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|Section2= }} Psoralen (also called psoralene) is the parent compound in a family of natural products known as furocoumarins. It is structurally related to coumarin by the addition of a fused furan ring, and may be considered as a derivative of umbelliferone. Psoralen occurs naturally in the seeds of ''Psoralea corylifolia'', as well as in the common fig, celery, parsley, West Indian satinwood and in all citrus fruits. It is widely used in PUVA (Psoralen + UVA) treatment for psoriasis, eczema, vitiligo, and cutaneous T-cell lymphoma. Many furocoumarins are extremely toxic to fish, and some are deposited in streams in Indonesia to catch fish. ==Uses== 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 monoadducts and 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. 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. Despite the photocarcinogenic properties of psoralen, it had been used as a tanning activator in sunscreens until 1996. Psoralens are used in tanning accelerators, although 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.〔 An additional use for optimized psoralens is for the inactivation of pathogens in blood products. 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. Prior to clinical use, amotosalen-treated platelets have been tested and found to be non-carcinogenic when using the established p53 knockout mouse model.〔Ciaravino V, McCullough T, Dayan AD: Pharmacokinetic and toxicology assessment of INTERCEPT (S-59 and UVA treated)platelets. Human Exp Toxicol 2001;20:533–550〕 The technology is currently in routine use in certain European blood centers and has been recently approved in the US.〔 http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm427111.htm〕〔http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm427500.htm〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Psoralen」の詳細全文を読む スポンサード リンク
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