major constituent of the plant Ammi visnaga it is a herbal folk medicine used for various illnesses, its main effect being as a vasodilator. It has a role as a bronchodilator agent, a cardiovascular drug, a vasodilator agent and an anti-asthmatic agent. It is a furanochromone, an organic heterotricyclic compound and an oxacycle. It is functionally related to a 5H-furo[3,2-g]chromen-5-one.
