Uses
An important use of psoralen is in PUVA treatment for skin problems such as psoriasis and (to a lesser extent) eczema and vitiligo. This takes advantage of the high UV absorbance of psoralen. The psoralen is applied first to sensitise the skin, then UVA light is applied to clean up the skin problem. Psoralen has also been recommended for treating alopecia. Psoralens are also used in photopheresis, where they are mixed with the extracted leukocytes before UV radiation is applied.
Psoralen is a mutagen, and is used for this purpose in molecular biology research. Psoralen intercalates into the DNA and, on exposure to ultraviolet (UVA) radiation, can form covalent interstrand cross-links (ICL) with thymines preferentially at 5'-TpA sites in the genome, inducing apoptosis. Psoralen plus UVA (PUVA) therapy has shown considerable clinical efficacy. Unfortunately, a side effect of PUVA treatment is a higher risk of skin cancer.
Despite the photocarcinogenic properties of psoralen, It had been used as a tanning activator in sunscreens until 1996. Psoralens are used in tanning accelerators, but users should keep in mind that psoralen increases the skin’s sensitivity to light. Some patients have had severe skin loss after sunbathing with psoralen-containing tanning activators. Patients with lighter skin colour suffer four times as much from the melanoma-generating properties of psoralens than those with darker skin The synthetic amino-psoralen, amotosalen HCl, has been developed for the inactivation of infectious pathogens (bacteria, viruses, protozoa)in platelet and plasma blood components prepared for transfusion support of patients. The technology is currently in routine use in certain European blood centers.
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