The chromones are a class of chemical compounds characterised by the presence of the structure 5:6 benz-1:4-pyrone in their chemical make-up. The first chromone in clinical use, khellin, was extracted from the seeds of the plant Ammi visnaga, and had been used for centuries as a diuretic and as a
8-Methoxypsoralen is a purified extract of the root ammi majus lynn, which was used in a crude form for centuries in the Middle East in the treatment of various skin diseases. In recent years it has been found that the purified extract, when taken internally, increases all skin responses to